[DSP-10] 5khz birdies and noise

[Lee Scott]

I am in the process of eliminating the small noises in the DSP-10.  I have 
at least eliminated any detectable digital noises and am now working on 
other noise sources.

Here's what I now have.

There is a 2kc wide wave of noise approx 3 dB in amplitude every 5khz. This 
noise wave decreases in frequency when you increase the receiver 
frequency.  It is controllable via the RF gain and it appears across the 
144 to 148mhz band much like rolling waves on the ocean. A 50 ohm 
termination is on the antenna input. The first mixer is on top of the board 
with 4 grounding straps.  The second mixer is on the bottom of the board 
and the case is well grounded.

The best way to display this noise on the waterfall is to start at 144mhz 
in cw mode and increase the frequency 100hz every 10 seconds. When you get 
to the top of the 5khz step with the 124mhz lo, the next frequency step 
will place the noise at the high end of the audio spectrum.

Second, I have a very narrow 5db birdie - but it's frequency increases in 
the audio spectrum as you increase the receiver frequency and is 
independent of the RF gain. I suspect it has to do with the software BFO. 
Changing RIT frequency offset will change the frequency of the birdie.

I am running V2.0 of the software.

Anyone have any ideas?? - would it help if I were to solder some shielding 
on the top of the board where the ground straps are?

Lee Scott - AA1YN