[Heath] The Heathkit IP-27

[Kenneth G. Gordon]

On 6 Jun 2012 at 10:08, Ron wrote:

> I have an IP-20 (which is similar), with bad Ge output and driver
> transistors. Replacing the transistors turned out to be more expensive
> than the supply was worth. I tried replacing with Si PNP transistors,
> but these failed almost immediately. I should analyze the design to
> see what mods were necessary to support Si transistors, but never had
> the time.
> 
> I suspect that restoring these supplies is not worth the expense
> and/or the trouble. If you discover otherwise, I'll be grateful for
> your comments.

I suspect you are correct about the worth of this idea. 

However, I am very interested in learning what would be necessary to 
convert such a device over to Si NPNs  (not PNP).

So far, the big difference is the Veb which can be quite "high" in Ge, but is 
much lower in Si: 20 V vs 2 V for instance.

Well, I have enough other projects to keep me busy for a long time, so this 
will probably go on the back burner for a while.

Thanks for your input.

vy 73,

Ken W7EKB