[Racal] Re. What have I done?

[Geoff Greer]

Hello Howard,

  My .02 on the manuals.   The words to describe the 6790Gm manuals shouldn't be said in public.  However, The Racal 1792 
is quite similar and what I have seen of the "workshop manual" it is a gem.  I'm told there are at least 3 versions of the 1792, 
Perhaps one of the other members can suggest which would be the best manual for you.

  BTW, I have both Racal and WJ HF radios and they have different personalities.  One or the other sometimes will do better 
on  a given signal.  The Racal seems to have it hands down on audio quality though.

73's 
Geoff Greer



5/29/02 14:04:15, "Thomas A. Adams" <103360.2133@compuserve.com> wrote:

>Hello Howard.
>
>I know what you're saying in that message title.
>
>I've been infected by the Racal bug for only about a month now, but I
>find myself the owner of THREE RA-6790/GMs, plus an RA-6793, and
>I'm currently awaiting the delivery from England of an RA-1772!!!
>
>I fell into a lucky deal on Racals; Gawd help me when I get hooked on
>Watkins - Johnson...
>
>Congratulations are definitely in order; you've graduated from the toys
>and "busy boxes" full of neat bells & whistles that they produce for the 
>ham / SWL market, and found out about the understated technical
>elegance of professional communications receivers.
>
>As far as I know, the green LED display illumination is the last version
>produced. Never heard of a "white" LED; are you referring to the older
>version that uses incandescent bulbs?
>
>As for the receivers themselves... I've already gotten a practical lesson
>in servicing the RA-6790/GM. While these ARE complex rigs, they're 
>not too bad to work on (I got a fault indication of unlocked PLL on the
>2nd conversion osc / BFO). 
>
>The only advice I can offer there is two points...
>
>1- UNDERSTAND TTL IC CIRCUIT THEORY BEFORE YOU DIG IN!!!
>And that means have a decent scope available to watch what's going 
>on...  I'd say 50 MHz or faster, and dual trace is useful. Trigger offset /
>delay is also a handy feature to have.
>
>2- Don't count on the commonly available manual (TM RA6790/GM-3)
>to be much help. The military these days thinks of "servicing" as a game
>of replacing whole subassemblies...  not a viable option for "real world"
>(ie, non-DoD warehouse supplied) users. 
>
>The most useful thing I found there was the schematics. With those,
>plus a bit of common sense and a dose of intuition about how the TTL
>logic is SUPPOSED to function, I got thru the crisis here. 
>
>Did you get the LF frequency extension package in your rig? I did, and
>it's excellent! :o)
>
>73's,
>
>Tom, W9LBB
>Sun Prairie, WI
>
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