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.


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.


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.


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.


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.



Stewart G8YQN



Glossary of Military Terms

See also Here

AWOL – Self explanatory except when used to state the obvious such as a component breaking loose and disappearing or hiding in a set for example.

FFR – Fitted for Radio – in a vehicle the fittings that are required to mount the radio and its components and provide appropriate power supply etc.

TAC HQ – Tactical Headquarters

Larskpur Radios – a system of radios in service prior to Clansman in 1978

Bowman Radio – a system of secure radios and IT applications superseding the Clansman range of radios.

Secure Radio – an encrypted device for point to point communication via the airwaves which hides intelligible speech or data from potential eves dropping.

Insecure Radio.  A device used for broadcasting intelligible speech or data and which can be received and understood by a human or machine equipped with a common radio receiver without the need for special equipment to decode the voice or data.

Radio Net.  Two or more radio stations working together on a common frequency for the purpose of radio communications.

GSM – a secure protocol for use over mobile telephone and radio systems.

Protocol or communications Protocol.  A system used to send and receive data for example, Packet Radio (AX25 or X25), TCP/IP, GSM usually determining the start and end of a transmission and the number of digits and their specific meaning within the protocols framework.

Low level voice procedure (or VP.)  A system comprising low level voice codes, prowords and callsigns for example which enabled the efficient passage of radio messages on a net.  E.g. “Hello Zero this is Two fetch sunray over”. Meaning hello control station this is 2nd troop (or section) bring your commander to the set over.  Prior to 1980.  Sunray is an appointment title for the commander.  After 1980 this obsolete example would have been replaced by Hello Zero this is Two Zero fetch 0A over.  Explanation:  Voice procedure changed during the Clansman Era following Exercise Lionheart when it was realised everyone knew what the voice codes (MAPCO, Slidex etc), callsigns and appointment titles meant – including the enemy who could eavesdrop on messages and hack the codes very quickly.  The callsign system and appointment titles were a “dead giveaway” as to who was talking to who and even indicated whether the transmitter was infantry, a tank, gun or piece of engineer equipment for example.  Blue forces were defeated by their lack of communication security during Lionheart and this led to a very intensive change programme.  The next generation VP was aimed to improve the situation by providing a better callsign system and voice codes to support radio messages VP was changed and included the new battle code, (BATCO). and was much more effective.  The time taken to encode and decipher slowed everyone down by a factor of three for several years, prompting a popular rising in face to face communication and promoting the dispatch rider or “”Don R” – until some add ons were invented, called secure orders cards, which meant radio messaging was speeded up again..

Ancillary – An item of kit – part of the set – such as an antenna or headset.  

Pineapple.  Clansman Elevated VHF Antenna

Going Tactical – Camouflage nets and all in a concealed location for example.  AKA a day out, picnic or field day or rally.

GS – as in GS Landrover.  General Service.  Not normally fitted for radio.

Civvy.  You lot (as opposed to soldiers).

Bathtub Curve of Failure.  A graph depicting the likelihood of failure against time for the life of equipment.  This model illustrates the two points in the life of any device where failure is most likely, such as the beginning of life when the device is first switched on, or the end of life.

FUG.  AKA Atmosphere – particularly when enclosed, confined and heated and comprising fumes and scents, and special lighting effects and sound effects.  The presence of warm sweaty bodies, loitering within tent to create a tobacco smoke, fart laden dimly lit bordello like scene for example.  The fug is usually created within a command post or vehicle and is essentially a special business environment or workplace comprising a bubble of specially created atmospherics.  The environment is created within a layered cover comprising a camouflage net outer layer, overlaid onto another hessian or tarpaulin layer and finally the tent skin itself.  These wrappers are specially arranged to exclude all light emissions and noise sources and it is within, that radio operators and commanders, sift assemble and route information and intelligence, and pass orders throughout the day and night.  Compare and contrast the atmosphere in the same location at day break, when the wrappers are thrown off in favour of fresh air, bacon and eggs, strip washes and gun cleaning.  Caution. Some combinations of fug can be deadly, for example when carbon monoxide is introduced to the mix.  Less deadly but more exotic mixtures can contain irritants such as CS Gas, various colours of smoke, old spice, Lynx, Brut, petrol fumes and camping gas, toast, parafin, steam, compo cooking etc.  Noise effects include morse code (before it was phased out), jokes, BBC world service, radio fans, voice and data messages, generators purring, human grunting, farting, snoring, banter, chatter and sometimes, the gentle rhythmic chatter of cicadas.

Warry.  or Warlike.  In simulations or combat, the appearance of looking the part.