[Heathkit] Final transistors for Heath SB 104A

[Ulrich Graf]

Hello John,

I had the same problem after the series transistors in my power supply
failed and the PA-transistors could not handle the overvoltage. After quite
a long search for substitutes I decided to redesign the PA. I used two
MRF454s for the new design. You may find an appropriate application from
Mororola (AN 762). Unfortunately you will need a new pcb. I described the
complete restauration and upgrade of my SB-104 on my website
www.dk4sx.darc.de
in the chapter "Restauration". It is very detailed and almost all modules
are involved. But the result is stunning. Even though you will not see any
changes from the outside I got a great middleclass transceiver with actual
technical performance now.

Vy 73,

Uli, DK4SX

2014-11-24 20:41 GMT+01:00 John King via Heathkit <heathkit at mailman.qth.net>
:

> I have learned that the 2n6456 final RF transistors are no longer
> available and I NEED to replace the four (4) in a Heath SB 104A. Has anyone
> found a suitable replacement transistor for this application? I have
> thoroughly checked with RF Parts and they no longer stock those transistors.
>
> Does anyone have experience substituting the final transistors in the SB
> 104A? If so what did you use as a replacement  and do you know where they
> can be found? Thanks and 73, John, K5PGW
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