[Premium-Rx] Racal 6778C - Diagnostic/Fault

[Danny Higgins]

Paul,

I'm not familiar with the US RA6778, but if it is based on the UK RA1778 
(which was based on the RA1772) then the problem is probably to do with 
the synthesizer.  The HF Loop board had 3 VCOs to cover the full range, 
and I think the top one switched in when the frequency was > 18.000 
MHz.  Try looking at the RA1772 handbook to see if the boards are similar.

Danny, G3XVR

Paul/Julie wrote:
> Attempting to identify cause/board that is responsible for a "Fault" Display on the front panel, and DS-3 a small red LED to light on the top edge of the third main board from the front of the receiver, and has the board number A08356. I am seeking a manual, to help diagnose the problem, but so far not successful. The other symptom is above 17.999 MHz, the fault light goes on and the audio basically disappears. However, the frequency continues to count up and down as the tuning dial is rotated. Below 18.0  MHz, the receiver performs correctly and all fault lights are off.
> I would appreciate any assistance, that might be available from the group.
>
> Thank you,
> Paul
>   
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