A VRC 321 Side Step Modification (Removing the +2Khz Frequency Offset) by Leigton Davies, GW3FSP

Background\Purpose

In military service the clansman HF sets used an offset of +2khz while in USB, CW (W) and CW(N). mode.  In AM the dial frequency is the carrier frequency.

The purpose of this modification is to remove the 2Khz frequency shift when using SSB and the CW ( W ) and CW ( N ) modes.  This has the advantage of the operator being able to see the same frequency on the 321 as QSO partners using an amateur rig.

This article has been revised to correct wire colour errors for the CW mode select diode placement. revised 12th Jan. 2014.

LSB Mod

I am assuming that the LSB modification is the same as I have previously posted, if not you will have to provide a suitable switch to operate this modification.

Going in…

Photo 1

Firstly you remove the set from the case , remove the 4 set screws holding the front panel in place and open up the front panel, looking at the rear of the front panel on the left hand side of the PA module is the Miscellaneous function PCB.

The mode switch wiring is routed to this in order to operate the mode settings.

In photo 1 above you see the DPDT switch I fitted to operate the LSB board, one section of the switch is unused, this section will be used to switch the side step on and off, connect 2 wires to the NORMALLY CLOSED contacts of the switch, feed the wires between the PA module and the front panel and pull the ends through to the side of the Misc function PCB where the loom wires connect to the PCB.

 Function Switch Connections

According to the circuit details in the EMER the function switch connects to the following terminals on the PCB:

  • AM – Pin 16.
  • SSB – pin 19
  • CW (N) and (W) – pin 20.

The CW mode switch positions are linked together at the switch.

However the numbering of these pins is ambiguous, so I removed the PA module and chased the wires from the mode switch to the PCB while noting the wire colour codes which are:

  • AM – White with Red trace.
  • SSB – Red with Black trace.
  • CW modes – Green with Brown trace.

 

Photo 2

Photo 2 – This shows the 2 diodes connected to the SSB and CW mode wire terminals, the negative end of the diodes connected to the PCB. I cut the wires to about ¼ inch from the body of the diodes, one diode to the Red/Black wire the other to the Green/Brown wire,  then twist the unsoldered diode wires together tightly and cut off about ½ inch from the diodes, solder them together.

Photo 3

Photo 3, right, shows the 2 diodes connected ( the black band of the diode to the switch wire ) to one wire from the switch, the other wire from the switch is connected to the White/Red wire for the AM mode.

 

 

 

Photo 4

Photo 4, Left, shows the completed wiring with sleeving pushed over the diodes.

Closing Up

Position the diodes and wiring to make sure they are not trapped when you close the front panel, replace the 4 set screws and tighten. 

 

Testing the Set

Tune to a convenient frequency on AM, monitor your transmission on a separate set switched to AM on the same frequency, you should be spot on frequency, switch both sets to USB. You should not need to adjust tuning on either set to hear your transmission, switch the 321 to CW (W)  and press the pressel, you should hear a 2Khz tone ( this is the 2Khz tone used to generate the CW signal ) switch the 321 to CW(N) and repeat the test, again you should hear the 2Khz tone.( The 321 uses USB for CW modes ). Set the 321 to SSB and switch to LSB ( if fitted ) and LSB on the monitor set,  when transmitting on the 321 you should be about 1Khz off frequency as the LSB mod needs to be 1Khz off frequency, tune the monitor set to resolve the signal.

As a further test, tune the 321 on SSB ( USB ) to a known transmission ( I used Shannon Volmet on 5.505Mhz )  you should hear a clear transmission, now switch to CW ( W )  you should still hear a clear transmission without needing to retune.

Mod done, box up the set and relax!.

Leighton. GW3FSP.

 

Replacing Expired Dial Lamps with LEDs in the VRC 353

A 2 Part Article By Leighton Davies GW3FSP

PART 1 - Replacing the dial lamps in a VRC 353 VHF Transceiver with LEDs

Revised 28th Feb. 2014

After thinking about the chances of finding genuine replacement parts for the dial lamps I decided to modify the VRC 353 with the modern equivalent.  This is a short description of what I did to replace the dial lamps with LED’s.

In this part the repair was carried out on a spare dial unit. In the second part the dial unit removal and replacement is discussed and I take the opportunity to turn off the 150Hz Tone.

LED’s

The LED’s used to replace the dial lamps are standard White 3MM 4v @ 20Ma maximum rating. I got them from CPC P/No – SC11538.

After experimenting with 4 led’s in series I decided on a 2.2k series resistor giving me a current of 6 Ma , this gave more than enough brightness to illuminate the dial unit, ( having now fitted the modified unit I would however suggest a slightly higher resistance, say 2.8k. or even higher )

Lamp Holder

The lamp holder is a plastic fitting secured to the top of the dial unit with 2 screws which also secure the cable ties for the switch loom, there are 2 wires connected to the lamp holder, one is white with a brown trace connected to the left hand terminal ( positive ), the other is yellow with a brown trace ( negative) , the yellow/brown wire is connected to the right hand terminal of the lamp holder.

Top View Dial Unit

Top View Dial Unit

BEFORE you disconnect the wires check the polarity of the supply ! and note which wire going to the lamp holder is positive, then switch off and disconnect the supply !.

Disconnect both wires from the lamp holder, unscrew both screws and lift out the lamp holder, you will find the positive is to the left of the holder, you will need to extend this wire, I used a length of thin red flexible wire., sleeve the joint.

 

 

Lamp holder removed

 

The flat edge of the lamp holder is towards the front of the chassis.

Unsolder and remove all 4 lamps, be carefull the plastic will melt very quickly.

I removed the 2 wires .

The leds I tested with my diode check meter to make sure I connected them correctly, with the led conducting the positive ends go to the resistor end of the lamp holder, I then fitted all 4 leds with the round end of the leds showing about 1/8th inch below the plastic.

I bent the led leads about 1/4 inch from the base of the led at 90 deg, more or less making a ‘ T ‘ shape , I cut the leads about 3/8 th inch from the bend, made a small loop in the ends of the leads and fitted them over the terminal posts, I started from the left hand end of the lamp holder.

Then soldered the left hand connection, fitted the next led, soldered the joining connection, and continued ’till I had all 4 leds soldered but leaving the right hand connection of the last led un-connected with the positive lead sticking straight up, I then cut the lead about 1/4 inch from the base of the led leaving that lead sticking up, I then looped the wires of the 2.2K resistor as close to the resistor as possible, trimmed the leads and fitted the resistor over the led lead and the connector post and soldered the resistor in place.

Side View Lamp Holder

Side View – Lamp Holder

I then connected a 24v supply, positive to the outer end of the resistor, negative to the end led, it worked !. the current was just over 6.5Ma with more than enough brightness to illuminate the scale when fitted to my spare dial unit.

I now replaced the lamp holder, connect the negative to the left hand led post, the extended positive wire to the outer end of the resistor.

Top view of Lamp Holder showing Wiring

Top view of Lamp Holder showing Wiring

 

 

 

 

 

 

 

I have taken 4 photo’s of the dial unit and lamp holder, hopefully they will be good quality, I used my ‘new’ Samsung galaxy 7 gizmo.

Turning off the 150Hz Tone

As an extra little job, while I had the set out of the case I turned the 150Hz tone off, this is done by the 10 turn pot marked ‘T’ on the PCB retainer fitted on the left hand side of the set just below the TX turret assembly, there are 3 pots, the ‘T’ pot controls the 150Hz tone, The ‘D’ pot controls the data level and the ‘A’ pot controls the mic audio to the modulator card.

If the retainer plate is missing, the 3 pots are below the red warning sign, the ‘T’ pot is towards the front of the set, the middle pot is the data ‘D’ and the rearmost pot is the ‘A’ pot for audio.

Now back to replacing the lamp holder in the 353 VHF set….

PART 2

On the terminal strip to the left of the synth module, the lamp holder wires go to tags 18 and 25.  The white with brown trace on tag 18, the yellow with brown trace on tag 25.

The positive supply is on the left of the lamp holder this needs to be extended to the resistor on the right of the lamp holder.  On my set the positive supply goes to tag 18, I measured full supply voltage.

One for the Pot

When I dismantle anything I use plastic tubs ( usually the tops from spray cans ) to keep the bits in, I suggest you do the same.

The Start...

The Start…

To start, the tag strip pcb is held with 3 screws, and one screw to the top pillar from the module to the right of the mode switch, remove the 3 screws and washers, also the 1 screw from the stud, put in a tub.

Tag Strip Removal

Tag Strip Removal

 

 

Remove the two studs from the left of the module and the one screw top right of the module, tub them.

 

 

Knob removed

Remove the mode switch knob ( set it at narrow first ) 3 screws, careful, the coupling will now fall out!  Put these bits in a tub, you now have to remove the round ‘nut’ holding the switch in,

( I used a blunt 3/4 inch wood chisel as a screwdriver) put the ‘nut’ and washer in the knob tub.

Tag Strip and Switch

Tag Strip and Switch

 

To remove the lamp holder the 2 screws holding it to the top of the dial unit must now be removed.  Unfortunately the left hand screw is under the chassis fitting for the tag strip removed earlier.  The 4 screws holding the dial unit must be removed to allow access to this screw, there is a sealing gasket fitted in a machined groove in the dial unit, be careful not to damage it.  Put the 4 screws and washers in a tub.

VERY gently, pull the module up and to the right, it will sit on the top of the chassis, move the tag strip left and then push the mode switch through the hole and to the left.

All 3 Detached

All 3 Detached

You will now have access to the lamp holder, there are several ties holding the loom together, these must be untied/cut and removed.

The dial unit will move just enough to allow removal of the 2 screws, do not lose them in the set! You will need to remove the cable clip on the left of the lamp holder, there may be other ties you may have to remove, GENTLY tease the wires up and over the top of the dial unit switches so you can see the whole of the lamp holder.

Dial Unit Moved

Dial Unit Moved

Slide the lamp holder to the left, you can now unsolder and remove the 2 wires to the lamp supply, remember to extend the positive wire!. the negative can be connected to the left hand led post.

Lamp Holder Ready to Remove

Lamp Holder Ready to Remove

( This is when I went for a coffee break ! )

After replacing the lamp holder and re-soldering the wires – the 2 screws ( with cable straps ) can be refitted.

Tease the wiring to the switches back into position gently! If you want to fit cable ties now is the time, you will need the smallest you can find.

Re-Assembly

Refit the 4 screws holding the dial unit to the front panel, make sure no wires are trapped.

Refit the module removed earlier, one screw and the two studs, short stud at the top.

Refit the mode switch, washer then the nut with the knob retaining ring, the large hole in the ring to the left.  There is a lug on the knob which fits in there, the coupling goes in next, ( try a spot of grease to hold it in place).  The slot in the mode switch needs to be horizontal ( narrow mode ) then fit the knob and tighten the 3 screws.

Next refit the tag strip, 3 screws for the pcb and one for the stud fixing.

The End

The End

(This is when I went for a break, 2 large coffee’s and a lump of fruit cake ! Yummy )

Powered up the set and – it worked!

Working

Working

This whole exercise took me 4 hours, including taking the photos with the Galaxy 7 and making various notes to get the photo’s in the right order, the modification to the lamp holder took about an hour including testing.

Have fun.

Leighton, GW3FSP

 

Curing the RT 321 Sticky Coil Drive Mechanism with a Selector Unit Coil Assembly Replacement

In this article Leighton Davies, GW3FSP discusses the ultimate option for the repair of a sticky coil drive mechanism in the UK\RT 321.

Caution.

USE STATIC PROTECTION !, DO NOT HANDLE THE PCB’S UNLESS YOU ARE USING A CONDUCTIVE MAT AND GROUNDING LEADS, REMEMBER TO EARTH YOURSELF WITH A WRIST STRAP TO THE MAT AND ONE LEAD FROM THE MAT TO THE SELECTOR UNIT PCB EARTH.

Purpose

I decided to carry out this repair in order to re-furbish the Selector Unit due to tuning problems caused by the coil drive mechanism in the set sticking and giving the characteristic continuous un-ready bleeps (often ‘cured’ by a sharp tap with a blunt object in the right place!).

There are several levels of repair and this one can be carried out if my ‘fix’ of lubricating the bearings, gears and coil tuning guides and screw drive does not cure the problem.

Testing the Replacement Unit

Before Stripping

Before Stripping

This can be achieved before replacing the coil pack by applying 12 volts across the motor terminals to drive the slugs in and out of the coils to check operation.  Also VERY lightly oil the sliding guides, the gears, bearings and the screw drive system.

Out with the old….

Dismantled Unit

Dismantled Unit

Removing the Selector unit as before (2 screws top and bottom, unplug the 4 coax leads, unsolder the link wires under the coax leads, and unsolder the tag strip connections to the PSU – (Or remove the PSU and tag strip from the chassis and move them to one side).

 

 

Another View of the Dismantled Unit

Another View of the Dismantled Unit

 

 

 

 

 

 

 

Remove the outer case completely from the internals and removed the small PCB with the relays fixed to the unit.

Connections to the Coil Assembly

Link Wire

Link Wire

Removing Wires.  The coil assembly is connected by very few wires;  2 to the motor ( note the + and – connections), 4 to the coils themselves (note which wire goes where) and 2 wires to the limit switches, one by the motor, the other via a feed-though terminal to the PCB.  When this link wire is removed from the coil pack, fit it to the new coil pack ( see photo).

 

In with the new…

New Coil Pack

New Coil Pack

Refitting.  Refit the coil wires, motor wires, switch wires and the small PCB with the relays, and the main PCB to the Coil Assembly.  GENTLY refit the Ledex Drive and Coil Assembly into the bottom case.  Be careful with the 4 wires to the coils, tweak them gently into position.

 

 

Screw the Coil Assembly and Ledex Unit back into the case.

Coil Pack Installed

Coil Pack Installed

Check all wires you removed have been replaced where they should be and have not come adrift as they are all single core and quite fragile.

Refit the top case and check all screws are tight.

 

 

 

Optional Test Rig

Test Rig

Test Rig

This bit is optional – I made up an extension cable using some flat ribbon cable from an old floppy drive cable from a scrap PC, there are 12 wires from the Selector unit to the tag strip, see photo, I then connected the selector unit to the tag strip using the ribbon, plugged in the 4 coax connectors, I used a mouse mat to insulate the selector unit from the chassis and checked everything.

 

I then powered up the set and checked that the Mhz tuning operated the Ledex and the Coil Assembly from 1.5 to 29.5 Mhz in 1 Mhz steps, it worked ! – end of optional test.

Re-Assembly

Refit the selector unit in the chassis, re-make the 12 way tag strip wires, plug in the 4 coax cables and re-fit the PSU.

Check the 12 wires AGAIN to make sure they are in the correct sequence.

Switch on and test the full Mhz tuning range 1.5 to 29.5 Mhz in 1 Mhz steps (slowly !).

When I carried out this repair I was happy to say everything worked.

General notes:

Hopefully if I need to repeat this with the other set that will be somewhat easier than this set, it took me several days to complete, as I had problems with a dirty Mhz switch which was not sending the correct signals to the Ledex De-coder to tune correctly.  This took a day to sort out by itself.

Leighton.  GW3FSP

An implementation of The Lower Sideband Modification to the UK\RT 321

By Leighton Davies – GW3FSP – July 2013

The mod kits for this job were obtained from Oliver Tillet G3TPJ, they are a small double sided PCB with pins for connection to the 321 set wiring, included is an instruction sheet with diagrams of the various works which are required and wiring instructions, these were read very carefully referring to the internals of the 321 in order to make very sure I would know exactly where and what I needed to do.

321 LSB Mod PCB

Switch Mod

The first problem anybody faces when doing this mod is how to provide an LSB switch. I decided to use the Elapsed Time Indicator (ETI) socket which has long been a dormant feature of the 321.

To achieve this I ran in the extra wiring required, the 2 red supply wires from where I was going to put my switch in place of the fuse holder originally for the elapsed time capsule which I removed after snipping the wires and insulating them, you may also have 2 small capacitors to remove, one across the ‘fuse holder’ one from the fuse holder to ground.

070713_0820_Animplement3.jpg

Lower Socket in location…

Wiring up

I then fed the red supply wire to the PCB location using the loom as a guide feeding the wire through the lacing cord leaving about 6 ” or so spare at the PCB end.

Complete PCB Showing Wiring

I then removed the wire from tag 14 of the tag strip, soldered on a length of white wire and sleeved the join, an extra white wire then from tag 14 to the PCB location again leaving an extra 6″ or so.

Siting the PCB

The lacing needs to be cut from the loom where the PCB is going to be fitted , I marked the coax from SK1 where I was going to cut it where the cable clip is.

 

Bracket and Clip…

…removed and ready to take PCB

Making Space

I then removed the cable clip and bracket, 1 screw for the cable clip and one for the bracket from the side of the chassis, and the nut and washers holding the bracket to the main chassis, once the bracket was removed I decided to put 1 washer and the nut back onto the screw and tighten down, I then snapped off the rest of the screw with pliers, I decided I did not want the rest of the screw moving about if I just snapped it off where it was.

I then removed the coax cable from SK1 to the next module from the set, cut the coax where I marked it , trimmed the sleeve back and connected the inner and outer to the required pins on the PCB.

Connected the 2 white wires to the required pins and then a red wire I had used for the 24v supply to the pin on the PCB, trimming the length of these wires to leave about 2″ of slack, I did not connect the ground wire as the coax outer braid does that and I’m suspicious of earth loops. I then checked all the wiring I’d done to make sure I had the correct wire going to the correct pin on the PCB and trimmed the pins back as far as I could.

Fitting the Board

I then used a small component bag opened out to completely wrap the PCB, this was then taped in place with ordinary insulating tape, I fed the PCB under the loom, secured it in place with a cable tie, re-fitted the coaxial cable and also fitted several ties to secure the loom where I’d removed the lacing cord.

 

That Switch…

Lower socket out...

Lower socket out…

On the original modification I fitted the switch straight into the hole using a thin washer inside the panel and another washer on the outside as the hole is about 1/8″ larger then the switch barrel, however I then tried the following method on the second set as an experiment and as it worked I then re-worked the first set to copy this switch fitting method.

I then placed the set so I could get at the back of the front panel with the panel flat on the bench, moving the wires gently out of the way I then stuck a small square of masking tape over the hole (about 1″ sq )

And pushed it firmly into place making sure the tape was flat and not pushed into the hole, I used a wad of tissue paper folded over repeatedly and pushed that on top of the masking tape, with the front panel closed this will push against the tape stopping the tape falling away from the panel.

Closing the front panel I then put the set on it’s end with the front panel uppermost.

I then mixed the Araldite I was going to use to fill the hole, I used just a bit more hardener than adhesive, mixed it well and poured it gently into the hole filling the hole very slightly proud of the panel.

Then left it to set over-night.

The base for the switch ready…

And believe it or not it had! (does what it says on the tin(ed)).  I opened up the front panel and removed the tissue paper and masking tape from inside the panel, grabbing my battery powered BnQ drill and put a small pilot hole through the centre of the filled hole first ( 3mm drill) VERY GENTLY !, then a 6mm, then 8mm finally the 12 mm.

The switch I decided to use was from Maplin Electronics and is a sealed IP67 spec switch, ( N25KA ) and I also fitted a switch cover ( YL01) which is a water/dust proof cover, done up tightly.

l Switch front

LSB Toggle Switch

 Final Wiring

The red supply wire to the PCB was then connected as was the feed to the switch, I took the supply from the tag strip sticking out of the metal screening can over the rear of the 2 audio sockets on the front panel, One tag strip has the 2 audio screened leads, the other has the PTT and audio out wiring, the 3rd connection from the bottom of the panel (the hinged end ) has 24 volts on it ( check to make sure ! ) the other red lead feeding the switch was attached there.

Running Up

I then closed and secured the front panel with one of the top bolts.  Connected power, headset, Turf unit and dummy load and switched on (fingers crossed), no bang !.  I dialled up on 20 metres – I think I used 14.202 Mhz , and tuned up, set to low power then set my 847 to 14.200 and tried USB to and from the 847, yes it worked, switched to LSB on both and dialled up 14.198 on the 321 and it worked.

Later that evening I tested this set with a neighbour Amateur and all worked ok on AM, USB and LSB.

The modification was then repeated on the other set with the same procedure and all ok.

Notes:

The photo’s were captured using an old web-cam which has proved far more usable to produce small but quite good quality pictures, these I have up-loaded to the 321 Yahoo Group site for your perusal.

(Editors note: I hear the iphone has become almost the defacto standard for photographers due to its image quality and portability.  These shots are not too bad and convey the meaning.)

Have fun guys!

 

Technical Diary – Servicing and Commissioning 2 New Second User 321’s

By Leighton Davies GW3FSP

Introduction

Leighton picked up two very reasonable VRC321′s and the Test Kit condition.  What follows is his diary leading up to commisioning the sets.  At the price he paid a working set would have been a miracle and both had minor faults.  The most common fault being the sticky Ledex which up until now outside of GCHQ the servicing of this has only ever been described as a violent tap on the case at the appropriate time.  Leighton demonstrated a more practical approach to bringing such a radio into service in an enjoyable series of posts on the 321 Yahoo Group.  The edited version follows with thanks to the contributions of Iain, G0OZS, Jim and others who contributed.  The posts are reproduced here by kind permission.

Stu – G4IYK

Selector+3

Selector Unit Side View – Coil Tuning Unit

 

20 May 2013 16:16 Subject: [321] 321 Group New member
Hi guys, thought I would introduce myself.
Been licensed since 1976, mostly on vhf/uhf, since getting my late father’s
call I’ve been a bit more active on the hf bands, started to collect
military sets last year when I bought two old WS 62′s and have been
re-furbing them, and , an old R 209Mk2 receiver.
My military experience in REME was limited to the WW2 kit up to the
introduction of the ‘A’ , ‘B’ and ‘C’ series sets, ie, the 18, 19, 62 sets
etc, with very little experience of the ‘new’ kit coming in then.  Just bought two UK/RT 321 sets and the ‘Conditioning Kits’ for them.Slowly getting the kit needed together to run up these two 321′s, so far I’ve got the TURF unit, headset with presell and the ‘C’ connectors and made up a set of various patch leads. All I’m waiting for now is the power lead, not having met these sets before any advice on starting up these sets would be very useful, I as yet have no manuals or ‘crib sheets’ on these sets, they were somewhat dusty when they were delivered having been stored by the previous owner who had not run them up having no time to get the bits for them.I have also joined the Clansmanuser.org site and submitted a post, still waiting for a reply there.Any help greatly received. Leighton. GW3FSP.
22 May 2013 00:51
Subject:    [321] Power supplies for the 321 etc
I’ve been trolling through the earlier posts on this group, and there are a few posts regarding what psu’s to use.
I have here a Collins 618T ( ex Concorde ) hf transceiver which did have a 3phase 400hz 115volt psu for the 1500v ht for the PA.I fitted the 28v dc inverter supply as obviously no 3 phase supply available, to run the set I use a 28volt aircraft battery floated with a 28v 42 amp switch mode power supply. The inverter psu takes 32 amps at full power ( 400 watts from the transmitter ) this will be the supply I will be using from home, the switch mode supply is adjustable from 20 to 30 volts so if needed I can reduce the supply to 24 volts, it depends on what the EMER’s state is the prefered supply voltege, unless somebody here can tell me ?.Also, I use on hf a Yeasu FL2100z Linear, at the moment I normally use it with either the Kenwood 530s or Yeasu 847 transceivers, I will be checking what input this needs for a decent output from say 100 up to 300 watts and then see what attenuator I need to make up for the 321.
Leighton. GW3FSP.
22 May 2013, at 15:45 Iain Moffat <iain@…> wrote:
>
> Leighton
>
> The Clansman 50A PSU used with the 321/322 set was 28v out – in truth the inverter in the 321 was happy with anything 22 to 32 volts – when running on batteries weirdness began at 22v or below (not that I should ever have let that happen!)
Hi Iain, you mention an inverter inside the ’321, I thought these sets were all solid state including the P/A ?.
Do these have a valve P/A ?
> Leighton. GW3FSP.
22 May 2013 20:33
Subject: Re: [321] Re: Power supplies for the 321 etc
Leighton
I may be slightly incorrect but I tend to call any DC-AC-DC PSU an inverter!
The 321 is all solid state unless you count the LEDEX preselector as electro mechanical. But the PSU is an isolated switch mode unit so essentially an inverter with 20-32v in and various stabilised voltages out – without the EMER I can’t remember them all but certainly 3, 5, 6 and 12v – I think the PA runs from something higher. The separate 250W PA for the 321 is based on valves with a transistor HT PSU.
The 353 VHF set really is hybrid and has valve PA and front end with 800v HT, and motorised turret and coarse tuning. The RT320 HF manpack although all solid state needs 110v for varicaps which comes from a non isolated switch mode PSU.
Regards
Iain
73 de G0OZS

 

22 May 2013 21:25 Subject:    RE: [321] Re: Power supplies for the 321 etc
Leighton
Now back at my desk I checked the EMER H592 pt 1 page 80 para 225 and block diagram following. The 321 PSU is fully isolated (so the + and – inputs are independent of ground and the set can be safely used in positive earth vehicles). The input is regulated to 15-17V and chopped to drive the transformer. There is a feedback loop to maintain a constant output from the chopper stage although the output is increased in high power TX mode. The chopper & transformer is actually described as an inverter in some paragraphs of the EMER and the block diagram. The transformer output at 28V (RX or low power TX) or 33V (in high power TX) is rectified and regulated in independent supplies giving
+5V
+3V
-6V
+33V or +28V depends on TX/RX – non critical supplies
+12V
+30V or +25V depends on TX/RX – PA supply
Most outputs are series regulated but the main +12V is switch mode for efficiency reasons
The chopper is synchronised to a synthesiser output at around 25KHz but will free run at 23KHz if synchronisation fails (useful for diagnostics ?)
The mean ALC uses the PSU to measure the PA current and sends an ALC control voltage to reduce PA gain as the current reaches 3A. The PSU will trip under the following circumstances
1. Short circuit of any output
2. PA current exceeds 3A despite the best efforts of the ALC

3. Output voltage high due to regulator failure

4. DC input below 20V or above 40V

Regards

Iain

73 de G0OZS

 

24 May 2013 12:11 Subject:    [321] UK/RT 321
Yea !, the power lead has arrived !.
I have a little shopping to do shortly then I’ll be taking a good hard look at both these sets before I decide to power them up one at a time and see if I’ve got 2 good sets.
Leighton. GW3FSP.
24 May 2013 18:12 Subject:    [321] UK/RT 321 sets
I appear to have 2 working sets !, both receive and transmit on AM, CW and SSB, the tuner works ok but I notice the Match control makes a definate ‘scratchy’ noise when turning it but it tunes ok thats the main thing.
Also when hitting TX on ssb there’s a burst of noise on my FT847 before speech clears and is of quite good quality considering I’m using a very second hand headset assy, One set I’m testing on AM outputs about 5 watts on low power and 25 watts on high power, I though AM was limited to 7.5 watts ?.
I wish my VMARS membership would come through, I really need to get hold of some documentation for these sets.
Right, back to play !.
Leighton. GW3FSP
25 May 2013 20:52 Subject:    [321] 321 sets
I spoke too soon !, been testing these two 321′s I have here, one of them on AM low power showed 5 watts, high power showed 25 watts, Then I checked CW low and high, then SSB low and high, the latter sets of figures were correct, left the set on whilst I re-filled my cofee, tried transmitting and I had about 1/2 watt out on CW, low power or high power, I think one of these sets has the P/A problem I’ve heard about where the ALC transistors protecting the P/A devices fail, am I right ?.
The other set performs as per spec, 5 watts low power all 3 modes and only high power on SSB and CW with AM at just over 5 watts.
I will however have to open up the TURF unit, the match control makes a definate scratching noise on the rx when it’s turned, why not known as it’s only supposed to adjust a pair of capacitors and a switch, hmmm.
Leighton. GW3FSP

 

26 May 2013 22:01 Subject:    [321] Clansman 321 Kit
Apparantly I’ve been suffering from finger trouble with these 321′s, found some instructions on tuning them up and set up what I’ve called the ‘good’ set, followed the tuning instructions to the letter and – looks as though I now have full power on AM,SSB and CW, the AM is now hitting just about 30watts on high and 5.5 on low, I’m wondering if it’s my finger trouble which caused the other set to shut down the P/A altogether , I shall see tomorrow when I put that one back on the bench.
20m been quite lively on the 321, listened to some ‘W’s chatting for quite a while no sign of any drift at all.
Leighton. GW3FSP.
27 May 2013 13:50 Subject:    [321] Clansman 321 Kit
Just had my ‘suspect’ 321 on the bench, and it’s definately suffering, the rx is quite deaf, listening on 14.070 to the PSK transmissions on my 530S signals are loud about S 9 + a bit, the 321 is picking them up but the ‘S’ meter is barely registering, also on tune, the meter is immediately all but full scale but I can peak the TURF, when I try low power CW into a 50 ohm dummy load I get 5 watts then power reduces to zero in about 3 seconds, Full power gives the same result, I get about 6 watts, so this one needs a lot of TLC, my VMARS membership should be ok from the end of this month so I can start downloading the manuals ready for the grand opening ceremony !.
I can hear the various motors churning away inside when I change frequency but not knowing what I’m going to be looking for I’m not opening this set untill I get the manuals and spend a few hours reading up on the internal systems.
Any hints of course will be very greatfully received !, Hopefully the fault will be common to the rx and tx systems, it’s on frequency, so I’m going to see what these motor driven systems are before thinking of anything else, One thing I have found is the BF115′s which I believe are fitted to the PA transistors as heat detectors, bought 10 of them, just in case!.
Might be a power supply problem but as far as I know these sets go into ‘bleep’ mode if it detects a psu problem, which I don’t get.
Back to the ’209, it’s time for another delve into it’s innards.
Leighton. GW3FSP.
Selector+4

Selector Unit Top View Showing Coil Drive Motor

29 May 2013 17:39 Subject:    [321] Clansman Kit
Decided to bite the bullet and open up the dud 321, following some info I received I removed the case with little trouble, One job I needed to do was to replace one of the little terminals on the bottom right of the front panel, did this ok no problems.
I then perused the internals, couldn’t find anything visibly wrong, so I then unplugged and replugged all the little coax connectors checking inside the plug and socket with a magnifier, nothing wrong there.
Wiggled all the soldered connections looking for dry joints, nope !.
Plugged in the headset, Turf unit, power and switched on, it worked !.
Tuned up the Turf on CW low power using the tune switch, I had low power CW and AM, also high power CW and AM, also the rx was on par with my 530S on 14.070 listening to PSK signals, and SSB was ok rx and tx.
Coffee time !, got back to the shack the set was bleeping !, then cleared and working ok, about 1/2 to 1 hour later noticed the carrier I was listening to started to rapidly shift up and down then normal, later the rx went quiet and the S meter went down, bleeping again, then cleared and normal, this frequency warble happens ittermittently with the occasional bleeping then everything comes back, Once when I switched the set off for a few minutes then on again the bleeping continued and I heard nothing from the tuning system untill I rapped a module marked No7 Ist and 3rd Local oscillator then the set tuned and burst back into life.
Further delving needed here, I think I’ll re-make all the solder joints on this module’s connections to the chassis. Unless you know better !.
Leighton. GW3FSP.
29 May 2013 22:56 Subject:    [321] Clansman 321
Been delving into the innards of this set, not simple!, however, I’ve re-soldered all the connections to the Local Oscillator module, could not find anything really, so I’ve now had this set tuned to 14.070 for the past 3 hours and it’s sneezed a couple of times but for the last 2 hours hasn’t done so much as a hiccup!.
I’m going to order up some BC107 spares , take the module out, open it up, connect it back up and do my freezer spray fault finding trick, might work (oops it just sneezed again) going to be the only way I think to find why this module is playing up, as it’s out of the case (a damn great big heat sink) I’ve rigged up a little 12v fan blowing on the top heat transfer plate to keep it cool.
If anybody has any other ideas as to the fault I’m all ears !.
Leighton. GW3FSP.
30 May 2013 22:02 Subject:    [321] Clansman 321 Kit
My dud set has now been on 14.070 listening to PSK for about 5 hours, it sneezed 3 times for about 10 seconds each time, I’ve ordered some spare transistors for this set and when they arrive I’ll be busy trying to find out which ones are failing in the Local Osc unit 7.
One question however, when I replaced the line terminal on the front panel I found a little potentiometer on the panel, just alongside the BNC connector, seems to be behind a fitting on the front panel with an allen key screw in it, any idea what the pot is for??.
Leighton. GW3FSP.

31 May 2013 12:59
Subject:    [321] Clansman 321 Kit
Never rains but it pours !, another fault has started giving problems, the selector system is stalling when tuning the set, The Ledex works immediately, but the motorised selector system sometimes stalls and will not tune until I give the area underneath the set where the selector sits a decent whack using a screwdriver held in place and then whacked with pliers, the motor then runs and tuning is completed, I have to say the noise this motor and tuning system is making does not sound happy at all.
Ho hum !, here we go, screwdrivers, pliers, spanners, soldering irons and de-solder station at the ready, ( I’m glad the other set is ok ! ).
Leighton. GW3FSP
Friday, May 31, 2013 7:34 PM Subject: [321] Clansman 321 Kit
Set all back together, I removed the selector unit, opened it up checked around inside, put a tiny amount of lube on the motor, gears, and slider mechanism, put it back together, set still works, and this time when I switched on the selector unit motored away quite happily and a little quieter than it has been, and – I checked the frequency transmitted at 29.999 mhz on AM and found it was out by about +2 Khz, I adjusted the little trimmer through the fitting on the bottom right of the front panel, frequency is now hovering around +/- 10HZ close enough for me !.
Now ‘on soak’ tuned to 14.070 again so I can hear the PSK, waiting for it to either sneeze again or go phut !.
I’ll be posting 4 shots of the selector, I appologise now for the quality of the pictures I’m using a fixed focus Fuji digital camera I’ve had for many years.
Leighton. GW3FSP.
Selector+1

Selector Unit – Underside view

June 01, 2013 11:38 AM Subject: [321] Clansman 321 Kit
Hi Stuart, Thanks for the reply, I checked the frequency on AM mode deliberately, as you pointed out using SSB I have to tune +2Khz to resolve the ssb signal, I had quite a long qso last night with a fellow amateur about a mile away using the set on both ssb and am to make sure all ok, he set 14.160 I set 14.162 and he came through perfectly on ssb without my having to fine tune at all, AM required me to tune down 2khz as the filters in this set are extremely sharp !, after several hours I checked the AM frequency again and it was +10hz at 29.999mhz.
So far after my delve into the selector unit it works far better and the set tunes first time without application of the persuader!, I think the main problems were the lack of lube on the gears and sliders for the coil slugs, it’s still a bit noisey but nothing like what it was, if I can get another module I’ll give that one a good going over then swop them over, the motor is 28vdc so I should be able to rig up a little circuit to drive the motor back and forth to make sure the tuning slugs move easily and hopefully a lot quieter.
Leighton. GW3FSP.
01 June 2013 23:49
Subject:    [321] Clansman 321 Kit
Been using this 321 for most of the day on 20m, since cleaning up the selector unit and giving it a little lube job and some TLC the set now tunes up on whatever frequency I dial up, power is lower on the higher frequencies but at both these sets have a MFG date of 1980 I’m not really surprised, I’ll have do a search on possible equivalents for the drivers and P/A devices and see if they are usable, RX has really picked up now the selector’s working better and matches the 530s using the same antennae, It still gives the occasional sneeze (bleeps) but only for 3 or 4 seconds, still wondering why, the transistors for module 7 have arrived but at the moment I’m going to put the R 209 Mk2 I have back on the bench for a while, and I still have the two 62 sets to finish off. it’s fun being retired, never a moment’s peace!.
Leighton. GW3FSP.
03 June 2013 18:26 Subject:    [321] Clansman 321 Kit
Along with these two 321′s I also picked up 2 of these – Test Kit Condition, NSN – 6625-99-620-3592, As far as I can see from the instruction plate inside these are used to carry out field tests on the 321 to check their operational status, are there any further or more detailed instructions for using these contraptions anywhere?.
They look quite fascinating bits of kit with all sorts of cables and fittings to test various bits of the set and before delving any further and trying to use one of these kits I thought I’d better ask for help and advice from those who know a darn sight more than me !.
The set I’ve ‘repaired’ I’ve now re-cased and is sitting on the floor awaiting use as I’m now working on my R 209 mk2 receiver for a while.
Leighton. GW3FSP.

 

03 June 2013 20:31 Subject:    RE: [321] Clansman 321 Kit
Leighton
The TKC is basically a power attenuator. It has a dummy load power meter for TX testing – the range is set by the radio selector based on expected output Power producing a ‘good’ reading. The path between working radio and RUT for RX testing is basically a 94dB
fixed attenuator plus a switched attenuator with the steps marked on the
large front panel rotary switches. To guard against TX to RX leakage the
input signal is mixed with a 200KHz oscillator and the mixer output is set by the radio selector (coarse) and the Adjust level (fine) controls. It can be used with a QRP rig like an FT817 (use 320 low power settings on HF or 351 settings on VHF) as quite a good signal generator for much less money than a real one capable of SSB ! One of these years I intend to produce calibration info for use with an FT817 and a meter scale overlay for power measurement in watts.RegardsIain
73 de G0OZS
05 June 2013 11:59 Subject:    [321] 321 driver and P/A transistors
Hi guys, has anybody got any up to date info on which alternatives are available for the driver transistors (VX6537A in my sets) and the P/A transistors (PT6748 in my sets) I’ve been snooping around various sites looking for possible replacements and I’m finding dozens but no link to the current devices, even my favourite site (datasheetarchive) has nothing on the 2 devices fitted which is rather strange as they have a very extensive archive on older devices.
There are loads of general purpose hf driver and P/A devices available for hf tranceivers out there but will they work in the 321 series?.
Leighton. GW3FSP.

09 June 2013 00:21 Subject:    [321] Clansman 321 Kit
My ‘repaired’ 321 set appears to be working well, it’s very stable once it’s ‘warmed up’ about 10 seconds after tuning, since I adjusted the frequency it’s still within 10hz, rx is very good and not all that noisy compared to my 530S and FT847, output however is low at the top end of the range but as this set has a MFG date of 1980 I’m not at all surprised, I’ve found several transistors which could be used as P/A replacements but it’s now deciding whether to get some of these alternatives and see what biasing differences exist and then try and fit them and see what happens.
Leighton. GW3FSP.
09 June 2013 07:48 Subject:    Re: [321] Clansman 321 Kit
Leighton
I think all 321s show a significant power variation with frequency – I seem to remember the spec in the EMER is 2-6w low power and 25 to 40w high power – i would normally expect 30w on top band, 40 to 45w on 80 40 and 20 and 25 to 30w on 10 and 15m
Regards
Iain
73 de G0OZS
10 June 2013 22:45 Subject:    Re: [321] Re: Clansman 321 Kit
Leighton
The manufacturer was MEL (Mullard Electronic Laboratories) in Crawley. It was already a Phillips subsidiary and I think has lost it’s separate identity since the 321 was built – I am not sure if it is still part of the Phillips group or even still in business
Regards
Iain
73 de G0OZS
Sent from my iPhone
Selector+2

Selector Unit Side View Showing Ledex Drive

11 June 2013 16:28 Subject:    [321] Clansman 321 Kit
The second 321 has now been given a little TLC on the selector unit, again removed the unit, covers off, removed 2 pcb’s and the panel with the 4 coax connectors, very lightly oiled the bearings, motor and the slug mechanism and screw drive, re-assembled the whole lot and tested the set from 29mhz down to 2mhz and very pleased with the results, tuning is quicker and quieter.
Checked the frequency at 29.9999mhz and it’s -12hz on AM. so I’m not adjusting the set for that size of error, the other, now TLC’d set is still within about +10hz. and so far having been soak tested for quite a few hours didn’t sneeze once, I can only assume the un-ready failures were due to the frequency error I corrected via the little adjuster through the front panel (I hope so!).
So far both these sets have proved fairly easy to open up and get into, I only hope I can keep them up and running without too many problems.
Leighton. GW3FSP.
13 June 2013 16:03
Subject:    [321] 321 Kit
Just sent off a request for several of the EMER’s for the 321 kit, at least I can then find out (more or less) how the internals of these sets work, and learn far more about the various modules and their workings, and find out if what I’ve done with the selector units was correct, too late anyway they’ve both been lightly lubed.
Both sets been run up from 80m to 10m with no further problems with the selector units which now go home and tune quietly and much quicker than they did before my TLC efforts.
For the time being this is all I can do with these sets so my postings will be rather sparse until I go through the manuals when I can download them and start asking more questions.
I hope my various missives have not been too onerous for those with far more in depth knowledge of these 321′s but I find the only way to learn about this new kit is to ask a lot of possibly mundane questions.

(On the contrary – please don’t stop ;) (Ed.))

And now more coffee and back to the 62 sets.

Leighton. GW3FSP.


 

 

 


The Operational Use of Clansman HF Radio during Operation Agila – Southern Rhodesia 1979 to 1980

Pangolin - Emblem of the Commonwealth Monitoring Force (CWW)

Pangolin – Emblem of the Commonwealth Monitoring Force (CWW)

Background and References:

This article was produced following a request for information about three years ago.  It is updated following a recent review with cold war warrior (CWW) whose photography surpasses my own efforts and who has kindly allowed me to illustrate this article with material he produced. Operation Agila was world news. Christopher  Wayne, the BBC war correspondent at the time was on the same plane out as our contingent and reported as we arrived at Salisbury Airport and were kitting up.

Mike Subritsky has given an excellent account of the job at Britains Small Wars. For my part, I was the signals corporal at RHQ 22 Engineer Regiment and prior to joining the regimental contingent I trained them to operate the Clansman HF radio net which was being deployed.  We also used kit and training provided by the School of Infantry at Warminster.

Commonwealth Monitoring Force (CMF)

The monitoring force were about 1200 personnel deployed from many regiments and from commonwealth countries, and the role was actually two fold; to ensure that the Rhodesian Army remained in confined areas  during a short ceasefire, and to enable the politicians to bring thousands of guerilla fighters from three separate armies into assembly places, reducing the  potential for further conflict. This was in order to prevent a massacre as the country was completely infiltrated by the guerilla forces – the war had been going on for fifteen years and the ruling power was exhausted. Mike Subritsky reports very clearly as to what it was like monitoring the assembly places and cold warrior has a pictorial archive which adds much detail.

22 Engineer Regiment Group

22 Engineer Regiment Group comprised a number of two man teams of a senior NCO and a Signaller with the task of liaising with the Rhodesian Army.  The regimental group worked across an area known as Sub JOC Chiredzi – in tactical speak.  Sub JOC Chiredzi was a Joint Operation Centre, covering a sizeable portion of the South and East of the country under the command of a Rhodesian brigadier.  One of a number of operational areas under the command of the Rhodesian Armed Forces under General Walls.

Execution

From arriving at Salisbury, Rhodesia and being kitted out and briefed, we subsequently deployed, Bob (my Sunray) and me from Salisbury Airport to Fort Victoria by RAF Hercules.

Hercules at Salisbury Airport - Courtesy of Cold War Warrior.

RAF Hercules at Salisbury Airport (Note aiming mark) – CWW

After a short stay, we moved from there by RAF Puma Helicopter to a place called Ngundu Halt on 27th December 1979.  On the trip out the helicopter dropped off several teams, one at Chiredzi.  We joined Alpha company of 9th Battalion the Rhodesia Regiment late in the afternoon on the day before the ceasefire. The following morning I set up our communications equipment in the Company command post, alongside their signals set up. This Company HQ consisted of an ops truck and a derelict store house.  Their radio set up comprised the less modern, but still state of the art, Racal Syncal TRA 931 portable HF set.  This maintained the rear link back to their Regimental HQ, and they also used VHF radio for the forward company net.

CMF Command and Control

While we had been deployed at company level, one of the other teams deployed at Chiredzi to monitor the Rhodesian regimental headquarters.  Further up the chain of command, our commanding officer and his entourage were deployed at Rhodesian Army Brigade level.

A typical operations room - courtesy of Cold War Warrior

A typical operations room showing 2xPRC320 Manpacks in operation – CWW

Our radio net was completely made up of brand new UK/RT 320s and we carried the full kit together with an 8 Meter Mast.  (We picked this kit up at Salisbury Airport on the way out so this makes me think the regiment had not yet fully Clansmanised by the time it was deployed on this operation).

The way we were deployed meant we could both hear what was happening on the company and regimental nets of our hosts, and respond with our own traffic when required to act or report.

My Only Need Is To Organise Return (MONITOR)

We gave new meaning to the word Monitor.  Ngundu Halt is a way station on the fort Victoria to Beitbridge Road and a vital supply route at the time, to and from South Africa. Life for the A company, who were still at war when we arrived, changed overnight on the day of the ceasefire 28th December.  The evening we arrived they were dealing with some gunshot injuries that had happened just before and which subsequently led to a casualty evacuation.  The following day the action simply died down and a different routine was adopted.  The company was dug in on a hillside and had been operating patrols in the area.  The routine remained tactical all through the week long ceasefire but relaxed during the day time.  Life comprised dry training which we took part in, card games, letter writing and sports, eventually we became better at all these things; Self Loading Rifle, General Purpose Machine Gun, EOD and volleyball which made for a fun routine, plus we made some really good friends over a Castle or Lion Lager at sundown. Snakes were not a problem in this location, but insects and spiders were, including some pretty vicious ticks, some rather novel ants, lizards and some bird hunting, and floor cleaning, scavenging spiders.  Oh and a troop of Baboon who lived nearby.

Radio Operating

The radio work comprised daily reports about military activity in the area, encounters with the terrorists or guerillas for example.

Reports were transmitted on schedule, on two fixed frequencies – one for day time and one for night time operation.  This work was mostly carried out on SSB and sometimes on CW.

I had with me enough copper wire to construct a dual frequency dipole built using natural supports and the 8 Meter Mast. In the main these skeds seemed to work well on both frequencies and these seemed to have been calculated for NVIS and up to 900KM.

Radio communications didn’t always work or go smoothly.  Some of the time there were problems and it took a while to get through to the operators at regimental level.  This was frustrating.  You could call for five or ten minutes and not get an answer.  We put that down to unreliable frequencies, time of day etc and worked with it.

During one encounter, which occurred immediately post ceasefire it became imperative to resolve this problem by switching onto the higher formation net in order to pass traffic directly.  The incident involved a stick (small band) of four or five “Terrs” (or terrorists), who were still trying to get to an assembly place but found themselves out on a limb when the ceasefire ended before they made it. They had got lost and subsequently found themselves facing up to police and soldiers from our Rhodesian company.  A stand off developed and my Sunray – Bob found himself negotiating between the two parties.

A kilometre away, in the ops truck, I could hear the reports and orders passing up and down their network.  This traffic had become quite excited, and the messages contained orders to end the stand-off by all necessary means, and if necessary this meant by “slotting” them.  As the incident went on, this was becoming more and more insistent, and Bob being in the middle, this was not a good position for him. I think nobody close to the situation wanted this to turn into a shooting match.  Fortunately a particular message ordering the company to clear the way and open fire was not being acted upon immediately. As I was monitoring the situation and trying to keep our HQ informed – communications on our net had dropped out which was causing me a bit of frustration and aggravation.  After I flicked onto the higher formation net, my calls to the CO got the desired response, and subsequent messages were sufficient to gain more time. Tension remained very high for a further ten minutes, and eventually the time came when I had to get a (fictitious) message to Bob which would order him to withdraw to a place of safety without alerting the Terrs to what was going on.

We thought that was it, once Bob was out of the way, the shooting would begin, but just as he withdrew, the Terrs put their guns down and surrendered. They were then lifted out to the nearest assembly place.  After their arms and ammunition were given up it was discovered in their luggage they were carrying enough cannabis to stupefy a heard of elephant.  Maybe that’s why they missed the ceasefire.  This “Dagga” was subsequently disposed of – resulting in at least one NCO losing his stripes.  Not this one, although I did have to justify to my commander going over his head, and to the Rhodesian CO whose orders he thought were being ignored for some strange reason.  He was looking for someone to court martial.  I owned up to intercepting a message which disarmed the situation slightly.

Keeping my hand in

Occasionally when time permitted, I took the opportunity to practice amateur radio using the PRC 320.  I had received my licence just the month before deployment and I legally obtained the callsign G4IYK\M\ZE which was a bit of a mouthful when it came to calling CQ.  I recall this reciprocal licence was quite difficult to obtain so I didn’t mind not being able to operate with a more succinct call.  Calling CQ was a wee bit tiresome and didn’t attract the pile ups quite like the local ZS and ZE callsigns did.  I focussed on making opportunity contacts with “local” stations in South Africa, Rhodesia and Zambia on 20 meters.  I had one very fleeting DX contact into the states.  I very recently confirmed one of these contacts with Brian Austin ZS6BKW – Now G0GSW.

R&R

About half way through the tour we moved back for R&R and A company disbanded, we stopped firstly at Fort Victoria for some regimental duties.  To remind you, this was where we had deployed RHQ together with a Royal Signals Detachment co-located with the Rhodesian Army Brigade Headquarters.

Here I learnt why we lost communications occasionally with our headquarters.  The Signals detachment were running a rear link comprising a VRC 321 located in the same room as our PRC 320 and this had an Adapter Telegraph Radio and a Siemens T100 teleprinter attached to it.  When they opened up, the radio noise drowned out the weak signals coming in from our locations out in the bush. A quick training session with the operator around how to tune the SURF 25 Watt and why he should do it, curtailed this interference.

We decided to go for a maximal tour of the country in our 72 hour down time.  Nobody wanted to spend time in barracks and the country was reasonably free to travel but there remained a threat from mines and  ambush – you just had to take steps – travelling alone was out. So we went to Victoria Falls for a long weekend, hitch hiking on armed convoys – and in return providing part of the armed escort. We put the radio in stores and headed for the road.  In the three days available we fulfilled a date with friends in Bulawayo, went on Safari in Wankie National Park, and watched the sun go down over Victoria Falls.   As there was a lot to see and do we gave sleep a miss, (instead watching the sunrise on the other side of the hotel, the following morning and visited the falls properly.)

Round Two

After this long weekend we went back into the bush and monitored Bravo Company of the same Battalion, this time near Chipinga, location vague, but much more comfortable -  except for the snakes – much more variety here.

Armoured Mine Proof Landrover (CWW) – (Note aiming mark.)

The role changed to supporting the elections.  Now located nearby to Assembly Places Hotel or Golf – See Mike Subritsky’s map To get there, we had an armoured Landrover to deliver so this time instead of the helicopters being used to deploy us, we had a very interesting 250 mile, mostly cross country, drive.

agila_armdlr320cik

PRC 320 Clip in Kit deployed in Mineproof Landrover (CWW)

This Landrover sported a 320 clip in kit.

As we settled into a different routine, this time round we managed to spend time with colleagues in assembly place Golf.  Our friends there were much worse off than we were, tactically – being virtually surrounded at all times by armed comrades.  Everyone was just waiting for the election to take place.  The guys were on permanent alert – they had Claymore mines and barbed wire entanglements surrounding their positions and were pretty well dug in.

There was some threat to their survival because the Rhodesian Army had a contingency plan to attack these assembly places if the circumstances presented themselves.

Some of the reports coming back from the Police and Army were about intimidation of the population in the build up to the elections – the perpetrators were located in assembly areas.  Many weapons were pointed at the Commonwealth forces deployed in the assembly places and the potential was they could easily have been slaughtered or taken hostage had that particular balloon gone up.  (And yet I noted the guys in the assembly places made the same sort of relationships as we had with our comrades, and it wasn’t all “war, war” while the peace lasted.)

We did a few trips from our base in order to get some rations from the APs.  They were quite rich compared to the Rhodesian Army where there were many supply shortages.  B Company had virtually run out of rations by that time so we did a bit of bartering as a means of supporting them and us.  The assembly place had regular supply runs from South Africa.  We encountered a new use for tampons – as sweat bands.  (Well, you know the supplies boys think of everything).

Organised Return

Eventually just as the election results were being announced, we were extracted from a bush airstrip by Hercules to Salisbury and after de-kitting straight back to UK by VC10.  The rest, they say is history and home in time for tea and medals.  The 320, ammunition and bush gear was handed in at Salisbury Airport and that was the last I saw of the 320 for a while.

I always regret not sticking the 320 in the suitcase and lugging it back when I had the opportunity.  It had been a lifeline throughout this job, and I had grown to cherish and respect its power and usefulness.  Having bought one recently it certainly brings back the memories and is a pleasure to operate.  Nowadays I am very much interested in operating these radios in the spirit of a living museum – and sixty meters is a great place to hear nets with one or more operators taking advantage of the Clansman synthesiser to lock on to an absolutely stable frequency, while using NVIS on less than 30 Watts PEP, working both nationally and on DX it is a very effective set indeed.

Cracking the 320 Case and Fixing a Turret Fault by Stewart Gebbie G8YQN

Developing a Fault

This might be interesting for those of you that have a UK/RT 320 that is having issues with the band changing turret switch.  In my Clansman collection I have two 320′s. One modified for LSB, still needing the case restored and the other I have restored, and it looks like a new one.  I take the latter out with its brand new Clansman battery, whip antenna, headset and Bergen. This set up is good for working the higher frequency HF bands and I go for walkies with it.

In early January we had a window of milder weather so I thought I would go out onto the cliffs above the sea near my QTH and make a few contacts.  The radio worked fine for the first 10 minutes but then it gave the high pitched whistle (or  not ready tone) indicating the band selection turret was in the wrong position.  I wiggled the switch and it would spring back into life…for about five seconds and this was subject to putting pressure on it anti- clockwise.  When I got home, and the radio had been sitting at room temperature for half and hour it worked perfectly.  SO – I was either going to have to figure out a repair or it was a summer outdoor radio only!

Going In…

I open the case, finding it best to remove the hex bolts from the back and slide off the back first, then remove the front. The main radio slides out of the front of the casing.

DO NOT GO INTO THE BACK SECTION AS THERE IS A WARNING THAT BERYLLIUM OXIDE IS PRESENT

Fault Finding

Once the case is removed there is a small cover on the top of the band change turret. Remove these six screws. You will now see the mechanism.  Now turn the band switch clockwise and you will see little metal fingers making contact with the turret.  For those of you old enough, this is just like the tuning turrets in the old VHF 405 line TV’s.  Each of the contacts rests in a little black receptacle. Turn the band switch clockwise until it is halfway between two tuning positions and the little metal fingers should all be resting against the black plastic retainer.  In my case two of the fingers were missing.  While in this mid way position use a strong light to check the metal fingers that have gone AWOL. In my case, they were hanging downwards.  Fortunately I always turn the turret clockwise as I knew that was the direction that put the least stress on the contacts.  With these two hanging down and if I had turned the control anti-clockwise I would have snapped them off.

Repair

With two little screw drivers I gently teased the fingers back into their correct positions sitting alongside the others in the black plastic retainer.

I rotated the band switch many times and they worked perfectly every time.  Problem solved.

Reassembly

I then started to re-assemble the radio for test.

Note that when replacing the back part of the radio, there is a tuning capacitor and this has to engage with the turret. This has a little half moon shaped black plastic projection that engages the back of the turret.  Make sure you have this aligned or you will damage this fitting to the point where the capacitor will not be suitably engaged.

The back panel also has two connectors to mate when reassembling so be gentle and make sure they engage otherwise you could bend the pins of the connectors.

Do not forget the gaskets when re-assembling. Then it is the boring task of putting back the zillion hex bolts on the front and back.

Testing

My test was then to stand the radio out as the temperature was a bracing 3C and leave it for an hour.  I then operated the turret and set, and it was back to its old self, working perfectly.

Lessons Learnt

The important lesson I learned from this is that you should always turn the band switch turret clockwise because it puts much less strain on the contacts.  If a contact does come adrift then you minimise the chances of breaking  a contact.  If this happens it is a much more difficult repair.  (A further risk of damage can be avoided by putting the set out of use immediately you experience the symptoms above and investigating the fault – ed.)

Post Mortem

What I believe happened is that I inadvertently turned the band switch anti clockwise and this pulled two of the contacts out.  In spite of their dodgy positions they were “kind of” making contact. The temperature change going outside and the resultant metal contraction or reduced springiness in the lower temperatures was just enough for them to lose contact.

Finally – ALWAYS TURN THE BAND-SWITCH TURRET CLOCKWISE IF YOU WANT TO PROLONG THE SECOND LIFE OF YOUR UK/RT 320.

Cheers

Stewart G8YQN

 

 

Adding an Artillery Command Post to a Military Vehicle Collection – Part 1 – Introduction

By Richard Taylor

Part 1 – New vehicle, new direction

Scorpion On Display at Weymouth

Scorpion On Display at Weymouth

To introduce myself, I live down in Cornwall and have been playing around with ex military vehicles for the past twenty years. During this time I have had a couple of Land Rovers, a Ferret and I currently have a CVR(T) Scorpion. The Scorpion is great fun – there is nothing like driving through a town in an eight ton armoured vehicle to turn heads – but it is not a practical vehicle. Going beyond about twenty miles requires a low loader and the cost that entails, but even twenty miles requires a crew, planning for possible breakdown and a fair bit of stress. Having discussed it with various friends, I formed a plan to acquire another vehicle that would be easier to drive and maintain and which would be hopefully as interesting to the public at rallies as the Scorpion is.

Motivation

I think that the relationship between enthusiasts and their hobbies is interesting, especially when it concerns ex-military equipment, uniforms or vehicles. Looking around various sites on the web you come across any number of motivators to pursue the hobby. Some do it out of respect for those that have served; some do it to relive a part of their life they enjoyed whereas others, such as me, see it as an engineering thing. I admire the functionality of military vehicles – they are built for a purpose and they have to carry out that purpose in harsh environments and under extreme conditions and they must do it without failing. It is here though that the enthusiast begins to diverge from the professional user. If I can give an example – I use Airwaves at work and have to wear a uniform. I have no idea how Airwaves works – to me it is not the set that is important but the traffic that goes across it. The radio is just a tool that I use to achieve the communication I need. It is the same as the uniform. I have to wear it to a standard, but it is just clothing. It wears out, it gets replaced. If I rip it, I get another one. I am sure that the servicemen who crewed the Scorpion in its twenty year service were not as attached to the vehicle itself as I am – it is again a tool, although not one I would care to come up against.

My Choice

So, let me get back on to the quest for another vehicle. Whereas with the Scorpion and the Ferret I chose them for their presence, engineering and to a certain extent the wow factor, this vehicle was going to be chosen on a different basis. I had set parameters – it had to be wheeled, soft skin, modern and big enough for me to go to a rally and get out of the rain. I did not want to go over my licence, which excluded HGVs, and I had to be able to drive it by myself as a default. More importantly, I wanted it to be fairly bland as I firmly believe that the non-descript vehicles are not being preserved to the same extent as the fancy stuff. The bulk of the British Army runs on soft-skin, and yet to go to a rally you would think that everything was either in the Military Police or had a gun on it. I also wanted something that I would be able to put into some sort of context at a rally, when it was not moving. I find that this is perhaps the biggest problem in exhibiting vehicles. When they move they look pretty good, but when they are just parked up they seem to lose their sparkle. I think that there are things that can be done to bring the lustre back such as wearing appropriate clothing, but it is too easy to become a car park.

Direction

I imagine by now that some of you are beginning to see where I am going. I am looking for a soft skin vehicle that has a function which it can carry out at rest and which will give the impression that it is doing exactly what it is designed to do. You guessed it – a radio vehicle!

C3IS

This linked quite nicely into one of my other interests, which is not radio, but command and control. I am fascinated by how commanders through the ages have been able to maintain the control over their forces during a battle to ensure that the outcome is as they desire and have planned for. The planning itself is a subject so vast that you could almost deal with it as a separate issue – how do you make sure that the right thing in the right quantity gets to the right place at the right time? That can be anything from troops, ammunition and weapons through to fuel and food. The key is of course communication. Plans have to be disseminated, and thereafter messages must pass to and fro as the situation develops and changes are implemented. If you add to this the fact that there is an equally large organisation in front of you that is trying its utmost to destroy you and your plan, you can see the scale of the problem.

Plan

My plan therefore is to try to recreate a command centre and to give an indication of the working of that centre during conflict. In this, I hope to show that the vehicle, as well as the radio gear, is an important part, but as I have said before, they are tools to be used in achieving the object. If I succeed in this, then the public will not necessarily be interested in what type of truck, radio or other communications gear I may have, they will see it more as an overall impression of a working unit.

The RB44

Rb44in service

If only it were that easy! Before you can make any decisions, you have to understand not only the C3 structure, the ORBAT, the systems by which C3 is implemented and then look at what is available. Luckily there is a lot out there in terms of information and also the recent move to Bowman has meant that there is Clansman gear out there which is workable and reasonably priced. I have found a vehicle, a 1991 RB44 with a radio shelter attached. It is ex Artillery, and its last role was as a Battlefield Meteorology System vehicle, capturing data relating to weather conditions that affect the accuracy and effectiveness of projectiles in flight. However, the basic vehicle was built to be adaptive and I may take the odd liberty to gloss over the equipment I cannot source and supplement it with stuff I can.

I will keep you posted!
RB44st2012

Adding an Artillery Command Post to a Military Vehicle Collection – Part 2 – Radio Considerations

(And Getting Licensed)

So what has this to do with radio?

Having made the decision to start investigating a command vehicle it seemed to make sense to understand what army radio involves. In this regard I am lucky in that a friend is ex REME and was involved in the maintenance and repair of Clansman and Larkspur sets and still works with the MoD on various radio systems. He therefore understands not only the theory but also the practical side and how the equipment was used in service.

Understanding the Clansman Radio Systems and Modules and Using the Working Sets

Once I started the research I soon realised that the whole field is much more complicated than I thought, and that it would be much more involved than I anticipated. Identifying the Clansman sets was quite easy as apart from a few rare and specialised sets, they divide between VHF and HF and between portable and vehicle mounted. Not only that, it is possible to mount portable sets in vehicles without too much difficulty and because the system is modular, instructions and mountings are readily available. The problem is knowing when to use any particular set or frequency and that required an understanding of basic radio theory. This involved many hours of research and discussions until it began to dawn on me that the project was feasible and that some of the sets would actually be capable of use in the amateur bands provided I obtained the correct licence. The next step was to dip my toe in the water and see what I could get.

Locating and Testing Radio Kit and becoming a SWL

The answer to the problem appeared to me to be to find an HF set that covered the amateur frequencies and to get it working. As I did not have the vehicle, a battery operated portable would be ideal, and this narrowed the search down to the PRC 320. I saw two at auction on a site and bought them. With hindsight I probably paid too much, but you learn by your mistakes and they were complete to the CES apart from batteries which I found on eBay. They received very well using the whip and I enjoyed sitting on the patio of an evening just listening to anything that was out there. I was surprised by the distances involved – I have heard Brazil, the United States and many parts of Europe just using the 320 as a man pack without any additional antenna, but I still had no idea whether it worked as a transmitter.

That was fairly easily solved. I took both sets to the War and Peace show at Beltring and a friend of a friend set them both up on his FFR and managed to transmit and receive successfully using the harness and a 4m antenna. I had hoped to be able to sell one there but that did not work out, so they came back with me. I am now considering adapting one to LSB but this is still in its infancy.

Antenna Theory and Practical Work

The next step was to look at the antenna. My ex REME friend pointed me in the direction of various sites about antenna theory, and using those as well as the PRC 320 user manual, I attached 40 odd metres of Kevlar wire to it and draped that all around the garden. Needless to say it was a complete failure and I could discern no difference between that and the whip. Back to the manual and to eBay and I bought a 5.4 metre fibreglass mast. After a bit of tweaking this was set up in the field with the whip attached to the top and the set connected. The test was to listen to the VMARS transmission on a Saturday morning, which I could not do with just the whip on the set, and the proof of success would be to receive this in an audible fashion.

I was surprised, but it worked. I managed to hear the broadcast pretty well – the net controller was extremely clear but what was more interesting was that I could also hear some of the responses from other users. One that sticks in my mind was a PRC 320 user from Conway who came across very well indeed.

More antenna theory and research was needed as even with a 5.4 metre lift it was clear that the whip had its limitations and I needed to look at other options. Draping wire around the garden or across the field did not seem to be the best way, even if this was an option shown in the user handbook, so it was back to eBay and the net. I managed to find an 8 metre telescopic mast and kit for a reasonable amount and the plan was to repeat the VMARS test but using both masts with an end feed antenna between the two. Looking at the tables in the handbook and on the set itself, and running a couple of checks using calculators on the net, a 40 metre length seemed to be the desired option. I ran this out using the tags on the antenna wire and then put up the 8 metre mast. I was surprised how well thought out this was and how easy it was to do by myself . If anything it was a sight easier than the 5.4 metre mast which kept flopping around and dismantling itself. Anyway – both masts were set up and the antenna connected and tensioned. Radio connected and switched on; a bit of a whistle whilst it tuned and then the reception was as clear as a bell. Again the net controller was perfectly clear but this time I could hear many more of the contributors and there seemed to be less in the way of background hiss than before. All in all it was a success and quite exciting.

Becoming Licensed

That is about as far as I have gone with the set at present. I have booked a course with the local Amateur Radio Club which I hope will result in my foundation licence in six weeks time. My research in the meantime will be to look at how I can achieve as much as possible from the set and power that I am allowed and this again points towards making the most efficient antenna that I can. I have set myself some parameters in this and that is that I have to use the material and kit that would have been available to the Army at the time. It would be too easy to use better, civilian kit but my aim with the whole set up is to be as tactical as possible and to live with the compromises that this entails. I have been advised to look at NVIS as one possibility, I am researching Dipoles, end fed, ladders and G5RV antennae and once the weather improves I will conduct some tests to see what works in what circumstances. I hope that the members of the forum and the local club will be able to help and that my knowledge will expand. Watch this space!