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2SB525C transistor cross reference help.

D

doffo

Well-Known Member
Oct 14, 2012
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Hello,

I put aside the President Washington as it still exhibits the same issues even after replacing the diode. I will try it another time.. For now I got out another radio, a President Grant that has the dual finals and the low-mid-high switch up front. TR35 at some point called it quits, and its a 2SB525C. Just wondering if there is a good alternative transistor to use thats more readily available. Do have some parts Cobra 29 radios if they happen to have something that will do.


Appreciate the help you all have been providing. Thanks.
 
Last edited:

According to the crew over at transmission1, you can use the BC640 transistor. Just turn it around because the pinout is backwards from the 2SB525. You may want to check the datasheets for both before you buy just to be sure.
 
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TM86 said:
According to the crew over at transmission1, you can use the BC640 transistor. Just turn it around because the pinout is backwards from the 2SB525. You may want to check the datasheets for both before you buy just to be sure.
Click to expand...
Thank you. I am kinda lousy at verifying and looking up the stuff to be sure its will work. Good to know there may be that part available if that is the case, I will have to make note, FLIP it around lol.
 
In this case there is a datasheet, but when you find yourself in a situation where you can't find a datasheet, the part number hints at what it is. In this case, we know right off the top that it is a PNP audio frequency transistor. In summary:

The Japanese did it like this:
The first digit +1 is the number of leads on the device, so 1 is a diode, 2 is a BJT or FET and 3 is a dual gate FET
The second and third denotes the type of device, SA=high freq PNP, SB=audio freq PNP, SC=high freq NPN, SD=audio freq NPN, SE=diodes, SF=SCR's, SG=Gunn devices, SH=unijunction transistor, SJ=P-FET, SK=N-FET, SM=triac, SQ=LED, SR=rectifier, SS=signal diode, ST=avalanche diode, SV=varactor diode, SZ=sener diode.
Then you have the serial number which is not telling you much followed by a revision suffix.

The Europeans did it like this:
AC=Germanium small sig audio
AD=Germanium audio power
AF=Germanium small sig RF
AL=Germanium RF power
AS=Germanium switching
AU=Germanium power switching
BC=Silicon small sig general purpose
BD=Silicon power
BF=Silicon RF BJT or FET
BS=Silicon switching BJT or MOSFET
BL=Silicon hifh freq high power
BU=Silicon high voltage
CF=Gallium arsenide small sig mesfets
CL=Gallium arsenide microwave fets
CV=various British military parts.

Mosfets, like the 13N10, the 13 represents the continuous drain current in A at 25°C, N is the channel type, and adding a zero to the last two digits gets you the Drain to Source voltage, so 100v.

Some of the older diodes used the RMA tube system. The example wiki uses is the 1N23, the 1 meant no filament and the N meant crystal rectifier. There are a lot of changes that took place over the years, so I won't drag this out. Anyone can look it up. Designation keywords to search for are JIS, JEDEC, EIA-370, RMA, Pro Electron, Mullard Phillips etc.

Then there are a ton of manufacturer codes, like TIP=Texas Insturments Power transistor, MRF=Motorola RF transistor etc.

Nowadays, its a total mess, there are many designation standards, and you are pretty much up the creek without finding the datasheet or testing a good one. At least the old stuff made sense.
 
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That is pretty good information. Saved it to a document to have on hand. Appreciate it.
 
From what I understand, BC640 along with BC636 and BC538 all should be candidates that would work? Also, the thread mentioned it needing to be 800 mW, but that particular one I am looking at is 625 mW. I may need help sourcing a working replacment if anyone has some time to look into it.

bc640 motorola.jpg
 
I just pulled it up off google, but havent shopped for it yet. I wanted to make sure 636 or 638 will still be fine to use.
 
As replacements, I often purchase the old NTE or the ECG line of transistors. I like the sealed packages they come in. That helps avoid fakery. The pin-outs and specifications are also clearly marked on the package. In your case, an ECG294 or NTE294 should work fine.
 
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sunbulls said:
As replacements, I often purchase the old NTE or the ECG line of transistors. I like the sealed packages they come in. That helps avoid fakery. The pin-outs and specifications are also clearly marked on the package. In your case, an ECG294 or NTE294 should work fine.
Click to expand...
Much appreciated. Helps narrow down the choices.
 
2SB525_sub.jpg

This is from a cross-reference book from the early 80s, published by Fuji-Svea. They were the first distributor to market japanese transistors decades ago.

If this transistor is not bolted to a heat sink I would use a TIP32 or TIP42 to replace it. But you'll have to spin it around since the base and emitter are on opposite sides from the original part. If it's bolted to a heat sink this is not so practical.

73
 
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nomadradio said:
View attachment 68095

This is from a cross-reference book from the early 80s, published by Fuji-Svea. They were the first distributor to market japanese transistors decades ago.

If this transistor is not bolted to a heat sink I would use a TIP32 or TIP42 to replace it. But you'll have to spin it around since the base and emitter are on opposite sides from the original part. If it's bolted to a heat sink this is not so practical.

73
Click to expand...
Nomadradio thanks for the cross reference. Good to have on hand. Luckily its just a small transistor not bolted up to anything. I did buy a NTE294. Most of them were 750 mW, but happened to find one at 1 w. I am sure 750 mW may of still been ok, but a different forum was saying to at least find one 800 mW.
 
I am confused about the transition frequency. The NTE294 says 200 MHz, while the TIP42C is saying 3 MHz? Does it need to be specific?
 

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