[Amps] Checking for IMD

[Colin Lamb]

>Also there is a basic flaw with two-tone tests. Two-tone 
>tests don't vary the power supply loading like a voice 
>signal would. 

Two-tone tests should be ok for testing the difference between tuned and no-tuned cathode input, since we are not testing the power supply dynamic qualities in this particular test.  The test is simply whether there is an improvement in distortion by the use of the tuned input.

Setting up the test as Tom suggests - to eliminate variables in the exciter - will give us meaningful data for the amplifier, but it may not give us meaningful data in the real world.  A real world test would be to use various exciters, various line lengths and various bands - then record the worst cases with and without the tuned input.  The true difference between tuned and untuned input might be the comparison of worst cases, rather than the comparison under ideal conditions.    

Colin  K7FM