AV-18HT - Breakdown of wavelengths for each band

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by VO1FZ, Jun 15, 2011.

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  1. VO1FZ

    VO1FZ Ham Member QRZ Page

    I've been trying to find out the number of 1/4 wavelengths utilized for 15 and 10 meters on the AV-18HT. I know it uses 3/4 wavelength on 20 and I'm wondering if it does the same for 15 and 10. I'm guessing it does for 15 by using the 40 meter stub. How about 10?
     
  2. NL7W

    NL7W Ham Member QRZ Page

    That's a good question... I bet K9STH can chime in here. He has had one for decades.
     
  3. N0AZZ

    N0AZZ Ham Member QRZ Page

    I've had one for over 3 years but can not tell you until recently had only used it on 40m a little and my main antenna on 80m. But last week I started using it on all bands 10-80m with my QRP rig a IC-703+. I noticed that I have worked several stations on 10/15m with it last week @ 5w SSB Central and South America, Canada so I guess it's working some. It will also load on 12/17/30m with a external tuner I have been running JT65HF QRP also same antenna with good results. I do have a good radial field with 64 radials stapled to the ground.
     
  4. K9STH

    K9STH Ham Member QRZ Page

    According to the manual on the HyTower, the stubs are positioned to give an "odd multiple" of a quarter-wave on 10 and 15 meters. The 80 meter section functions as a 3/4th wavelength on 20 meters. Doing calculations it appears that the 15 meter and 10 meter stubs produce a 5/4th wavelength.

    HyGain was very conservative in their gain figures showing unity on 80, 40, and 20 and 2 dB on 15 and 10.

    I do know that without any additional cost kits that the HyTower functions on 30, 17, and 12 meters very well. The 160 meter coil kit is virtually worthless! With the base loading coil I was lucky to get a 539 report on 160 meter CW running about 80 watts on weekdays. During contests I basically couldn't work much of anything. So, I took out the coil and added a quarter-wave wire in parallel with the HyTower that runs in a convoluted pattern that just happens to be very close to an antenna that was developed by Electrospace Incorporated for the U.S. military. With the antenna change I was suddenly "busting" a number of pile-ups during contests. Since I added an 800 watt linear a few months ago, contacts during contests are definitely easier.

    Glen, K9STH
     
  5. VO1FZ

    VO1FZ Ham Member QRZ Page

    Thanks Glen. If those calculations for 15 and 10 are accurate, it would produce a fair amount of high angle radiation along with excellent low angle radiation. I would imagine the ground losses would be a whole lot less as well what with getting the current maximums up so much higher.
     
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