[Premium-Rx] Racals & Digital Radio Mondiale

[GandalfG8 at aol.com]

Hi Tom
I don't know how the 6790 compares to the 1792 in this respect but I bought a 
100KHz IF board for the latter a while ago with a view to doing something 
very similar.
I was originally looking for a 10KHz IF to play with DSP software but 12KHz 
should also be possible.
The board is very over engineered for what it does and generates a phase 
locked local oscillator based on the frequency standard in the set that is then 
mixed with the standard 455KHz IF.
For my purposes I needed to drop that local oscillator from 555Khz to 465KHz.
The divider chain is built with discrete logic so a bit of track cutting and 
linking should sort out the division ratio. The onboard VCO centre frequency 
will need reducing too but if absolute stability isn't an issue it might be 
possible to just add some padding capacitance.
There's also some output filters that may need to be modified but again that 
shouldn't be too much of a problem.
I haven't tried this as yet, time is always the commodity least available, 
but see no reason why it shouldn't work.
This is worth doing on the 1792 as the boards are available and the mounting 
posts already fitted too.
I don't know if such an add on is available for the 6790 but it should be 
possible to use the 1792 board if you can find one.
I have a file containing schematic and fitting details of the 1792 module if 
you'd like a copy.
regards
Nigel
G8PZR

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.qth.net/pipermail/premium-rx/attachments/20030611/e1f9006c/attachment.htm