Zener Noise (was: 1N4007 varactors)

[Mike Andrews]

Come again?

When I see "GR", I think "General Radio", and salivate gently. They
made some really, really nice test gear.

 

[Steve Nosko]

Nice touch, Bill.
73, Steve, K9DCI

 

[Jim Thompson]

When I see "GR", I think "General Radio", and salivate gently. They
made some really, really nice test gear.

And then let themselves get sucked, by marketing, into large
mainframe-based testers, and lost their ass.

I watched the money-making portable test division in Phoenix get
trashed by the shit-heads in Massachusetts... now you know _part_ of
the source of my animosity toward Massa2shits ;-)

...Jim Thompson

 

[RST Engineering]

I've used noisecom for some years, but they are hard to buy in
onesie-twosies and are rather expensive in quantity when you only need one.

They USED to sell seconds that didn't meet spec, but I don't see that offer
on their current website.

Jim

 

[John Larkin]

Come again?

Tim

Is it a General Radio noise generator? I have an old GR noise
generator, and the manual talks about moving the magnet around to
optimize something.

John

 

[Gerhard Hoffmann]

OK, then. A zener makes a poor noise source according to what I'm reading.
Noise.com used to sell off-spec diodes by the onesies for we poor peons to
play with, but for whatever reason that doesn't seem to be the case any
more.

Given that a zener (at whatever current) is a poor noise source, what is a
good source of electronic broadband noise from low HF through high UHF --
say, 5 to 500 MHz.? (No smart remarks about spark gaps.)

We had this already yesterday in '97 and '98.
The internet does not forget anything, so watch your mouth

<http://groups.google.de/group/rec.r...+Hoffmann+noise&rnum=1&hl=de#9147bca6602ef8d1>

But, my final solution was to buy an Agilent 346c.

regards, Gerhard

 

[Winfield Hill]

Jim Thompson wrote...

I watched the money-making portable test division in Phoenix
get trashed by the shit-heads in Massachusetts... now you know
_part_ of the source of my animosity toward Massa2shits ;-)

That's an amazing extension. Plenty of healthy Massachusetts
companies have been sucked dry by their out-of-state owners.
Obviously the ability to mis-manage a company from a distance
is not notably a Massachusetts sin, unless you're obsessed with
the Harvard Business School's modest influence on the issue.

 

[Tim Williams]

When I see "GR", I think "General Radio", and salivate gently. They
made some really, really nice test gear.

Ah, had a feeling it was something about a manufacturer...

Unfortunately(?) no, it appears to be Elgenco, and I also now remember not
finding much info on this device after I picked it up. It's a rack mount
unit BTW.

Tim

 

[Roy Lewallen]

That's one thread, perhaps the first in a series. That thread
doesn't have the waveforms I was referring to (although there
are some waveforms in posts 51 and 66). Tony, Bill, Roy and I,
and some others here wasted masses of time on this subject over
a period of a few months, eight and a half years ago. . .

For the record, that was Roy McCammon, not me.

Roy Lewallen, W7EL

 

[John Larkin]

Jim Thompson wrote...

That's an amazing extension. Plenty of healthy Massachusetts
companies have been sucked dry by their out-of-state owners.
Obviously the ability to mis-manage a company from a distance
is not notably a Massachusetts sin, unless you're obsessed with
the Harvard Business School's modest influence on the issue.

It is sadly true that many of the old-line Rt 128 companies are
gone... DEC, Data General, GR, Sensitive Instruments, Clevite,
Transitron, probably others. Have others popped up to take their
place? Analog Devices, for sure.

John

 

[Clark]

Just ask for samples, I got five of them a few years ago.

 

[Robert Baer]

OK, then. A zener makes a poor noise source according to what I'm reading.
Noise.com used to sell off-spec diodes by the onesies for we poor peons to
play with, but for whatever reason that doesn't seem to be the case any
more.

Given that a zener (at whatever current) is a poor noise source, what is a
good source of electronic broadband noise from low HF through high UHF --
say, 5 to 500 MHz.? (No smart remarks about spark gaps.)

Jim





We took

Wouldn't a zener running in (or near) the (easily seen on curve
tracer) negative resistance mode have lots of noise?

 

[Ken Smith]

Wouldn't a zener running in (or near) the (easily seen on curve
tracer) negative resistance mode have lots of noise?

There's noise and then there's noise. Any signal we don't want we call
noise. A noise source for instumentation needs to have a flat spectrum.
The noise on a zener is a good example of the former and poor example of
the latter.

 

[Phil Hobbs]

What's the light-flash waveform look like from a spark plug? What do
you drive it with?

Don't you have gobs of femtosecond lasers around your place?

John

You use one of the circular-gap plugs, run it to a HV supply via a 10M
resistor, and just discharge the capacitance of the plug--you get a nice
irregular relaxation oscillation. It isn't the absolute most beautiful
pulse, but (a) it's easy to shield so you get rid of the pickup, (b)
it's surprisingly bright, and (c) the rising edge is way under 1 ns,
which should be fine for the VHF to low UHF range. I might stick one on
my sampling scope sometime and find out more about its actual
performance, but this is a pretty common trick.

There are femtosecond lasers around here--my fastest one is about 20 ps,
but it's continuously tunable from 420 nm to 10 microns, when it's working.

Cheers,

Phil Hobbs

 

[Winfield Hill]

John Larkin wrote...

It is sadly true that many of the old-line Rt 128 companies are
gone... DEC, Data General, GR, Sensitive Instruments, Clevite,
Transitron, probably others. Have others popped up to take their
place? Analog Devices, for sure.

We have scads of large wealthy "newer" high-tech companies
headquartered here, that you may not often hear of, like
Thermo Electron, Bruker, Summit Technology, EMC, etc., and
others you do know, with a substantial presence, like Agilent.

Many software and Internet companies are headquartered in MA,
like Peoplesoft, Novell, etc., and many others have a large
presence, like Sun, Red Hat, IBM, Microsoft, etc.

We all know scores of top-tier biotech companies with their
headquarters in MA, who have massive high-tech employment here.

 

[Allodoxaphobia]

It is sadly true that many of the old-line Rt 128 companies are
gone... DEC, Data General, GR, Sensitive Instruments, Clevite,
Transitron, probably others.

Have others popped up to take their place?

Why sure. Can you red Chinese tech manuals?

 

[Allodoxaphobia]

Why sure. Can you red Chinese tech manuals?

Funny how my Made-In-China keyboard with its @#%^$}# sticky "a" key
laid that out. :-\

 

[John Larkin]

We have scads of large wealthy "newer" high-tech companies
headquartered here, that you may not often hear of, like
Thermo Electron, Bruker, Summit Technology, EMC, etc., and
others you do know, with a substantial presence, like Agilent.

Ah, Bruker, my arch-enemy. I make the gradient drivers and temperature
controllers for Varian. I've also had bad experiences with Bruker AXS
in Madison. They both seem to be very NIH and very PhD oriented, so
they're hard to deal with and especially sell to.

John

 

[Mark]

depends upon the resistance and temperature of the filament

a small grain of wheat bulb will work to 500 MHz..


Mark