A few years ago while tackling the design error
in the "Transmogrification of Blind Joe Death"
conversion of the ETO Alpha 77dX into the 77sX,
I had a chance to speak with several of the original
designers of the 77 series, and talked about
T/R switching.
If any of you remember, the scheme in the 77dX
was a MagnaCraft reed relay mounted on a
small PCBd in the plenum, and a Jennings
RJ-1 for the output, with the coil termianls right near
the input relay PCBd, with some passive
components nearby. The 77 series published
a "50 WPM" QSK ability.
Asked about PIN diode design, the concensus
was that RF feedback in mistuned situations reduced
the MTBF. Seeing as how there were non-amateur
service applications for these amplifiers the
reliability factor must have been very important.
Alpha began using PIN diodes later in life, did they not?
Any reports on that picture of reliability?
Hal
W4HBM
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