Tim,
I Started using a parallel tuner , with a 4 gang tuning capacitor ,
this was fine up to about 45 watts , with the tx tapped 2 or 3 turns
up and the Ae fed from the top of the coil .. classic top band
tuner. Using my HF swr bridge. which actually works fine at 500 and
reads the correct power as well , I simply tuned for minimum reflected
power.
Then thanks to E-bay and others came powers over 100 mW erp and blue
lights from the tuner ..
At that point, the original coil, now with new pespex spacer's, the
ww2 (cellulose ?) spacers having burnt out ... I made a variometer
out of a length of brown drain pipe and some marly fittings from b&q
, the original coil is now tapped 7 turns up and acts as the feed
auto transformer ... this set up works well and will take 200 watts of
carrier , latest slight improvement was to tap the capacitor down the
coil and tune for minimal reflected power , good swr but requires a re
tune if I qsy more than 50% of the band ..may be too higher Q as the
tune changes with the wind blowing the wire about ....still use the swr
bridge, but take it out before running wspr ..
Its not what is in the air ...its what's in/is the ground that matters
GL - 73 - G ..
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From: "tim hague" <[email protected]>
Sent: Sunday, March 28, 2010 11:10 AM
To: <[email protected]>
Subject: LF: Antenna Matching
I'm just about to apply for my 500kHz NoV, I've got around 100W of Tx
power available and I'm looking for some information on antenna matching,
my Tx antenna is just going to be a 132ft Marconi T with a 50ft vertical
section, can I get away with just a series tuned matching cct or are the
voltages across my matching C going to be very high, I have a wide spaced
C approx 200 to 700pF.
Thanks Tim M0AFJ
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