andym Posted January 3, 2016 Share Posted January 3, 2016 I recently bought a Racal VRM5080 VHF radio on eBay, which came with an antenna base with built-in 563 AAMTU. When plugged up it makes encouraging TUAAM-like whirring and clunking noises when changing frequency, but with two Clansman antenna sections in it the SWR is appalling. Does anyone know what length whip it's expecting to find? Andy Quote Link to comment Share on other sites More sharing options...
g0ozs Posted January 3, 2016 Share Posted January 3, 2016 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 Quote Link to comment Share on other sites More sharing options...
gordonb Posted January 3, 2016 Share Posted January 3, 2016 Andy, I can't help with your specifc query except to say, as I'm sure you already know, 2m was the default for mobile work. I am though very interested in the radio, I must have seen the same ad as I was sorely tempted, but have too many big green radios already, and that aerial base looked difficult to mount on a Ferret. I'd be interested to hear how you get on with it, by pm maybe? Gordon G7KNS Quote Link to comment Share on other sites More sharing options...
andym Posted January 3, 2016 Author Share Posted January 3, 2016 Thanks both, and for info the fixing centres are identical to Clansman antenna bases. It would bolt straight on except that on my 432 there isn't enough clearance between the bottom of the AAMTU and the hull to clear the connectors so I've had to add a spacer ring. Andy Quote Link to comment Share on other sites More sharing options...
g0ozs Posted January 3, 2016 Share Posted January 3, 2016 (edited) 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 Edited January 3, 2016 by g0ozs Quote Link to comment Share on other sites More sharing options...
andym Posted January 12, 2016 Author Share Posted January 12, 2016 To answer my own question and for future reference, a kind soul has provided the information that the AAMTU is indeed expecting a 2m whip. Andy Quote Link to comment Share on other sites More sharing options...
Diana and Jackie Posted December 29, 2017 Share Posted December 29, 2017 (edited) http://www.amateurtele.com/print.php?artikel=265 Use Google Translate. Racal (Kapsch) VRM 5080 Cheaper than a Clansman 353 - and no final tube (valve) Note does not fit the Clansman series radio mounts. Diana Edited December 29, 2017 by Diana and Jackie Quote Link to comment Share on other sites More sharing options...
g0ozs Posted December 30, 2017 Share Posted December 30, 2017 You can still get the mounts from helmut-singer.de (http://www.helmut-singer.de/stock/1756077493.html) - if the mounting blocks are missing from the radio then Dave G8XUL has published a 3d printer model at https://www.thingiverse.com/thing:2680033 that cost him 29p to manufacture for me ! Iain 73 de G0OZS Quote Link to comment Share on other sites More sharing options...
andym Posted December 30, 2017 Author Share Posted December 30, 2017 Mine came with a set of mounting bars on the top as it had obviously been part of a stacked installation. I made up a 'sandwich' plate to align with a Clansman shock mounting assembly (sorry about the picture quality). Andy Quote Link to comment Share on other sites More sharing options...
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