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Author Topic: Too many transistors  (Read 3382 times)
K7MDO
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Posts: 325




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« on: October 20, 2012, 07:05:46 PM »

Just recently an older local ham died and I "inherited" most of his stuff.  I guess I was surprised by the quantities of some of the items.  He had a huge organized selection of resistors but they were all from the 1950's and earlier and on checking them they turn out to have very disparate values from their markings. 

However, I found a large box of plastic organizers filled with carefully identified transistors (5, 10, or sometimes 20 in a bin).  Probably a thousand or more and each bin clearly labeled.

I know most are of little value but I did notice several bins with RF power transistors.  Ones like Motorola 2N5591, etc. 

Do any of you "homebrewers" have any idea if those are of any interest anymore?  Or, have they gone the way of tubes already?

Just curious, 73, Tom
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PBPP
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Posts: 40




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« Reply #1 on: October 20, 2012, 08:01:29 PM »

Those old transistors are getting harder to find and are sought
after by hams / hobbyists who repair old equipment / radios. 
Germanium transistors immediately come to mind.

I'm sure you can find buyers if you want to sell them.

~ Mitch ~
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WB6BYU
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Posts: 13010




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« Reply #2 on: October 20, 2012, 08:20:03 PM »

Discrete transistors are still quite useful for homebrew projects, and will get harder to find
as more devices are only manufactured in surface mount packages.

For many circuits discrete transistors are preferred, as they don't usually become obsolete
as fast as some integrated circuits that might be used instead.

Depending on the source of the collection, sometimes it can be difficult to track down
specifications on some of the types.  I have several hundred types that I've accumulated
over the years and ended up putting all the information in a database to make it easier
to choose a device for a specific project (though most projects can be built using just a
few common types.)  There are a lot of parts that I haven't been able to find data for,
and in that case I use a simple tester to determine type, pinout, and beta, and they try
it in a simple oscillator circuit to see if it oscillates on HF or VHF.
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K8AXW
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Posts: 3636




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« Reply #3 on: October 21, 2012, 09:08:00 AM »

Before I would entertain any thought of disposing of these old transistors I'd contact surplus solid state vendors to see if they would be interested in them.

Electronics123.com comes to mind.  There are many more.
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K7MDO
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Posts: 325




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« Reply #4 on: October 21, 2012, 03:59:55 PM »

Well I am encouraged by the responses.... I think first I will catalog what there is and after hearning you folks suggestions, I won't just toss them... not that I could really have done that anyway....

Maybe use Xcell for a spreadsheet....

Probably rather find a good home for them than anything else.

Thanks for the help, 73, Tom
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WB6BYU
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Posts: 13010




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« Reply #5 on: October 21, 2012, 04:25:23 PM »

While Excel would work for storing information, I found the database program (I used the
one in AppleWorks originally) allowed me to do queries such as, "find all of the PNP transistors
with an fT greater than 350 MHz in a TO-18 case and list them in order of the quantity on hand."

But it is a pain when you have to convert to another program.
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KD0REQ
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Posts: 849




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« Reply #6 on: October 21, 2012, 07:54:33 PM »

as I collected transistors over the years, from extras as I ordered for a project, or by disassembly of old stuff, I looked them up and tested with a go-nogo squeal tester, and binned them according to their ECG (now NTE) cross reference.  when I need to slap something together or fix an item, I know exactly what I have. I got that right at least.

as the dual gate MOSFETS disappear as the germaniums already have, that junk box is becoming quite dear.

in 5 or 10 years, if you dump that stock, you may welll regret it.
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AC2Q
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Posts: 348




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« Reply #7 on: October 25, 2012, 11:50:27 AM »

I need a pair of SRF3417 RF Power transistors?

Let me know, please?

TNX
AC2Q
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W9GB
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Posts: 2597




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« Reply #8 on: October 26, 2012, 05:17:16 PM »

Quote from: AC2Q
I need a pair of SRF3417 RF Power transistors.
Mike -

You likely have a Mirage 3016 RF amplifier.  For replacements, I normally call RF Parts.
The SRF3417 is no longer available.
http://www.rfparts.com/transistors.html

Earlier 2008 discussion by KM3F -
https://www.eham.net/ehamforum/smf/index.php?topic=2145.0

The Toshiba 2SC2782A-(MP) will mount in the same locations and match up. $85.90
http://www.rfparts.com/pdf_docs/2SC/2SC2782.pdf

The difference between the 2SC2782 and the 2SC2782A is that the “A” version is RoHS compliant, and uses an Aluminum Nitrite insulator (color gray) on the header versus the original part which used Berillium Oxide (color white).  Select the "A" version.

I would NOT drive these transistors with 15 VDC (as KM3F suggested) ... You are not overclocking an Intel CPU!!
You can always look to 28 VDC and 50 VDC RF transistors -- if that is what you desire.
« Last Edit: October 26, 2012, 05:34:03 PM by W9GB » Logged
AC2Q
Member

Posts: 348




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« Reply #9 on: October 29, 2012, 11:23:57 AM »

Once again, to the AUTHOR fo the Thread:

I need a pair of SRF3417 RF Power transistors?

Let me know, please?

TNX
AC2Q
 
 
 
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K7MDO
Member

Posts: 325




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« Reply #10 on: October 29, 2012, 09:19:17 PM »

The transistor you specify is not one I seem to have.  Is there a different manufacturers equivalent part number?

I have a lot of 2N5591's and similar but I think too low power for your application?

T
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ONAIR
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Posts: 1735




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« Reply #11 on: November 17, 2012, 10:24:50 AM »

Save them.  They will be worth a fortune in 20 years! 
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