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 Post subject: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 1:34 am 
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i have distortion in a nice little vintage portable GE am/fm radio.

it is aligned perfectly and the whole 6 electrolytic capacitors have been changed.

what are the chances of finding a good germanium 2SB187 nos ?

also NTE crosses that part to NTE158.

would a newer NTE be better to use rather than trying to find an original 2SB187 ?

steve

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Last edited by Dutch Rabbit on Sep Sat 05, 2020 2:09 am, edited 1 time in total.

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 Post subject: Re: GE @SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 1:51 am 
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Location: Mountains of Mourne. Ireland.
Data: https://alltransistors.com/transistor.p ... istor=9975

https://www.ebay.com/itm/121496571951


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 Post subject: Re: GE @SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 1:53 am 
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Others, lol
https://www.ebay.com/sch/i.html?_from=R ... 7&_sacat=0


:) Greg.


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 Post subject: Re: GE @SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 2:08 am 
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will a nos be defective since it is Ge ?

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 5:05 am 
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Location: Mountains of Mourne. Ireland.
Steve... you can read about your TO1 package transistor a third of the way down this page...
Problems with TO1 transistors
https://www.markhennessy.co.uk/articles ... istors.htm

if... yours has suffered from the tin wisker problem mentioned in the first part of Mark's article, you can "zap" them with a charged Electrolytic. Don't shock youself. lol


But... generally, germanium transistors are remarkably reliable.
I have oceans of radios all running on Ge transistors.
:) Greg.


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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 6:01 am 
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Not NOS nor tested, but the price is right. Can get them out sometime next week. PM your mailing address if you want 'em.


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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sat 05, 2020 6:52 am 
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ok, perfect, will pm addr on saturday.

thx,

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 12:32 am 
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i have this transistor tester.

will it check Germanium transistors for leakage and "goodness" ?

i've only used this probably twice in my life.

steve

https://www.ebay.com/p/1018296529

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 2:05 am 
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Here's a link to the manual for it; https://bkpmedia.s3.amazonaws.com/downl ... manual.pdf

It apparently does work on Germanium Transistors.

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 3:32 am 
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fifties wrote:
Here's a link to the manual for it; https://bkpmedia.s3.amazonaws.com/downl ... manual.pdf

It apparently does work on Germanium Transistors.

Yes I have one, measures leakage & if xistor operates the audio osc circuit, gain is considered OK. Does not give a actual gain reading. Other than leakage readings, does not match transistors.

One I have shorted it's 1000 mfd P/S caps, had to fix it before use.

For germanium I like the B&K 960 better, though now days usually requires a total restore. B&K used cheap resistors most are 40-50% off value. Isn't necessary to restore the tube circuitry, that's only for RF signal output(alignment).

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 6:35 am 
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35Z5 wrote:

For germanium I like the B&K 960 better, though now days usually requires a total restore. B&K used cheap resistors most are 40-50% off value. Isn't necessary to restore the tube circuitry, that's only for RF signal output(alignment).

I use my B&K 960 just for the generator function. I've had it for 15-20 years, and never opened it up. I've verified it's signal accuracy using the digital readout of my Sony ICF 2010, which has a long wave band, encompassing 455 kilocycles.

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 6:43 am 
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i will have to dig that tester out and see what it says. i have the manual and everything.

is there a good Si cross for the Ge 2SB187 ?

unlike tubes, i know very little about transistor specifications.

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 6:57 am 
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I think you're worrying for nothing. The Transistors you're getting should both be good.

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 7:21 am 
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not worried about them. i 'd like to see what mine does for the heck of it.

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 4:21 pm 
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Dutch Rabbit wrote:
i will have to dig that tester out and see what it says. i have the manual and everything.

is there a good Si cross for the Ge 2SB187 ?

unlike tubes, i know very little about transistor specifications.

steve

Silicon replacements bias differently than Ge. Probably 95% of time require other part values altered. Si also generally base differently & probably 99.99% will have higher gain, in some circuits can lead to birdies & other oscillations.

I have a P-780A converted to Si outputs, in this radio at least a 50% improvement over Ge. Of course it has a 5½" speaker, sets with 2" bumble bee in tin can speaker will never exhibit a difference. Radio is now a daily player.

viewtopic.php?f=4&t=377043

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 06, 2020 4:43 pm 
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yes, i did some research about the polarity and bias when going from Ge to Si.

i was just wondering if there was a quick drop in Si replacement, but i guess not.

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Mon 07, 2020 4:40 am 
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If you are stuck for any generic replacement for the 2SB PNP series audio output transistors in vintage transistor radios, you can simply replace them with the AC128. And in rare cases where the output transistors are early germanium NPN types, you can use the AC127.


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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Mon 07, 2020 5:30 am 
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thanks for that info. i might experiment.

steve

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 Post subject: Re: GE 2SB187 Audio Output in a Portable Radio
PostPosted: Sep Sun 13, 2020 2:04 am 
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fixed

thanks all and to fifties for the transistor.

steve

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