Why can't I get swr down on 80m?

[WA7KKP]

I risk sounding like a stuck record again, but here goes . . .

the G5RV antenna is NOT a multi-band antenna -- ask Louis Varney, who designed it only to work on 20 meters.

Start over with a basic dipole, feed it with ladder line or open-wire line, get a good wide-range antenna tuner, and it will work just fine on any frequency you want, as long as the dipole is long enough for the lowest frequency you plan to operate.

Gary WA7KKP

[WN9HJW]

I risk sounding like a stuck record again, but here goes . . .

the G5RV antenna is NOT a multi-band antenna -- ask Louis Varney, who designed it only to work on 20 meters.

Not exactly. It would be fair to say it's not an "all-band" antenna, but it is multiband in the sense that it does work on multiple bands.

He did not design it "only to work on 20 meters". He designed it as a 20 meter antenna, but I doubt if he tried to make it work ONLY on 20 meters.

It also happens to work fairly well on several other bands. 80, 40, 15 and 12 meters. What's the big deal?

[W5DXP]

I doubt if he tried to make it work ONLY on 20 meters.

If he had designed it ONLY for 20m operation, he would not have needed a twinlead series matching section.

I risk sounding like a stuck record again, but here goes . . .

Have you ever read what Louis Varney, G5RV himself, wrote in his "The G5RV Multiband Antenna ... Up-to-Date" article in The ARRL Antenna Compendium, Vol 1?

the G5RV antenna is NOT a multi-band antenna -- ask Louis Varney, who designed it only to work on 20 meters.

We cannot ask Louis Varney (SK) but here is a direct quote by him from his article in The ARRL Antenna Compendium, Vol. 1.

"The G5RV antenna, with its special feeder arrangement, is a multiband center-fed antenna capable of efficient operation on all HF bands from 3.5 to 28 MHz."

Those are Louis Varney's words, not mine. (He admittedly got carried away with his "efficient operation" on 30m, 17m, 15m, and 10m but he gives detailed information about why he believes it should work on all HF bands.) I have a couple of Smith charts on my web page that show why the G5RV is an efficient resonant antenna system on 80m and 40m (as well as on the 20m design frequency). Efficient 12m operation was (IMO) just a lucky accident.

http://www.w5dxp.com/G5RV.HTM

[KF4ZGZ]

The G5RV is designed as a flat-top antenna. Having it as an inv. vee is most likely your problem.
While everyone else is arguing over the antenna and what it is or isn't, do what you can to make it flat.
Even if it means lowering the center height.
I would be the swr will get better the flatter the antenna gets.


Matt

[W5DXP]

I would be the swr will get better the flatter the antenna gets.

Here's the problem with the G5RV on 3.75 MHz. The 102' dipole is shorter than 1/2WL so the feedpoint impedance contains capacitive reactance along with a low resistance, e.g. 34-j344 ohms, resulting in an SWR of 20:1 on the 300 ohm series section transformer. The series section transforms the impedance at the twinlead/coax junction to 14.7+j7.6 ohms causing a 3.5:1 SWR on the 50 ohm coax which is too high for most built-in autotuners. That is based on a horizontal dipole at 40 feet high so fiddling with height and making it horizontal is not going to cure the incompatibility with built-in autotuners that are limited to SWRs less than 3:1.

[G3TXQ]

Have you ever read what Louis Varney, G5RV himself, wrote in his "The G5RV Multiband Antenna ... Up-to-Date" article in The ARRL Antenna Compendium, Vol 1?

Or, go back to his original 1958 article. Its title was "An effective multiband aerial of simple construction", and the first paragraph included this:

Operation on 1.8 and 3.5Mc/s was an important requisite, but efficient operation on 7, 14 and 28Mc/s was also desired

I'm afraid that typing a falsehood in a large font doesn't make it true - all it does is perpetuate yet another "Ham Myth"!

73,
Steve G3TXQ

[G4SKO]

I just pity the poor 'stard who relies on this antenna for 10M......It really is quite dismal.

[W5DXP]

I just pity the poor 'stard who relies on this antenna for 10M......It really is quite dismal.

Most of the experts agree that a G5RV works well on 80m, 40m, 20m, and 12m - but not on 10m.

[N0AZZ]

Back to the real problem buy a good manual external tuner the highest quality you can afford, consider it a lifetime investment which it is I have several.

[KJ4VTH]

I've had success on 10m with a "shorty" G5RV, the 52' version, racking up DXCC in the past year, but it is not really fit for 80m. The full-size version is a bit on 80m better but not much as described above.