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Old November 30th 15, 11:51 PM posted to uk.radio.amateur,rec.radio.amateur.antenna,rec.radio.amateur.homebrew
Michael Black[_2_] Michael Black[_2_] is offline
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First recorded activity by RadioBanter: Mar 2008
Posts: 618
Default High power tuning caps?

On Mon, 30 Nov 2015, gareth wrote:

As we seem to be winning the battle in part against the ne'er-do-wells
and their attention-seeking gratuitously abusive personal attacks, what
technical
matters can we discuss today to keep the momentum going?

How about is anyone still making their own wide spaced tuning caps for their
ATUs by
lots of shaped aluminium (aluminum to the Yanks) plates, or has the Cheque
Booker's (CBers)
approach of using auto ATUs taken over?

Nobody has yet come up with a replacement for high voltage variable
capacitors, so they still have to be made. It's low level capacitors that
are getting scarcer.

But I'm not sure that's a reality. I scrapped some old tube two-way radio
strips a few weeks ago, realizing I'd never use them, and got some
variables from that. There is still lots of equipment out there that can
offer up variables, though maybe not high voltage ones. Keep an eye out
for old radios, grab the variables from them if nothing else.

There may be enough high voltage variable capacitors out there for those
who need them. It's just a matter of shaking them out of someone's junk
box.

There have also been some articles in the past (maybe recently but I
haven't seen any ham magazines up close in a long time) about making your
own high voltage variables. And int he early days of radio, there were
aritcles about making variable capacitors (albeit for non-power
applications), so looking for those will likely offer up some useful
details.

Transmitting loops need high voltage caps, so that's where some of the
build it yourself information resides.

Michael