50 Gigohm Resistor?

[Michael A. Terrell]

Gosh, I *have* done a lot of silly things.

Great! That is what makes, and keeps electronics interesting.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Robert Baer]

Not necessarily seriously, when you've got 10M in a (an?) 0603 SMT, do
you have to take heroic measures to deal with ordinary leakage?

Thanks,
Rich

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

 

[Spehro Pefhany]

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

ITYM "scheiß"


Best regards,
Spehro Pefhany

 

[Winfield Hill]

John Larkin wrote...

[1] a *silicon* jfet. TI was actually making some germanium jfets
at the time, and they were pretty good for low-noise RF front-ends.

Whoa!, just when was that?

 

[Ken Smith]

Ken Smith wrote...

They wanted response down to 0.1Hz?

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

 

[Ken Smith]

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

ITYM "scheiß"[/QUOTE]

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

 

[GregS]

ITYM "scheiß"

Either way, no-clean flux is no fluxxing good.[/QUOTE]


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

 

[John Larkin]

John Larkin wrote...

[1] a *silicon* jfet. TI was actually making some germanium jfets
at the time, and they were pretty good for low-noise RF front-ends.

Whoa!, just when was that?

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

 

[Rich Grise]

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

ITYM "scheiß"
[/QUOTE]

According to "Google Translates", it's 'Scheiße'.

Cheers!
RIch

 

[Winfield Hill]

John Larkin wrote...

John Larkin wrote...

[1] a *silicon* jfet. TI was actually making some germanium jfets
at the time, and they were pretty good for low-noise RF front-ends.

Whoa!, just when was that?

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...

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?

 

[Rich Grise]

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.

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

 

[Spehro Pefhany]

According to "Google Translates", it's 'Scheiße'.

Du bist ein Klugscheißer!


Best regards,
Spehro Pefhany

 

[Tim Williams]

Which, by the way, is _like_ VS, to a pubescent boy who was raised
in the forest by a family of cows. ;-)

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

Tim

 

[John Larkin]

John Larkin wrote...

John Larkin wrote...

[1] a *silicon* jfet. TI was actually making some germanium jfets
at the time, and they were pretty good for low-noise RF front-ends.

Whoa!, just when was that?

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...

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?

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

 

[Phil Allison]

"Ken Smith"

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

** Who did ?

You are just making up this shite.





......... Phil

 

[Ken Smith]

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.

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.

 

[Robert Baer]

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

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

 

[Robert Baer]

[...]

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

ITYM "scheiß"

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.

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

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.

 

[Tony Williams]

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.

 

[Rich Grise]

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

Tim

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

Cheers!
Rich