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Gordon I agree 2m was the default for mobile VHF - 3m is really too long to drive around with and 1m is only going to match well at the high end of the band around 70MHz. The radios are nice - however I have only used mine with resonant antennas so far (1m for 70MHz or 1.5M for 50MHz) however - the AAMTU is for later when I get the SUMB roadworthy and progress to fitting the radios. Andy A partial manual is at: http://armyradio.com/download/product_manuals/VRM-5080.pdf (all credit to Ben at Armyradio for making it available!). The full technical manual with circuits is now available from VMARS. Unlike earlier but similar looking RACAL ATUs which used an analogue voltage to switch between pretuned high, mid and low band matching networks, these ones receive digital frequency data on pin D of the ATU socket to enable "radio silent" tuning so it ought to be close even prior to transmitting. Interestingly the full manual gives details for BCC543 and BCC587B AAMTUs but not BCC563. In both cases it seems to need 5 seconds on high power TX to complete tuning, after which 3 bars should be seen when measuring TX power in test mode. The ATU connector pinout is A CLOCK B SILENT C 24V ATU D FMD (Frequency / Mode Data) E 0V F PTT3 G FE (I think this is a word sync for the serial data) The full manual is a bit too long to retype here but the following is a summary hopefully not so detailed as to raise any "fair usage" complaints. The VRM5080 supports two ATUs the BCC543 and BCC587B. The 543 has a bandpass characteristic and is tuned in two stages - first into an internal dummy load (silent tune) and then into the antenna (similar to the Clansman TUUAM). The 587 is a band switched fixed unit that simply selects the band based on frequency data from the radio (more like the old voltage-operated AMU for the TRA-967 family). BCC543 Silent tune is triggered by the channel change but tuning into the antenna requires pressil operation and enough time to complete the process. When using the BCC543 once the channel is changed the radio powers up the AAMTU, - and operates the "SILENT" control which selects the dummy load - the ATU then uses its PTT line to key the radio which is forced to 10W output regardless of panel settings - once keyed the BCC543 has 22 seconds to tune or give up. On completion of tuning the ATU releases its PTT. It is notable that the manual just doesn't mention frequency data for this AAMTU - it isn't clear whether the radio sends frequency data or the AAMTU uses it in this case. Logically as an SWR-driven tuner it shouldn't need frequency data unless to pre-tune. A subsequent operation of the Pressel by an operator causes the radio to be keyed -initailly on medium power, the ATU to be powered and the antenna selected. Again there is a 22 second window to tune or give up. The ATU uses its PTT line to signal success to the radio - low during tuning changes to high when complete. On success the radio will then switch to the panel selected power level and enable side tone and the "T" in digit 9 of the display. The manual warns that there is no operator indication of tuning failure. Although presence of sidetone and a T in the 9th display character should only occur after completion of the tuning cycle this can occur under high VSWR conditions despite tuning failure. With the BCC587 there is no PTT keying and the ATU is always powered. The band switch is triggered by frequency data sent from the radio when the channel is changed. This does beg the question as to how your BCC563 AAMTU fits in - the photo is clear enough as to what it is but the manual does not describe it I guess it uses one or other of the 543 or 587 interfaces so probably monitoring RF power between the ATU and the radio, when the radio is set to something other than mid power, may give some insight into whether there is a silent tune cycle and whether it is completing successfully. As it is labelled as a AAMTU I think it is more likely to behave like a 543 with separate silent and into-the-antenna tuning cycles. My guess is that the bad SWR is a consequence of having failed to complete the into-the-antenna cycle. I suspect to investigate further you will need to make a breakout box to allow monitoring of the signals between SK1 and the ATU. Iain 73 de G0OZS

Andy I have a manual somewhere - going out now so will find relevant section and get back to you. I believe that changing channel is not enough to complete tuning and you need to also transmit for a few seconds to complete the process. Regards Iain

Martyn I certainly hope we can do it again ! Regards Iain

Steve, Jerry & all It was a pleasure to meet you all this afternoon and put faces and names together Adrian Thanks to you and your family for your hospitality and for letting us meet at your workshops. I think my daughter made several friends (including the ones with four feet!) too ! Iain

Gordon I remember playing with salvaged ones as a boy and taking them apart to see what was inside - but I belong to the time when there were electronic ignition projects in the like of "Practical Electronics" and "Wireless World" so all solid state for me .. Iain

Adrian Looking at google earth/maps is it near Bedfield Garden & property Service which is a predefined location in the IP13 7EH post code? The Sherman hull in google street view is likely confirmation enough Iain

Adrian We will leave here at 1pm - my mapreading and satnav permitting we should be there a bit before 2pm coming via Thorndon and Bedingfield If you need to guess who we are we should be in a green Defender 90 hard top with Union and Saltire flags on the antennas My daughter has tested the biscuits (she only wanted the ones with jam in) I may have some disposable coffee cups if it will save you washing up ? Iain

Chris The DIN circuit labels are decoded at: https://en.wikipedia.org/wiki/DIN_72552 - here are the ones for indicators [TABLE] [TR] [TH=colspan: 2]Turn indicators[/TH] [/TR] [TR] [TD]49[/TD] [TD]flasher unit in[/TD] [/TR] [TR] [TD]49a[/TD] [TD]flasher unit out, indicator switch in[/TD] [/TR] [TR] [TD]49b[/TD] [TD]out 2. flasher circuit[/TD] [/TR] [TR] [TD]49c[/TD] [TD]out 3. flasher circuit[/TD] [/TR] [TR] [TD]C[/TD] [TD]1st flasher indicator light[/TD] [/TR] [TR] [TD]C2[/TD] [TD]2nd flasher indicator light[/TD] [/TR] [TR] [TD]C3[/TD] [TD]3rd flasher indicator light[/TD] [/TR] [TR] [TD]L[/TD] [TD]indicator lights left[/TD] [/TR] [TR] [TD]R[/TD] [TD]indicator lights right[/TD] [/TR] [TR] [TD]L54[/TD] [TD]lights out, left[/TD] [/TR] [TR] [TD]R54[/TD] [TD]lights out, right[/TD] [/TR] [/TABLE] A much more authoritative source is the single-circuit test circuit in the Hella catalogue/databook at: http://www.hella.com/hella-ae/assets/media/HMEA_Relays%20and%20Relay%20Devices.pdf on page 36. Internally the flasher unit has a relay or transistor switch between 49 and 49a (prehistoric Lucas units had a bimetal strip thermostat that heated up due to the bulb current to break the circuit hence the dependence of flash rate on load!). The ground 31 is only for the internal workings of the flasher unit and the bulb current leaves 49A, through the indicator switch to ground via the bulbs. See example internal circuits at http://cdn.instructables.com/FFW/PL59/GU4HW87K/FFWPL59GU4HW87K.MEDIUM.jpg (a 2 terminal unit with only 49 and 49A) and http://mgaguru.com/mgtech/electric/et104.htm (B and L are 49 and 49A, P would be a C terminal in DIN coding) Iain

Howard Richard's suggestion of putting it across L and R (on the indicator bulb side of the switch) is sound, as only one bulb is powered and the resistance of the dashboard bulb is much higher than that of the unused indicator - so the unused indicator just functions as a path to ground and does not get enough power to be illuminated. This approach is perhaps less good for dead indicator detection as it will only detect a failed L bulb by failing to flash when indicating R (or vice-versa); the recommended circuit as per the VW diagram uses the bulb currently active as the path to earth. Regards Iain

Howard One gang of the indicator switch should be between 49a and the left or right bulb - the dashboard light is on the other side of the switch nearest the indicator unit and also connected to 49a; see the 3-terminal version of the circuit at: http://www.netlink.net/mp/volks/htm/signals.htm Also note that some sources suggest connecting the dashboard bulb from the fuse (+ve) to 49a - I think this facilitates dead bulb detection as the path to ground is via the indicator bulb. HTH Iain (who was once an electrical engineer!)

Graham Another mystery solved We will no doubt speak in the new year - Monday and Thursday evenings are probably best, for various reasons Happy New Year and all the best for 2016 Iain

Likewise - I have the biscuits already Adrian My daughter is 8 - she has been to W&P for 4 days without getting herself squashed but I guess I should ask if she is welcome or I should book the baby-sitter on Saturday afternoon ? Regards Iain

Graham It appears from this http://www.ebay.ie/itm/Ex-Military-Land-Rover-Carawagon-Depot-Storage-Unit-FV790842-/131134003226 that it was a mains float charger - so I guess it is 240V - if the bulb measures open circuit to an ohmmeter it is likely a neon. For others interested there are fairly clear photos at http://www.thexmod.com/item_detail.asp?id=20915 Regards Iain

Graham Best wishes for Christmas to you and your family too There is a 5-pin 24V connector used in quite a lot of RACAL kit - I think without one to hand it is based on a 14mm or 16mm diameter shell and was used by RACAL for a lot of non-clansman stuff. It seems odd to have +, - and separate ground for a 24V DC supply though. If the bulb is intact seeing if it glows when powered by a 24V battery out of circuit is probably the safest way to find out - visual inspection as to whether it is a filament bulb or a neon may also be a clue - a neon could only be 240V Regards Iain

Hi Graham I will try & give you a call tomorrow - how late in the evening is too late ? Iain

Signed with the following comment: I doubt that properly deactivated weapons (i.e.. to current UK standards) present a significant risk of reuse and in any case the UK experience of handgun prohibition shows that removal of legal weapons has little impact on use by professional criminals and terrorists who commit pre-mediateted crime. On a separate matter I inherited certain items which would I think remain lawful under the directive from my late father and I believe that the registration requirements are not proportionate if deactivation is done properly. I also believe that the regulations need to allow for transfer of collections from a deceased collector to their heir in a safe and orderly way with provision for compensation to the heirs if the items cannot be transferred. In countries where de-activation standards have changed either previously or as a result of this directive there needs to be a lawful and affordable path for collectors and museums to have certificated deactivated weapons re-deactivated to current standards if necessary to remain lawful holders.

I am not a re-enactor (my presence here has more to do with radio) but my father was a lifelong collector and I kept a few of his most treasured items for sentimental reasons. I think that even if the regulations are framed in terms of items being "placed on the market" allowing existing collections to remain in current hands, there will need to be some kind of provision for those who inherit collections to have them re-deactivated to current standards or surrender them in an orderly way for the compensation that would have been due if the deceased had done so earlier. Iain

Graham I am maxed out tomorrow - I can give you a call Saturday - what time is best ? I know Les (he drove up to Suffolk for a PSU once!) I have only theoretical knowledge of Ptarmigan/Triffid but will be happy to help as much as I can Regards Iain

It does indeed look rather like this one: https://canmore.org.uk/site/114354/unknown-x-craft-aberlady-bay-firth-of-forth

I have to declare a slight interest in weapons effects having been on the fringes of civil defence communications before 1989. Compared with the 28cm or 20cm nuclear shells, the explosive yield of Davy Crockett was quite small - tens of tons according to various online resources. It also seems to have been fused for ground or near ground detonation. So I expect radiation - whether in the form of direct neutron radiation beyond the fireball, neutron irradiated material from the surroundings or unburnt plutonium, would have been a significant and lasting part of the total effect. As the lowest yield member of the W54 family - capable of up to 1KT in other uses - it likely had a relatively large amount of fissile material to compensate for the relatively small size of the explosives used to form a critical mass and lack of a heavy tamper (and therefore poor compression and a small duration of criticality). As such I would have expected it - and any other compact low yield fission device - to be quite dirty. The 17 July 1962 above-ground live test of Davy Crockett which claimed to yield around 20 tonnes was at a range of about 2.7km compared with a fireball of 18 feet (air) or 29 feet (surface), blast minor damage radius (+0.25 atmospheres overpressure) of 500 feet / 160m and a 30 RAD neutron dose radius of 600 feet / 125m based on the graphs and scaling laws published by Glasstone and Dolan in 1977 ( a somewhat incomplete scan is found at http://nnsa.energy.gov/sites/default/files/nnsa/inlinefiles/glasstone%20and%20dolan%201977.pdf and a better version at https://www.fourmilab.ch/etexts/www/effects/ ). As such the launch party should be fairly safe if upwind and the main danger to troops in the open is blast out to around 200 metres and the main danger to troops under cover is immediate neutron flux. Also note that the critical mass is a few KG, but the energy released in a 1KT explosion requires the fission of just over 50 grammes - for 20 tonnes only a few grammes of the critical mass undergo fission and the rest is either dispersed as Plutonium (not environmentally friendly!) or transmuted to other radioactive materials, all with half-lives much shorter than DU - so therefore much more radioactive and widely dispersed than the few pounds of DU in an APFSDS projectile. Iain

Looking at the size of it - a bit over 10 metres? and conning tower amidships the best match would be type XXVIIB "Seehund" - The Seehund vertical fin extends forward fromn the rudder, level with the top of the hull, until it blends with the hull, but this wreck appears to have a separate vertical fin with a space forward where the hull expands to full diameter, so has lost the skin (leaving the more substantial rudder post) or is not a perfect match to the Seehund - a photo of the front end (round and torpedo like in the earlier German mini-submarines Molch and Hecht, pointed in Biber, or a sharp vertical edge in Seehund) would help to confirm or shed further doubt! See: https://en.wikipedia.org/wiki/Seehund which has links to the others at bottom and http://www.uboat.net/types/midget.htm http://speyer.technik-museum.de/de/highlights-im-museum/ausstellungsbereiche/marineausstellung-u-boote/kleinstunterseeboot-seehund.html The numbers made would strongly suggest that anything German of that size likely to be found was a Seehund (200+ made compared with 50 or less Hecht) - and only the Seehund was diesel/electric and able to travel far. The other mass produced boats (Biber and Molch) were smaller and single seat. I don't think it is a Biber (no cutaway sides for torpedos) and the Molch conning tower was far aft where as this one seems to have projecting metal remains amidships. What is odd is that none of these boats had the range to get that far under its own power and only Seehund had 2 crew positions of the mass produced minisubs, so they could only really have been used as a taxi to ferry something inshore from a larger ship or U-Boat. It did have significant external load capacity for 2 torpedos which could have been reused for cargo, I suppose. Iain

OK - let us propose the 2nd January at 2pm at Bedfield with biscuits !

Adrian That sounds like too good an invitation to refuse. I think the Saturdays I can do are the 19th or 26th December and the 2nd of January - the 2nd of January is better for me as I will have child care options. I can bring biscuits and a supply of disposable coffee cups, if it helps ? As to times does 2pm to 4pm seem reasonable having regard to lunch and sunset at this time of year ? Regards Iain

Dear All (or at least all in or near Suffolk) There were a couple of comments on the "Do any forum members live near Felixtowe " thread that the HMVF members in Suffolk ought to get together, so I have started this separate topic to continue that discussion separately from solving Richard's logistics problem. For what it's worth I usually have a babysitter on Monday and Thursday evenings (although the next 3 weeks are a bit more complicated) so those would be my preferred days. I think I would prefer between Xmas and New Year or early in the New Year as I will have a lot to do before Xmas. Please suggest dates that would work if you are interested. Again for babysitter related reasons I'd prefer early evening (say 7pm) to later. Or possibly a Saturday afternoon if other kids will be there to keep each other busy (I dont't know how long my daughter's game? Do folks feel that a pub or a village hall would be better ? Do we want to meet somewhere central in town with food or somewhere out of town with plenty of parking for vehicles ? I suspect it will depend on who is interested and where they live where we look for a venue - I work at Martlesham Heath and live north of Stowmarket so anywhere between Felixstowe and Stowmarket will be "on the way home" for me Regards Iain

Richard Item now retrieved and available for onward delivery in the UK. At least it's already boxed ... Folks I will start a separate topic to suggest a social meet in Suffolk over the holidays as there seems to be some interest ... Regards Iain