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Date: Mon, 06 Aug 2001 13:13:16 +0000
To: rsgb_lf_group@blacksheep.org
From: "Brian Rogerson" <brian@esoterica.pt>
Subject: Re: LF: RE: <TECH> RA1792
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Thank you to Alan, and to Andy and to Tracey and yes I would be interested in
the IEEE488 interface.  For those of you wondering, I was trying to cascade
the CW filter of my TS850 after the front end of the RA1792.  The intention
was do a narrow search and record as well as recording the full band, the
other
output of the aerial splitter was already occupied.  Q-Fiver with a BC
something
or other I think it was called, first saw it used in the QTH of Ken Alford,
G2DX.

Someone said that the RA1792 is easy to work on, it is, I do not think I have
ever seen another equipment as easy to access.  Yes the computer, module A6
is on the right and has a brand new RS battery.  I removed the module and
cleaned all the sliding contacts at the suggestion of the supplier and also
the pcb pads which sit on the pillars in the casting and since reassembling
there has been no more jumping but it is only five days and much too early
to rejoice.  

When I found nothing coming out of J2 at 455 I thought the BNC must be there
for some reason and persisted and eventually identified DCF39 which confirmed
the 100KHz IF with the 2.2KHz BFO offset I was using.  I managed to "get" the
system working and in fact recorded Larry on Argo but at 30 sec dots because
I hadn't had time to calibrate the frequency.  The recording on SpecLab was
better and it is now on my web site after a bit of a  struggle with HTML.
I hope to have better luck with Argo tonight provided last night's propagation
wasn't a freak product of the CME and M class flares.

With thanks, Brian


At 09:30 06/08/01 +0100, you wrote:
>
>All the RA1792s I have seen (admittedly all of the same vintage,
>manufactured within a couple of years of 1981) use a 455kHz 2nd IF.  But
>since they also only have 10Hz steps there is obviously a later version, so
>it is possible later models could have a 100kHz output.
>
>As for the random parameters junmping...   The Rx uses battery backed up RAM
>for non volatile parameter storage, and the NiCd battery will eventually
>give up, so you could try replacing this - they are cheap enough to just
>try.  On the receivers I have seen, this it is mounted on a PCB  on the
>right hand side of the chassis when you open up the top of the unit.  But I
>suppose that over the years things could have changed and it could be on the
>more difficult to get at front panel PCB.
>
>Andy  G4JNT

73 Brian     CT1DRP     IN51QD     41 09 58N  08 39 11W
http://homepage.esoterica.pt/~brian