>Subject: Re: 3-500Z/ G
>Sent: 3/30/1997 7:20 AM
>Received: 3/30/1997 7:32 AM
>From: Carl, km1h@juno.com
>To: measures@vc.net
>
>
>On Sat, 29 Mar 97 20:06:01 -0800 Rich Measures <measures@vc.net> writes:
>>>Subject: Re: 3-500Z/ G
>>>Sent: 3/29/1997 5:33 PM
>>>Received: 3/29/1997 6:46 PM
>>>From: Carl, km1h@juno.com
>>>To: measures@vc.net
>>
>>>the Ameritron Pi-L . My own theory is that network is the cause of
>>the
>>>problem.
>>Which problem?
>
>The AL-82 propensity to blow tubes, bandswitches and plate chokes. I only
>appears when the amp is used on 160 to 40M where a Pi-L is used in place
>of the straight Pi on the other bands. It does not happen with the
>AL-1200 or AL-1500, just the AL-82.
How are the tubes being blown, Carl?
What is the breakdown v of the AL-82 bandswitch? Is the AL-82 bandswitch
similar to the AL-80 bandswitch? Have you measured the resistance of the
VHF suppressor resistors (Rs) in an AL-82 whose bandswitch arced? In the
AL-80?
In the AL-80, Rs, damage is often not visable--even though an ohm meter
test indicates a large change in resistance. IMO, when HF (10m/12m
mainly) damages Rs, external signs of overheating are apparent. However,
intermittent VHF parasitic oscillations are so brief that external damage
is seldom visable. I have seen suppressor resistors that appeared to be
shiny-brandnew , whose resistance suddenly quadrupled some time around
the occurrence of a 'big-bang'. ..
It seems me to that a HV-RFC fire or arc on 160m, 80m, or 40m is quite
unlikly to be caused by 160m, 80m, or 40m RF.
Rich
R. L. Measures,ag6k,805-386-3734
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