[Boatanchors] Re: [Johnson] G5RV info request
Fred Neff
[email protected]
Sun, 04 Jan 2004 10:24:11 -0500
Morning, Gents!
What a great forum! I have had some pretty good results with my home-brew G5RV, but after reading, and going to the listed websties, etc. I can't wait to start experimenting with the Windom design.
Joel, your comments "gave me paws" (as Pogo would say)...
I have noticed that my Waters dummy load/watt meter only indicates about 45-50 watts, even though the radios (Collins KWM2-A or Yaesu FT840) indicate full 100+ watt output, whether I use my home-brew G5RV, or Folded half-wave 80 meter dipole. Both are ~ 36' high, inverted V's. The G5RV flies a few feet below the 80meter dipole. The ends are well over 25' above ground.
Signal reports are consistantly good on twenty meters and 80 meters for SSB phone. Monitoring via a signal scope/station monitor shows near-perfect waveform.
>From what I inferred from your post, the SWR readings may actually be considerably higher than what is indicated on my tuner...could that be the reason for the apparently low output measurements via the Waters?
Obviously, the lowest-loss feed line is preferable. 1/4 (for 20 meters) wavelength 300-ohm twinlead gives near 1:1 swr when used with 10 turns of RGU-8 mini8mini instead of a balun, when measured with an MFJ antenna analyzer at the terminal end of the feed before any additional coax is added to bring it into the shack.
My Kenwood tuner gives me the option of either matched, or straight-through paths to my radio. When measured at the rig, the G5RV antenna gives 2:1 swr @ 14.275, and 1.5:1 @38.50 direct, without any tuning...both will yield 1.1:1 with a few minor tweaks, and an occasional 1.0:1 swr when everything is perfect and I take the time and patience to really trim it with the antenna analyzer.
It seems as if the ten turns of coax works much better than the usual "store-bought" baluns, traps, etc.
I have been told that ladder line would give even better results using the same configuration, but I don't really know how to get the lengths, number of turns of coax, etc. to get the final figures without a great deal of experimentation. If there are any equations for these things, I sure wish I could get a hold of them. Any ideas where I could look? Inductance coils, loading coils, etc. leave me stumped...without a formula to calculate their dimensions, I'm dependent on being told what to do, which doesn't leave me much room for experimentation without a lot of hit-or-miss guesses, and a lot of trimming and/or failed attempts.
Many thanks for the swell info, if anybody can answer those two questions, I would be most grateful.
73's To All,
C. Fred Neff
KB9RMT
"Too Bad Ignorance Isn't Painful..."
From: Brian Hunsaker
To: "Joel R. Hallas"
CC: KENNETH A CRIPS
, [email protected],[email protected], [email protected], [email protected],[email protected] Subject: [Boatanchors] Re: [Johnson] G5RV info request Date: Sun, 4 Jan 2004 07:38:02 -0600 At 1:22 PM -0500 1/3/04, Joel R. Hallas wrote: >Gents, > >I am a happy G5RV user, but think I should point out something about >both the >G5RV and the various Windom antennas. These antennas happen to have >various >frequencies at which they have a somewhat reasonable match to 50 ohm >coax, >however, at most frequencies they have a rather high swr, perhaps >5:1 to 10:1. >This will look lower at the transmitter end of the line due to the >loss of the >reflected signal getting to the bridge. > >Take a look at Fig 14 of Chap 24 in the current ARRL antenna book >and see the >additional loss in coax as a function of swr. For example foam RG-58 >has a loss >of about 1.5 dB/100 ft when matched. An SWR of 5:1 will add another >1.5 dB so >half the power will not get to the end of the coax. It gets >progressively worse >when the SWR gets higher. > >After measuring the SWR from my G5RV, I replaced my small coax with >9913 which >improves the situation but doesn't eliminate it. > >The Windom seems to work best in those areas with good ground >conductivity where >the vertically polorized radiation from the feed can help. For those >of us with >rocks under the antenna, Horizontal is still best for any height. > >Just my $.02 > >Joel Hallas, W1ZR > >Brian Hunsaker wrote: > >> At 7:49 PM -0700 1/2/04, KENNETH A CRIPS wrote: >> >Before you purchase the AES G5RV take a look a the link below >>this outfit >> >makes the best >> >wire antennas I know of. Their G5RV is the best "store bought" >>G5RV in know >> >of. >> >However the Carolina Windom they make is hands down a better >>antenna >> > >> >http://www.radioworks.com/PDFantenna.html >> > >> > Ken >> > >> > >> > >> > >> >Kenneth A. Crips Station W7ITC Cheyenne, Wyoming. >> > >> >_______________________________________________ >> >Johnson mailing list >> >[email protected] >> >http://mailman.qth.net/mailman/listinfo/johnson >> >> I just purchased a Windom (80 - 10 version, 132') from Antennas >>and >> More - (www.antennasmore.com), and it is a real killer. I am >>getting >> great reports on 80, 40, 20, and they are all without a tuner. In >> fact, it loads up on 20 better with out a tuner, than if you put >>a >> tuner in the line. Mine is about 35' above the ground. Price - >>$122 >> with shipping. They have G5RVs also, but I agree with Ken that >>the >> Windom is a better aerial. >> >> My two cents, >> >> Brian - W5YE >> -- >> r. b. hunsaker >> *** The Ark was built by an amateur - the Titanic by >>professionals. *** >> >> --- StripMime Report -- processed MIME parts --- >> multipart/alternative >> text/plain (text body -- kept) >> text/html >> The reason this message is shown is because the post was in HTML >> or had an attachment. Attachments are not allowed. To learn how >> to post in Plain-Text go to: http://www.expita.com/nomime.html >>--- >> _______________________________________________ >> Johnson mailing list >> [email protected] >> http://mailman.qth.net/mailman/listinfo/johnson My Windom is all horizontal, so ground conductivity does not come into play. My swr is less than 2:1 on all bands, except 15 (which the manufacturer advises you in his literature). Also, regarding the subject of "loss from high swr", check out Kurt N. Sturba's (pseudonym) excellent work on antennas and the "myths" related thereto. "Aerials I, II, or III" is a must for anyone who is serious about learning what is and what is not, in their construction, and performance. Reflected power is not actually "lost", as most folks think. 73, Brian -- r. b. hunsaker *** The Ark was built by an amateur - the Titanic by professionals. *** _______________________________________________ Boatanchors mailing list [email protected] http://mailman.qth.net/mailman/listinfo/boatanchors ** List Administrator - Duane Fischer, W8DBF/W9WZE ** ** For Assistance: [email protected] ** $$ For vintage radio info, see the HCI web site $$ http://www.w9wze.org
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