[Lowfer] Re: Amplifiers for 136k

[Bill Ashlock]

Johan and all,

My exciter tests last night indicated similar coax matching characteristics 
as with the loop PA the night before. In testing I have found the following 
to be true which was not evident before:

1) When one drives a coax with a 0 ohm source the load at the other end has 
to be really close to the Z of the coax or the waveform becomes very 
distorted. This applies even when the wavelength of the signal is 50 times 
longer than the length of the coax.

2) The sensitivity to load mismatch drops off as you add series resistance 
to the driven end up the the Z of the coax.

3) The emitter follower complementary driver (emitters tied together) is a 
bit less forgiving to coax mismatch than the common emitter complementary 
driver (collectors tied together). It is MUCH less forgiving to an 
accidental short circuit of the output.

Bill A

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