Good afternoon, Byron:
I haven't spotted a source of the transistors you need, but you may wish to
keep your eye on the Antique Electronics Supply web page (www.tubesandmore.com
<http://www.tubesandmore.com> )
They have been adding at some germanium devices to their offerings.
73,
AA2PM, Paul Mondok
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-----Original Message-----
From: TenTec [mailto:tentec-bounces+aa2pm=earthlink.net@contesting.com] On
Behalf Of Byron Tatum
Sent: Monday, March 14, 2022 10:10 PM
To: tentec@contesting.com
Subject: [TenTec] Model 315 Receiver
I received no replies to my post regarding the transistors in the Model 315
receiver. I am speaking of the A138, A154, A2739 and BC418B devices. In trying
to find data on them it appeared some were germanium devices. I looked at the
Argonaut #505 schematics and found some identical circuits (exact same resistor
and capacitor values) as used in the Model 315. An example is the IF
Amplifier, the model 315 Q-1 uses a A154 as IF amp and the model 505 uses a
2N5134 (silicon device). The dual transistor Q4-A,B in model 315 is an A2739
however in the model 505 each corresponding transistor is a 2N5133 (silicon
device). This continues throughout the comparisons of model 315
identical circuits to model 505 ones, in general the A138 was replaced by the
2N5133 or 2N5134. The A154 was replaced by the 2N5128 and the A2739 by a pair
of 2N5133.
I would surely like to hear from someone who has knowledge of these
transistor types and what the ones in the model 315 are. I have gone into my
model 315 and sure enough the devices are all just as shown on the schematics.
I am curious about the logo on these transistors, all three part numbers have
the same logo stamped on them. It is the capital letter A inside of a diamond.
The A138 is a black epoxy appearing case (gold leads), the A154 is a white
ceramic appearing case and the dual unit A2739 appears as a metal can TO-39
size case.
Thank you,
Byron W5FH
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