[Boatanchors] Need help with Swan 14C

[Heinz und Hannelore Breuer]

Hello,

two weeks ago a posting by a well known ham appeared on various
boatanchor lists where a Swan 14C was offered. No condition was given
only that no cables are included. Well I should have asked ...

The Swan 14C is a DC Converter module which plugs into the Swan 117-X
power supply to use a Swan 500C transceiver and others mobile with a 12V
DC input.
The 14C was airmailed and arrived last week. It had pieces of plaster on
the outside as well as on the inside and far worse the original power
transistors had been replaced. The 14C originally used 2 transistors
type MHT 1840 which are rated 60A @ 45V and according to the Swan 500C
manual "are responsible for a large portion of the unit's cost. No
compromise has been made."
Well the power supply now has been hacked with 2 transistors 2N4279 and
so far I have not found any data for those. I also have not checked them
if they work properly as I could not confirm if they are able to handle
the current and I don't want to destroy them if they are still ok. 
According to the manual the 14C draws as much as 40A when the 500C is in
TUNE position. Normally it draws 9A in receive and an average of 16A in
transmit. Anyhow the way the transistors are mounted they will certainly
overheat or already have.

I contacted the seller and he said I should have asked details before
and that he had a more informative description on his website ...
Needless to say I was not aware of his website.
Anyhow if I get a pair of transistors capable to handle 40A and if the
transformer is still ok I could rebuilt the whole thing, repaint it,
exchange nearly every single screw and might finally enjoy my Swan 500C
in mobile operation.

I would appreciate any data on the old transistors type MHT 1840 and the
new ones 2N4279. Has anybody successfully replaced the transistors in a
Swan 14C and which transistor did you use?


73
Heinz DH2FA, KM5VT