Strange frequency lability in 6700 on 2m bband

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  • Updated 8 months ago
Sometimes when I listen to a beacon on 2m, the signal ocillates a couple of Hzs and sometimes not. Sometimes switching off the SDR helps. Not happened on HF so far. This is SK4MPI, 300kms away.
This problem actulaized after the upgrade to 2.4.9. , never with the old SDR software.
Please comment

Juha Varis OH1JJ








oscillates a couple of herzes, but sometimes it does not appear. Not noticed it on HF bands.
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Juha Varis

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Posted 8 months ago

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Johan / SE3X

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Hi Juha, I have only a vertical for 2m so don't think I will hear it. Distans probably less than yours. But I will ask a couple of friends in Östersund who has good antennas and equipment to see that the beacon itself doesn't have a problem. Will be tonight, while they both work today.
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Juha Varis

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Tusen tack Johan
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Martin Ewing AA6E

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I believe it's propagation. It might be caused by reflections from a high aircraft near the line of sight. If it does not occur with local signals, it's not a radio problem.


I saw a lot of "interesting" frequency structure on a very distant 2M beacon when I was using a 6700. (The 6700 has higher maximum freq resolution than other Flexes.)


73 Martin AA6E
(Edited)
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Juha Varis

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Thanks, I suspect that too, beacuse local hams cw signs looked ok during the 2m activity test yesterday
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Mike - W8MM

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To rule out time-base issues, try synching to a very stable 10 MHz reference (if you have one available) and see if that has an influence.  A few Hz at 2 meters is only a few 1/10 Hz at 20 meters, so you might not see time-base issues at HF.
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Juha Varis

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Could you briefly describe how to do it, Yeas I have very stabile reference equipments
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Johan / SE3X

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Juha, friends I had hoped could help are both travelling and not home now. If I could get some answers I will be back here.
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Mike - W8MM

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Connect a very stable 10 MHz source to the "10MHz In" RCA jack on the back of the radio and restart the 6700.  This will allow the 6700 to use the external 10 MHz source as its frequency reference and bypass the internal time base.  If there is a time base problem, this procedure should isolate it.

Also, please see this community conversation to see if it is similar:  https://community.flexradio.com/flexradio/topics/problem-6700-timebase-drifting-sweeping-maybe-500-h...