2 GHz buffer with 2N390x

Gee, I wish I were smart enough to design that.

I once tried fairly hard to bandage up a MAT14 supermatch quad NPN to make it work at higher bandwidth, by using gussied-up Darlington connections with 40-GHz SiGe:C NPNs to return the AC base current to the collector circuit.

It didn't work, because AFAICT there's no simple way to get rid of the time constants formed by Rbb' and the interelectrode capacitances without trashing the noise.

Cheers

Phil Hobbs

Looking at his graphs, I figure that after the Ft's run out, the signal is coupled through the various Cbe's. But that's not much in the way of gain. Thermal runaway could be interesting too.

The electronic mags are pitiful these days.

Speaking of buffers, BUF602 is slick.

That reminds of of a guy with a brand new two year degree who believe th at he could get 5W of RF at 27 MHz form a 2N3055. I gave him one. As I expe cted, he didn't even get a miliwatt output, which was as low as I could mea sure in my home shop at 17. He was like Sloman. He knew everything, yet he often needed help to repair a TV.

The guy is no lightweght. Maybe he was in a hurry or something.

that he could get 5W of RF at 27 MHz from a 2N3055. I gave him one. As I ex pected, he didn't even get a miliwatt output, which was as low as I could m easure in my home shop at 17. He was like Sloman.

Even I know that a 2N3055 is as slow as wet week.

And I certainly don't know everything, though I do know a lot more than Mic hael Terrell. The best definition of an expert is somebody who knows the li mitations of their knowledge.

Entirely possible that he had done this, using a brand new epitaxial '3055. Which shouldn't even exist, it should've been discontinued and put in a new type number, say. While the one you had was made on the old process, and barely useful for audio.

Although getting 5W even from an epitaxial version would probably require more skill than he had, anyway. I'm not doubting that possibility.

Tim

Getting that amount of power might have been possible in the past.

The specifications for 2N3055 are quite relaxed.

When some manufacturer tried to make some better transistors, but the die was out of specs for the intended transistor, but well inside

This was fine, but some manufacturer labeled even failed VHF power transistors as "2N3055". When such transistor was put into a typical DC/audio circuit, the transistor might oscillate like hell somewhere in the VHF/UHF range :-)

2. > Which shouldn't even exist, it should've been discontinued and put in a n

ew

It was in a Pace 2300, a popular CB radio made by Pathcom in the '60s an d '70s. He was convinced that the custom RF output in a TO-3 was just an or dinary audio transistor. I showed him the RCA Databook that showed it had n o chance of working. He claimed that RCA didn't know what they were doing. The Databook was from 1967, and I may still have it somewhere.

He had an attitude like Sloan. Anyone with a degree was infallible, and anyone else didn't deserve to live. I used to piss him off when I passed hi s bench at the shop. I would tell him what part was bad. He would curse me out, but more often than not he would yell, Do we have that part in stock. I took care of repairs of industrial electronics, and I knew our inventory better than anyone in the shop.

he

that he could get 5W of RF at 27 MHz form a 2N3055. I gave him one. As I e xpected, he didn't even get a miliwatt output, which was as low as I could measure in my home shop at 17. He was like Sloman. He knew everything, yet he often needed help to repair a TV.

Which guy? There are too many guys in this thread. :)

Dr. Sergio Franco.

Michael Terrell wrote in news: snipped-for-privacy@googlegroups.com:

You would like to come in here under that guise, but we have the evidence! You are all tied up in the guy wires.

ve

s I

new

nd

re

and '70s. He was convinced that the custom RF output in a TO-3 was just an ordinary audio transistor. I showed him the RCA Databook that showed it had no chance of working. He claimed that RCA didn't know what they were doing . The Databook was from 1967, and I may still have it somewhere.

nd anyone else didn't deserve to live.

Michael Terrell doesn't seem to noticed that I don't have any kind of degre e in electronics - my Ph.D. is physical chemistry. I don't think that anybo dy would ever think that anybody with a degree would be infallible, and I'v e certainly worked with enough people with degrees to be well aware that it isn't remotely true.

him what part was bad. He would curse me out, but more often than not he wo uld yell, Do we have that part in stock? I took care of repairs of industri al electronics, and I knew our inventory better than anyone in the shop.

A useful skill.

to

o the

the

eve that he could get 5W of RF at 27 MHz form a 2N3055. I gave him one. As I expected, he didn't even get a miliwatt output, which was as low as I cou ld measure in my home shop at 17. He was like Sloman. He knew everything, y et he often needed help to repair a TV.

Huh S. Franco wrote one of my favorite opamp books. I better go read the article. (I thought it was hooey from the comments.)

George H.

on"

Huh OK his gain graph droops at ~100MHz... So what is the Ft (typical) of a 2n3904?

George H.

I've measured 30-300 MHz depending on mfg 1994-2015. Processes evolve and generic partnumbers, too.

Thanks! GH

350-400 MHz at ~10-30 mA iirc.

Cheers

Phil Hobbs

That reminds me of the moped tuning that the guys did in my high school days. Going 50mph on a screaming 50ccm engine running way beyond redline. Unfortunately one classmate died that way, the brakes couldn't hold up.