Wa2nan - True-talk 102' G5rv Antenna
I have a few questions about the WA2NAN True-Talk 102' G5RV antenna. I have a Kenwood TS-450SAT and am wondering if the radio's built-in antenna tuner will work for this antenna? I would mount it about 40' high as an inverted "V" in a North/South manner. Also, would the steel mast have a bad effect on the antenna? I would like to operate on 80, 40, and 20 meters. Thanks very much!!
I can't answer your question about the auto-tuner, as I have no experience with it, but as for the steel mast; no, there should be no adverse effect! Hams and commercial SWBC sites have been using steel masts and towers for antenna supports for years!
In fact, half slopers use the mast as part of the radiating system, and of course, there are always verticals which used the tower AS the radiator !
String it up and enjoy! If your auto-tuner will not match all the frequencies, get an external tuner with additional matching range. You might want to consider getting a balanced tuner and feeding the antenna as a convention balance-fed doublet rather than a "G5RV" design. You will probably find that it works much better that way !
The ladder line needs to be kept a few inches away from the steel mast.
You internal tuner might be able to match the G5RV, and it might not. No way to tell until you try it. The internal tuner on my IC-746Pro matched my G5RV on all bands from 160m to 6m.
73, Ron KR2D
To answer your question, No. The tuners in tranceivers are to be regarded as trimmers, if an antenna is almost resonant at the frequency you wish to use then the in- built tuner will do it. A G5RV requires an external ATU and very often these will not allow the use of 15 metres and sometimes 10 metres.
My WA2NAN 102 ft G5RV tunes perfect on 15 meters as a flat-top. 40 meters is 2:1 without a tuner and 20 Meters is 3:1 without a tuner and the same for 80 Meters. Don't even think about 10 Meters it's at least 5-6 S units down from my AR-10 Vert.
My USED TS440s Came with the built-in Tuner but it does not have much range but I never use my antennas out of the bands I designed them for anyway. Well....I used my 160 M dipole for 60 M a few timesw but it was only about 2.5:1 and the tuner did handle that mismatch ok.
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I can't say for your Kenwood, but my ICOM 746 Pro tuner had no problem finding a match 80 to 10 meters with my homebrew 102' G5RV.
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If you install an SWR meter between the tuner and the G5RV to measure the actual SWR on the coax, you might change your mind. EZNEC says the SWR is 30:1 resulting in 6.7 dB loss in 80 feet of RG-8x used on 15m. That's about 80% of your power wasted heating the coax on 15m. A G5RV is NOT a good 15m antenna. Probably the only reason your autotuner can match it is because the transmission line is acting as a dummy load.
Originally Posted by k1fbi
73, Cecil, www.w5dxp.com
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Originally Posted by W5DXP
The G5RV was meant by design to be a 3/2w 20M antenna.
Mine is a 102' version and is fed with 450-ohm "window line". It'll cover the lower end of 20M with a VSWR of less than 1.4:1.
If your particular full-size G5RV will not resonate with a fairly "close" match on 20M, something's amiss with its feedline...and as 'DXP points out, the coax is likely being used as a dummy load.
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I have the 204' version and with a Yaesu 920 driving and think it best to use a external tuner, but to be honest I have never tried it with just the radio tuner. Also I would strongly advise contacting Kerry, the builder of the True- Talk, he is very helpful and always willing to listen. Kerry
I have my 204' up 55' on a tower and Kerry said to use at least 12 inches stand off for the ladder line.
Great antenna by the way..