Saturday, January 23, 2010

Snow and SWR

Again we have snow. It's snowing all night and temperature is below zero. I know that rain could influence the SWR, but now the resonance frequency of the dipole is 50 KHz lower in the 80 meter band, with snow on the wires. Have anyone experiences with this phenomenon?

CW QSO's on 40 meter: YU4ØAF - RA3DUO - LY2QT - TA3TX - AM7LE - K8CW.

11 comments:

  1. Paul, I always have an SWR problem with rain or snow. Had the problem when I had a dipole. And have the problem with my Buddistick. There is no getting around it. At least I never found a solution. Except wait until everything dried out. And until then, use my antenna tuner. I always keep a small tuner, with a bypass switch, between rig/swr meter and antenna.

    73 Dick

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  2. Many years ago I had a small vertical antenna with top loading coils. The SWR would also change when the coils became wet. One suggestion was to spray them with WD40, which would make the rain run off. However that might not be so easy to do with an entire 80m dipole. If your dipole has end loading coils (like my short one in the attic) it might help to just spray the coils.

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  3. Hello Dick and Julian, thanks for the answers. Oh, I wish spring was here. I will look for WD40 or something like that. till now I have to wait till the snow is gone. 73 Paul

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  4. Paul, as ice and snow collects on a wire antenna, the weight might stretch it, changing length even bringing it closer to the earth. That might affect resonance, also.

    I still like having a little MFJ tuner in line, only enabled when weather related swr problems develop. 73 Dick

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  5. Paul, an elecraft T1 would be nice! Rather fancy one of those myself. M0BHJ form the radio club bought one lasy year and is making it himself. Being a lazy person not fond of intricate soldering I'd buy it made myself. I like the idea of a little tuner, of whatever make, for standby use in bad weather.

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  6. Hallo Paul, ik heb er ook last van op mijn vertical. Sneeuw heeft niet zoveel effect, maar regen wel. Ik had een aantal jaren geleden een Diamond CP6 die ook erg gevoelig was voor slecht weer, met dezelfde problemen die jij hebt met de dipool. Overigens hadden ze voor het noorden 7cm sneeuw voorspeld, maar er is hier helemaal niets gevallen...73, Bas

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  7. @Dick and Adam: I do have an MFJ autotuner but I need new PL connectors for RG213 coax. I ordered them and I expect them this week. Now I have an very old piece of coax (35 years old) between it. I replaced all the old coax with RG213 now. Before that I never used an antenna tuner, but for the multiband vertical I need one especially for the lower bands. 73 Paul

    @Bas: intussen is die 7 cm sneeuw wel hier gevallen. Van mij hoeft het niet meer. 73 Paul

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  8. Anonymous2/10/2010

    Unsure if this would be the same issue, but the loss on your Coax changes depending upon temp. When its cold, there's less resistance along the conductor as opposed to when its warm. Working for a communication company, we are constantly balancing our equipment when the temps swing.

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  9. Hello Anonymous: thanks for your reply. It's a new phenomenon for me, thanks for the information. 73 Paul

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  10. I use a good silicone spray on Buddipole traps and connectors and it really helps keeping the swr low when it rains. Our arctic winters here in Canada includes freezing rain and my PAR end fed dipoles often get encrusted with ice up to 18mm or more. Tuners don't help much with those conditions and we wait till the ice falls off or melts.

    Nice blog you have here.

    Bob VE3MPG
    http://ve3mpg.blogspot.com/

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  11. Hello Bob, thanks for the hint. We had a lot of snow this winter, normally out winters are more wet and less snow. 73 Paul

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