[Premium-Rx] VLF version of the RA6790/GM

[Cecil Acuff]

I think there was also a preamp involved as well...

Cecil...
----- Original Message ----- 
From: "Dan Rae" <danrae at verizon.net>
To: <DAVEINBHAM at aol.com>; <premium-rx at ml.skirrow.org>
Sent: Friday, February 24, 2006 12:48 PM
Subject: Re: [Premium-Rx] VLF version of the RA6790/GM


> DAVEINBHAM at aol.com wrote:
> 
>>  
>> Does anyone know what it takes to get a Racal RA6790/GM to actually 
>> tune down to VLF.
>>  
>>  I found and copied a set of the VLF EPROM's so the radio now tunes 
>> down to 0Hz but, unfortunately, it is deaf below about 400 kHz. 
>> Obviously, the VLF version of this excellent radio had a different 
>> mixer, but is there anything else different in the VLF version ?
> 
> 1:  The A2 (first mixer card) is different.  A different mixer box, much 
> larger,  special filtering in the LO injection chain to remove noise 
> near the first IF, and a narrower first roofing filter, 16 kHz.
> 2:  The second mixer card has an even narrower 8 kHz roofing filter.
> 3:  There are some slight changes to the A7 1st LO synth output stage, 
> to give a slightly higher level of output.
> 4:  The firmware, which you have.
> That's about it...  AFAIK
> 73
> Dan
> ac6ao / g3ncr
> 
> 
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