RCA transistor house numbers

megajocke · 6th March 2006, 11:29 PM

I have found a couple of TO-3 power transistors made by RCA that I don't know the specs for. I was planning to build a car sub amplifier using a 2n5631 and a 2n6031 that I had in the parts bin but just found out that the 2n6031 has all its terminals shorted together.

In the parts bin there are a couple of telecom power supplies that convert 50V to +-10V or +-15V. They use two of RCA (SGS in some of them) N121230-3 NPNs driving a transformer in push-pull so they have to be at least 100V parts. I have at least 8 of these so I could parallell if needed.

I saw them mentioned in this thread:
Rca Mosfet?

One poster claims them to be 120V, 12A. Does anyone know max power dissipation or any other useful data?

I also have 2 of RCA N121122 NPN transistors, but they were used in another application, as a standard class B amplifier driven by a single 50V rail used to generate ringing voltage. I don't know how heavy load it was supposed to drive, but probably not too heavy as the emitter resistors are 1 ohm.

My power supply puts out +-40V unloaded with 14V input. I have not measured how much it sags under load as I have built it on a breadboard and I don't want stuff melting

A quasi-complementary with 1 or 2 pairs of N121230-3 maybe?

djk · 7th March 2006, 08:21 AM

Switching power supply transistors have no safe area when operated in a linear amplifier.

I have 600pcs of 2N6274, a 50A, 30Mhz, 100V, 250W part. They cost over $40 each 20+ years ago. At 7V they will handle the full 250W, at 100V the SOA is only 6W !!!

The MJ15015/16 pair have 180W SOA at 60V, and only cost about $1.50 each, used in Crown, Carver, and others.

megajocke · 7th March 2006, 10:07 PM

Well, power transistors aren't that cheap here in Sweden I'm afraid

Farnell is the only place I can find that stock them but their price is 60SEK (~$7) a piece. MJ15003's are easier to find, and they cost about 40SEK (~$5) in most places.

I found 2 pairs of 2SD718 and 2SB688 in the parts bin. Datasheets can be found on alldatasheet.com and they look suitable. I'll use both pairs in the amp. The speaker is 8 ohms so the amp shouldn't complain too much.

The circuit is going to be a mix between P3A and Douglas Self's Blameless amplifier.

djk · 7th March 2006, 10:56 PM

$7?

Ouch! I paid $1.23 for the MJ15015s and $1.30 for the MJ15016s.

The 2SD718 and 2SB688 should be fine for what you want.

6th March 2006, 11:29 PM	#1
megajocke diyAudio Member Join Date: Jan 2003 Location: Solna	RCA transistor house numbers I have found a couple of TO-3 power transistors made by RCA that I don't know the specs for. I was planning to build a car sub amplifier using a 2n5631 and a 2n6031 that I had in the parts bin but just found out that the 2n6031 has all its terminals shorted together. In the parts bin there are a couple of telecom power supplies that convert 50V to +-10V or +-15V. They use two of RCA (SGS in some of them) N121230-3 NPNs driving a transformer in push-pull so they have to be at least 100V parts. I have at least 8 of these so I could parallell if needed. I saw them mentioned in this thread: Rca Mosfet? One poster claims them to be 120V, 12A. Does anyone know max power dissipation or any other useful data? I also have 2 of RCA N121122 NPN transistors, but they were used in another application, as a standard class B amplifier driven by a single 50V rail used to generate ringing voltage. I don't know how heavy load it was supposed to drive, but probably not too heavy as the emitter resistors are 1 ohm. My power supply puts out +-40V unloaded with 14V input. I have not measured how much it sags under load as I have built it on a breadboard and I don't want stuff melting A quasi-complementary with 1 or 2 pairs of N121230-3 maybe?

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7th March 2006, 08:21 AM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	Switching power supply transistors have no safe area when operated in a linear amplifier. I have 600pcs of 2N6274, a 50A, 30Mhz, 100V, 250W part. They cost over $40 each 20+ years ago. At 7V they will handle the full 250W, at 100V the SOA is only 6W !!! The MJ15015/16 pair have 180W SOA at 60V, and only cost about $1.50 each, used in Crown, Carver, and others.

7th March 2006, 10:07 PM	#3
megajocke diyAudio Member Join Date: Jan 2003 Location: Solna	Well, power transistors aren't that cheap here in Sweden I'm afraid Farnell is the only place I can find that stock them but their price is 60SEK (~$7) a piece. MJ15003's are easier to find, and they cost about 40SEK (~$5) in most places. I found 2 pairs of 2SD718 and 2SB688 in the parts bin. Datasheets can be found on alldatasheet.com and they look suitable. I'll use both pairs in the amp. The speaker is 8 ohms so the amp shouldn't complain too much. The circuit is going to be a mix between P3A and Douglas Self's Blameless amplifier.

7th March 2006, 10:56 PM	#4
djk diyAudio Member Join Date: Feb 2001 Location: USA	$7? Ouch! I paid $1.23 for the MJ15015s and $1.30 for the MJ15016s. The 2SD718 and 2SB688 should be fine for what you want.

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