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Old 15th March 2013, 01:31 AM   #1
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Default RCA transistor - vintage search

Hi all
I thought it would be easy to find RCA power transistor data but buying an OEM manual to find the specs of a transistor seems crazy.
Can anyone look up the leading details of an RCA 36643 medium power T039 transistor which is allegedly similar to 2N3053 or
the NTE listed equivalent NTE128? Well, maybe these are OK in some applications such video amplifiers but as an audio driver, I am
nervous about SOA as much as Ft, Hfe and Vceo etc.

Any assistance or comments would be helpful to make sure an old Fisher amp. keeps running at its best for a few more years.
If you want to consider the application, its a Quasi, single 46V rail and EF 36642 outputs which I guess are like homotaxial 2N3055s.
The amp. is a Fisher 440T receiver, the manual and schematic are posted here.
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Last edited by Ian Finch; 15th March 2013 at 01:35 AM.
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Old 16th March 2013, 02:26 PM   #2
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I've got the RCA Power Transistor databook SSD-204c, dated 1975. It is not in there. 2n3053 specs, Vceo 50v w/ base open 100ma, Ic .7a, Pt @ 25c 5W, Hfc @ 20 mhz @ 10v Vce >5, Cob @ 10 Vcb @ 0 Ie <15 pf, Cib @Veb .5 @ Ic 0 <80 pf, thetajc 35 degC/W, thetajfa 175 deg/W. The SOA is flat @ Ic 7 A til the DC line drops @ Vce 6 until it ends @ Vce 40 & Ic .25.
The 1986 RCA SK catalog shows the 36643 as equivalent to SK3024/128. That is npn Vceo 80 Pt 7W, Ic 1a, Hfe typ @ Vce 10 @ Ic .15 A 100, Ft 150 mhz,
The 5 digit RCA TO3 transistors in my 1970 build dynakit ST120 weren't in the catalog either.
I replaced the 5 digit RCA TO5 transistors on one channel of my ST120 with NTE249 for the input, and NTE49 NTE50 for the drivers with the heatsinks. This was in 1990 when one drove to a store to buy transistors. These days I would use MPS8099 for the input transistor and TIP31C TIP32C for the driver transistors. The 5 digit transistors on right channel are working on into the 21st century, without the TIP mod b-e capacitors. The NTE drivers have b-e capacitors installed, to cut the slew rate.
Hope this helps.
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Last edited by indianajo; 16th March 2013 at 02:40 PM.
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Old 16th March 2013, 02:49 PM   #3
Bill_P is offline Bill_P  United States
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I have the RCA Transistor Thyristor & Diode Manual SC-15 from 1971. All the proprietary RCA part numbers are in the 40xxx series. There are no listings for any part numbers beginning with 366. The 366xx parts are probably special part numbers exclusively sorted for Fisher. They may have specified limits on breakdown voltage or beta and were likely sorted from standard production of a particular part number. Finding out what that part number is may well be impossible at this point.

Further thoughts: SAMS Publications sold "Photofacts" which were folders of servicing information for electronic devices. Sometimes these folders had more data on semiconductor replacement than the manufacturers provided. The folder for the Fisher 440T is #1094, Special Equipment Data section. This covers serial numbers 20001 to 29999.

Last edited by Bill_P; 16th March 2013 at 02:57 PM.
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Old 16th March 2013, 02:58 PM   #4
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Is this to be trusted?
https://www.google.co.uk/search?q=rc...ient=firefox-a

Seems that 2N3053 will fit everything!
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Old 16th March 2013, 07:00 PM   #5
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Thanks folks, I appreciate your help in looking up this ancient relic. With the reference SK3024/128, I was able to dig a bit more and cross-reference the datasheet with some dubious ones on the web. This seems close or at least a good one-size-fits-all solution. The 80V Vceo seems unnecessary but if it also suited higher power models, you could understand just the one part being specified since 2N3053 is only a 40V Vceo. Perhaps these were just selected standard parts again.

On the subject of NTE equivalent lists, how could they rate their NTE128 as an equivalent? Agreed Harleyjon, you have to ask that question. In another example of simplistic advice, I first laid eyes on Tandy's Radio Shack transistor manual around 1980 and saw they stocked only about 30 general purpose types. Fine, but they then spent the rest of the sizable manual tabulating them as substitutes for any type you could dream up!

Here are some datasheet links for reference. Unfortunately, the parametric curves of old parts don't get published often but my inclination is now to go with 2N3019 as a replacement. Comments welcome.
SK3024-128 datasheet and application note, data sheet, circuit, pdf, cross reference | Datasheet Archive
http://www.datasheetcatalog.org/data...onics/9040.pdf
http://www.datasheetcatalog.org/data...5pxuz3rx7y.pdf
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Last edited by Ian Finch; 16th March 2013 at 07:10 PM.
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Old 16th March 2013, 08:16 PM   #6
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The way NTE worked, RCA & GE gave away the interchangeability manuals for their repair lines, NTE copied the number with imported parts and made the sale. I tried to buy SK parts 1985-90, nobody in town had any stock, only NTE parts. After they killed the golden goose, NTE started showing Interchangeability on the internet. I've still never seen an NTE paper catalog except behind the counter at the distributor. It is odd how NTE has evolved into a high priced alternative of cheaper industrial numbered parts.
Been looking at MPS8099 vs 2n3053, the old parts have way more Cob and Cib. Can't find Cob spec on TIP 31 MPSA06 etc. I think adding C to b-e was dynaco's solution to PWB's that weren't checked out for oscillation with faster parts. The same might apply to Fisher. A 2n3019 may meet the base specs of the old part, but unless an old production part, probably is a much faster part rebranded with the old number.
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Last edited by indianajo; 16th March 2013 at 08:21 PM.
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Old 16th March 2013, 10:05 PM   #7
Enzo is offline Enzo  United States
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I am certainly no fan of NTE et al. In fairness, they don;t claim equivalence necessarily, they claim their part number will work in place of the original in most cases.

I have always had paper NTE books on my shelf for reference. I have one a few feet to me left right now, but it is usually faster just to punch up the NTE web site as I sit here to cross something that it is to go grab the book. About the only reason I do that anymore is to find the price on an NTE part to compare to the real part, when suggesting someone avoid NTE.

I don't doubt SK was hard to find by 1990, the line folded.


NTE and the others was a way to have a genreal replacement line without having to stock a lot of types from a lot or manufacturers. Your electronics store signed on to NTE as a franchise and your entire line of needs was covered. If you need to order a part, there is little reason to pay for NTE when you can just as easily order the ral part. But if you walk into a local parts store, then you are paying for the convenience.

I try to steer techs away from it, and cost is a major reason. They cost more because they have to maintain all the cross database, plus each part is packaged and labelled. In the old days, if I wanted a Moto 2N4401, the guy went back to the bin and grabbed me one - no bag, no label. All the replacement lines have always cost more than the real parts, right from the start.
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