g0ozs

Bob I havent been inside an IBMU - if it has commercial PSU modules then they probably will protect themselves from a short circuit as you say - I am more used to the tants failing in the PRC320 where usually the result is several transistors or an unobtainable undocumented voltage regulator IC being destroyed. Widney Aish who made the IBMS certainly used commercial Weir modules in the "10 amp" mains PSU for use with the IBMS so it doesnt surprise me if they did the same in the IBMS - I'd appreciate some internal photos as I sold mine several years ago without looking inside Regards Iain

Bob Reflowing potentially dry joints can do no harm and may find some problems - candidates are usually heavy components that rely on the PCB pins for mechanical support (so more likely transformers and connectors than tantalum capacitors) - the problem with the tantalums is that they can fail short circuit and do additional damage to other components subjected to high voltage or high current as a result. I will look forward to the pictures and updates Iain 73 de G0OZS

Translated Caption: "English Aeroplane, dragged/towed by an armoured car"

Bob Colin is involved with Thorpe Camp museum near Woodhall Spa http://www.thorpecamp.org.uk/index.html, http://thorpecamp.wix.com/visitorscentre#!contact-us/cyha and http://www.dambusters-hamfest.net/ - he doesnt put an e-mail address on line so I probably shouldnt post it here - he should be contactable via Thorpe Camp as he is their webmaster - the radio shack page has a phone number at http://thorpecamp.wix.com/visitorscentre#!radio-shack/c210s Iain PS I agree it looks like the microprocessor is reporting low input incorrectly - maybe a PSU fault inside the IBMU or an a/d converter fault at a guess

Bob If VLO is seen before a battery is placed on the tray it is likely the supply voltage is (or appears to the microprocessor) low - can you measure the supply voltage with a meter ? I dont know how low it can go and still work - when I had one I always ran it off a Clansman 50A mains PSU at 28V and never tried with batteries ? I have just moved house and my workshop is in boxes and distributed across the van, the garage, and three different storage facilities so I'm not really in a position to take on the repair If you are in Lincolnshire it would be worth a word with Colin G4DDI at Thorpe Camp if you ever go there both about the repair and joining VMARS Also note that the IBMU will refuse to charge very flat batteries - although my recollection is that it sees them as short circuit and reports s/c for the relevant tray position - you need a DCCU and slow charger tray to safely get them back to a sufficiently charged state that the IBMU will run a reconditioning cycle on them Regards Iain

Bob It's probably worth checking the fuse with an ohm meter or continuity tester out of circuit - if blown there is a quite considerable chance that a replacement will also blow due to a fault within the IBMU. I think PTS Norfolk (aka GTEN98 on e-Bay) are the most likely source of spare fuses in sufficient quantity to be able to risk some during repair. If it is completely dead and not doing the power on self test then I'd guess either the internal PSU is faulty, something is loose inside, or the microprocessor board is faulty. I think it would be worth a look inside before powering up with a new fuse in case anything is obviously loose and can be reconnected Regards Iain

Bob What seems to be wrong with the IBMU ? I havent ever seen spares for them apart from the battery trays and link cables so you are very likely to end up consuming another one for parts - as a microprocessor controlled piece of kit they are harder to debug and fix than the radios if the issue is non-trivial. Regards Iain

Monty Thanks very much - most interesting indeed (and I have seen or made all of the errors made by the B-team in the WS11 video during my amateur radio field day participation over the last 30 years ! ) Iain

Andy The headset cable does use all 7 see: http://www.g0ozs.org/clansman/audio.shtml But you could probably get away with sharing a wire for the left and right headphone. I'm not sure the Stalwart had a Harness (IB3/CB3 or IB3/CB2) fit which only makes sense in a single radio setup if there is an intercom requirement and I think the one photo I have seen (cant remember where unfortunately) showed a 353 in place of the original Larkspur B47. So it was probably a simple setup with the 353 connected to the ARFAT connected to the TUUAM much as in a minimal FFR landrover setup. If you plan to use a 352 clip-in then the 7-pin cable from the 2nd audio socket goes to the initiate box which in turn goes to the TUUAM. Looking at the EMER Tels L212 (VHF Antennas Technical Handbook - Technical Description) I see the pinouts are 353 to ARFAT (12 pin): Pins not mentioned are not used ! Pin S - +24V Pin H - Tuner Keying Pin P - 0V Pin L - TX Inhibit Pin O - Silent Tune ARFAT or Initiate to TUUAM (7 pin): Pins not mentioned are not used ! Pin B - Silent Tune Pin C - +24V Pin E - Earth Pin F - Key 351/2 to Initiate All 7 pins are connected through from 1SK2 to 1PL1 so a headset can be connected to 1SK2. Pins D and G of the audio sockets are connected internally to the initiate box The ones used internally to the Initiate Box are Pin C (+24V from Radio) Pin E (ground) Pin F (PTT) The output pin B going to TUUAM is grounded to Pin E for silent tuning. Note also that there is 20V DC signalling from the TUUAM to the radio on the coax inner Hope this helps Iain

Jack I checked one of my 353s and the official user manual - the display flashes if the frequency is set to 76.000 or above and the June 1975 user guide gives the tuning range as 30.000 to 75.975 Regards Iain 73 de G0OZS

Jack I will try one of mine at 79MHz and let you know if it locks The min power setting is well under a watt so probably not much extra current than receive Regards Iain

Jack The 353 should operate down to about 20V and my experience with using it from batteries at 24-25V was that the squelch started opening intermittently as the battery got flat before it turned off but there was no whine. There is always a "chuntering" sound from the motor driven coarse tuning but I wouldn't call that a whine either. Do you get sensible readings "in the green" on the various meter switch positions - that will show up any major issues, but not necessarily something that works but is under stress - my guess would be that it is either an internal motor that isnt stopping or an issue with the inverter that generates the HT supplies for the front end and PA valves causing said inverter to squeal (much as some camera flash units do when charging). You will find that switchmode/inverter PSUs draw more current at low input voltage to achieve a given output power so that may be making it more noticeable. Noisy PSUs are usually due to loose transformers or coils acting as buzzers/loudspeakers and may require mechanical rather than electrical repair. If it has a motor failing to stop I would be surprised if the PLL managed to lock - is the frequency readout backlight flashing ? If you have a frequency meter it may be worth checking that the output matches the dial setting within a KHz or so and is stable. Unfortunately I am not aware of any full circuit diagrams for the 353 that have escaped into the Internet so you probably have to get hold of a spare set for parts and start swapping to do any meaningful diagnosis. Unlike anything else in the Clansman range it is a Valve/semiconductor hybrid and has significant high voltage hazards and large moving parts in the form of motorised turret tuners inside so great care is needed if it is powered up outside the case. One other thing you can do is try it on different bands - the motorised turrets switch tuning components for high/low/mid bands so any problem specific to one band should be absent on the others - I think they are roughly 15MHz wide so if you test it at 30, 50 and 70MHz any different behaviour would be interesting ! The 321 draws significantly less current about 8-10 amps on full power CW TX versus 12-14 amps for a 353 at 50W - the RX power consumption is also much higher for the 353 than the 321 at about 4 amps. Have you tried to key the transmitter into a dummy load yet ? That may show up more evidence - if PSU related I'd expect it to get a whole lot louder ! Regards Iain 73 de G0OZS

Dan Yes there was a long wheelbase 3-tonne SUMB - I think they were made towards the end of the SUMB production run as late as 1968-1970 as support vehicles for the AMX-30 tank in quite small numbers - I have never seen one advertised or photographed in the UK though. Whether the towing capacity was any greater I don't know as I understood the braking system to be the same - my initial thought would be that converting from 1500KG onboard plus 1000KG unbraked trailer and 3000KG onboard with no trailer needs very little upgrade to the brakes. Having said that a SUMB in good condition stops violently when the brake pedal is depressed enough to trigger the air ! Regards Iain

Dear Edd and Lynda My sympathies in your loss - I lost my own father in 2013 who was a militaria collector and I know how much is involved. It would probably help if you gave some indication where in the UK you are located I think he and I were both members of the PRC320 yahoo group so I recognise the name Best Regards Iain Moffat

Hi This is the plate from mine - Poids Total En Charge is the GVW I think. You probably need to look at a Berliet to get a similar French vehicle of sufficient capacity (there was a nice Berliet recovery on e-Bay last year but I dont have the space to keep one ...) I had similar plans when I bought my first one as I had a 2.5 tonne trailer at the time so glad to save you the same surprise. They are fun vehicles given a bit of investment in brakes and the fuel system though Iain

Hi The official towing capacity of the SUMB is actually only 2 tonnes for a braked trailer and 1 tonne unbraked according to the handbook MAT2719 "Masse maximum remorquable" which surprised me as it is so much bigger and stronger than a Landrover 101 ! Welcome here and nice to see another SUMB fan online ! If you find one and need any docs let me know. Regards Iain

Welcome here ! Hope to hear you on air some time (although we arent well provided with hill tops round here!) Iain 73 de G0OZS

Lauren Congrats on the new project - I look forward to seeing it in the arena at W&P before too long ! Iain

This looks closely related to the Schneider tank !

Jack I havent done exactly that - if a suitable EMER isnt in the VMARS archive the best chance is usually http://www.greenmachinesurplus.com/land-roverfitting-inst-91-c.asp who seems to have the best collection for sale http://www.greenmachinesurplus.com/clansman-320351-with-scb-into-land-rover-ffrpt8sup-2-662-p.asp is probably what you need as the TUUAM isnt on the dexion (so must be in a wing box) Regards Iain

Best wishes to you all for a successful, happy, healthy & safe year in 2015 Iain

Robin An afterthought on the starting - 40 years ago my dad had a S2 diesel on our farm in Scotland and he always left a small parrafin greenhouse heater under the engine overnight - I don't ever remember it struggling to start. Admittedly I think the lowest temp I can remember was only -12 centigrade so not quite Canadian conditions. It was of course easier because our vehicles lived in a corrugated iron shed so nothing to blow out the heater ! Regards Iain

Hi Robin Thanks for confirming that the choke lamp is the heater - I reckon on a count of 10 maximum. It did start today (I think about -5 centigrade early this morning) but took longer than I expected. I think it needs the alternator belt tension looking at - I could hear it squeaking a bit - but system voltage was approx 13.5v when I had warmed it up. As I understand it (I have some photos in the papers that came with the vehicle) Withams sold it as a soft top - the previous owner said he had fitted the hard top for security as he used to take it into London regularly and I am happy the heat stays in - he didnt say if it was civil or military hard top but I am now convinced it's civil based on further investigation of the dexion fitting challenge - there are holes I need to drill which would be there if it was Military ! From what I can see in terms of drilling etc and the side stalk and wing box that came with it it was "cosmetically converted" to FFR after release but is 100% GS with no evidence of radio at all inside. No idea about the snow vent - it was added after the Withams photos. I don't believe it does any harm so will leave it for now. The lightweight is in the previous keeper's drive - the first four photos were taken the day I went to examine it and the rest when I got it home. @ & M109A3UK We took it for a 60 mile round trip to Cambridge to visit an amateur radio friend today - having had a look at his FFR and realised from your post that it is a civil top, I think I understand the dexion problem now - because I was expecting pre-drilled holes yesterday I couldnt see it but the vertical posts fit at the ends of the bulkhead and I need to replace rivets with bolts there, and drill the "internal gutter" to take the bolts at the top end. Regards Iain

Here are the promised photos

Thanks Mash ! The condition is mostly a credit to the previous owner and Ashchurch depot I think. Now the questions start. (1) I have read elsewhere that the "choke" symbol lamp at lower right on the warning light panel is the glowplug/heater confirmation lamp - is this correct ? (2) Does the "rear heater" lamp at upper right actually do anything in what was originally a soft top 2.5 normally aspirated diesel 90 ? (3) I have obtained a set of dexion to fit a GS 90 hard top and am using the picture at http://git.me/photo/2014/09/26/1991050249079142656/2375650317888242688/Ex-MOD-Land-Rover-Defender-90-Winterised-Wading-200TDi.jpg as a guide - I cant work out how the vertical black support pillars are fixed to the bulkhead - does anyone have a drawing or closer photo to show me. I suspect my kit doesnt include metal brackets for the bottom and top of these pillars and I will need NSNs/Names/Descriptions to help source them. This is the bottom of the pillars And these are apparently where they attach but the photo of the 90 TDi seems to show them mounted further aft so I think there is a metal plate fitted to the top and projecting behind the bulkhead further outboard than the one shown ? If I can at least get a drawing I can always make one if a ready-made source is not available. Thanks in advance Iain