[Kenwood] TS930/940 PA modules.

[Cleeve]

I have recently been involved in making one decent TS930, from a pair
of partially working units....in fact they both work now !!! The
problems were PA and driver related, and also that the Motorola driver
and PA transistors are now obsolete, and no longer manufactured.
However, there are still stocks available from some Motorola  suppliers,
and I got both the driver transistors, MRF485, and PA transistors,
MRF422 (sold as a pair) from Kenwood EU, who had to get them from
Kenwood Japan. The MRF485 cost 21.82 pounds sterling each, plus a UK
sales tax, and the MRF422 cost 132.77 pounds sterling for the pair, plus
the UK sales tax, which is 17.5%. For comparison, the current cost of a
used 930/940 in good condition is around 500 pounds sterling.

	My thoughts are, that as stocks of these transistors diminish, their
price is going to escalate, possibly making the repair of "over
stressed" examples of both the TS930 and TS940 a very costly exercise.
If we reach this stage, there may well be many examples of these
transceivers, with working receiver sections, and "duff" PA modules. My
question to the group, is, does anyone know of, replacement driver and
PA transistors, which could be used in the original PA module, or, of
any work that has been done commercially, on the design, and production
of a replacement PA module, using more up to date devices, mosfets etc. 

	As a CW operator of some 50+ years experience, I would say that the
TS930/940 transceivers were the benchmark of their day, and still remain
in the league of "ultimate" rigs, for the CW operator today. It would be
a shame to consign such rigs to the scrap heap, for the lack of
affordable spares. Sincerely, John. G3JVC.