How do you know it was a VHF parasitic?
What were the circumstances of the event?
On 2/13/2011 7:44 PM, Hal W5GHZ wrote:
> My AL811H just went into VHF parasitic oscillation and took out a brand new
> set of
> 811A's, plate choke, several capacitors and a couple of resistors and the
> fuses. This
> is the second time this has happened. Guess it is time to rebuild this amp
> from the
> ground up with all of the new parasitic supression techniques and an enhanced
> supply (six filter caps instead of four). I will also be putting in the
> I have an old Heathkit SB200 and with new tubes and it easily puts out 900
> watts into a
> 50 ohm dummy load with the currents all in spec. However, I run it at 600
> watts. The
> AL-811H used to run 800 watts until it started acting like a two meter MPO.
> Hal W5GHZ
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