2elm 6m antenna (HB9CV) for HF use - Elmers Forum at eHam.net

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eHam.net Forum : Elmers : 2elm 6m antenna (HB9CV) for HF use

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2elm 6m antenna (HB9CV) for HF use	Reply
by PH0SSB on October 25, 2004	Mail this to a friend!
I'm using a 2elm. 6m antenna (HB9CV) on HF , with some help of a tuner. It works on all bands except on 24 and 28Mhz. Are there any other HB9CV users who use this antenna on HF? And are there any suggestions so that I can tune this baby on 24 and 28Mhz aswell? But I still want to use it on 6m ! Traps?? Come on Elmers , give me a hand... '73 Jannes PHoSSB

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by K5LXP on October 25, 2004	Mail this to a friend!
http://www.hamuniverse.com/multidipole.html

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by K0ZN on October 25, 2004	Mail this to a friend!
Hi, Short version: you are trying to use a Honda Civic as a dump truck to carry gravel !! It isn't going to work very well. That 6 M antenna presents an EXTREMELY reactive load on any HF band and the SWR will be extremely high. The reason it "works" is because a good deal of energy is being radiated by either coming down the OUTSIDE of the coax or by the supporting structure in some fashion. With a tuner you can "force" energy into the coax, but with a wildly high SWR the losses are horrific. I hate to sound like Scrooge, but there is no reasonable or practical way to make a 6 M antenna a decent HF antenna... that is just the laws of physics. You can never get something for nothing. Your time would be MUCH better spent making a true HF antenna. 73, K0ZN

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by KT8K on October 26, 2004	Mail this to a friend!
Traps are for tuning to shorter wavelengths, not longer, so they won't help your HB9CV get you on anything below 6m. I agree with the others - your feedline is probably doing most of the work on HF. I imagine you probably don't have a balun at the antenna feedpoint (or it wouldn't even receive much). You might be able to get to these bands by changing the length of the coax. Extend it with any 50 ohm jumper cable and see how it tunes then. Odds are that you will lose one or two other bands in the process, but if it works you could switch it in and out as you change bands. Better yet, build or acquire a multi-band dipole ("fan dipole", or something like the Alpha Delta DX-CC) or something like that, and suspend the feedpoint of it from the top of your tower - you will be amazed at the difference. 73 & good reception de kt8k - Tim

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by WB6BYU on October 26, 2004	Mail this to a friend!
The HB9CV is particularly poorly suited for operation on the lower frequencies because of the phasing of the two elements. As you go lower in frequency, these get electrically closer together with a phase shift that gets closer to 180 degrees. In other words, close together and out of phase, so the radiation from the two elements will tend to cancel each other. The gamma matches are not well suited for operation on other frequencies, either. The best method to operate it on the HF bands will be to unplug the coax cable from the tuner and connect the ground side of the plug to the single wire output on your tuner: this uses the coax as a random wire antenna. (Which is probably what is happening on the lower bands anyway.) The next method would be to add a 6m trap on the ends of one of the elements (perhaps the front one) with long enough extensions to make it resonant on 10m. This would give you a single element rotatable dipole on that band while still hopefully maintaining the 6m behavior of the beam.

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by PH0SSB on October 27, 2004	Mail this to a friend!
Some additional information is required I believe : I only use the inner core of the coax , I use the build in 4:1 balun depending of the freq. I worked stations throughout europe ( some asian and african) with reasonably good report. Output is about 100W , but the mode I use is SSB so max 50W peak Due to tuner SWR is good on (almost) all bands , and the set does not reduce power in these cases. Keep the advise comming......... Jannes PHoSSB

RE: 2elm 6m antenna (HB9CV) for HF use	Reply
by WA2JJH on February 12, 2005	Mail this to a friend!
Your better off using THAT 10M IMAX-2000 24 foot 5/8th wave vertical for 10M and 12M and 1/2 wave vertical performance on 15M. Use a POS MFJ TUNER for lack-luster performance down to 20M. Lets not get into basic beam theory and element length, spacing of elements AND RESONANCE.

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