Subbing TO92 transistor for TO39?

[62vauxhall]

If, when searching for a replacement transistor in a TO39 package, a TO92 is suggested, is the package style going to make a difference?

The TO39 in question is 2SA497 and the suggested TO92 is KSA1013.

Since there is a complimentary TO39 - 2SC497 involved, presumably that would mean a KSA1013 mate is needed as well?

EDIT: That seems logical but unfortunately KSA1013 does not seem to have a compliment.

 

[markthefixer]

the 2sa497 is an 80 volt 0.8a 0.6 watt 50 mhz transistor.

I don't have a circuit to reverse engineer, to see if they are running close to (what?) limit

1. high voltage
2. High current
3. power dissipation.

plus jumping from 50 mhz to 175 mhz would require a bit more care.



The ksa1013 data from my notes:
512-KSA1013YTA to-92L ecb 160v 1a .9w 100mhz 160-320hfe $0.34 (R=60-120, O=100/200, Y=160/320)
512-KSC2383YTA to-92L ecb 160v 1a .9w 100mhz 160-320hfe $0.17
so YES, it does have a complement.


seems like you may be best served using:
512-KSA1220AYS to-126 ecb 120/a160 1.2a 1.2w/20w 175mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 1.2w/20w 175mhz 35-320hfe $0.40

these have a bigger case, can be heat sinked, but can do a watt naked. leads may be a snug fit in the pcb holes.

 

[62vauxhall]

the 2sa497 is an 80 volt 0.8a 0.6 watt 50 mhz transistor.

I don't have a circuit to reverse engineer, to see if they are running close to (what?) limit

1. high voltage
2. High current
3. power dissipation.

plus jumping from 50 mhz to 175 mhz would require a bit more care.



The ksa1013 data from my notes:
512-KSA1013YTA to-92L ecb 160v 1a .9w 100mhz 160-320hfe $0.34 (R=60-120, O=100/200, Y=160/320)
512-KSC2383YTA to-92L ecb 160v 1a .9w 100mhz 160-320hfe $0.17
so YES, it does have a complement.


seems like you may be best served using:
512-KSA1220AYS to-126 ecb 120/a160 1.2a 1.2w/20w 175mhz 35-320hfe $0.39 (R=60-120, O=100/200, Y=160/320)
512-KSC2690AYS to-126 ecb 120/a160 1.2a 1.2w/20w 175mhz 35-320hfe $0.40

these have a bigger case, can be heat sinked, but can do a watt naked. leads may be a snug fit in the pcb holes.

Thanks Mark, that helps a lot. I happen to have four KSA1220AYS on hand and yes, as you pointed out, the pins are too wide for the hole. No matter though, either "micro-shaving" the pins or maybe carefully enlarging the holes should make them adapt.

I would have gotten those transistors I have locally, probably by special order and not too long ago. I'll stop by that shop tomorrow and see if they can do likewise for KSC2690's.

 

[orange]

AS a professional klutz, I can't recommend that.

 

[62vauxhall]

After removal, I checked the TO39 SA497 / SC497 pairs with DMM on diode function and one of them was no good. That was just before replacing them with those KSA1220 / KSC2690 pairs. I then discovered (via bright DBT) one of the 2N3055 main outputs was bad. I checked all 4 of those previously and at that time they were OK.

In any case, I replaced both 2N3055's on that one channel. The (60 watt) DBT then glowed orange when the variac was at full power. I pulled all TO92's on the driver boards (those I replaced and the originals still in place), checked each one. All OK so re-intalled.

Still seeing about .5 volts offset. Just wondering if it might be worthwhile trying that KSA1013 / KSC2383 pair instead of the KSA1220 / KSC2690 pairs I just installed? I checked and re-checked polarity and am sure it is correct.

 

[orange]

You know that if you look hard enough sometimes you can find stocks of obsoleted semiconductors online NOS?

 

[62vauxhall]

You know that if you look hard enough sometimes you can find stocks of obsoleted semiconductors online NOS?

Yes, did that once. I bought 4 oddball obsolete transistors for the motor control of a NAD CD player. Found originals from some outfit in California. $8 each + shipping = about $50 Canadian. Turned out they weren't the problem, it was an SMD with about 50 pins. Found one of those too. Tried installing - blew that then chucked the CD player in the garbage.

Wish to avoid such expenses for experimental purposes.