[Premium-Rx] Racal IF Converter question

[Thomas Adams]

Greetings!

I've been looking at a project that's been on the back burner for a 
while; setting up a pair of Racal RA-1772
receivers for diversity operation with a Racal MA-168 Diversity 
Combiner Switch.

Currently, I'm doing polarization diversity that's based on 
demodulated audio of RTTY, using the audio switching
built into the Universal M-7000 and M-8000 digital decoder boxes.

I think the MA-168 can do better. It takes IF signals from both 
receivers and bases it's choices on the IF signal
voltage, instead of on the demodulated audio.  The MA-168 then 
demodulates the IF signal and essentially combines
the receiver outputs into a single line level audio channel. That 
would work a lot better for me, because I want to
insert an outboard DSP box in front of the digital decoder boxes.

All well and good, but there's a fly in the ointment...  the MA-168 
takes an IF input frequency of 100 KHz, and the
last IF of the RA-1772 is 1400 KHz.

Apparently somebody else along the line encountered this same 
problem, because Racal produced an external add-on
for the RA-1700 series rigs, the MS-561/2. It appears to take two 
channels of 1400 KHz IF and a 1000 KHz oscillator
input (from the RA-1772's synthesizer) , and spits out two channels 
of 100 KHz IF signal.

Here comes the question...

The MS-561/2 was apparently intended for a purpose other than 
diversity setups; the IF inputs are marked for the main
IF output, and the ISB option output from the receiver. It was 
clearly intended to deal with two outputs from ONE receiver,
not converting the IF frequencies of TWO receivers.

I can't find a schematic or specs of any sort on the MS-561/2, and 
there's no mention of it in the RA-1772 manuals.

Are the two converter channels of the MS-561/2 identical, so that the 
box can be used for diversity setups without any
changes?

Thanks,

Tom, W9LBB

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