Jerry,
There are a couple of legacy transistor manufacturers. One mostly for
ICs is Lansdale Semiconductors. Then there is the universal
replacements of NTE. There is in fact another industrial manufacturer
of obsolete transistors. It is Advanced Semiconductor Inc, and they
feature MRF parts. I think they were the folks who bought the drawings
and processes of Motorola RF division.
Note that MRF was a Motorola part, but Moto became Freescale
Semiconductor. I think the discrete products spun off as ON
Semiconductors. I see they are not listing RF but do list some types of
transistors such as drives.
There is a lot of surplus semiconductors languishing in warehouses, and
sometimes in old local surplus electronic parts houses of the few that
are left. You might make an effort to get spares which would enhance
the resale of your Corsair just to have a spare set of finals. If ever
you sold it. If you look in the boxes under hams' tables at swap meets
a lot of times you find discrete transistors and many hams don't realize
what they have in these old boxes.
You are right, many substitutions can be made for old transistors. Non
conventional solutions might even include paralleling multiple smaller
transistors in compact modules to replace a larger package. But, before
going that far, you likely can find a similar package NOS. (New Old Stock).
I think the web has a beautiful conversion of a Corsair or similar model
to a non PTO VFO. The Corsair has good "bones", and makes a worthy
conversion subject.
Stuart Rohre
K5KVH
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