[AMPS] parasites prove it?

[Rich Measures]

>
>Has anyone tried lining the input or output cavities of PAs with the
>"lossy" material used in anechioc chambers to suppress RF reflections?

€  I recommend using a 3" dia. resistance-wire suspended loop to dampen 
the output compartment resonance, esp. in the TL-922, 3K-A and 2K-4. 

>The effect is to reduce the "Q" of the cavity, so that instead of
>reducing the series "Q", as applied in nichrome wire transmission leads,
>etc.(and which might reduce power slightly by introducing series loss in
>the tuned circuit), the overall cavity "Q" is reduced, thus greatly
>damping any oscillatory tendencies. If this works, the reduction in "Q"
>is free/lossless.

€  However, one would still have to deal with the anode-circuit resonance 
itself.  
>
-  cheers, Ian
>
>> .  One problem with conducting such a test is that parasites do not 
>> always cooperate.   However, with a sample/hold spectrum-analyzer, it 
>> would be possible to show that the amplitude of damped-wave VHF ringing 
>> in the anode-circuit of a HF amplifier is reduced by decreasing VHF-Q.
>........


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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