On 11 Oct 2005 14:03:55 -0700, wrote:

A radio that needs 16A in operation, but 25 during tune is a
pain in the butt on a nominal 20A power supply with over current
protection that kicks in above 22A!

Myself, I never tune using full power. With my 706g, I either
put it on "AM", or reduce the drive to a pretty low level. I did the
same on my 730. Only with a good match would I ever test full
power output. I do the same with my tube TS-830.. heck, actually
any transmitter... :/

Quite wise.

Nevertheless, large currents are drawn by some radios in low power.

For example, I owned a Alinco DX70-TH and their EDX-2 autotuner. When
it autotuned, the tx power was reduced to about 10W out, but it still
drew in excess of 20A tuning into some loads on some frequencies...
which would trip the overcurrent protection in one of my power
supplies, so it was unusable on that power supply.

People do rough tune radios on full power, and I, like yourself,
question the wisdom of that practice.

I designed a device to make manual low power tuning with an IC706x
more convenient ( http://www.vk1od.net/IC706TuneMate/IC706TuneMate.htm
). It has been interesting that almost all of the feedback that I have
received on the article is from screwdriver antenna users who insist
that it is absolutely unecessary, they tune their screwdriver for
maximum RF Po indication on the IC706x meter using full power in RTTY
mode. (Achieving high RF Po indication depends indirectly on low VSWR
because of the PA load protection scheme.)

Owen
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