[Fwd: Re: [HEATH-TEMPE] IG-18 Mods]

[Ron]

Looks like the original transistors specs are 80V, 1A. The
circuit is powered by 43V Typical (46V max.), so the absolute
minimum Vce of replacements (taking turn on transients into
account) should be in the 50V range. Even though actual
current is quite low, high current capability (meaning,
large collector area) will give you better thermal stability,
even at low currents.

In addition, you want the replacement transistors to be of high
hFE (to alleviate the mod of adding an emitter follower to Q3).
This last requirement rules out the ridiculously expensive NTE
transistors. I think the 2N5087 is an even worse choice
(Ic=50mA).

You may wish to view the Fairchild KSB1116 and KSD1616. Mouser
price is 10 cents and 9 cents respectively. One can buy 10 each
and match a pair. If you do, note the different TO-92 pinout.

-- Ron



Charles W. Morehouse wrote:

> Hi All,
> Well after some research, The RCA transistors, 40361, 40362 and 40408 
> are no longer around.  They cross to:
> 40361 = NTE128 = Mouser 526-NTE128  $2.03
> 40362 = NTE129 = Mouser 526-NTE129 $2.71
> 40408 = NTE129 also
> I decided to replace the original filter caps with 1500 uf units of the 
> same mounting.  Hate to tack components under the board.
> Luck, 73.
> Wayne;
> W4GBW,

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