MPSA42 Transistor in Linear circuit (HX-1681)

[George Gleim]

Hello Green Guys,

I have another question that I'd like to put to the group if you don't
mind.  In the Heathkit HX-1681, there is a transistor (Q-411) that
provides a path to ground and triggers the T/R relay in the Linear Amp.
The transistor is a MPSA42.  I found out that this transistor can handle
the relay in my Ameritron AL-811 Amp just fine (24 volts, 100 mAmps) but
cannot handle the 130 volts 100 mAmps required by my Heathkit SB-230
Amp.

I know that I can install a more  robust switch like the SoftKey
modification that Harbach sells (www.harbach.com) but does anyone know
if I can simply replace the MPSA42 with a different transistor to
achieve the same result?

And, does anyone know where I might find a replacement MPSA42
transistor?  (Dan's Small Parts doesn't carry it, nor does SS of NE,
Radio Shack...)  I may have damaged the currently installed transistor
during my testing.

Thanks much folks!

George

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