The moral is - DON'T USE A G5RV.

Specially one with any coax in the feedline.

If you've bought one, you've been robbed.

Use a random length dipole, longer than about 1/3 of the wavelength at the
lowest frequency of interest. Choose a length which makes best use of the
size of your backyard. Take the 450 or 600-ohm balanced line all the way
back to the shack. You will need a tuner and a choke balun at the tuner.
For multi-band operation you will need a tuner whatever you do.

If you find it inconvenient to feed the dipole in the middle, and you have a
relatively low local noise level, then feed it at one end and make an
Inverted-L of it. It will then very likely work very well also on 160
metres.

And you will never think of using a G5RV again !

By the way - Louis Varney, G5RV, a real genuine English gentleman, now no
longer with us, designed his antenna to work most efficiently ONLY on 14.15
MHz, perhaps the best day-or-night, all-year-round, any part of the sun-spot
cycle, DX frequency. It's very good. And you may not need tuner even with
the coax. Works great with the old fashioned TS-520 with its built-in tuner
!
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Reg, G4FGQ