>
>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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