[1000mp] Linear Amplifier TL922A

[Tom Rauch]

> Can't but agree on the TL922 bandswitch problems--we have one at the
> Historical Amateur Radio Club station (W3GR) and the switch contact is
> nearly completely burned out on ten.  Hard to replace yourself, and
> expensive to have done.

Virtually all TL922 switch failures can be traced to one of three 
problems.... either relay timing in the relay contacts, momentary 
loss of proper load, or improper tuning.

Of course the failures all center around the bandswitch being the 
lowest voltage breakdown component in the tank. What you really 
want is something large that can take a momentary arc being the 
weakest part, not something as fragile as a switch contact.

(I'd add an intentional spark-gap from the tuning cap stator lug to 
ground, perhaps something like heavy #8 wire or a thick metal 
bracket. Set the gap so it is as close as possible without arcing in 
normal operation.) 
73, Tom W8JI
W8JI@contesting.com