Thanks. I don't know if this is of any interest, but see below for my original attempt at reverse engineering what attenuator and blocking cap was used in my 346A noise source. The circuit was based on the info in the April 1983 HP Journal. Sadly the HP Journal didn't provide the value of the attenuator or the coupling cap for the 346A so that was why I had to try and work it out using the simulation below. I compared against a VNA measurement of my own HP 346A noise source.
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I ended up with about 1200pF for the coupling cap and about 16.2dB for the attenuator. This gave the best curve fit for the model.
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If you look closely, there are two VSWR plots and two Z complex plots and I adjusted the blocking cap and the attenuation value to try and get the real and imaginary parts of the impedance to overlay as accurately as possible when compared to a VNA measurement of a real 346A noise source. I ended up with a diode resistance of just 15 ohms in the hot state. This seems really low but it is the only way to get a match for the real and imaginary parts of the impedance across LF through to about 20MHz.
The traces almost overlay perfectly below 10MHz.
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You can see that the power transfer suggests a relative loss of only about 0.25dB between 10MHz and 2MHz although this assumes the noise output is flat with frequency. This is partly why my first attempt at an ENR table wasn't quite right at the 2MHz and 3MHz cal points. This agreed with my first attempt at measuring the output noise. The value of the coupling cap is quite critical to the level response below 3MHz so hopefully this cap is stable over time and temperature. I hope this simulation is interesting. I'm not sure how much value it adds to the discussion though.
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FWIW, I couldn't find the date codes on the 346A and 346B at work yesterday, but the HP logo and Hughes Aircraft property tag date the 346A to sometime before the mid 1990s.? ?Likewise, the Agilent logo and Raytheon property tag put the 346B at probably early 2000s.? I assume one would have to disassemble either to find the date code.? That would be a CLM (Career-Limiting Move) where I work....? ? ? Jim?
On Sat, Oct 19, 2024 at 12:54 PM, jmr via groups.io <jmrhzu@...> wrote: I had some free time today to play a bit more with the 346A and the PSA analyser. This time I tested a common emitter amplifier using the classic 2SC3355 BJT from NEC. This was a very special BJT in its day that could deliver a sub 1dB noise figure when driven from a 50R source. I've designed quite a few amplifiers with this BJT and I'm lucky to have the manufacturer's non-linear model for it and this model has been proven many times to give realistic results for noise figure.
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See the simulation below. This predicts a noise figure of about 0.8dB and this is about right. Because the input is unmatched, the input VSWR is about 8:1 and so this represents a significant mismatch at the amplifier input. This should be a good test for the 346A because of the mismatched input of this amplifier.
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It's hard to read the text in the image above but the simulation shows a flat noise figure of 0.86dB across 2-20MHz. The gain is just over 21dB.
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I built the amplifier and tested it for gain and input s11 on a VNA. The VNA source power had to be turned down really low to -40dBm to prevent any compression. This is a full two port test using an Ecal module to correct the ports of the VNA to be exactly 50 ohms. To compare against the PSA analyser the test must be done with a very small signal or subtle amounts of compression in the 2SC3355 could spoil the comparison.
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The VNA shows a significant mismatch at the input (as expected) and the gain varies from 21.63dB at 2MHz to 21.46dB at 18MHz. The gain is very flat in other words and so is the noise figure.
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See below for the result I got for noise figure and gain using the 346A noise source and the PSA analyser with my external preamp at the PSA input.
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You can see it did a good job here. However, I think the ENR table isn't quite right yet. There does seem to be a bit of a stubborn bump at 5MHz so I think the ENR value at 5MHz needs to be turned down maybe 0.03dB or so. This plot is taken without averaging to show how smooth the results are even without averaging. It may be that the ENR value at 2MHz and 3MHz may need a tiny tweak as well, but I'm not too fussed about this.
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This is the same ENR table as I used for the last tests. So it looks like the ENR table (across 2MHz to 10MHz) for this 346A noise source is close to being complete :)
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I had some free time today to play a bit more with the 346A and the PSA analyser. This time I tested a common emitter amplifier using the classic 2SC3355 BJT from NEC. This was a very special BJT in its day that could deliver a sub 1dB noise figure when driven from a 50R source. I've designed quite a few amplifiers with this BJT and I'm lucky to have the manufacturer's non-linear model for it and this model has been proven many times to give realistic results for noise figure.
?
See the simulation below. This predicts a noise figure of about 0.8dB and this is about right. Because the input is unmatched, the input VSWR is about 8:1 and so this represents a significant mismatch at the amplifier input. This should be a good test for the 346A because of the mismatched input of this amplifier.
?
?
It's hard to read the text in the image above but the simulation shows a flat noise figure of 0.86dB across 2-20MHz. The gain is just over 21dB.
?
I built the amplifier and tested it for gain and input s11 on a VNA. The VNA source power had to be turned down really low to -40dBm to prevent any compression. This is a full two port test using an Ecal module to correct the ports of the VNA to be exactly 50 ohms. To compare against the PSA analyser the test must be done with a very small signal or subtle amounts of compression in the 2SC3355 could spoil the comparison.
?
?
The VNA shows a significant mismatch at the input (as expected) and the gain varies from 21.63dB at 2MHz to 21.46dB at 18MHz. The gain is very flat in other words and so is the noise figure.
?
See below for the result I got for noise figure and gain using the 346A noise source and the PSA analyser with my external preamp at the PSA input.
?
?
You can see it did a good job here. However, I think the ENR table isn't quite right yet. There does seem to be a bit of a stubborn bump at 5MHz so I think the ENR value at 5MHz needs to be turned down maybe 0.03dB or so. This plot is taken without averaging to show how smooth the results are even without averaging. It may be that the ENR value at 2MHz and 3MHz may need a tiny tweak as well, but I'm not too fussed about this.
?
This is the same ENR table as I used for the last tests. So it looks like the ENR table (across 2MHz to 10MHz) for this 346A noise source is close to being complete :)
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Dear All,
Which brings us to the question of what was in the original version of ¡°Fluxite¡±?
The modern product is quite different.
The old one was amazingly effective at stripping oxide- I used it and still use my precious circa 1970 tin of it for soldering brass and copper hardware- microwave cavities, waveguide flanges etc etc.
After soldering I clean the job with an organic solvent to remove the grease/rosin part of the flux, then hot soapy water for the next clean, then water rinse. Assemblies I¡¯ve built with this procedure show no corrosion after 30+ years.
I would n¡¯t use it for electronic assembly where such cleaning is not practical.
I¡¯m equally curious about what was in the RCA flux mentioned.
No room for error soldering large transmitter feeders- I recall being invited to touch the outside of the 6 1/4¡± feeders at a major analogue UHF TV transmitter and feeling the warmth conducted through the pressurised air from the inner conductor. Impressive.
Regards,
Alwyn
_____________________________________________________
Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.
SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom. _____________________________________________________
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Re: HP8753B VNA question regarding if I purchase one
George,
The 8753B will need a test set like the 85047A to reach 6GHz, or the 85046A up to 3GHz.? The 8753D has a built in test set, and is available in 3GHz and 6GHz versions.? These all use APC-7 connectors, so you will need adapters and cables to work with whatever connector system you use.? The adapters may be expensive.? You will also need calibration standards (short, open, and load) which can also get expensive.
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As others have mentioned, the NanoVNA series of devices is available at very low cost and includes SMA cables and standards that are acceptable for many purposes.? You would still need some adapters if you use connectors other than SMA.? I personally have a couple of 6GHz 8753Ds, but I find that for most measurements I use the NanoVNA units because of their portability.
?
If you want the solid feel of an HP unit, you might want to look at the 8712 (1.3GHz) or 8714 (3GHz) units.? They have built-in test sets and use N connectors.
--John Gord
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On Fri, Oct 18, 2024 at 09:52 PM, Frank Mashockie wrote:
Something seems fishy about this study
Well... if you follow their methodology... they washed with 'pure water'
They don't give the temperature of the water? Though... that may be in Rudolf, or one of the ASTM standards.
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As was mentioned in the thread... zinc chloride is extremely soluble in water, and ammonium chloride is pretty soluble...and the solubility increases with temperature.
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Not saying it is... but perhaps trying to clean away an 'activated' rosin flux, with water isn't the greatest idea, if you want to get rid of the 'activists' ... like ammonium chloride... the rosin is going to keep some of it suspended.
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If I had to guess... and I guess I have to... I'd think the sodium hydroxide solution is 'passivating' the exposed metal... while the sodium hydroxide solution is acting as an electrolyte, for enhanced local electro-chemical reactions... between the suspended 'activators' and the metal... covered by the remaining rosin flux.?
Again just guessing that that could explain enhanced corrosion... where you would expect the least corrosion.
?
Of course we don't dip out fine HP test equipment into sodium hydroxide solutions...at least... not more than once? anyway.
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Re: HP8753B VNA question regarding if I purchase one
An HP VNA, and a budget usually don't go well together. The VNA is only a small part of the story, as it will need to be calibrated every time you use it, so you will need a calibration standards kits, which (for one that is good) often exceeds the price of the used VNA bargain. You will also need adapters that connect between the very expensive, and delicate connectors on the VNA, and the rough and tumble cables and connectors that you may use to connect to your fixtures. Oh, and you shouldn't really use any rough and tumble connectors and cables. Good VNA connectors and cables are also expensive. You haven't mentioned what you want to do with your VNA, so I would also include some good books and a lot of learning in the mix. If you just want to experience a VNA, and try it on a bunch of different things, there are some new little kits that come with everything you need, for under $50. Look into the nano VNA. It is an excellent VNA for someone who is new to the whole idea. -Chuck Harris On Sat, 19 Oct 2024 10:02:34 -0700 "G H via groups.io" <gkhoefer@...> wrote: Hello Group,
I am pondering the choice regarding purchasing an HP VNA.
What model of HP VNA would be a good choice regarding this topic, for
a retired hobbyist on a budget?
I have a good selection of Test Equipment in my selection, acquired
over time. A lot of it is HP gear.
I have worked my entire career in the field of electronics, mostly
working in the field on servicing and maintaining electronic systems.
Using a lot of other HP gear but not really using a VNA.
I saw a HP8753B for sale and I would like to ask the group if this
would be a distinct unit? It has option 006, (6GHz) range.
Are they hard to repair? Any weak points on these units?
All recommendations accepted and any comments.
Thanks in advance,
George
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As a welder that sometimes uses oxy-acetylene to weld or braze, and Argon/CO2 gas mixture to weld with MIG or TIG, flux is often unnecessary depending on the atmosphere in the case of MIG or TIG, or how you adjust the oxygen/fuel ratio in the case of Oxy-acetylene. A mix that has too much oxygen will burn the steel, and oxidize metals like copper. A mix that is neutral, will simply heat the metal, without burning. And, a mix that has a little too much fuel, will reduce the metal oxides, removing them and cleaning the metal to be as shiny as a new penny. Hydrogen under high temperatures will also reduce the oxides and leave behind a clean and pure metal. It also prohibits any nitrogen or oxygen in the mix, which further, it keeps the hot metal clean and pure... A lot of things that are just what a flux does. So, in my view, the hydrogen atmosphere acts as a flux. As to your criterion for being a flux, which do you think your hydrogen atmosphere fails? Chuck Harris On Sat, 19 Oct 2024 09:53:23 -0700 "Roy Thistle" <roy.thistle@...> wrote: On Fri, Oct 18, 2024 at 04:24 PM, Chuck Harris wrote:
And why do you think hydrogen isn't a flux?
I had an 'discussion' with my Greek friend, that a 'Greek tortoise' (
*Testudo graeca marginata* ) is not a turtle... but from where he
from... there is no word for 'turtle.' I had a chat with a local
Cree, that a 'Painted turtle (Chrysemys picta picta) is not a
turtle... but, he told me about "Turtle Island."
Anyway... not even the herpetologists, actually know what a 'species'
is... but, they sort of agree... on many of them.
The same goes for 'flux'
I don't know that is is sufficient... but, it's necessary... at least
by consensus... that a flux has... at least three properties.
Shielding Wetting
Deoxidation
And about hydrogen gas... or banana peel srcrapings... people can
decide for themselves.
And by the way... a tortoise is not a turtle, is not a terrapin.
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Re: HP8753B VNA question regarding if I purchase one
Based upon your post, aside from HP VNAs, and depending your intended use(s) for one, you may want to take a look at the various Nano VNAs available.
There are several groups.io groups which are forums for the Nano VNAs.
DaveD KC0WJN
Thanks for all the fish.
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
toggle quoted message
Show quoted text
On Oct 19, 2024, at 13:02, G H via groups.io <gkhoefer@...> wrote:
?
Hello Group,
I am pondering the choice regarding purchasing an HP VNA.
What model of HP VNA would be a good choice regarding this topic, for a retired hobbyist on a budget?
I have a good selection of Test Equipment in my selection, acquired over time. A lot of it is HP gear.
I have worked my entire career in the field of electronics, mostly working in the field on servicing and maintaining electronic systems. Using a lot of other HP gear but not really using a VNA.
I saw a HP8753B for sale and I would like to ask the group if this would be a distinct unit? It has option 006, (6GHz) range.
Are they hard to repair? Any weak points on these units?
All recommendations accepted and any comments.
?
?
Thanks in advance,
George
|
HP8753B VNA question regarding if I purchase one
Hello Group,
I am pondering the choice regarding purchasing an HP VNA.
What model of HP VNA would be a good choice regarding this topic, for a retired hobbyist on a budget?
I have a good selection of Test Equipment in my selection, acquired over time. A lot of it is HP gear.
I have worked my entire career in the field of electronics, mostly working in the field on servicing and maintaining electronic systems. Using a lot of other HP gear but not really using a VNA.
I saw a HP8753B for sale and I would like to ask the group if this would be a distinct unit? It has option 006, (6GHz) range.
Are they hard to repair? Any weak points on these units?
All recommendations accepted and any comments.
?
?
Thanks in advance,
George
|
On Fri, Oct 18, 2024 at 04:24 PM, Chuck Harris wrote:
And why do you think hydrogen isn't a flux?
I had an 'discussion' with my Greek friend, that a 'Greek tortoise' ( Testudo graeca marginata) is not a turtle... but from where he from... there is no word for 'turtle.'
I had a chat with a local Cree, that a 'Painted turtle (Chrysemys picta picta) is not a turtle... but, he told me about "Turtle Island."
?
Anyway... not even the herpetologists, actually know what a 'species' is... but, they sort of agree... on many of them.
?
The same goes for 'flux'
I don't know that is is sufficient... but, it's necessary... at least by consensus... that a flux has... at least three properties.
Shielding
Wetting
Deoxidation
?
And about hydrogen gas... or banana peel srcrapings... people can decide for themselves.
?
And by the way... a tortoise is not a turtle, is not a terrapin.
|
Fishy? Sometimes our "gut feelings" about how something should work can be very wrong. That is why experiments are done. The study would have been better if they had stated exactly what fluxes were being used. Unless the formulas were so ubiquitous as to be common knowledge, they should have stated the manufacturer, branding and physical characteristics of the products used. Although we can't easily know all of the affiliations of the researchers, it is somewhat comforting that they all worked in engineering departments at a university. My guess is that they did not mean a water/powdered zinc/ammonium chloride paste, but rather a compound just like the solder paste that started this thread: zinc chloride in petroleum jelly. That being the case, the petroleum jelly's hydrophobia, tends to keep the ZnCl away from the water that is necessary to make it corrosive. It also keeps the air away from the copper that is necessary for causing the copper to oxidize. I have never, and I do mean never, found the ZnCl flux I have used to be at all corrosive. If anything, bare copper wires stay bright under the flux. -Chuck Harris On Fri, 18 Oct 2024 21:52:10 -0700 "Frank Mashockie" <fmashockie@...> wrote: Here's an interesting article claiming zinc chloride has a slower
corrosion rate than RA and amines/amonnia.? They specify rosin
activated with halides (Cl, Br, F, containing compounds).? Zinc
chloride is a metal halide.
Something seems fishy about this study.? The zinc chloride performed
better than the copper wire alone?? Hmmm...
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Hi Brad, Ok, so I guessed right. That same stuff has been used over the last 100 years for the exact same purpose. What does yours say on the jar/can? There are a couple of varieties, depending on what the specific purpose was. The stuff I use is labeled: Top of Can: Caution Eye Irritation, Harmful if Swallowed Seek Medical Attention BURNLEY SOLDERING PASTE NON-CORROSIVE CLEANS AS IT FLUXES NET WEIGHT 2 OZS 57 G MADE IN U.S.A. Bottom of Can: BURNLEY SOLDERING PASTE CLEAN PARTS TO BE SOLDERED APPLY FLUX SPARINGLY, THEN SOLDER. MFG BY: BURNLEY BATTERY & MANUFACTURING CORP. NORTH EAST PA, 16428 The sides talk of how the product had been in continuous production for over 80 years... I have had it for more than 30. Note the mix of grams and ounces, and the zip code. This indicates that it was made after the US started "metrification". It was bought from US DOD surplus and came from materials that were released to scrap by NSA's spook training school, judging by the paperwork that came with the scrap lot. When the joint gets soldered, the tin/lead is absorbed into the surface of the copper, and the flux floats to the surface, riding on the petroleum jelly/wax component. As I said earlier, the inside of the can is still shiny tin plate. Will something bad happen down the line? I don't know, In the more than 50 years I have been using similar stuff it hasn't, and I do know that similar stuff was used by manufacturers that made TV sets and radios. Back in the day, component manufacturers didn't always have climate controlled warehouses, and leads weren't always shiny and pristine even when new. A tiny bit of a slightly aggressive flux made the soldering go much better. -Chuck Harris On Sat, 19 Oct 2024 21:00:35 +1100 "Brad Latta" <bradley.latta@...> wrote: Hi Chuck,
It is a paste containing 27% Zinc Chloride, I hope
when heated with soldering iron on a point to point circuit
connection the remnants would not be corrosive, mostly I use it to
be able to wet ( with solder) crusty tube point to point wiring for
equipment that has been exposed to high humidity in storage, Brad
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HP8970B calibration memory questions
I bought a HP8970B (serial prefix 2950A), and I am not sure of the state of the internal RAM backup battery. The service manual says to check address 65460, which should contain 128, if the stored IF gain/attenuator calibration values are OK. I found "27" there, which would indicate lost calibration. But the 8970 signals no error on power up or measurement.? Also, the values at 6992 (from sf 93.3) and on, seem quite reasonable as 5dB steps (3.173, 10.189, 32.339, 100.44, ....).
So I am not sure if the instrument is accurate. Other operator checks (own NF etc) come out OK, it also produces reasonable NF and gain results.
I will replace the battery in any case, but should I try to keep the existing values, either by providing backup power, or manually re-typing the extracted values?
Or, should I do a full calibration? I think I have all the gear needed. I guess HP437 instead of 436, and HP3457 instead of 3456, would be OK? (also have 435 and 3455, if these would be better suited.)
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Hi Chuck,? ? ? ? ? ? ? ? ? ? ?It is a paste containing 27% Zinc Chloride, I hope when heated with soldering iron on a point to point circuit connection the remnants would not be corrosive,? mostly I use it to be able to wet ( with solder) crusty tube point to point wiring for equipment that has been exposed to high humidity in storage, Brad
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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I use boric acid for
musical instrument repair of brass to brass connections. once
complete i spray 50/50 alcohol (90% cheap stuff is fine here)
and water while still pretty warm...all gone and clean.
¸é±ð²Ô¨¦±ð
On 10/18/24 5:26 PM, John Griessen via
groups.io wrote:
toggle quoted message
Show quoted text
On
10/18/24 13:44, Ed Marciniak wrote:
Does the molten zinc chloride prevent
surface oxides from re-forming?
I have experience making my own tin bronze alloy in a natural gas
forced air furnace.
Molten boric acid does keep oxides from forming on the top of the
melt --glowing yellow-orange...
Seems very similar -- zinc chloride salt is acidic in water as is
boric acid...
.
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Here's an interesting article claiming zinc chloride has a slower corrosion rate than RA and amines/amonnia.? They specify rosin activated with halides (Cl, Br, F, containing compounds).? Zinc chloride is a metal halide.??
?
Something seems fishy about this study.? The zinc chloride performed better than the copper wire alone?? Hmmm...
?
https://dergipark.org.tr/en/download/article-file/3231061
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On 10/18/24 13:44, Ed Marciniak wrote: Does the molten zinc chloride prevent surface oxides from re-forming? I have experience making my own tin bronze alloy in a natural gas forced air furnace. Molten boric acid does keep oxides from forming on the top of the melt --glowing yellow-orange... Seems very similar -- zinc chloride salt is acidic in water as is boric acid...
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Why do you think that RCA went to such extreme measures to prevent its formation in the system?The cooling system was copper and brass, while the tubes and sensors were stainless stel.
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
Please check under the directory?
and see if the files you have are there. If there¡¯s no directory for the instrument, please create one. I just checked and there¡¯s nothing for the 10240B, so create a directory something like
10240B 0.18 uF Blocking Capacitor
and upload the file(s) into the directory. I don¡¯t off-hand know if there are copies of the files you have.?
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Frank Mashockie
Michael A. Terrell
Dr. David Kirkby, Kirkby Microwave Ltd