Recently, I posted a question to our club’s mailing list regarding a QRN problem I was having. I said:
“I have an odd QRN problem here that seems related to snow. It sounds like some kind of electrical switching noise, similar to what you’d hear from a bad dimmer switch. I only get it, however, when there’s snow it seems. Earlier this morning, for example, the 20m band was very quiet. Now, after the snow has started, the noise is up around S9.”
Both George, K9KAZ and Clay, W8JNZ replied that what I may be experiencing is “snow static.” Apparently, snow flakes pick up a charge as they form and fall, and when they strike your antenna, discharge. You hear this discharge as noise.
George wrote, “We had the same problem with rain static
in commercial service. Sometimes so bad communication was impossible.” Clay noted, “Charges can build up in some cases to quite large voltages being generated, even harmful for delicate equipment. Rain has also been known to do the same thing.”
George also passed along the following URLs:
http://www.austin-insulators.com/radio/insulators.html
http://www.qsl.net/k1fz/2wirenotes.html
http://larc.unl.edu/log.issues/log1098.html
http://www.weathernotebook.org/transcripts/1997/05/22.html
http://stories.contesting.com/ARRLDXCW/arcw96_k1ki.html
This phenomenon is quite interesting. It’s certainly another reason to make sure your station is well-grounded. While I’m pretty sure that the noise source that’s giving me fits is electrical and not snow static, I do now note that falling snow does increase the overall QRN level.
As for the electrical noise, it seems to have gone away for the time being. My plan is to purchase and build the Sniffer field strength meter kit. Then, when the noise reappears–and you know it will–I’ll wander around the neighborhood with the FSM and try to locate the source. More on that later.
When it is very cold outside, especially in Alaska, we always experienced this problem. The air is so cold that it freezes all moisture from the air, then any breeze or prcipitation crated static pulses on the antennas. In the early days of SGC communications, their SG-711 transceivers were sold to the state “flying fuzz”….and virtually all the equipment failed in short order. The receiver front ends were solid state with no circuitry to ground the antenna and when the aircraft would fly in cold weather there would be a tremendous static build up on the antenna circuit. We finally solved the problem with a couple of back to back schottky diodes in the antenna circuit to ground, and replacing all the internal switches with similar diodes (a newly in house designed antenna couple helped, not the SGC design).
We experienced similar problems in the maountains near Chiang Mai, Thailand. As we arrived over lower altitudes near Vientianne the problems disappeared.