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Re: webpage



Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi Paul!


My, I bet that was some EME setup!

Date: 11 January 2001 15:26
Subject: RE: webpage


>Original poster: "by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <paul-at-abelian.demon.co.uk>
>

>VSWR isn't an issue - the lengths of feeder required are
tiny compared
>to the free space wavelength of TC frequencies, so no need
to make the
>same allowances as you would at HF. The characteristic
impedance of
>the cable is irrelevant for the same reason.
>


That's a fair point and one I'd not considered . . . OK, so
heating losses allowing, we can run our RG213-U at 5kV less
allowance for spiky damped waves! But there will still be
more volts than there ought to be if the tapping point on
the secondary is off, e.g. 100 ohms instead of 50 ohms, and
any serious mismatch there will have repercussions on the
loaded Q of the link coil which is calculated for a 50 ohm
load.  In view of the very sharp tuning I've found (not a
surprise) I'm currently thinking of digging out my old 6L6
rig and - suitably modified -using it as a booster for the
signal generator to help set the thing up - having a "power
signal generator" of say 10-20W will make the tuning a *lot*
easier.  QRP-ing a spark transmitter I have found to be less
than straightforward ;-)

>I've seen RG8 and N type connectors used for a few tens of
kV quite
>successfully, although you have to watch out for that
metallic dust
>that falls off the plating and spreads across the PTFE
bits - some
>risk of explosive failure if there's a lot of stored energy
behind it.


I hadn't actually intended using any connectors, well maybe
4mm plugs, but that's worth watching, as of course are those
nigh-inevitable loose strands from the braid which almost
always manage to winkle their way inside the plug :-o

Dunckx