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Zener Noise (was: 1N4007 varactors)
Jim wrote: "...what is a good source of electronic broadband noise
from low HF through high UHF -- say, 5 to 500 MHz.?" A linear feedback shift register. Small, repeatable. 500MHz should be no particular problem these days. (There's an idea for some IC manufacturer...32 bits clocked at 1G/sec repeats every 4 seconds, which would be OK, but I'd prefer 40 or more bits. Should fit nicely into a 5 pin SOT-23: power, gnd, reset, out, ...) |
Zener Noise
In rec.radio.amateur.homebrew Tim Williams wrote:
"John Larkin" wrote in message ... I've got a gaussian noise generator, ... GR? Come again? When I see "GR", I think "General Radio", and salivate gently. They made some really, really nice test gear. -- Mike Andrews, W5EGO Tired old sysadmin |
Zener Noise
Nice touch, Bill.
73, Steve, K9DCI "Bill Turner" wrote in message ... ORIGINAL MESSAGE: "Phil Hobbs" wrote snip and can calibrate the frequency response with a spark plug. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I generally use a pipe wrench, but I'll try anything once. Bill, W6WRT |
Zener Noise
On Wed, 11 Jan 2006 23:47:37 +0000 (UTC), "Mike Andrews"
wrote: In rec.radio.amateur.homebrew Tim Williams wrote: "John Larkin" wrote in message ... I've got a gaussian noise generator, ... GR? Come again? 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 ****-heads in Massachusetts... now you know _part_ of the source of my animosity toward Massa2****s ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
Zener Noise (was: 1N4007 varactors)
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 "Clark" wrote in message ... Try this http://www.noisecom.com/ |
Zener Noise (was: 1N4007 varactors)
On Wed, 11 Jan 2006 17:00:09 -0600, "Tim Williams"
wrote: "John Larkin" wrote in message .. . I've got a gaussian noise generator, ... GR? 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 |
Zener Noise (was: 1N4007 varactors)
On Wed, 11 Jan 2006 10:08:19 -0800, "RST Engineering"
wrote: 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.radio.amateur.homebrew/browse_frm/thread/e072aa7cef573f99/9147bca6602ef8d1?lnk=st&q=Gerhard+Hoffmann+noise&r num=1&hl=de#9147bca6602ef8d1 But, my final solution was to buy an Agilent 346c. regards, Gerhard |
Zener Noise
Jim Thompson wrote...
I watched the money-making portable test division in Phoenix get trashed by the ****-heads in Massachusetts... now you know _part_ of the source of my animosity toward Massa2****s ;-) 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. -- Thanks, - Win |
Zener Noise
"Mike Andrews" wrote in message
... I've got a gaussian noise generator, ... GR? 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 -- Deep Fryer: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |
Zener Noise
Winfield Hill wrote:
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 |
1N4007 varactors
Asimov wrote:
I never tested a zener when used as varactor but I think these have a much greater reverse saturation current (even far below breakdown threshold) and it is this that might cause comparatively more noise than a conventional diode with a tiny leakage current. Well, at least that is what the junction noise equations would seem to indicate. They also have a whale of a lot more capacitance than a conventional diode. So I don't think it's a fair comparison. Roy Lewallen, W7EL |
Zener Noise
On 11 Jan 2006 17:52:16 -0800, Winfield Hill
wrote: Jim Thompson wrote... I watched the money-making portable test division in Phoenix get trashed by the ****-heads in Massachusetts... now you know _part_ of the source of my animosity toward Massa2****s ;-) 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 |
1N4007 varactors
Roy Lewallen wrote:
Asimov wrote: I never tested a zener when used as varactor but I think these have a much greater reverse saturation current (even far below breakdown threshold) and it is this that might cause comparatively more noise than a conventional diode with a tiny leakage current. Well, at least that is what the junction noise equations would seem to indicate. They also have a whale of a lot more capacitance than a conventional diode. So I don't think it's a fair comparison. Okay, if we are discussing strange and high capacitance varactors, what would you think of using a PIN photo diode as a varactor? They have more chip area per dollar and per package size and capacitance than many rectifier diodes, and that are made to have low leakage current and often have low inductance packaging. For example: http://rocky.digikey.com/WebLib/Osra...pw34fa_fas.pdf looks like a nice 15 to 70 pF capacitor. I guess you would have to keep them in the dark, unless you wanted to tune them (biased by a high resistance to a fixed voltage) with a variable intensity light beam. |
Zener Noise (was: 1N4007 varactors)
Just ask for samples, I got five of them a few years ago.
"RST Engineering" wrote in message .. . 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 "Clark" wrote in message ... Try this http://www.noisecom.com/ |
1N4007 varactors
"Highland Ham" bravely wrote to "All" (11 Jan 06 09:47:40)
--- on the heady topic of " 1N4007 varactors" HH From: Highland Ham HH Xref: core-easynews rec.radio.amateur.homebrew:90890 HH Zener diodes are often used as wide band 'noise generators'for use in HH an impedance bridge used in conjunction with a receiver. I understand to generate the noise that the zener diodes are operated within their normal breakdown current range. However, as a varactor it isn't desirable to have a breakdown current flow. The only tiny current that flows is a saturation current which is related to setting up the P-N junction boundaries within the semiconductor. M*i*k*e |
Zener Noise
RST Engineering wrote:
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 "Winfield Hill" wrote in message ... We took bench measurements, did calculations, found the scientific literature (it was a subject that occupied physicists in the late 50s, see posts 72-76), and we did plenty of speculation. Wouldn't a zener running in (or near) the (easily seen on curve tracer) negative resistance mode have lots of noise? |
Zener Noise
In article et,
Robert Baer wrote: [...] 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. -- -- forging knowledge |
Zener Noise
John Larkin wrote:
On Wed, 11 Jan 2006 14:10:32 -0500, Phil Hobbs wrote: John Larkin wrote: On Wed, 11 Jan 2006 10:08:19 -0800, "RST Engineering" wrote: A hot resistor. How about a thermistor or a lamp filament that was 50 ohms at some high temperature. You could heat it with DC, sense its resistance/temp, and let it make noise, all in a single part. Old vintage noise figure meters used gas tubes. And I think there was a pencil tube that mounted in a waveguide and made shot noise. And, of course, the old photomultiplier trick. I still like the flashlight/photodiode trick. You can get a really good calibration just from the dc, and can calibrate the frequency response with a spark plug. Cheers, 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 |
Zener Noise
John Larkin wrote...
Winfield Hill wrote: Jim Thompson wrote... I watched the money-making portable test division in Phoenix get trashed by the ****-heads in Massachusetts... now you know _part_ of the source of my animosity toward Massa2****s ;-) 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. 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. -- Thanks, - Win |
Zener Noise
On Wed, 11 Jan 2006 19:20:09 -0800, 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? Why sure. Can you red Chinese tech manuals? |
Zener Noise
On 12 Jan 2006 16:04:15 GMT, Allodoxaphobia wrote:
On Wed, 11 Jan 2006 19:20:09 -0800, 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? Why sure. Can you red Chinese tech manuals? Funny how my Made-In-China keyboard with its @#%^$}# sticky "a" key laid that out. :-\ |
Zener Noise
On 12 Jan 2006 07:44:35 -0800, Winfield Hill
wrote: 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 |
Zener Noise (was: 1N4007 varactors)
depends upon the resistance and temperature of the filament
a small grain of wheat bulb will work to 500 MHz.. Mark |
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