40m harmonics on 20 / 15 / 10m 6600

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  • Updated 4 weeks ago
Hi all, following problem:

Two Panadapters, FDX mode, 2 SCUs in use.

Both ANT1/ANT2 are terminated with 50Ohm Dummyload.

PAN1 /SCU1: ANT1/ANT1 40m 
PAN2 /SCU2: ANT2/ANT2 20m (or 15, or 10)

When I am transmitting on 7.100kHz with 100W I do get quite a strong harmonic on 14.200, 21.300 and 28.400. Signal strength gets lower from 20 to 10m. On 20m it is S9+ and I do get strong distortion on the band.

Is this behavior to be expected? I want tom work SO2R on upcoming WAG contest and since this is happens even without antennas ... listening will be hard on 20/15/10 when TRX on 40m.

With "real" antennas attached problem stays the same (that was when I first noticed it).

Any help or idea is appreciated.

73, Volker, DL4RCE
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Volker Geith

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Posted 4 weeks ago

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Joe N3HEE

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Volker, 

You should only see the second harmonic when connected to a dummy load.  You should not see phase or wideband noise when connected to dummy loads.  Something is leaking your signal ?

Noise usually will get much worse when connected to antennas.  It all depends on antenna separation and polarization.  You may also need to use a set of external band pass filters. 

I have lots of issues with wideband noise and noise coming from electronic devices with switching power supplies which radiate signals on the second harmonic of my transmit frequency.  No amount of filtering will fix that type of interference.

Joe
N3HEE
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Volker Geith

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Hi Joe, thanks for the fast reply.

I do not see any phase or wideband noise when connected to dummyloads.

If it is typical to see the harmonic on 20/15/10m then I am Ok. Just wondered if this should happen.

Funny thing is that with 100 or 10W the second harmonic stays at -48dbm, no matter what. When reducing to 1W it slightly drops, so this "leak" must happen before the amplifier stage!?

And to the third part you are right, I am not talking about those influences.

Regards

Volker
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Mark NS9N

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Hi Volker, just a thought, where do you have your preamp gains set. If not at zero, try that and see what happens. I was seeing all kinds of crazy things until Flex recommend that I put the gain back to zero as stated in the manual. Just a thought.
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Volker Geith

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Hi Mark, thanks for the reply. I tried this as well. Does not help for the harmonics. But I did see that one antenna had a "+8" which I set back to zero. Thanks for the hint.

Regards

Volker