multi CQ DXer

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I have never seen this before.  Some one calling CQ DX simultaneously every 500 Hz. If I were to guess, he is in SSB mode with a tone on the input either a square wave or over driving with a sine wave. Any thoughts??

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Dave

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Posted 3 years ago

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K2CM

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I see this periodically on CW. When I see it, not sure what the correct frequency is to call the guy on, and let him know he has a problem.

I had this happen to me once many years ago with a homebrew 2mtr transverter with a design problem.

I used a crystal frequency of a couple of megacycles in one of the stages, that inadvertently mixed in the final stage to output two frequencies. Found the problem when a friend asked me which of the two frequencies I wanted him to transmit on. Had a lotta stages with a lotta crystals....very bad design.

I suspect the fellow was using a home brew rig with a 455 if. A 455 oscilator is getting into the final and mixing with his desired signal.

This is the general idea...am sure somebody out there can explain it better.
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Dave

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This makes sense. the signals are about 455 Hz apart. BTW, I assume that you can not intentionally do this, or can you. It seems to be spurious emissions. 
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Ken - NM9P, Elmer

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I have seen this often on HF, but would never have identified it without the panadaptor.

I saw a station a couple of years ago in a major DX pileup, that had Eight (8) separate carriers spread over 3 KHz calling the DXpedition.  I couldn't tell if he was doing it on purpose to maximize his chances of getting through, or if he was running Audio keyed CW from a popular multi-digital program and was overdriving it with his compressor on and generating multiple spurs.  

He finally worked the station.  Then a few minutes later, I heard the same signal with a different call calling again.  It may have been a club station or husband/wife.

Ken - NM9P
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Steven G1XOW

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its the latest contest winning formula - splatter gun the entire band and let the punters find where you are really listening. Great game - but way too easy for SDR ops.
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Chris Tate - N6WM, Elmer

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Spurious badness.
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Les Brown

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I had a problem like this many many years ago with my Yaesu FLDX-400. I was transmitting up and down the band, even outside the band. I only realized there was a problem when I received a notice from the authorities. It turned out to be a bad crystal. Once replaced, everything was good.
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K1UO - Larry

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Just noticed the multiple TX spurs this morning on 80 CW from a Midwest station calling the ZL7G DXPedition.  He had completely readable transmit spurs approximately every 600 Hz away from his fundamental calling frequency and each spike peak down about 5db from the previous until they disappeared into the noise. total bw covered was about 10kc on the panadapter.  I emailed him to explain what I was seeing /hearing and saw he was running a Flex6700 and SPE2K amplifier the same as I am.  The TX spurs were spaced about the same as his cw tone setting I would guess.   I also asked him if he was by chance running in diversity mode when he was transmitting as when I reported something similar to Flex a few days ago I was running diversity.  I will be interested in his response if I get one.   I first noticed the spurious  CW spurs on my TX panadapter but when I dropped out of diversity they disappeared and the TX signal looked "normal".  no-one emailed me to say anything about my TX signal so I don't know if the spurs were being transmitted.   The above post is the first noted concerning SSB Mode.
(Edited)
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Ken - NM9P, Elmer

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Unless the station had some severe RF feedback going on, I suspect the station was using an audio modulated CW program like FLDigi to generate CW and was either 1) over-driving the rig, 2) had a DAX driver corruption that requires closing and reopening DAX, or 3) had left the processor ON with SSB mode.

I would be interested to hear what you receive in response....
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K1UO - Larry

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FOLLOW UP:  The station op (A member of many large DXPeditions btw) told me that in his hurry to get on 80M CW for the DX station that he was on the wrong antenna and not tuned properly for that particular antenna.   He further stated that 80M CW was a seldom used band at his qth.   Nothing further to add but it definitely was not what is normally displayed on a panadapter by an overdriving or audio distortion situation

.  In the above SSB view that started this conversation, Dave doesn't mention the same SSB signal also shows at 14054.5 and 14057.XX although dropping in intensity like the CW signal I noted this AM. 

  I need to ask the station what level firmware he is using and other particulars. 

(Edited)
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Dave

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Larry,
What I said was: "If I were to guess, he is in SSB mode" I don't know for sure, just a guess.

As you observed, the first and third harmonics are down in amplitude for the other signals. This is consistent with either a square wave input or a over driven sign wave which is being clipped. In any case, this not intentional. 

Thanks for your input to this.It greatly help me understand what is going on.

Dave
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K1UO - Larry

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OK..  this multiple TX spurs ,approximately every 500Hz as described above, was observed again this AM on my Flex 6700 panadapter. This time from a TX station I know that has a Flex6700.  This time on 160 meter CW.  Daves signal level was about S2 here in Maine as he was QSOing a VK3.   There were multiple signals on the Band but this was the only one with the multiple TX spurs.  Each spur just slightly weaker than the primary until they faded out over a 3 kc span. I am on the latest firmware BETA this time but the previous times I observed this was on a previous firmware level.  I turned off WNB and NB to see if they had any affect on this one signal but there was no change.  It was indeed coming from the other stations Transmitted signal.  BTW  this also showed up on cw skimmer as multiple TX streams (around S2/S3 signal strength) on this station and each stream was completely readable.  All other signals on the Band were fine and looked normal on the Panadapter.  Naturally I never thought to take a screenshot this time :(
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K1UO - Larry

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Follow Up:    I did contact the station and he was indeed using his Flex6700 at the time.  It was determined that this particular spur problem was caused by transmitting into a "mistuned swr" .  I do not know what level of swr  triggers this multiple tx spur problem but readjusting the "high swr" into his normal operating range did indeed fix the tx spur problem. 
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Kevin

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Does a high SWR usually increase the chance for RF floating around the shack? If so, maybe a marginal component, device or connection is the actual cause of the spurs and the higher SWR is just exacerbating the situation. It seems to me a high SWR should cause nothing more than higher line losses in coax, maybe some foldback of output power, and maybe some increased RF in the shack?

Kev