From: "James Moritz" <j.r.moritz@herts.ac.uk>
Organization: University of Hertfordshire
To: rsgb_lf_group@blacksheep.org
Date: Mon, 6 Aug 2001 15:56:23 +0000
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Subject: LF: <Tech>RA1792 IF out
Message-ID: <E15Tllv-0004lB-00@gemini.herts.ac.uk>
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Dear Brian, LF group,

My RA1792 also has a 100kHz IF output; it is generated by a 
module that sits in the place intended for the ISB option. I have no 
documentation for this module - but I had a peek inside, and it 
appears to contain a mixer, LC filters, and a PLL conversion 
oscillator locked to the main reference oscillator, which mixes 
down the normal 455kHz output. I suppose it is intended to adapt 
the RA1792 to work with modems intended originally for receivers 
with 100kHz IFs like the RA17. I don't think it does anything special 
to the signal apart from shifting it in frequency. I don't suppose it 
would be a problem to disconnect it and use the original 455kHz 
output instead.

I have not had any problems with the RA1792 jumping from one 
state to another - but I did have a similar problem with some 
Marconi - Adret signal generators, which also appeared to be 
caused by the back-up batteries going flat; the less often they were 
used, the more often they would reset themselves at apparently 
random intervals when they were switched on.

Cheers, Jim Moritz
73 de M0BMU