And why do you think hydrogen isn't a flux? -Chuck Harris On Fri, 18 Oct 2024 13:01:21 -0700 "Ed Marciniak" <edr10000@...> wrote: It *IS* possible to solder without flux, using hydrogen in a carrier
gas, but it requires a high enough temperature for the hydrogen to
reduce surface oxides, and a relatively clean (thin oxide) surface.
There is lower flammability limit to consider, as well as whether the
hydrogen might be a problem. I wouldn¡¯t choose to use forming gas to
seal a crystal can, for example.
One might use sputtered gold surfaces devoid of oxides, freshly
plasma cleaned, a gold tin solder preform and a GaAs laser diode chip
vapor phase cleaned, and want a reducing rather than inert carrier
gas, when cleaning flux residue becomes infeasible.
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Re: Anyone got documents for these instruments?
I have pdf files for the following equipment if you need any of them:? 400EL - 461A - 462A - 3406A - 3478A - 5316A - 6285A - 6286A - 6296A - 8590 - 8591A - 10240B
David
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Re: Anyone got documents for these instruments?
On Fri, 18 Oct 2024 at 23:12, David Kirkby < drkirkby@...> wrote: The "selective level meters" were already in the list of instrument types, but there were no instruments of that type. Now there is the 3746A. I have no idea what those instruments do. It's not a type of instrument I have come across before.
I had a look. It's basically a tunable power meter. How does that differ from a measuring receiver?
I notice HP says it measures RMS power. Whoever wrote that obviously does not know that whilst RMS power can be calculated mathematically, it has no physical meaning.
so is a pointless measurement. What they mean is mean power.
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Re: Anyone got documents for these instruments?
Hello David,
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I have just uploaded the files which I mentioned as possibly of use, some into new directories. There are a couple which I wouldn't know what appropriate directory they would fall into (I know the instruments themselves) so I uploaded them into the head directory as you suggested to sort out later.
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I hope these are of use to some here.
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Again my kind regards and have a good weekend!
They are fine. I did make a few changes to the files and directories.?
1) Renamed the directory 3746A to
"3746A Selective Level Measuring Set". 2) Renamed the file you uploaded to
3746A_Selective_Level_Measuring_Set_Service_Manual.pdf? as it's a service manual.
3) I managed to find an operating manual on the Keysight website, so I uploaded that myself and put it in the same directory.
I also updated the wiki,? to add that instrument to the list of selective level meters. The "selective level meters" were already in the list of instrument types, but there were no instruments of that type. Now there is the 3746A. I have no idea what those instruments do. It's not a type of instrument I have come across before.
In the case of the 3764A, I changed the directory name to "3764A Digital Transmission Analyzer", and the filename to
3764A_Digital_Transmission_Analyzer_specifications.pdf as it did not appear to be either a service manual or user manual. I'm not 100% sure what it is to be honest, but it seems to be more of a description and specifications.
I'll probably tweak the other filenames you uploaded, but that gives you some idea of the sort of thing I'm trying to keep.?
Dave
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The wiki page Home has been updated by Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...>.
Reason: Added entry to the wiki for the 3746A Selective Level Measuring Set, which now points to a directory with both the operating and service manual.
Compare Revisions
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Thanks. I have made several RF noise sources over the years and probably the best (and oldest) one is based on a Noisecom diode. This is a high output diode and so it is easy to achieve low VSWR with it because it requires lots of attenuation to get a reasonably low ENR. This one has removable SMA attenuators on it and if configured for ~13.6dB ENR it has an output VSWR better than 1.015:1 across LF through to about 1GHz.
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I tried measuring the BFR91 test amplifier with it and got the result below. This is quite good although I wouldn't normally use this 13.6dB ENR noise source to measure a noise figure as low as 4dB. I would normally change the output attenuator to lower the ENR.
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The Noisecom diode in this homebrew noise source is quite expensive but it usually works quite well. It isn't quite as stable as the 346A over time and temperature though. I think the spec for this Noisecom diode is a 0.01dB typical change in ENR per degC.
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I have other noise sources that use really cheap diodes (less than $1) but these tend to drift at up to 0.1dB per degC. I'm not sure how stable they are over time and they are quite sensitive to changes in the bias current level as well. So the cheapo noise sources have to be used with some caution. I usually check them against a MMIC eval board I have here where I know the noise figure and gain.?
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The plot below is for the Noisecom diode source measuring the BFR91 test amplifier and it goes down to 2MHz. I can explore below 2MHz but I'm not sure it will help the analysis of the 346A noise source.
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I have no idea of hat flux was used on that trasmitter, but I completlty dismanted and resooldered ever fitting because it had had many leaks over the years. The ports were most;yy for lrge pipes, and 1.25? inches deep. many had wetted less than 1/8' inch. which har cracked from the water pressure and vibration over the years. The final tubes require a minimum flow of 20 GPM, or sensors would shut down the 7 KV HV supply. I believe the TTU-25 series was still in production until the mid sixties. This was a very low serial number and passed the final test on the day I was born, in 1952. There was a TTU-1 version which was 1 KW, and used as the exciter for the larger design. Ours had had that section? catch fire, and was repaired with the three cabinet version, from the original production.
RCA used Citric acid to flush the cooling system, once a year. It was added to the cooling system, then run the transmitter without plate voltage for an hour to dissolve anything? in the system that had built up. Then it was flushed twice, with distlled water that was at operating temperature, then filled with more distilled water? and tested for conductivity. & KV would cause the water to breake down into oxygen and hydrogen, and cause major damage.
You might luck out and find the installation manual for that series online. If so, it was very detailed? about every item, since RCA treated BBroadcast equip,ent as industrial grade, built for a long serice life.
On Fri, Oct 18, 2024 at 2:06?PM ebrucehunter via <Brucekareen= [email protected]> wrote: Something over 65 years ago I helped? install an RCA UHF transmitter.? RCA furnished a liquid flux, I think they called Kempane or something like that.? It came in a bottle with a brush and was used for soft soldering flanges on large copper transmission lines with a torch.? It worked very well.? In years since I wished I had some for soft-soldering waveguide flanges.? Is there a present day generic equivalent?
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Bruce, KG6OJI
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I recommend sci-hub.? You can get across paywalls for articles if they have them in their database.? This one is in there.
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-Frank
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Ed,
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the reactions are well documented. I laid them out for you.? Here's a DOI for a paper of interest on the subject.? The hydrolysis of zinc chloride in the presence of heat is what makes the process possible.??
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-Frank
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The VSWR of a 346A below 10 MHz will necessarily be less than 1.052:1 since this corresponds exactly to the value of a 16 dB attenuator that equips all 346A. Contrary to what has been affirmed above, it is totally certain that the attenuator used is of the class of 8493C which guarantees it as totally flat over a few GHz and this from DC. Whatever will be the diode impedance, the difference in the measurement of the VSWR will hardly be seen. It would have to be exactly 50 ohms in order the VSWR will be excellent and of course it could not be possible due to the DC block.
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Sorry I misspoke there.? I meant to say the following:
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using 'plumbing' flux on electronics (i.e. flux containing zinc chloride).? To make an argument for using zinc chloride based flux is a bit silly when you have so many fluxes available to choose from that are much more friendly to electronics.
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-Frank
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I agree that there are lots of contributors to overall uncertainty. However, I don't think a bias inductor is used to feed the diode with the correct current.?
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The HPJournal from April 1983 gives the internal circuit for the 346B and this shows how the diode is matched using some resistors and a stub. I assume the 346A is the same but with a larger value attenuator at the output.
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Looking at my old notes, I worked out that there is something like a 16dB attenuator at the tip of the 346A noise source and the blocking capacitor must be something like 1200pF.? I worked this out from a 1 port measurement of the 346A and I compared this to a model based on what is inside the 346 noise sources. Based on my findings, I think the coupling cap is something like 1200pF in my 346A but this may vary across device to device. I also worked out that the equivalent resistance of the diode and the matching resistors was about 44 ohms for my 346A.
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It *IS* possible to solder without flux, using hydrogen in a carrier gas, but it requires a high enough temperature for the hydrogen to reduce surface oxides, and a relatively clean (thin oxide) surface.
There is lower flammability limit to consider, as well as whether the hydrogen might be a problem. I wouldn¡¯t choose to use forming gas to seal a crystal can, for example.
?
One might use sputtered gold surfaces devoid of oxides, freshly plasma cleaned, a gold tin solder preform and a GaAs laser diode chip vapor phase cleaned, and want a reducing rather than inert carrier gas, when cleaning flux residue becomes infeasible.
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Yes, I had a digital noise generator in mind. It is a rather simple circuit.
The HP 3561A (and later models) dynamic signal analyzer has such a source, and uses it for various measurements. HP3561 only goes up to 100kHz, but with modern chips, 10MHz would be easy.
10MHz is in the "oscilloscope range", so you are not limited to GHz techniques. Of course, you could also make a (zener) diode noise source and calibrate it (after some amplification) with a HP3400, or a modern scope, with built in RMS calculation. Exact amounts of amplification up to 10MHz are also no problem with modern chips.
Most modern AWGs can also produce noise at least up to 10MHz. You would need some attenuation to get down to HP364 levels, but attenuation is also easy at 10MHz.
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I¡¯m probably restating the obvious, but more is more happening than just the VSWR. You have the DC block characteristics to consider, the noise diode mismatch uncertainty, and any effects related to the diode bias supply. A conical inductor might be good to 50GHz, but the might not work well at 1MHz, shorting some of the noise output to the bias supply (or allowing power supply, stray RF or other noise into the diode).
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And all of that is on top of the attenuator not having constant attenuation vs frequency.
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I suppose because sometimes a more aggressive flux is necessary to solve a certain problem. I guarantee that if you don't use a flux when soldering your electronics assemblies, you aren't making good solder joints. It pays to keep an open mind. -Chuck Harris On Fri, 18 Oct 2024 11:38:40 -0700 "Frank Mashockie" <fmashockie@...> wrote: This is a pretty silly argument to make.? As Roy says, many chemicals
are hygroscopic including zinc chloride.? They absorb water readily
through water vapor in the air.? And that is how zinc chloride can
become acidic.
I'm sure it is a mistake we've all made before - using flux on
electronics.? But there are so many readily available fluxes for
different applications, I'm not sure why you'd make an argument for
using it now.
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Eventually, the water will boil off, long before solder reaches its melting point.
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I¡¯ve never thought to ask anyone, but:
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Does a similar process happen to oxide deposits?
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Does the molten zinc chloride prevent surface oxides from re-forming?
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Are some of the reaction products soluble in the molten zinc chloride?
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Are there other flux components that carry out one or more of the above roles?
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Zinc chloride fluxes are used for? brazing to bind two metals together due to the hydrochloric acid formed during hydrolysis which occurs when the flux is heated.? The HCl reacts with the metal oxide layer of the metal.? Here's a series of reactions with iron sulfate:
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ZnCl2 + 2H2O > Zn(OH)2 + 2HCl
FeS + 2HCl > FeCl2 + H2S
ZnCl2 + H2S > ZnS + HCl
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Now most of the HCl is a gaseous product, but you can see that the presence of zinc chloride continues to reduce the by-products of the initial reaction with the metal oxide layer.? It doesn't matter that the ZnCl2 is neutral under ambient conditions.? Because the process of heating it will create acidic byproducts like HCl.??
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Citric acid. For acetic acid you need vinegar.
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On 10/18/2024 9:38 AM, ¸é±ð²Ô¨¦±ð wrote: IIRC lemon juice is mild acetic acid
¸é±ð²Ô¨¦±ð
On 10/18/24 6:26 AM, Jim Ford via groups.io wrote:
Thanks, Chuck.? I've forgotten much of my chemistry since I switched majors from biochemistry to EE about 40 years ago.? IIRC, fluxes come
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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I am under the impression that KFBK in Sacremento used balanced dipole vertical antennas. Might be wrong about this. A center fed vertical does not need a ground system.
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On 10/18/2024 9:31 AM, Michael A. Terrell wrote: No. I've only wrked on Comark, Gates and RCA TV transmitters, butt I received the salvage of a 5KW Channel 8 NTSC tranmitter from Vietnam, after it was shot up by the enemy, and the engineers were killed I had a similar transmitter at Ft Greely. but it didn't have the two amplifer cabinets. That Aural fiinal would have been great for a Two Meter repeater!
The RCA used water cooled power tetrodes that were designed for just the TTU-265 series of UHF ransmitters.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Dr. David Kirkby, Kirkby Microwave Ltd
Michael A. Terrell
Frank Mashockie