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Re: HP8753B VNA question regarding if I purchase one

 

On Sat, 19 Oct 2024 at 18:02, G H via <gkhoefer=[email protected]> 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.


It very much depends on your frequency range of interest, but for use to 6 GHz, you would be hard to beat an 8753B or later. There's a lot of information on my company websites about the 8753 series.?


You will generally want to use it with an S-parameter test set. Either the 3 GHz? 85046A or 6 GHz 85047A. Do not buy an 85046B, as that's 75 ohm. I did actually convert a 75 ohm 85046B to 50 ohm, by stripping the parts from a similar 1.3 GHz 50 ohm test set. I was not bothered about performance above 1.3 GHz, as I have a 20 GHz VNA too. At the time it was economical to do the conversion, but I don't think it is now.


Models with options like the 6 GHz 006 will generally fetch more than instruments without it, but don't worry about buying options, as someone here will supply codes to unlock all the options. So option 002 (not that useful), 006 (6 GHz), and 010 (time domain) are easy to get free.

My company sells VNA calibration kits, and more customers have 8753s than any other single VNA. It's very popular among both hobbyists and commercial companies. Last year I visited the National Physical Laboratory (NPL) in the UK, and they have an 8753 too. (NPL also have the more advanced 8510C, and the mega expensive PNA-X series).

Are they hard to repair? Any weak points on these units?

?
There's a lot of information available on this site on them, including at least some circuit diagrams.


All recommendations accepted and any comments.


If you can get one at a reasonable price, I don't think you will regret it.?

?

Thanks in advance,

George


Dave

Re: HP8753B VNA question regarding if I purchase one

 

If the 8753B is a good price and the screen is OK then it is a far superior instrument to the "Nano" devices. The displays can get? bit dim with age. If you keep the unit there is a LED upgrade that also give colour.
You do NOT have to have a test set to use the instrument.?

A test set makes things easy but for simple transmission tests you just need a resistive power splitter and some cables. For reflection a directional coupler is required. This could be a single component. For a bit more versatility at lower cost a HP 8502A can be used.
You will learn a lot more about network analyser operation using an 8753, a power splitter and directional coupler than touching the screen on a Nano or even a full switching test set.
Talking about the cost of "proper" calibration kits and Nanos on the same thread is a bit of an oxymoron.? A home made short and open and a reasonable quality standard termination is good enought for most users. The kits supplied with the Nano are not metrology grade....
Dave, the group owner sells excellent cal kits at sensible prices.
?
Robert G8RPI
(8753B, 85047A, 85046B, 8754A, 8502A, DG8SAQ and Anritsu S311 owner with both HP and Kirby Microwave Cal kits)
File Notifications #file-notice

Group Notification
 

The following items have been added to the Files area of the [email protected] group.

By: DF6NA Rainer <df6na@...>

The following items have been added to the Files area of the [email protected] group.

By: DF6NA Rainer <df6na@...>

The following items have been added to the Files area of the [email protected] group.

By: DF6NA Rainer <df6na@...>
File /All HP, Agilent and Keysight instruments in folders by part numbers/A 80000 to 89999/85031B 7 mm (APC7) Mechanical Calibration Kit, DC to 6 GHz/Vector_Network_Analyzer_Calibration-Kit-Definitions.pdf updated #file-notice

Group Notification
 

The following items have been updated in the Files area of the [email protected] group.

By: Dr. David Kirkby, Kirkby Microwave Ltd <drkirkby@...>

Description:
These coefficients will often be in the VNA firmware, and manuals for older VNA calibration kits. There are often small differences between the firmware, manual and this document! Ask on the list for more information
Re: HP8753B VNA question regarding if I purchase one

 

¿ªÔÆÌåÓý

I second John¡¯s wise words. The 8752 is also a nice 3GHz machine that has a built in test set.?

I love my 8753D/E and S units and they can be quite economical if you are in no hurry and don¡¯t need to have them shipped.?

Not all of the HPs have APC7¡¯s, but beware the ones that have Ns. Some, but hardly all, are 75¦¸, and buying one expecting otherwise can ruin your day. I have had at least one 50¦¸ N connectors 8753.?

Also beware the cost of test cables. Good ones are expensive. But you can usually find some for sub $100 at MIT flea hamfest or some place similar.?

Good luck!



On Oct 19, 2024, at 14:06, John Gord via groups.io <johngord@...> wrote:

?
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.
?
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
Re: HP8753B VNA question regarding if I purchase one

 

¿ªÔÆÌåÓý

As a retired hobbyist, I doubt very much that he will need to do all the calibrations you mention. Seems like he would just like to play with one. A lot can be accomplished and learned without most of what you mention. Welcome him, do not scare him away. ¨C Mike

?

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831

?

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Chuck Harris
Sent: Saturday, October 19, 2024 1:37 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] 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

>

>

>

>

>

?

?

?

?


Virus-free.
Re: Solder Flux

 

Hello All,
here are some infos about standards for soldering fluxes and their chemical composition:
https://www.sos.sk/a_info/resource/pdf/ine/Fluxes_EN.pdf
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

Here's another amplifier that should have flat noise figure down to below 2MHz. This is a high reverse isolation amplifier using two dc coupled BFR91 BJTs. It has ultra low port VSWR and the noise figure is about 8.3dB up at RF.
It works up to several hundred MHz and has about 13dB gain. I've used this amplifier many times in various test systems here so I know it well.
?
It is possible to reduce the noise figure by several dB by adding a choke to one of the bias resistors but I've removed the choke to make sure the noise figure and gain is very flat to low frequencies.
?
In the plot below I used four averages and the subtle bump at 5MHz is still there. It's much easier for me to see it on a sweep by sweep basis and I can only post up single sweep responses here.?
?
The main thing to note is the noise figure is once again flat vs frequency and if the 346A is accurate at 10MHz where it shows a noise figure of 8.3dB and a gain of 12.99dB I think it's reasonable to suggest I've also made a good noise measurement at 2MHz as this BJT amplifier should have flat noise right down to low frequencies.?
?
I have also tested a few InGaP MMICs and these don't show a flat noise response at low frequencies. They have some 1/f noise and this can slightly affect the noise figure at 2MHz.
?
Re: Solder Flux

 

The 'bullet' connectors for the center conductor on thoe assemblies often overheat. Every joint between the transmitter and antenna? have some contact resistance, so it causes damage, over time. The WACX tower site used a large rectangular waveguide to leave the transmitter room, and up to the antenna, 1700 feet above ground. They were soldered at all seamms and flanges We wee losing he Nitrigen used to pressurize it This cased problems, because it would distort the RF if the pressure wasn't correct. During the annual tower baintence, a climber leaned back against the orner of the waveguide to reach a bolt. It was aryying 165 KW of RF in the 550 MHz range. He ot a nasty RF burn, because that was where the invisible crack was. Mostt people don;t know that the flalenght oof each section has to be calculated to b properly spaced to put them near the zero crossing point at the station's frequency? If thety are near the maximum, you have high RF losses and turn a lot of your signal into waste heat wich leads to failures
The only other place I've dealt with presurized feeds was at a Cable TV headeend. Our idito manager refused to buy new dryier cartridis for the compress air, so we lost several feet of the 4 GHzz heiiax at ground level.
His, "you just want to waste money" took


On Sat, Oct 19, 2024 at 3:30?PM alwyn.seeds1 via <a.seeds=[email protected]> wrote:
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.
_____________________________________________________
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

Another way to expand on the 2SC3355 test is to add a 10dB attenuator at the input. I used a decent Suhner attenuator with ultra low VSWR and it has 10.10dB attenuation at 10MHz when measured on a VNA.
?
When I add this at the input of the 2SC3355 amplifier the gain drops by 10.1dB and the noise figure goes up by about 10.1dB across 2-20MHz. The Y factor becomes really low when using a 5.5dB ENR source with a DUT noise figure of about 11dB but the result was still quite good. I think the bump at 5MHz is still there but it's lost in the trace noise on this particular sweep below. The system is struggling a bit here because the Y factor is quite low with the 10dB attenuator inline.
?
?
Replacing the 10dB attenuator with a precision 3.00dB attenuator at the input gave the response below:
?
?
I do think there is a very slight issue with the ENR table at 5MHz and I could probably improve things if I used averaging to find out how much to tweak it by. However, I'm not sure it's worth the effort because I'm unlikely to ever do any critical noise figure measurements down at 5MHz :)
?
These test results look good to me and it may be the case that the ENR down below 10MHz will be a bit more drifty over time and temperature anyway. So it might be a wasted effort to try and improve it any further.
?
?
?
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

As I mentioned earlier, you can work out the resistive equivalent of the resistive matching network and the diode when it is in the hot state. Just put the 15R (hot diode resistance) in parallel with the 22R? and then put this in series with 34R. You end up with about 43 ohms resistance.
?
I suppose this ought to be 50 ohms but maybe it is a compromise because the ESR of the blocking cap and the connection path will rise with frequency (could be several ohms by 18GHz) and also you have to factor in the impact of the open stub matching section (not shown) up at higher frequencies. The open stub shouldn't affect the simulation below 20MHz so I didn't include the 30 ohm resistor or the stub. Only the original designers at HP will know for certain why these values for the matching resistors were chosen.?
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

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.
?
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.
?
?
?
?
?
?
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.
?
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.
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

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.
?
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 :)
?
?
?
?
?
?
?
?
?
?
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

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 :)
?
?
?
?
?
?
?
?
?
?
Re: Solder Flux

 

¿ªÔÆÌåÓý

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.
_____________________________________________________
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.
?
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
Re: Solder Flux

 

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.
?
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.
?
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.
?
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.
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
Re: Solder Flux

 

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.
Re: HP8753B VNA question regarding if I purchase one

 

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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.
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All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994)
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On Oct 19, 2024, at 13:02, G H via groups.io <gkhoefer@...> wrote:

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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.

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Thanks in advance,

George
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