[hpsdr] Tone in 20m/15m after switching to CWL/CWR

Ramakrishnan Muthukrishnan ram at rkrishnan.org
Mon Dec 9 07:45:26 PST 2019

Just a followup after analyzing the ozy schematics, it seem to me that there is a short somewhere with the signal line carrying the "dit" with ground. DB-9's pin 5 is ground, pin 6 is dit, 7 is dah. I feel there is some kind of a short in the path till FPGA input. Poking with a multimeter didn't yield anything obvious. I will keep analyzing..


On Mon, Dec 9, 2019, at 6:18 PM, Ramakrishnan Muthukrishnan wrote:
> Hello:
> I have a good old Atlas based system with Penelope, Mercury and Ozy 
> connected to the boards. At this point, I am just listening with 
> Mercury as I do not yet have my pennylane setup and don't have alex 
> boards. So, the antenna is connected to the RF in of mercury. I can 
> listen to stations just fine (with PowerSDR mRX PS, latest available 
> release from the Github) on SSB on every band.
> Now, if I switch the band to 20m and push the CWL or CWR button, I get 
> a constant tone - like a series of dits (as if I keep the dit paddle 
> on). If I tune around the frequency, the tone follows there too. I do 
> not have anything connected to the DB25 port of the Ozy. I see the LEDs 
> on Penny (at least the leds 2, 3 and 4) dancing while this is 
> happening, so it looks like it is transmitting when I just switched the 
> receiver to 20m CW. Pushing CWL/CWR on 40m or 80m seem fine and I don't 
> hear the tones.
> Has anyone seen this? Or it is that I have setup my systems wrong? I am 
> returning to HPSDR after a very long time, so I may have missed 
> something.. I have latest firmware versions of Mercury and Penelope. I 
> also have PTT explicitly disabled in the "Options" tab under the HPSDR 
> setup. What are the other ways to disable Penny (other than physically 
> pulling it out of the Atlas board)? I am somewhat puzzled why Penny is 
> trying to transmit when I am not transmitting at all. (I don't have a 
> dummy load connected to the output too, so I was a bit alarmed).
> Would appreciate advice.
> 73
> -- 
>   Ramakrishnan VU3RDD


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