[ETO_Alpha] Alpha 89 Question

[Chris Codella, W2PA]

Bob,

D9-13, the receive diodes, are relatively cheap, $12 each, but D1-2, the 
transmit diodes, are expensive at $125 a piece, if I recall correctly.  
All are available from Alpha.

They are reliable unless you abuse them.  The one case I've run into 
myself was accidentally transmitting into the amplifier with about 100W 
of RF with the amplifier in "OPR", but without triggering the keying 
line.  This ruined one of the expensive diodes, one of the cheap ones, 
and the fuse F1.  The transmit diodes are tricky to replace without the 
jig that Alpha uses, but it can be done.  The receive ones are easy.  
Apparently the weak link here is reverse-biased transmit diodes. 

Other than that, my 89 has been very reliable - still running the 
original 1994 tubes which seem to be at full strength.  I use QSK almost 
all the time on CW and the PIN diode switching makes it completely silent.

73,
Chris, W2PA