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Old September 21st 04, 02:15 AM
John Steffes
 
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We use an antenna tuner to feed our W8JK antenna for use for shortwave
reception for two reasons:
1. The 8JK has a high impedence input so it is fed with 300 ohm ladder
line; thus the use of the tuner (in this case) acts as a balanced
transformer.
2. The 8JK was "cut" for 20 meters. For use on other frequencies, the
tuner acts (with adjustment) as a conjugate match that provides a 50 ohm
input to the receiver.

Results of the tuner appears to peak signal strength as the impedence of
the receiving antenna is transformed by the matching provided by the tuner.

Tuners are passive in nature; that is, they require no amplifier
electronics and associated power. They may be unbalanced input to
balanced output (or vice versa) or unbalanced to unbalanced
input/output. Preselectors on the other hand are active devices. They
vary in design and may provide matching as well as gain.

The selection of the device you choose will depend on the type on
antenna system you employ.

In any case, good luck!

John
Sanjaya wrote:
I've read and heard both sides of the argument about
antenna tuners being great, or not helping at all and are
a waste of money. I've been told they are only for shortwave
transmitting, and I've been told they work well to improve shortwave
reception on faint signals. I've had it suggested to me that I
get a pre-selector instead.

I can't find anyone who actually experimented with either a tuner or pre-selector... at least
none of what I've read and heard was stated as "experience"... rather
it seemed like theory or conjecture.

Does anyone here actually use a tuner or pre-selector for shortwave listening, and if so,
with what results? I'm looking at the MFJ-959C antenna tuner at
http://www.universal-radio.com/catal...amps/2574.html
Note that it says "for receive only".



 
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