I recently got an Elecraft K2 going. I remembered I had bought a 405 amp at a
ham fest years ago but never tried it out so I fired it up with the K2. The
thing worked yielding 50 watts out for about one watt in! Then about an hour
later when I tried it again the RF sensing T/R delay circuit would not work.
It cuts on but will not turn off unless you turn the amp off. Apparently some
smoke escaped from a component in this circuit. :-) If any of you has
experience with this amp and can point me in the right direction on what to
check first it would be appreciated.
Once I get the amp working again I'm thinking it's needs an amp key circuit to
key the amp before the RF is sent from the exciter. I think someone has come
up with a circuit for this and used the Accessory 12v RCA jack as the input for
the amp key signal (12v removed from it of course), but I've not been able to
find any information about the mod on the WWW. As it is now, the RF from the
exciter keys the amp so it shortens the first element of the first letter sent.
Of course if I do that I'll need to add an amp key circuit to the K2 also
because it does not have one. Another mod that would be helpful would be an
attenuator on the input to prevent me from hitting it with the full 10-15 watts
the K2 produces. That might release more smoke. Any help along these lines
would also be appreciated.
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