Problem with transmitting

General discussion and support for the Peaberry SDR V1.

Problem with transmitting

Postby ha8ap » Wed Aug 28, 2013 9:56 am

Hello everyone!

I came across a problem with a Peaberry SDR v1 radio (80 – 40 M) which is the property of a friend of mine.
It does not transmit in CW mode or rather it transmits a very weak and muddy signal, which I can hear on my control receiver.
Above-mentioned SDR receives without fail.
I use PowerSDR-IQ 1.19.3.15 on Windows Xp Sp3 and my laptop is a HP 6730b with DualCore and 2GB of ram.
I updated the firmware to the latest (2013.01.19) version but it did not solve my problem.
Fortunately I have another Peaberry SDR v1 (my own, which works flawlessly) to which I can compare it.
As it turns out, you can measure a significantly smaller radio frequency signal on the points of U10 IC 17,18,19,20 than on the well-functioning counterpart’s points.
I have tried it on another computer but it did not help.
I attached an audio file. This is what I hear on my control receiver.
Any helpful tip would be greatly appreciated.

73! Toni
Attachments
sample_audio.mp3
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Re: Problem with transmitting

Postby AE9RB » Fri Aug 30, 2013 4:54 am

The first few cycles are strong and clean then it drops in power with distortion. It sounds like something isn't biased. Perhaps U7, T3, or Q9. Look at the voltage dividers R30, R31, R40 and R41 first. Something very likely isn't soldered completely. It's really hard to find these types of problems with test equipment so your best bet is visual inspection.
73 David AE9RB
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Re: Problem with transmitting

Postby ha8ap » Sat Aug 31, 2013 1:17 pm

Hello David!

Thank you very much. It worked. I would never have thought of that solution. It even solved the heating problem with the U10 when transmitting. As it turns out R31 had different value than it should have (it was a faulty resistor).
The device works perfectly.
Thanks again.

73! Toni
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