Brand of TO-3 transistors?

[Larryhere40]

I hear ya! Learning the hard way, on my own!

 

[llwhtt]

Those Motorola MJ21193/94s are fake, Motorola semiconductor division had be sold off, or whatever happened, to ON Semi by the time the 211xx series came out. The last Motorola date codes will be around 1999/2000. Another reason for fake is there are no date codes on them. Also the printing is off by 90 degrees.

Craig

 

[Larryhere40]

That’s good to know ! How do you order a matching pair? Do the part numbers show, a special order, or just luck? What is considered a close enough gain? Thanks any buddy out there!

 

[llwhtt]

I think the general consensus is that if they have the same date code they are fairly well matched considering today's production tolerances. Using emitter resistors helps to share the load also.

Craig

 

[Larryhere40]

Thanks for your response and input! It’s greatly appreciated. I can use all the help I can get, being a dyi guy. Retired and loving it! Is there a code for the date, never seen an actual date. I will look again. I have ordered a transistor tester like the previously mentioned,,to compare different transistors for gain! When I did my search, the nte284 and nte285 were a matched set with no more than a 10% difference! But other brands and similar ones don’t say there matches! I can’t believe how complicated it is to replace transistors like that! I thought you would just cross reference and that’s it. Lol

 

[reddish75]

Thanks for your response and input! It’s greatly appreciated. I can use all the help I can get, being a dyi guy. Retired and loving it! Is there a code for the date, never seen an actual date. I will look again. I have ordered a transistor tester like the previously mentioned,,to compare different transistors for gain! When I did my search, the nte284 and nte285 were a matched set with no more than a 10% difference! But other brands and similar ones don’t say there matches! I can’t believe how complicated it is to replace transistors like that! I thought you would just cross reference and that’s it. Lol

Nte transistors a poor choice for replacements

Transistor matching generally reserved for input pair transistors

Output transistors are mostly not matched r.e gain but do use the same type throughout the repaired channel even if the others tested good

 

[chazix]

Nte transistors a poor choice for replacements

Transistor matching generally reserved for input pair transistors

I'm always puzzled by the animus toward NTE. I'll grant that they're expensive, and that their cross-reference has to be taken with a grain of salt, but those things are not deal-breakers for me.

The only other objective knock I've seen - and I'm not sure I believe it, though it isn't beyond belief - is that it might be possible to buy two NTE parts of the same part number, but actually receive two parts from different original manufacturers.

But in this case, as I think the OP alluded to, you can buy a matched complementary pair under a single part number (NTE285MCP). And I think most designers of complementary output stages would say that gain matching is important because the symmetry helps to lower inherent distortion in the stage. Other than NTE, where the heck else are you going to find a legit supplier of matched complementary TO-3 transistors?

 

[gadget73]

matched based on what though, post-manufacture testing, or just "this is the complimentary part" ? Unless they actually test the parameters and match them based on those results I'd wager its just done by type.

 

[Larryhere40]

I agree with both! But my theory was the numbers with the Mcp added were done so due to manufacturer guidelines, to run and time of production! Which may not be testing, but reduces the odds of getting a out of spec pairs! They leave it up to the buyers to check what they have, to keep the cost down! I’m sure some quality control is kept like any other factory! Hopefully my opinion will be taken with a grain of salt!! Lol