Spurs at 14mhz

General discussion and support for the Peaberry SDR V1.

Spurs at 14mhz

Postby Nazim » Fri Jan 18, 2013 7:52 am

Hello Everyone,
I'm at step 20. Got receiver working and was able to tune in to ham stations in a 3000 km radius on a 20 and 40m using just two Petlowany coils sticked behind the window as antenna.
Quite an achievement!
The only thing which bothers me is a spurious screen on 14mhz. On 7 and 10 mhz there is only a smalish spike in the middle of the screen, but 14 mhz looks like a hacksaw (screenhost attached)
Could it be result of a bad assembly (bad transformer winding, grounding problems?) or a software misconfiguration?
I'm using Linrad 03.46 on GNU/Linux x64. Will try to setup a Quisk and check if there are spikes on a Quisk screen.

All the Best,
Nazim
Attachments
14mhz-spurs.png
14mhz-spurs.png (20.32 KiB) Viewed 12216 times
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Re: Spurs at 14mhz

Postby Nazim » Fri Jan 18, 2013 3:11 pm

Checked with Quisk, spurs are still there
Nazim
 
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Re: Spurs at 14mhz

Postby DJ&OA » Fri Jan 18, 2013 6:28 pm

Hi Nazim,

Check your switching power supply, or try to use a battery.

73, Rainer
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Re: Spurs at 14mhz

Postby AE9RB » Sun Jan 20, 2013 12:26 am

Nazim, these seem excessive. 1kHz can be from USB. I've attached what my 40-30-20 radio looks like on 20m with a dummy load. It could be anything: filters (T2), antenna, tuner, power supply, USB cable.
Attachments
Rocky.exeScreenSnapz001.jpg
Rocky.exeScreenSnapz001.jpg (36.25 KiB) Viewed 12184 times
73 David AE9RB
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Re: Spurs at 14mhz

Postby Nazim » Sun Jan 20, 2013 2:59 pm

Hi David and Rainer,

Thank you for advise. I'll check with a dummy load, another power supply/battery and shortened cables.

All the Best,
Nazim
Nazim
 
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Re: Spurs at 14mhz

Postby AE9RB » Sun Apr 21, 2013 3:39 pm

I accidentally reproduced this in my lab because I forgot to check the power supply voltage after working on another project. Make sure you are testing with 13.8VDC.
73 David AE9RB
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Re: Spurs at 14mhz

Postby Nazim » Thu Aug 29, 2013 1:07 pm

Rewinding transformers, changing power supplies and USB cables gave no results.
Finally, I've applied a liquid rosine flux to U10 and U11 pads and re- heated them.
Magically, spurs almost disappeared. Now my Linrad screen looks beautifull.
Thanks for your suggestions! Hoping my experience will be useful to others.
Nazim
 
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