RCA 18538A: Searching for data sheet

Fun. I have a few reels of fast PNPs myself. ;)

Cheers

Phil Hobbs

We bought 11K of BFQ149 and 7K of ATF-50189 before they went EOL. Then I designed my little GaN output stage, so we don't need them.

It works to at least 80 volts! It's really fast without an output filter, but a little ragged looking, so we'll go for beauty.

Picture of solder-side tracks?

Interested to see if there's a feedback winding on the choke. Bipolar self-oscillator of some kind.

With the RCA branding, there's a very slight chance they could be thyristors. Hope not.

RL

SK was RCA's line for TV shops and industrial repairs.

The only datasheet that I could find for SK4093 is a CMOS IC. a 2SK4093 is a FET.

Very pretty!

My usual use of fast PNPs is as a wraparound transconductance enhancer for JFET front ends. That's my second-best design, which I often use in work-for-hire situations. (I keep the best one for licensing.)

Cheers

Phil Hobbs

Good precaution. Gain or switching-time grading/matching were often conditions for 'house' numbers.

RL

That's filtered. We might charge extra for the fast version, without the output filter. I can also charge extra for the high-voltage version!

Well, if you need any of those SOT89 PNPs, we've got them.

MMBTH81 is SOT-23 and kinda fast and still in production for now.

That was a house number, so there wouldn't be a published data sheet.

Thanks. I have a reel of BFG31s in stock, and two reels of BFT92s.

Most of my prepping supplies are JFETs: BF862s and CPH3910s--I think about 40,000 overall. That's certainly a career's worth in our business.

Lately I've been doing a lot of pHEMT bootstraps for SiPM/MPPC applications. I need to figure out a good way to reduce their source resistances, so that I can bootstrap 50-pF ON Semi SiPMs out to 500 MHz or more. Their 0.3 nV 1-Hz flatband noise is unbeatable, and the 1/f noise gets suppressed by the decrease in the detector admittance at low frequency. Even a 5-GHz PNP isn't good enough to apply local feedback to a 12-GHz f_max pHEMT.

I'd buy reels of those too, but they're several times more expensive.

Cheers

Phil Hobbs