radi...@aol.com wrote:
Hi Kevin,
I have confirmed that 2 of the 4 finals are bad. both are on one side
of the push pull. Both open base connection One has collector to
emitter short. The other open emitter.
I have not yet checked the drivers I might be able to test them
without removal. I have a friend trying to scare up a Mitrek
Aside from the transistors which I know are hard to find, and the
cooked 12 ohm resistors, Is there something else I need to look for?
I doubt it. Usually the resistors go because of the imbalance from one
or more of the transistors failing.
I recommend replacing all of the output together with matched gain
transistors, if you choose to repair the PA.
We think it was an intermittent Duplexer or antenna issue that caused
it to blow. We have since replaced the repeater, amp, and duplexer
but a desense condition has returned after a few weeks. The antenna is
a 4 bay folded dipole on a 100 foot tower. this Antenna replaced a
Stationmaster only about 3 years ago. Tower is Rohn 45? guyed with
Phillystrand.
Thanks for your help.
Marty
What kind of desense? Does the repeater properly duplex on a known good
dummy load?
Kevin
