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#8
February 2nd 07, 05:30 AM
posted to rec.radio.amateur.antenna
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Matching Issue ........... I think!
Denny wrote:
Hmmm, I can't make much of this diagram and the group has decided to use passive aggressive behavior to "teach you"... You are asking for help and getting didactics thrown in your face... Shame on them! I doubt you can feed this antenna on 40 with coax... You will need to either put a tuner at the feed point, or resort to open wire line and a tuner at the radio... My first impulse would be to turn this into a top loaded vertical with an elevated counterpoise, the vertical self resonant on 40 and loaded for 80... Feed it at the bottom of the vertical section with the braid going to the 17 foot horizontals (some tuning needed)... Use a loading coil about half way up the vertical for 80 and short it out for 40... The counterpoise (the 17 foot horizontals as best I can make out) would be coil loaded at at the center connection of the 2 "radials" so they are resonant on 80 with a shroting clip for 40... A relay will select for you, or you can walk out and manually move the clips... Go to the library there and get an interloan copy of Moxon's "HF Antennas for all locations"... He has an excellent discussion of loaded radials/counterpoises, etc... With his help you should see how to make your antenna play... Any problems drop me an email through and I will give you a fax number where you can shoot me a diagram of your antenna and we can discuss it... cheers ... denny / k8do the physical antenna stays as is and works extremely well on 75. What has me asking the questions is that I was told a 1/4 wave piece of coax would get it to work on 40. Maybe I need to run it thru some modeling software and see what actually does need to happen to get 40 to work. -- I SPILLED SPOT REMOVER ON MY DOG..............AND NOW HES GONE!! |
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