[AMPS] parasitics

[Rich Measures]

>In message <19980421063130.AAD25156@[205.231.11.91]>, Rich Measures
><measures@vc.net> writes
>>At VHF, with a conventional Pi-output, there is No VHF load on the 
>>amplifier, even if a 50 ohm VHF-rated termination is connected to the 
>>output.  
>>
>
>Presumably the usual resistive suppressor in series with the anode only
>works to dampen the vhf resonance when the other end of the suppressor
>has reasonably low Z path to ground.
>
Indeed.  Perhaps it would be best to use two Tune capacitors in parallel, 
one variable and one fixed, to assure that the suppressor would always be 
sure to see at least one reasonably low Z path to ground.  

>Is there a case for adding a shunt suppressor load to cope with when
>there is a high Z anode load at vhf - a state where the voltage gain
>will be highest? 

This is essentially what the parallel Ls/Rs suppressor does when it is 
placed in series with the anode lead, however, to visualize it one needs 
to convert the Admittance [Y] of the suppressor (at the anode resonant 
frequency) to a parallel equivalent resistance [Rp] load on the anode. 
>.....


cheers
Rich...

R. L. Measures, 805-386-3734, AG6K   


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