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

By Leighton Davies GW3FSP


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 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 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
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.
73 de G0OZS


22 May 2013 21:25 Subject:    RE: [321] Re: Power supplies for the 321 etc
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
+33V or +28V depends on TX/RX – non critical supplies
+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



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 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 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
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
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
73 de G0OZS
10 June 2013 22:45 Subject:    Re: [321] Re: Clansman 321 Kit
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
73 de G0OZS
Sent from my iPhone

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.