PMT pulse amp

And some that are claimed to be aren't ... :-)

I sure wish there was SPICE data for some of the really hot RF parts. PolyFet does a nice job there for their power devices. The usual S-parameter sets aren't all that useful for pulse apps.

I have 5 papers on how to use S-parameters in Spice.

If there's interest I'll coalesce and post them to my website. ...Jim Thompson

Probably very helpful for lots of people. Maybe not for pulse apps though. Thing is, S-parameters are given at particular "normal" bias points and in pulse apps you are banging the device between zero and pedal to the metal.

Ha! The 4 most important ones are already posted to the S.E.D/Schematics page of my website. (The 5th is just a quick cheat-sheet for hand conversion between z-y-h... etc. ...Jim Thompson

If

The RF jocks ignore specs like DC bias and actual signal swing limits. RF is like some liquid you squirt into a hose and see how much comes out the other end. S-params are about half of what you need when using these things as pulse amps. For instance, you can offset their bias point and get a lot more swing for unipolar pulses... and change the gain and impedances in the process.

MMICS also tend to have peculiar frequency rolloffs, so mapping s-params to time-domain response is more work than just measuring it.

John

Unfortunately I may need to use a Maxim part soon. The big boss wants a demo widget and a Max part is the only one I can find that works out of the box. I'm told it's not for a product, though, and DigiKey has a few dozen more than I need for the demo on the shelf. I feel so dirty.

If

In pulse apps you also have stuff that rings and then wants to go below the negative rail, a.k.a. ground in MMIC cases. Datasheets and models are usually silent about that. Some properties would be important, such as that of the body diode.

Buy spares.

I never buy only what I need, particularly with SMT parts. They are cheap, though.

demo

than

And they tend to fall into two catagories.

1. Never need another.
2. Use all your spares in under a year.

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than

I'm putting some of my retirement $ into reels of BF862s. ;0

Cheers

Phil Hobbs

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than

Sorry, I meant management (is cheap). The parts are $5-$8 each.

demo

box.

more than

Good luck with that. I have a garage full of obsolete, now almost worthless parts.

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box.

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Some day, we will be rid of brain dead bean counters. :)

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box.

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Sure, but if you had a garage full of LH0063s, say, you'd be rich. BF862s are unique AFAIK, and there are lots of things you can make with them that won't be possible if they get discontinued.

Cheers

Phil Hobbs

Somehow, I think that 12,000 cubic feet of them would drive the price down. :)

Pretty please.

If

The 4 most important ones are already posted to the S.E.D/Schematics page of my website. (The 5th is just a quick cheat-sheet for hand conversion between z-y-h... etc.) ...Jim Thompson

Yeah, but fortunately your mum tossed out all your comic books when you were at summer camp, which is what made mine so valuable today. ;)

Cheers

Phil Hobbs