My G5RV's are 'get on the air' antennas with 100w and an ATU, but a
dipole per band or set of fan dipoles work better in my experience and
have a useful and predictable pattern but take more work. TANSTAAFL per
Robert Heinlein. The G5RV ladder line to coax splice has been a
reliability problem, especially when a balun is added to keep the RF off
the coax. b.t.w. the DX Eng ladder line and center insulator for same
are a joy to use and well thought out.
RE the "old old timers" not caring about SWR, 100% modulated AM at 1kw
into a 10:1 SWR would present quite a voltage challenge to an ATU, the
coax, balun, and connectors. I remember arc's in my air core B&W balun
at two hundred watts AM out of a Johnson Valiant.
Last time I ran full power into a store bought "full legal limit rated"
G5RV the coax failed, so no QRO operation for them. The instructions
said "full legal limit", I thought a suspect claim, so I called the
manufacturer, and they said "no problem". Stupid of me to have
believed them. Caveat emptor for most antenna manufacturer claims!
Grant KZ1W
On 2/2/2011 6:59 PM, Barry Kirkwood wrote:
>
> snip
>
> Once a generation of amateurs who had happily used open wire feeders and who
> gave not a damn about SWR had gone to the great ham shack in the sky, or
> converted to txs in tin boxes that had coax connectors on the output, things
> changed.
>
> Low SWR became all the rage. Gentlemen even wrote learned articles reporting
> studies where G5RV like dipoles had their dimensions tweaked in an endeavour
> to get something like 50 ohms non reactive at the feedpoint. 15m was always
> a problem but, hey, the thing had never been meant to work on 15.
>
> Bit like the search for the Philosopher's Stone or the Lost Ark.
>
> Seems like this tradition is alive and well today right here on Tower Talk.
>
> My advice:
>
> Relax!
>
> Build the G5RV to a reasonable approximation of the original design. If you
> want a balun wind say 10 turns of the coax around a 100mm/ 4 inch plastic
> pipe before hooking it on to the bottom of the balanced line. Back in the
> shack , see what you get. If necessary use an ATU to get the antenna to suck
> power.
>
> Then enjoy amateur radio. Chances are you will be pleasantly surprised by
> the performance of this modest antenna.
>
> 73 es gl
>
> Barry ZL1DD
>
>
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