In reply to G3CWI:
on the hill the VSWR
was so high that the warning message was flashing on the FT817
I was lucky that it did not take the external PA out
VSWR warning on the FT817 when used with an external PA?
Surely a problem with the PA matching and not the antenna then?
73
John GM8OTI
In reply to G3CWI:
There’s a good article on FT-817 VSWR metering here:
http://www.ka7oei.com/ft817_vswr.html
In reply to GM8OTI:
No, that’s not it. On the hill I took the PA completely out of circuit and just connected the antenna to the FT817 directly. It’s something of a mystery that will not be solved until I can put the aerial up I suspect.
The 817 and PA are fine back here again.
73
Richard
G3CWI
Sunny morning so the first job was to see what was wrong with the 20m GP. Once erected, a visual check revealed something odd. It looked a bit small. This was something that I had thought when I put it up on Kinder but I gave it no further attention as I had measured it carefully.
Of course it could not be the wrong size as I had checked that on my return home. But the antenna analyser showed that it was resonant on 17.6MHz - no wonder it did not work well on 20m. Taking it down I re-measured 16ft 6 inches …perfect. What could possibly be wrong? While measuring a fourth time I noticed something odd with the steel tape. At around the 16ft 6 inch mark I noticed a much smaller marking showing 13ft 6 inches. At that point it dawned on me. The tape measure is marked in inches and the way they are written led me to believe that 166 inches was 16ft 6 inches. Dohhh.
I had an antenna that was a tad long for 18MHz but way too short for 20m. No wonder it was not working properly.
Mystery solved.
73
Richard
G3CWI
In reply to G3CWI:
Hi, Richard.
I had a deja vu … this afternoon I did the same thing, I set up my radio on a hiking trail and attached the top of my 28 foot wire to the top my my 31’ telescoping whip and started pulling out and friction fitting the sections. Just over half of them were extended when the banana plug popped into view… oops it was a 16’ wire.
So I snipped some length of my 32’ counterpoise and used that wire on the antenna mast instead. The 16’ counterpoise was fine for 20m/30m but didn’t want to play on 40 so I found a little more wire in the bottom of my pack to make up the difference…
Something I remember on a coffee mug at work… “Measure twice, cut once.” … sage advice 
73!
Martin.
VA3SIE/P.