[Lowfer] Amplifiers for 136 kHz

[Bill Ashlock]

>Why would he loose a couple of DB by using a feedline on 136kc??? The >amp 
>and antenna will work just like any other amateur band amp and >antenna. 
>Match the output of the amp to the feedline and the antenna >to the 
>feedline. The amp is just going to have a lowpass filter that >is designed 
>to present 50-ohm output impedance to the feedline across >a certain 
>bandwidth that the builder will select which of course will >be the whole 
>136kc amateur band. Am I missing something?

I think you are basically right on this Mike as long as the band is only 2k 
wide. One difference between the typical amateur application a what we are 
doing is the near-0 ohm output Z of complementary stage. However, one should 
be able to use a three-component 'T' filter with one inductor in series with 
the transmitter and the other in series with the coax - the capacitor in the 
middle to ground. This what Lyle uses in his "Simple Lowfer Beacon" design 
but the component values must be selected for the exact frequency of use.

The reason I gave up on this type of matching between exciter and the woods 
final, 3 years ago, was the need to cover at least 15k without additional 
tuning. The waveform out of the filter gets real whacky when you get much 
off the designed frequency. I couldn't afford to add additional 2db 
variables in the quest to learn all I could about these "useless" antennas - 
right Jay? :)

Bill

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