50 Gigohm Resistor?

Not really; make sure they clean the board - the so-called "no clean" is sheist.

ITYM "scheiß"

Best regards, Spehro Pefhany

Whoa!, just when was that?

Well, not exactly but very close. They want to be able to claim very linear operation and very flat responce at low frequencies.

In article , Spehro Pefhany wrote: [...]

Either way, no-clean flux is no fluxxing good.

I had to have a board very clean due to circuit layout. Any thing on the board had an effect. The trouble with the clean flux, the water spray cleaning, made caps absorb moisture which then had to be baked. Addition cleaning under the chips was necessary because the cleaning process was not sufficient. Some flux cleaners ended up causing problems with some caps. Basic alcohol was necessary.

greg

Must have been about 1970. We were working with Offshore Navigation Inc, trying to build them improved Raydist receivers that had low noise figures and immunity from overload. Raydist was similar to Loran, an HF hyperbolic navigational system used out in the gulf to locate drill sites and stuff. The TI ge jfets were impressive... noise figures around 1 dB and excellent overload behavior, important when you were close to one transmitter and far from the other. The Raydist people, cheapskates, didn't go for it, and satellite navigation killed Raydist a few years later.

I'll check my old TI books...

John

According to "Google Translates", it's 'Scheiße'. :-)

Cheers! RIch

I looked in my thick 1973 TI Transistor and Diode Databook, which has lots of JFETs of various types, but they're all too new. Do remember any part numbers?

had an

chips

I once worked at a place where they had a huge ultrasonic cleaner - once when I saw an anomalous 40 KHz superimposed on whatever I was scoping, one of the other techs said, "That's Branson noise", which meant it was from the Branson ultrasonic cleaner. I also seem to remember "vapor degreasing", where they have a tank of hot freon, and when you'd lower the board into the vapor, the freon vapor would condense on the relatively cool board and when it ran off, it rinsed off all of the residue with it.

They might have used them in conjunction, like dip in the US tank, in liquid freon, then rinse in the vapor or something like that. It was very long ago. :-)

Cheers! Rich

Du bist ein Klugscheißer!

Best regards, Spehro Pefhany

I'd recognize that phrase anywhere! -- Since when were you from Wisconsin? ;-)

Tim

-- Deep Fryer: a very philosophical monk. Website:

Nope. I have the huge red 1965 TI binder, the one with expensive "solid circuits" in it, and they're not there, either. I think they may have been samples that never hit production. I didn't do the RF front end, but I worked with the guy who did.

Lots of gate leakage, as I recall, so silicon jfets must have killed them.

That TI catalog has some interesting stuff... GaAs diodes, weird logic, barbaric linear ICs, resistors, tantalum capacitors. And the price list!

John

"Ken Smith"

You are just making up this s**te.

........ Phil

In article , GregS wrote: [....]

Yes, I too sometimes like a drink after work. The banned stuff works way-way better. The various Freons did a better job of carrying away the flux. The other chemicals in there helped to lift if from the board.

Today, I use stuff called "ensolve" that is supposed to be environmentally nice. It is ok but not perfect.

had an

chips

Yup! Get 'em drunk and stiff as a board!

had an

chips

Ages ago, i made my own vapor degreaser to develop KPR images for PCBs, using TCE which, stupidly, is banned ("replacements" are worse in numerous ways). Such a degeaser would clean anything and the heat would keep moisture out.

Big K's KPR? That's a blast from the past.

OK, OK! Actually, I'm Minnesot'n, so, family of giant mosquitoes. ;-)

Cheers! Rich