Anybody heard of a neon tube military noise generator? - Page 1
Forum section: electronics / rf-microwave

author: midnightvisions
author_rank: Contributor
timestamp: February 13, 2025, 07:23:15 am
content: Is this snake oil or does it have a practical use?GSH-2 Vintage Military Noise Generator neon tubehttps://www.ebay.com/itm/116053466629

author: Gyro
author_rank: Super Contributor
timestamp: February 13, 2025, 08:36:01 pm
content: I don't speak Russian so I can't help with the datasheet but gas discharge tubes have long been used as noise sources. The only other tubes I've seen that look anything like that are optical spectral tubes but I've never seen a hot cathode one.Presumably it would need to be mounted in some sort of waveguide or cavity for the frequency range stated.

author: Simmed
author_rank: Frequent Contributor
timestamp: February 13, 2025, 08:45:20 pm
content: the weird chirpy discharge noise

author: LaserSteve
author_rank: Super Contributor
timestamp: February 13, 2025, 09:11:57 pm
content: That goes directly across a waveguide, and is driven by DC, usually with a 1 Khz modulation for the detector in the Noise Figure Meter.Hot cathode is a good idea when you want a low firing voltage and a copious amount of collision noise.Yes, they exist. Principal use is testing of receiver front ends for Noise Figure.Doesn't have to be anything special, tube wise, fluorescent lamps have been used in a pinch. However, that lamp would have its fill pressure adjusted for a desired set of characteristics. The Soviets liked large waveguide, lower frequency RADAR and TROPOSCATTER. Hence the longer than usual tube.There are nice write-ups in both Bell Labs Technical Journal and the RADLAB series on the technique.'Merican one:https://www.ebay.com/itm/234658880642In the above listing, Pin is the anode, cup is the hollow cathode. Hollow means it uses electron impacts for advanced levels of Emission. Our side of the curtain prefered Argon for the fill.Steve

author: David Hess
author_rank: Super Contributor
timestamp: February 13, 2025, 10:22:06 pm
content: The gas discharge noise tubes that I remember were like a gas discharge regulator tube, but were designed to operate within a static magnetic field, which I guess was tunable for maximum noise or something.

author: TimFox
author_rank: Super Contributor
timestamp: February 13, 2025, 10:28:14 pm
content: Quote from: David Hess on February 13, 2025, 10:22:06 pmThe General Radio 1390 generator used a 6D4 triode thyratron (in a 7-pin miniature glass envelope) connected as a gas-discharge diode. A permanent magnet’s field across the tube stabilized the discharge to give a steady noise output up to a few MHz, further amplified by a vacuum-tube amplifier.Magnetic stabilization of discharges dates back to the Poulsen arc used in the “Federal Arc” transmitters around 1910. A large electromagnet armature from a Federal Arc, found in a scrap yard, was used to construct an early cyclotron of Lawrence.

author: Analog Kid
author_rank: Super Contributor
timestamp: February 13, 2025, 10:45:11 pm
content: Seems like this component isn't "dodgy" at all.Maybe this thread should be moved? perhaps to Other Equipment & Products?

author: ZGoode
author_rank: Frequent Contributor
timestamp: February 13, 2025, 10:47:15 pm
content: I saw the title of this and also immediately thought of the GenRad 1390. I just bought one of those and am looking forward to see how random it is compared to an atmospheric noise souce or HP 347a/346a

author: coppercone2
author_rank: Super Contributor
timestamp: February 14, 2025, 12:47:22 am
content: I thought of this before and I am glad to see someone did it

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: February 14, 2025, 10:02:13 am
content: Hi Chris,Quote from: Gyro on February 13, 2025, 08:36:01 pmBut there are/were some: For example i have four pieces of the K81A.See the PDF.Best regards

author: Gyro
author_rank: Super Contributor
timestamp: February 14, 2025, 10:13:59 am
content: Oh sure, there are / were standard vacuum noise diodes, that work by running the cathode / filament in starvation. I'd just never seen a Neon filled hot cathode one like OP shows.

author: 5U4GB
author_rank: Super Contributor
timestamp: February 14, 2025, 11:03:38 am
content: Isn't a military noise generator a drill sergeant?

author: ftg
author_rank: Frequent Contributor
timestamp: February 14, 2025, 01:16:34 pm
content: Quote from: LaserSteve on February 13, 2025, 09:11:57 pmI have two. One in WR-90 for X-band and one in WR-34 nominaly for 22.00 to 33 GHz, but the soviet noise tube in it is rated for 54 to 60 GHz.I should finish my PSU for the WR-34 one and include proper switching in it, so that the NF meter can modulate it.Quote from: LaserSteveYep. Used that trick a lot when checking Ku-band LNB's on the bench. Just hold it up to the ESL lamp and if it is working, the noise floor at the IF will rise by 10 to 30dB.

author: LaserSteve
author_rank: Super Contributor
timestamp: February 14, 2025, 03:00:28 pm
content: For various uses in Microwave Amateur Radio, we also use Sky, Moon, and Sun Noise. The Sun emission is the same in relative way, long term.Every year, at least one of the US gatherings of microwave hams has a big instrument company bring a state of the noise figure measuring instrument. Where a meter of the calibrated cable and precision APC to SMA adapters costs around $3000. The precision cables are very carefully installed with a torque wrench. From what I'm told, the exposure of the unit to the LNA specialists is worth the trip in yearly sales. Think about a precision VNA with Noise Figure as its specialty. (30,000 to 60,000$ Tool)I have two waveguide LNAs that I've very proud of at 10 Ghz, but they are 1.2 dB hotter than the state of the art. I would have never got that number without a trip to a conference.Noise Figure measurement is a serious business.Steve

author: TimFox
author_rank: Super Contributor
timestamp: February 14, 2025, 03:02:17 pm
content: Quote from: Gyro on February 14, 2025, 10:13:59 amThe 5722 is a vacuum diode designed to operate in "saturated emission" mode, i.e. not space-charge limited, for noise generation.Without the smoothing by space charge, the electron current's shot noise gives a noise power that can be calculated directly from the DC current value, which is varied by controlling the filament current (cathode temperature).irms= (2q Idf)1/2https://tubedata.altanatubes.com.br/sheets/201/5/5722.pdf

author: LaserSteve
author_rank: Super Contributor
timestamp: February 14, 2025, 03:22:38 pm
content: Please see attached.Steve

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 14, 2025, 03:29:14 pm
content: Made in 1918 and if my translator is correct a shelf life of 6.5 years?

author: joeqsmith
author_rank: Super Contributor
timestamp: February 14, 2025, 05:07:57 pm
content: Quote from: ftg on February 14, 2025, 01:16:34 pmI would like to see some photos of it if possible.I was attempting to make a relatively narrow band spark source recently.https://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg5803009/#msg5803009

author: TimFox
author_rank: Super Contributor
timestamp: February 14, 2025, 05:20:17 pm
content: The paper cited by LaserSteve has a photo of the discharge tube mounted in a waveguide.The discussions I have read in noise books also show this type of tube mounted at roughly 45owith respect to the waveguide.I remember seeing somewhere the use of a small fluorescent-light tube for this purpose.

author: TimFox
author_rank: Super Contributor
timestamp: February 14, 2025, 06:17:24 pm
content: See the paper cited by LaserSteve for a similar long tube mounted in a waveguide.

author: Arylia
author_rank: Newbie
timestamp: February 14, 2025, 06:24:12 pm
content: Yes, I recently got a similar one (a ТГ1П to be precise) while buying a bunch of soviet surplus tubes, they're used to provide a precalibrated noise source for military radio stations and such. Some are fairly interesting in that they require to be in the presence of an external permanent magnet to run proper

author: TimFox
author_rank: Super Contributor
timestamp: February 14, 2025, 07:03:24 pm
content: DC magnetic fields are often used to stabilize gas discharges, since the days of Poulsen.

author: coppercone2
author_rank: Super Contributor
timestamp: February 14, 2025, 09:52:26 pm
content: Does anyone have info about how the tube is mounted, kind of like how a coaxial to waveguide feeder is well defined?It is difficult to think about, with the coaxial cable its a 50 ohm to waveguide transition (500 ohm?)What is the gas tube. I am thinking different implementations would have a different power transfer and there must be a implementation that maximizes the power transfer from the gas tube.If you replace the center conductor of a coaxial cable with a ionized gas tube, and feed it into a transition..

author: valcher
author_rank: Contributor
timestamp: February 14, 2025, 10:10:52 pm
content: All that is -http://www.155la3.ru/gsh.htm

author: joeqsmith
author_rank: Super Contributor
timestamp: February 14, 2025, 10:48:00 pm
content: I would have liked to have seen one pulled apart as well. Also, one in operation.

author: coppercone2
author_rank: Super Contributor
timestamp: February 14, 2025, 11:57:05 pm
content: in that case does the top go into the wave guide, it looks about the right lenght for a coaxial to wave guide adapter 'antenna'and is that a resistor on the tip (series resistor)?

author: joeqsmith
author_rank: Super Contributor
timestamp: February 15, 2025, 12:57:10 am
content: Why 15 degrees? Were they trying to get as much of the tube exposed to the waveguide as possible and still be able to mount it? In the one cutaway, it appears waveguide is loaded with absorber or some other material. What is the intent of that? Other paper talks about terminating the second port of the waveguide to prevent reflections and shows no other materials inside the waveguide.I got an unexpected results when playing with the sparkgap and waveguide. I was using a GDT that you would use for transient suppression. Their body appears to be ceramic. I suspect these are filled with argon. I don't believe any of the ones I used have any sort of radioactive material to aid in ionization. See link.If I place a GDT inside the waveguide and cause it to arc, I get very little detectable signal from it. Even if I use a higher breakdown part. If I use an open air spark gap and lower voltages, the radiation levels appear much much higher. I would not expect the ceramic body or the argon to effect the radiation like that. Application notes I have found make no mention of emissions from these tubes.https://bourns.com/docs/technical-documents/technical-library/gas-discharge-tubes/publications/bourns_gdt35_dc_breakdown_voltage_designnote.pdf

author: coppercone2
author_rank: Super Contributor
timestamp: February 15, 2025, 01:19:43 am
content: I think its a kind of hack, you would think a proper one would have a proper waveguide built for it. maybe its good enough for testing the systems @ a reasonable cost that you can install in a practical waveguide installation (military crap), it might mean the only access is like some "pipe" hanging in a crawl space, specifically if part of the system is damaged.Those GDT make me think of capacitors, can it be something with reactance? a 'spark gap' has a poor high frequency design, and a GDT is like a optimized electrical part (the barrel shaped ones, with two metal caps on each end)and there is something about the spark itself, I think the GDT is designed to not have like a hot spot, because that would quickly fail, I never took one apart, does it have multiple arc points or some kind of plasma diffuser or something (shorter arc duration?)Look at this picture, it has some kind of micro-feature on the 'electrodes'that looks like a perforated plate or 'honeycomb'I think they are engineered to have some kind of 'arc control measures'. Maybe it rapidly cools the arc (diffusion)And there are other coating, think of tig electrodes. thorium is not the ONLY one, but it might be the 'best' one. Yttrium, lanthanum, cerium all do things to arcs.So I think they want the arc to strike easily but also be as broad as possible. I guess actually they DONT want it to extinguish actually, because that means it protects better! The lower voltage you can hold the arc the more it protects the circuit to ensure the full lenght of the transient passes

author: LaserSteve
author_rank: Super Contributor
timestamp: February 15, 2025, 07:22:26 am
content: Noise is proportional some what to tube length. Also need a "soft" discharge plasma. GDTs are more of a short arc gap at very high pressure. Different beasts operating in different regimes.Yes a triggered GDT makes noise. However, not designed to run CW and not the right shape, size, and characteristics. In fact they are designed to quench their own arc. All that metal structure around the surge/lighting arrester is going to shape the noise output in a bad way.There are large differences in properties between a long positive column discharge tube (Neon Signs, Fluorescent Lamps, Noise Tubes, Gas Lasers) and short gapped tubes aka "xxxxTrons" where xxxx is a name.Generally something small like an NE2 need not apply for the job.The electrodes will be outside of the guide, and orientation is up to the designer. Along, Across, E plane, H Plane, slanted, Diagonal across the guide wall corners, have all been used.You have reading to do Young Grasshopper! (Partial TV quote from 1979s/80s show Kung Fu):http://www.hparchive.com/Application_Notes/HP-AN-57-1.pdfhttps://frank.pocnet.net/other/Signalite/Signalite_NoiseSources_1974.pdfHere's one of two Mumford papers, if you read one paper, this is it:https://archive.org/details/bstj28-4-608http://dbl.musicweb.ch/dbasetubes/-%20Tube%20Data%20Books/Philips%20-%20Mullard%20-%20Valvo/Philips%20Gas-Discharge-Tubes.pdfMore modern gas noise sources are long tubes running CW with an imposed audio modulation for the lock-in amplifier to detect. Usually filling the whole waveguide with a tube is not done in modern instruments, fill factor might be between 30 and 50% of the waveguide short dimension.https://www.one-electron.com/Archives/RCA/RCA-LB/LB-803%20RCA%20Labs%201950%20Gaseous%20Discharge%20Noise%20Sources%20for%20SHF.pdfhttps://www.coultersmithing.com/OldStuff/pdfs/Pch8.pdfMore modern systems are AILTECH 7514 and Eaton 2075, and they use solid state noise sources.Modern sources are reverse biased C-E breakdown in RF packaged transistors, poor quality Zener diodes followed by a MMIC, specially designed semiconductor "Noise" diodes etc...Diodes are made by Noisecom:https://noisecom.com/Steve

author: joeqsmith
author_rank: Super Contributor
timestamp: February 15, 2025, 03:17:01 pm
content: I suspect there may be some confusion. When I mentioned the GDTs used for transient protection, I am not attempting to use them for a noise source like the original post. Rather they are used as part of a spark gap transmitter.The following thread shows some of my experiments starting in the few MHz. The last posts you can see a microwave dipole attached to one of these GDTs.https://www.eevblog.com/forum/rf-microwave/fly-swatter-ham-radio-transmitter/In the 10+ GHz range I was playing at, I was commenting on how much of a signal I would see from an air gap vs the GDT.

author: coppercone2
author_rank: Super Contributor
timestamp: February 15, 2025, 05:06:26 pm
content: there still might be some commonality between the two things since they are both trying to couple energy into a waveguideReading the intro to the special tubes section of one of the documents, I wonder about using a laser to heat up gas in a wave guide too

author: LaserSteve
author_rank: Super Contributor
timestamp: February 15, 2025, 07:36:25 pm
content: I've done air breakdown with lasers. Very much getting off topic, but if the noise pulse is only nanoseconds long, it would be difficult to detect. For reasons beyond the scope of this now badly drifted thread there would be stability and spectral shape issues too. Yes there would be noise. But there are interesting things around Dirac Spikes that require math beyond my comprehension.Air breakdown with lasers generally requires nanosecond or shorter pulses from the laser. All sorts of nonlinear effects occur when you do that. In fact, this ends the discussion of what and why.Remember the goal of a noise source is a flat reliable constant source of noise at a known temperature.Spark in a waveguide has been done and published at 10 Ghz. Search WA5VJB.Steve

author: coppercone2
author_rank: Super Contributor
timestamp: February 15, 2025, 08:59:22 pm
content: lasers are NEVER off topicI think they point us to the correct location. Every time you get information about what a system does when a laser gets involved there is zero ambiguity or clot to go through about the impedance of wiring or the test setup being effected by electrical factors etc

author: benseno
author_rank: Regular Contributor
timestamp: February 15, 2025, 11:50:58 pm
content: On Russian sites this tube is mentioned as Neon gas discharge noise generator in the 7500...10300 МГц band.Seems USSR produced series of tubes each working in specific frequency band to cover wider band without gaps.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 17, 2025, 01:11:46 am
content: Quote from: LaserSteve on February 15, 2025, 07:36:25 pmGoogle hits were mostly antennas, but there was this gunn diode transmitter:http://www.arrl.org/files/file/Technology/microwave/cheap10gig.pdfIf you have a link, please post it.Quotehttps://www.eevblog.com/forum/rf-microwave/experimenting-with-waveguides-using-the-litevna/msg5799801/#msg5799801

author: ftg
author_rank: Frequent Contributor
timestamp: February 17, 2025, 11:08:23 am
content: Quote from: joeqsmith on February 14, 2025, 05:07:57 pmThe X-band one has the tube go from corner to corner across the waveguide for about 20cm distance.So very wide band coupling. Made by former Magnetic Ab from Sweden.DC feed is via a high voltage BNC and some incredibly stiff, likely +50years old RG59.The X-band one is missing the end terminator, but the WG-34 one does have it.I'll snap some photos later when I come across it again.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 17, 2025, 05:57:46 pm
content: Quote from: ftg on February 17, 2025, 11:08:23 amThanks. I am really curious if your waveguide has anything besides the tube, like the one paper shows.Further searching for the suggested WA5VJB, I did find this PDF:https://palomararc.org/Scope/scope2010.pdfOutside of mentioning Bose, it really didn't offer anything.Kent Britain WA5VJB gave a whirlwind tourof very early radio electronics. While mostradio operators in the room were familiarwith the frequently recited narrative of earlyradio spark gap experimentations, Kentuncovered new territory by focusing on theextremely compelling contributions of Indianscientist J.C. Bose. Bose demonstrated radiotransmission in 1896 in Calcutta in front ofthe British Governor General. The three-miletransmission was impressive enough that hewas invited to repeat his demonstration tothe Royal Society in London in 1899. Bosewas offered the position of Professor atCambridge, but he declined.It is believed that Marconi, who was presentat the meeting of the Society, stole Bose’snotebook. Marconi’s “Coherer”, introduced in1901, was (coincidentally?) an exact copy ofthat of Bose. Kent also gave a presentation onthe many different types of waveguides. Hisexamples ranged from the very small, to theextremely large, from the humble and simple,to the gloriously complex. The stories behindmany of his photographs were ample proof ofan extremely interesting career.

author: ftg
author_rank: Frequent Contributor
timestamp: February 18, 2025, 04:04:36 pm
content: I also found what looks like a WR-137 waveguide noise source while searching for the WR-90 one, so here's some pictures of both of them.Here's the model X121 WR-90 waveguide noise source made by Magnetic Ab from Sweden.Side view of the WR-90 noise source, showing the top to bottom slope of the noise tube.Top view of the WR-90 noise source, showing that the noise tube is in the middle.View down the "throat" of the WR-90 noise source, whowing how thin the noise tube used here is.The cable is normal, but stiff with age RG-59 coaxial cable. The connector seems to be one of those high voltage BNC's.I don't have the experience to say if it SHV, MHV or something else.I guess the tube has a heater only at one end or is a cold cathode one.The WR-137 one for 5.85 to 8.20 KiloMegacycles has the tube go through the middle of the waveguide in a way similar to the X-band one. I guess the upper end of the WR-137 also classifies as X-band.The usual side view. This time we see that there's cables at (with cut ends, so no idea about the original connector) at both ends.So I guess hot cathode this time.View down the "throat" of the WR-137 waveguide noise source, showing the slightly thicker noise tube.As you folks might have guess, I don't have the original power supplies for these and thus have not tested them.

author: joeqsmith
author_rank: Super Contributor
timestamp: February 18, 2025, 04:10:11 pm
content: Thanks for taking the time to post those. It's interesting that yours have nothing inside the waveguide besides the tube where that one document shows something else added. I assume with yours, one side of that waveguide was terminated during normal use.Have you ever tried to run one and measure it?

author: coppercone2
author_rank: Super Contributor
timestamp: February 18, 2025, 04:10:25 pm
content: if you put a neon tube infront of a wide band horn antenna, does it pick up across all frequencies?I was just thinking to try putting a hand held UV tube lamp (4x aa battery) infront of an antenna. But the problem is they are battery powered switchers that might contaminate the tube signal.The waveguide just acts as a band pass filter. I don't think its interacting with the tube in the style of some kind of resonator?Does it really need to be in the wave guide for some reason or can you just use a wave guide after a horn to do the same thing. Bad power transfer?

author: ftg
author_rank: Frequent Contributor
timestamp: February 18, 2025, 04:43:55 pm
content: Quote from: joeqsmith on February 18, 2025, 04:10:11 pmYes, the other end would be terminated in normal use.I have not run these, as I don't have the power supplies for them.And also have not built them yet. Assuming the tubes are in a working condition.Quote from: coppercone2 on February 18, 2025, 04:10:25 pmThe tube is not really a resonator in any real way.Waveguides can be considered high pass filters, they'll mode weirdly at above the cutoff, but it's not a brick wall.The only way you'll receive anything with a fluro tube is if you run it as a plasma diode, or the RF field is strong enough to light it.Alan Yates, VK3ZAY did some neat experiments with NE-2 neon lamps as plasma diodes.http://www.vk2zay.net/article/49But those would be a topic on its own right and is not really relevant to noise generator tubes.

author: coppercone2
author_rank: Super Contributor
timestamp: February 18, 2025, 04:48:20 pm
content: but there is a link for a ebay tube meant to do it. what would happen if you ignited it with whatever its meant to be ignited with and held it infront of a horn?and you are right about it being a high pass filter, in that case, what about the higher frequencies generated by the tube?you can plop this in front of a antennahttps://www.ebay.com/itm/116053466629My guess is that it would make noise but not have a uniform power across frequencies, (not flat). ?

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 18, 2025, 05:34:11 pm
content: Here is a waveguide noise source at WR-28 (Ka-band, formerly used on a 35 GHz radar). I removed the tube from the enclosure. Just like the WR-90 and -137 examples above, the tube is inclined with respect to the waveguide, increasing the surface area presented and hence the noise coupling. The WR28 flange is on the left, to the right one can see a bulge beneath the waveguide, I'm assuming that's where the termination goes.The tube itself is aBendix 6359-TD13, with a 6505 date code. The linked data sheet shows an application circuit - I might try this out sometime. Note that the filament is only used during startup, and is removed from circuit after discharge is established. Amusingly, it calls for selenium rectifiers! The ENR spec is 16 dB - hmm, I thought that this would be higher, given that it was used on radars that lacked an LNA (receive signal fed straight to a mixer diode).Such devices are no longer used in modern radar applications, they've been replaced by solid-state noise sources. For precision measurements and calibrations, we use 346B series sources. Once the instrument is well calibrated, an internal noise source (less precise) is used to periodically verify that things haven't drifted too far from nominal.We also use radiometric emissions from the sun, though the amplitude varies significantly over a solar cycle (11 years). It's mostly done for verifying pointing accuracy of the antenna. One can use solar flux measurements from solar observatories to try and estimate the expected receive power (for absolute calibration):https://www.spaceweather.gc.ca/forecast-prevision/solar-solaire/solarflux/sx-4a-en.phphttps://www.spaceweather.gc.ca/forecast-prevision/solar-solaire/solarflux/sx-5-flux-en.phphttps://www.swpc.noaa.gov/products/solar-cycle-progression

author: coppercone2
author_rank: Super Contributor
timestamp: February 18, 2025, 06:03:41 pm
content: there you go the sun is a plasma

author: A.Z.
author_rank: Super Contributor
timestamp: February 19, 2025, 07:27:13 pm
content: Quote from: 5U4GB on February 14, 2025, 11:03:38 amnot sure he goes up in frequency to RF

author: coppercone2
author_rank: Super Contributor
timestamp: February 19, 2025, 09:56:23 pm
content: definitely is a giant squarei heard some boots carry AM radios around when they are sneaking around past curfew to help detect the hat

author: radiolistener
author_rank: Super Contributor
timestamp: February 20, 2025, 12:23:37 am
content: According to documents that you can google, this is ГШ2 - Генератор Шума (Noise Generator). ГШ-2 is the continuous gas-discharge noise generator which is used as a source of calibrated power for radar and microwave communication receivers, as well as for equipment where uniform microwave power is required over a wide frequency range.Working range: 7500 - 10300 MHzFilament voltage: 10.3 - 12.6 VAnode voltage: 150 - 260 VFilament current: up to 1.4 AmpsAnode current: 120-150 mAThe operating resource is 7500 hours.The noise spectral power varies from 59 kTO to 70 kTO. (I have no idea what this unit kTO means)The body has a diameter of 19 mm, and the overall dimensions of the ГШ-2 are 385x25 mm.Weight does not exceed 40 grams.Here is datasheet:https://lampes-et-tubes.info/mwot/GSh-2.pdf

author: benseno
author_rank: Regular Contributor
timestamp: February 20, 2025, 08:48:52 am
content: Quote from: radiolistener on February 20, 2025, 12:23:37 amCould be thermal noise power:https://www.calculatoratoz.com/en/thermal-noise-power-calculator/Calc-33062

author: coppercone2
author_rank: Super Contributor
timestamp: February 20, 2025, 11:07:36 pm
content: it does say to use a heat wedge resistor as a noise generator toothey have their own units?I think it might be K*T0 ?searching for it seems to show alot of things about bolometers but I will not try to get to the bottom of this

author: joeqsmith
author_rank: Super Contributor
timestamp: February 20, 2025, 11:52:46 pm
content: Quote from: coppercone2 on February 20, 2025, 11:07:36 pmThere was that published document a couple years back where they made a transmitter using a resistor as the source, nothing else. No amplifier, no power source, just the noise off the resistor. Now granted, the horns were fairly large but it seems like they were getting a decent range from it. Seems like it was a university experiment, but I am not sure. I may have saved the paper if you can't find it and are interested in reading it.

author: coppercone2
author_rank: Super Contributor
timestamp: February 21, 2025, 12:12:31 am
content: It does make sense because its something like a glo bar source, which is used for THzhttps://hackaday.com/2023/01/27/a-single-resistor-radio-transmitter-thanks-to-the-power-of-noise/

author: ftg
author_rank: Frequent Contributor
timestamp: February 21, 2025, 09:02:24 am
content: We used an oven pilot light at white hot as a low cost signal source for 100 - 1000 GHz at one job.Modulated with a chopper, which also allowed us to do an implementation of a kind of lock-in amplifier in software.Radiation pattern was shaped by the funky fixture it was in.

author: coppercone2
author_rank: Super Contributor
timestamp: February 22, 2025, 02:33:46 am
content: A ha, I remembered there is a certain type of IR emitter chip, that is basically a highly engineered nichrome filament in a metal transistor cylinder package.https://www.ist-ag.com/sites/default/files/downloads/Datasheet-HISbasic-HIS550R-A.pdfits a interesting 'solution'They add nano-texturing to make it emit better or something like that.But its only 600C. Needs upgrade to 1600Chttps://www.infrasolid.com/en/technologyI wonder if you can do that for lower frequencies like THz or GHz

author: ftg
author_rank: Frequent Contributor
timestamp: February 24, 2025, 08:30:36 am
content: One can do it for the 100 - 1000 GHz band at least, because we did.

author: coppercone2
author_rank: Super Contributor
timestamp: February 24, 2025, 09:36:26 pm
content: the nano texturing?

author: ftg
author_rank: Frequent Contributor
timestamp: February 25, 2025, 09:16:08 am
content: Quote from: coppercone2 on February 24, 2025, 09:36:26 pmNope, open air electric gas stove pilot light.

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2025, 09:23:10 am
content: What is getting white hot here, I associate pilot light with cigarette lighter flame, and electric start with a HV sparker, for stoves.I think I am imagining a different stove, I don't associate it with anything flowing white hotPilot lights always burn a small flame, and electric start stoves click to light a flame.I never saw a stove that heats anything near white hotdo you mean you run a resistance stove at overload? (spiral coil). But you mention gas. Is this some kind of special industrial contraption?