[UK-CONTEST] Receivers

[Danny Higgins]

Hi Ken.

It is a PIC based controller with a 4 line x 20 character LCD.  It 
continuously polls both receivers and displays the frequencies on the 
LCD.  I can get the TX to follow either RX, plus or minus an offset of 
up to 99.99 kHz for split working, or I can leave it locked on any 
frequency while I tune both receivers.  It can change the TX output in 
1dB steps from 2W to 250W, 100% duty cycle, 24/7 into a 3:1 VSWR, but 
fully protected against open/short circuit loads.  I can select either 
of 2 RX antennas to either RX and select either of 2 TX antennas (when I 
get another co-ax relay).  The controller also selects one of a set of 
13 HF sub-octave filters.  The audio from each receiver is fed to stereo 
headphones and I can have the audio split or mixed, with a balance 
control to set the relative amplitude of each.  There is a built-in 
switchable audio CW filter.  It is all contained in a 2U unit that sits 
in a cabinet with the RA3702 with 25 software controlled illuminated 
pushbutton switches.

It has been designed as a fully functioning SO2R contest/DX station.  
CQWW last weekend was its first real test and I still have a few more 
software tweaks to do before AFS and the HF CC contests.  Future 
enhancements will be a SoftRock SDR on the 1.4 MHz IF and an increase in 
power to 500W.

Danny, G3XVR (ex Racal)

 Ken Eastty wrote:
>> Equipment:  Racal RA3702 dual HF RX, MA3752/TA3762 solid state 250W TX
>> with homebrew SO2R controller
>>
>> Antenna: 40M dipole up 35 feet
>>
>> Danny, G3XVR
>>
>>     
>
> I wouldn't have thought that the RA3702 was ideal for contest working,
> presumably the homebrew controller overcomes the poor ergonomics?
>
> What's this about receivers (with digital IF's?) 'falling over' in the
> presence of large numbers of strong signals? If that's true it's rather
> disappointing.
>
> Ken Eastty
>
> G3LVP
>
>
>
>