[Premium-Rx] Racal 1792

[k0dan]

I have a very clean 1792 up for grabs if anyone is interested in it (please contact me directly: k0dan at comcast.net ). It is very clean and perfect electrically. It exhibits NONE of the problems reputed to this model.
73
Dan
K0DAN
  ----- Original Message ----- 
  From: GandalfG8 at aol.com 
  To: chris at radiodx.com ; premium-rx at ml.skirrow.org 
  Sent: Friday, September 26, 2003 03:41
  Subject: Re: [Premium-Rx] Racal 1792


  Hi Chris

  The 1792 is a great receiver but things to watch out for...

  CPU batteries, if not changed, can leak and cause damage to the CPU board. This can range from mild surface corrosion, if caught early, to really severe damage if not.

  The LCD displays deteriorate with time. This can range from a slight bleeding of the smaller characters to a total mess.
  Slight bleeding is usable but, once started, it is lilkely to get worse although slightly bleeding displays can remain usable for quite a long time. New displays are still available but not cheap and getting harder to find. 

  There are two main version of the RX. Early ones do not have backlighting or BITE, later ones do. Later sets will usually sell for quite a bit more.

  Make sure the "correct" filters are fitted. Some sets were supplied from new, in the UK at least, with a set of narrowband filters and just LSB. Sometimes filters get removed or changed later.
  Unlike the 6790 the 1792 does not auto detect the filters, so what the display tells you may not be true. I think this applies to the later sets, with BITE, too but not quite sure on that, 

  The set may, or may not, have an interface card fitted. These plug into the end of the CPU card. If the card isn't fitted it won't affect the operation of the receiver so long as the correct ROMs are fitted. Fitting a card later may need a new set of ROMs. I have heard, but again haven't confirmed for myself, that an RX with a ROM set for the IEEE interface, for example, won't function if the interface is removed.

  The tantalum capacitors, used throughout the RX, are known to be unreliable and can fail at random, usually going short circuit. Some users recommend changing all the tantalum capacitors in the set as a precautionary measure. That's quite a lot of work, and perhaps overkill, but they do give problems and failure of one capacitor can shut down the RX completely if it pulls down the power feeds.
  Don't let this put you off too much. Other sets share this problem, I know of 6790 owners here who've complained of the same thing, and many sets seem to work ok for years without it being an issue.

  If you can get to look at the set, or get hold of some decent photos, the three most important things to check for are that the CPU board is clear of corrosion, and the battery not leaking excessively, that a decent set of filters are fitted, and that the dsiplays are sharp and clear.
  And, of course, that no modules are missing but that should be fairly obvious:-)
  There's no cover over the filters as in the 6790 and, with crystal filters anyway, the marking should be clear on top.
  Mechanical filters are harder to identify. The sets sold here, with narrow passbands only, had all Collins mechanical filters except for one crystal unit in the 100Hz position. The other clue on these is that there's no USB filter fitted.

  It will be obvious from the front panel/display if its backlit and with BITE, or not, and if the three points above are ok, and all seems to be working well, then it should be a nice receiver.

  Unlike the 6790, the 1792 always had the RF preamp fitted. Internal links enable the preamp to be bypassed if required but this is rarely done.
  There are a couple of other options, ISB and a 100KHz IF output that are sometimes fitted, but lack of these don't affect normal operation.

  I think that's about it for now:-)

  Nigel
  G8PZR











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