What Germanium PNP transistor do I use?

D

[email protected]

Jan 1, 1970
0
What Ger PNP transistors do I use for the following circuit in a
radio: HF AMPLIFIER, MIXER; LF AMOPLIFIER, DRIVER and AUDIO OUTPUT?

Does anyone know whether the numbers of the trasnsistors are
standardized? Or each manufacturer use its own? It seems that there
are tons of numbers out there such as 2N107, 2N239, 2S678, etc.......

God Bless!

Daniel

M

Michael Black

Jan 1, 1970
0
What Ger PNP transistors do I use for the following circuit in a
radio: HF AMPLIFIER, MIXER; LF AMOPLIFIER, DRIVER and AUDIO OUTPUT?
You don't.

Germanium transistors were pretty much obsoleted forty years ago, by
silicon transistors. There is a far better range of silicon transistors,
and generally they have far better specs than germanium transistors.

The only reason you'd use a germanium transistor at this time is if
there was a specific reason for using germanium. There are still some
things where germanium transistors can be useful, which is why some
are still being manufactured, but the average hobbyist wouldn't have
need for those uses. And there is no reason to use germanium transistors

If you are looking for germanium tranistors because you have a schematic
that uses them, and then you can't find the devices specified, it's because
the schematic is decades old and you need to drop that schematic and
find soemthing more modern, than try to find germanium transistors
to use in the schematic.

The reason some of us have germanium transistors lying around is because
we accumualted them decades ago, when they were still common. Beyond
taht, you'll have to go out of your way to get them.

Michael

I

ian field

Jan 1, 1970
0
Michael Black said:
You don't.

Germanium transistors were pretty much obsoleted forty years ago, by
silicon transistors. There is a far better range of silicon transistors,
and generally they have far better specs than germanium transistors.

The only reason you'd use a germanium transistor at this time is if
there was a specific reason for using germanium. There are still some
things where germanium transistors can be useful, which is why some
are still being manufactured, but the average hobbyist wouldn't have
need for those uses. And there is no reason to use germanium transistors

The OP might want to preserve originality while repairing an old radio,
otherwise I'd select a fairly ordinary silicon PNP type and tweak the bias
if necessary.

C

Chris

Jan 1, 1970
0
What Ger PNP transistors do I use for the following circuit in a
radio: HF AMPLIFIER, MIXER; LF AMOPLIFIER, DRIVER and AUDIO OUTPUT?

Does anyone know whether the numbers of the trasnsistors are
standardized? Or each manufacturer use its own? It seems that there
are tons of numbers out there such as 2N107, 2N239, 2S678, etc.......

God Bless!

Daniel

Hi, Daniel. I've got to assume you're working with an existing radio
circuit, probably an older one made in the 1960s when germanium PNPs
and negative supplies (positive GND) ruled the earth. Those were the
days.

Here's the drill. Find the standard JEDEC 2N number, either in the
schematic or printed on the body/case of the transistor. Then go to

http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/Search?OpenForm

and type in the manufacturer part number for the transistor. The NTE
cross reference will probably work for you. NTE parts are available
at many different places, including many TV/radio repair shops. You
can also get these online at many places. You can go to their main
page:

http://nteinc.com/

to find a distributor.

Good luck
Chris

J

Joerg

Jan 1, 1970
0
Michael said:
You don't.

That's right, unless it's hobby and there are tons of them in the box.
My favorites were AC127 for audio, AF126 up to FM band, and AF239 for
the really hot stuff.

Germanium transistors were pretty much obsoleted forty years ago, by
silicon transistors. There is a far better range of silicon transistors,
and generally they have far better specs than germanium transistors.

The only reason you'd use a germanium transistor at this time is if
there was a specific reason for using germanium. There are still some
things where germanium transistors can be useful, which is why some
are still being manufactured, ...

Where? Where? <drool>

All I've found so far was new old stock so it can't be used in any new
design. Ge would be really handy for very low voltage applications such
as starter circuitry for a single fuel cell converter.

... but the average hobbyist wouldn't have
need for those uses. And there is no reason to use germanium transistors

If you are looking for germanium tranistors because you have a schematic
that uses them, and then you can't find the devices specified, it's because
the schematic is decades old and you need to drop that schematic and
find soemthing more modern, than try to find germanium transistors
to use in the schematic.

The reason some of us have germanium transistors lying around is because
we accumualted them decades ago, when they were still common. Beyond
taht, you'll have to go out of your way to get them.

And that accumulation habit has rescued my old Minolta camera where I
really needed a Ge diode. The old OA91 works like a champ after being

M

Meat Plow

Jan 1, 1970
0
The OP might want to preserve originality while repairing an old radio,
otherwise I'd select a fairly ordinary silicon PNP type and tweak the bias
if necessary.

I've repaired several old time transistor portables using germaniums
scavaged over the years from all sorts of 60's portable crap. And that
relates a lot with how I got my start with this stuff back in the
60's. But I agree that if this is an experimental or kit that the OP needs
to find something more current dated unless he's just into that kind of
stuff.

D

[email protected]

Jan 1, 1970
0
Michael:
Thanks for your education. But I have an old 4-transistor superhet.
want to build this radio. So I want to find out what Ge transistors I
knowledge is severely limited, but I know the first transistor is very
different from the
last two (a pair) that do the audio output job.

Best! Daniel

D

[email protected]

Jan 1, 1970
0
Thanks, Chris, for your help. I tried the Web sites. Fantastic!
Best! Daniel

P

Phil Allison

Jan 1, 1970
0
<[email protected]
Thanks for your education. But I have an old 4-transistor superhet.
want to build this radio. So I want to find out what Ge transistors I
need.

** You will have to post that schematic somewhere.

BTW

Why are no transistor numbers on it?

...... Phil

H

Homer J Simpson

Jan 1, 1970
0
Michael:
Thanks for your education. But I have an old 4-transistor superhet.
want to build this radio. So I want to find out what Ge transistors I
knowledge is severely limited, but I know the first transistor is very
different from the
last two (a pair) that do the audio output job.

Where will you find the other parts? Loopstick, tuning capacitor, IF
transformers and audio transformers?

http://www.rpelectronics.com/Defaul...ail=/English/Content/Divisions/Div_95_650.asp

D

[email protected]

Jan 1, 1970
0
Phil said:
** You will have to post that schematic somewhere.

BTW

Why are no transistor numbers on it?

..... Phil
Phil:
The only information on the schematic about these transistors are HF
andOscillitor, IF,
Driver, and Audio Output. Thanks! Dan

D

[email protected]

Jan 1, 1970
0
Where will you find the other parts? Loopstick, tuning capacitor, IF
transformers and audio transformers?

P

Phil Allison

Jan 1, 1970
0
"Homer J Simpson"
Where will you find the other parts? Loopstick, tuning capacitor, IF
transformers and audio transformers?

** I can see those question coming at us like an express train down a
tunnel.

...... Phil

P

Phil Allison

Jan 1, 1970
0
<[email protected]
The only information on the schematic about these transistors are HF
andOscillitor, IF,
Driver, and Audio Output. Thanks! Dan

** So you are refusing to post that schem ?

Or explain where it came from ?

........ Phil

D

Jan 1, 1970
0
D

[email protected]

Jan 1, 1970
0
Phil said:
** So you are refusing to post that schem ?

Or explain where it came from ?

....... Phil

*****Oh no, Phil. Not at all. But I have no idea how to post it
online. Am I supposed to
scan it in first? Or....? I got the schematic from a old dairy kept
by my uncle. He passed
away years ago. He was an electrician and a radio hobbist. I guess he
kep the schematic
himself for a long time, or perhaps he once wanted to buid it himslef,
but did. Now my
kids are interested in building it. Best wishes to you! Dan

P

Phil Allison

Jan 1, 1970
0
*****Oh no, Phil. Not at all. But I have no idea how to post it
online. Am I supposed to
scan it in first?

** That would help.

Then get a real news account instead of the Google abortion you are using.

Then you can post it on ABSE = " alt.binaries.schematics.electronic"

Or....? I got the schematic from a old dairy kept
by my uncle. He passed
away years ago. He was an electrician and a radio hobbist. I guess he
kep the schematic
himself for a long time, or perhaps he once wanted to buid it himslef,
but did. Now my
kids are interested in building it. Best wishes to you! Dan

** Good thing it was not a plan for a moon rocket......

....... Phil

H

Homer J Simpson

Jan 1, 1970
0
*****Oh no, Phil. Not at all. But I have no idea how to post it
online. Am I supposed to
scan it in first? Or....? I got the schematic from a old dairy kept
by my uncle. He passed
away years ago. He was an electrician and a radio hobbist. I guess he
kep the schematic
himself for a long time, or perhaps he once wanted to buid it himslef,
but did. Now my
kids are interested in building it. Best wishes to you! Dan

You cheapest source would be a \$5 radio from Wal-Mart.

C

Chris

Jan 1, 1970
0
*****Oh no, Phil. Not at all. But I have no idea how to post it
online. Am I supposed to
scan it in first? Or....? I got the schematic from a old dairy kept
by my uncle. He passed
away years ago. He was an electrician and a radio hobbist. I guess he
kep the schematic
himself for a long time, or perhaps he once wanted to buid it himslef,
but did. Now my
kids are interested in building it. Best wishes to you! Dan

Hi, Dan. I like the idea of working from the diary to discover what
your uncle was thinking. But there are a couple of gotchas here.

First off, many ideas jotted down in notebooks aren't really
complete. I know many of mine aren't. He may have been just writing
in an idea to fill out later.

Also, an old AM radio design with less than 5 transistors is probably
taking a shortcut somewhere. Not necessarily a bad thing, but even if
it's a guaranteed working circuit he just copied down, it's probably
relying on a trick we'd have to see to evaluate choice of
transistors. I'd hate to see you and the kids go to the work of
trying to put something together from scratch and have it fail because
of some free newsgroup advice. ;-)

As a bonus, layout in RF circuits is pretty important, to prevent
unwanted oscillations in the amplifier stages. Working from a
schematic only, as a relative newbie you might end up going down a
rabbit trail there, too.

guaranteed to work and provide a good educational experience. You
could do worse than getting the Elenco AM-550TK (5 transistor, no ICs,
old-style transistor radio kit with good educational brochure
explaining the circuit), building it with the kids, and then raising a
glass to the memory of their dad's uncle when they turn it on and it
works. Similar in many ways, you get all the parts you need, almost
guaranteed success if you have any soldering and assembly skill, and
after you're done, you'll understand a lot more about his idea (and
possibly where the shortcut is).

http://www.elenco.com/

Good luck
Chris

M

Michael Black

Jan 1, 1970
0
Joerg said:
That's right, unless it's hobby and there are tons of them in the box.
My favorites were AC127 for audio, AF126 up to FM band, and AF239 for
the really hot stuff.
But otherwise, it's a question like "where do I get a tunnel diode, I want
to build this circuit I found in a book or on the internet...". And the
poster doesn't realize how old the schematic is, or that tunnel diodes
at their best were mostly a novelty (with some real exceptions) and for

In order to stick with the circuit, they will have to work really hard to
find a tunnel diode, and may pay good money for it. And before that,
they really should evaluate why they want to make that circuit. IN most
cases, it's because they don't know better (because they want to build
something simple, and it certainly is a simple circuit).
Where? Where? <drool>
I thought people talked about power germaniums still being made and used.
The talk would have been in one of the sci.electronics.* newsgroups sometime
in the past decade, but that's the best I can provide as a pointer.

Michael