High SWR on G5RV

I'm running a Yaesu FT-450AT with a built in automatic antenna tuner. It is connected to a RadioWavz G5RV antenna with an air-balum choke at the connection of the coax and feed line. The antenna tunes up fine on 80, 40, 15, 12, and 10 meters, with SWRs in the 1.1:1 - 1.2:1 range. But, it will not tune on 20 meters. My understanding is that the G5RV is resonant at 20 meters and thus should be the most likely band for the antenna/radio to tune on. But I cannot even measure the SWR on 20 meters as the meter is pegged.

Anybody have an idea as to why my antenna will not tune on 20 meters.

Something else that's strange, I've worked some of my farthest DX on 20 meters even though the SWR is out of sight.

John, KE5UKI

 

::I wouldn't trust the SWR reading from the FT-450 in this case. Here's why: If the SWR is above 3:1, the FT-450 transmitter shuts down entirely and produces no output power at all; thus, it's impossible to work DX, or really anything else, if the "SWR is out of sight."

Something's wrong, there.

WB2WIK/6

 

I certainly agree with Steve. I would put an external SWR meter in the line and see what it reads. There is something amiss with your internal metering ! You should check the SWR on the line itself, on the antenna side of the tuner to see if the antenna is, indeed, resonant, or not.

Good luck ! 73, Jim

 

G5rv swr

Hi John,

I have a homebrew ZS6BKW antenna. The ZS6BKW is a derivative of the G5RV and exhibits lower SWR on most bands (even some WARC bands). I have an FT920 and it works well with the internal tuner 80-6 except for 75, 30 and 15. It also has been pretty good in performnance. My current record is 6000 miles per watt.

FWIW

73, JP, K8AG

 

The ZS6BKW is not the same as a G5RV. It was designed by a station who is now G0GSF. Its a different length so its an entirely different dipole.
see www.reflections.co.nz/index.php/archives/43
then go to ZS6BKW antenna revisited from sprat #129

Its a far better antenna.

How you are able to load up all these bands from an internal ATU is a mystery.
I think on some bands the power output must be about 10 watts, but as the G5RV was specifically designed for 20 metres in 1946 and not for 10, 12,15, or 17 metres because these were not ham bands in 1946 defies logic

G0GQK

 

Why is it a mystery? When I had a G5RV, the tuner in my IC-746Pro would match it on all bands 160m to 6m.

 

Zs6bkw

The ZS6BKW was based on the G5RV, but it was optimized using a computer (for what that is worth).

As for matching all of those bands, rigs like the FT920 list a max SWR as 3:0, however my guess is that depends on bands.

It is quite a bit shorter than the G5RV (90' vs 102'), but I have found it very convenient covering a lot of bands well enough.

73

 

But how well did it work? I can match my transmitter into a 50 ohm dummy load without a tuner. But I sure wouldn't want to try to WORK ANYBODY with it !

 

Using an antenna analyzer, what is the impedance seen by the tuner on 20M?

 

The ZS6BKW is not the same as a G5RV. It was designed by a station who is now G0GSF. Its a different length so its an entirely different dipole.
see www.reflections.co.nz/index.php/archives/43
then go to ZS6BKW antenna revisited from sprat #129


I had my doubts, but built one of these anyway. No tuner on 6 bands.
Also, keep in mind that when using a tuner, unless it's out at the antenna, there is high swr on you coax. So if you're using a g5rv what your swr meter says is usless. It only tells you whats happening at the radio not out at the antenna.