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Author Topic: MW Mixing Products All Over HF  (Read 2966 times)

Offline ChrisSmolinski

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MW Mixing Products All Over HF
« on: January 18, 2015, 2042 UTC »
Earlier today I had an interesting problem - mixing products from MW stations all over HF. I actually noticed it a few times on the overnight SDR recording as well.  I could not hear them on another radio, so that seemed to rule out them being "real", but instead being something produced specifically by the one radio.

After checking a few things out, I noticed one of the barrel connectors on the incoming coax, connecting two sections, was loose. I tightened it, and immediately the mixing products all vanished. The signal levels went up a little, as well. Perhaps something in the loose connection (dirt, etc) was acting like a rectifier?
Chris Smolinski
Westminster, MD
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Offline redhat

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Re: MW Mixing Products All Over HF
« Reply #1 on: January 19, 2015, 0904 UTC »
Ah, you've stumbled upon the rusty bolt effect :)

https://en.wikipedia.org/wiki/Rusty_bolt_effect


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Offline 57Hemi

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Re: MW Mixing Products All Over HF
« Reply #2 on: February 28, 2015, 1215 UTC »
I've had this happen a couple of times over the years. The first time, I thought my receiver had something very wrong with it. Once I calmed down, I retightened all my connections and it disappeared. About the same time, I had a "mystery carrier" in my NRD-515 that stumped me until I checked the interconnect cables inside it. It was just one of the interconnect plugs (really cheap cables with crimped connections!) had oxidized and was causing it. I soldered all the plugs and put De-Oxit on the jacks and never had another issue with it again.

 

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