OT question about receiving loop antenna

[Vic Rosenthal]

I have an RF Pro 1b receiving loop antenna which I use for diversity
reception on my K3. It used to be sold by Pixel Technologies, and now it
is handled by DX Engineering. If there is someone else who has this same
antenna, please contact me off list.

My antenna seems to be producing a strong (-50 dBm) spurious signal that
starts around 7400 kHz and drifts down. It is frequency modulated at the
line frequency. I have replaced the preamp and I still have the problem.
I am pretty certain that it is not an external signal, but I would like
someone else to check theirs for the same issue as a sanity check.

--
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
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[Alan - G4GNX]

May I suggest checking all your PSUs. I had the same issue once and it
turned out to be the PSU running a tuner. I binned the PSU and installed
a tried and tested new one. No more issues.

73,

Alan. G4GNX


------ Original Message ------
From: "Victor Rosenthal" <[hidden email]>
To: "Elecraft Reflector" <[hidden email]>
Sent: 12/11/2020 14:16:53
Subject: [Elecraft] OT question about receiving loop antenna

>I have an RF Pro 1b receiving loop antenna which I use for diversity reception on my K3. It used to be sold by Pixel Technologies, and now it is handled by DX Engineering. If there is someone else who has this same antenna, please contact me off list.
>
>My antenna seems to be producing a strong (-50 dBm) spurious signal that starts around 7400 kHz and drifts down. It is frequency modulated at the line frequency. I have replaced the preamp and I still have the problem. I am pretty certain that it is not an external signal, but I would like someone else to check theirs for the same issue as a sanity check.
>
>-- 73,
>Victor, 4X6GP
>Rehovot, Israel
>Formerly K2VCO
>CWops no. 5
>http://www.qsl.net/k2vco/
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>Message delivered to [hidden email]

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[Vic Rosenthal]

The problem was that the supply voltage was slightly high, causing
increased gain in the preamp which allowed it to break into oscillation.
A 10 ohm resistor fixed it.

Thanks to those that responded!

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/

On 12/11/2020 16:16, Victor Rosenthal wrote:
> I have an RF Pro 1b receiving loop antenna which I use for diversity
reception on my K3. It used to be sold by Pixel Technologies, and now it
is handled by DX Engineering. If there is someone else who has this same
antenna, please contact me off list.

> My antenna seems to be producing a strong (-50 dBm) spurious signal
that starts around 7400 kHz and drifts down. It is frequency modulated
at the line frequency. I have replaced the preamp and I still have the
problem. I am pretty certain that it is not an external signal, but I
would like someone else to check theirs for the same issue as a sanity
check.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]