IP-27 Transistors

[Bob & Bettina Groh]

There might be one 'bug' in the ointment when switching silicon for
germanium - the Vbe's are quite different (roughly 0.3 v for germanium
vs. 0.7 v for silicon).  Depends on how hard they're driven, etc but
that is a rough order of approximation.  Point is that the base drive
may be a little anemic.  Not quite sure what the driving circuit is like
but you might have to do a little juggling around.  You can also have
problems with unmatched transistors, saturated transformers, etc.  I
have a few battle scars from struggles with exactly such conversions.
Certainly worth a try and it might work great.  Will be glad to help if
I can.

73
Bob Groh, WA2CKY

Mark Graalman WB8JKR wrote:
>
>  Hi Greg,
>
>  Those are germainium but I see no reason why silicon
> units wouldn't work. Any silicon with TO-3 case,
> col E rating of about 70 v and 5 to 10 amps with a Hfe
> of at least 80 should work fine. Actually, a 2N3055
> would probably work.
>
> BTW, the 2N301 crosses to a ECG 121
>
> Mark  WB8JKR
>
> On Tue, 1 Oct 2002 17:49:50 -0700 Greg WB8NGA <greg at BOWSER.COM> writes:
> > Just wondering if someone knows of a good replacement
> > for the two series pass transistors for the IP-27 power
> > supply?  Mine are 2N301's but they aren't being made
> > anymore.
> >
> > Thanks in advance,
> > Greg
> >
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