Or better still, Shorten the L until it is self resonant at 1.9mhz, thereby
lowering the amount of horizontal polarisation. Then use a simple hairpin
coil across the feedline typically around 5microhenries. This will then when
chosen correctly match at your chosen ideal spot say 1825.
And provide a DC short to ground for the antenna. No Caps needed. 73 Clive
GM3POI
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tom
Boucher
Sent: 02 September 2018 18:20
To: 160 reflector
Subject: Topband: Air wound coil
Bob W7RH - you don't need expensive hard-to-find vacuum capacitors to match
a quarter wave 'L' or 'T' on top band. I use cheap multilayer high voltage
disc ceramics and these have been working perfectly at QRO levels with my
inverted 'L' for years.
I use 1600pF made up from 1000pF + 470pF + 220pf all rated at 6.3KV and
available (over here) from CPC at less than $4 for 10.
Antenna is slightly longer than a quarter wave so it is inductive and the
capacitors form the other part of the L-match network.
73,
Tom G3OLB
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|