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Re: Testing dummy loads with a VNA

 

Test port cables is a good idea.

But calibration kits...the 8754A doesn't do calibration.

But if he gets bitten by that bug, he'll have another VNA soon! B-)

-Dave

On 3/8/20 8:34 PM, bownes wrote:

Test port cables and calibration kits to match.?

Welcome to the insanity!

On Mar 8, 2020, at 20:10, Jinxie <paul666@...> wrote:

?Yeah, but I don't like the Nanovna type stuff; it's not a/proper/ VNA
in my view. How about I buy the matching S-parameter test set for my
VNA? I've been <mailto:I@ve> offered one for USD450 Would that solve
all my problems? And is there anything else I might need in the future?
--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Testing dummy loads with a VNA

 

On 3/8/20 8:10 PM, Jinxie wrote:
Yeah, but I don't like the Nanovna type stuff; it's not a/proper/ VNA in
my view. How about I buy the matching S-parameter test set for my VNA?
I've been offered one for USD450 Would that solve all my
problems? And is there anything else I might need in the future?
$450 seems a bit steep, but admittedly I've not been watching that
market. It would certainly give you good functionality, including the
specific functionality that you need for the task at hand. I can't help
but think you should be able to get away a good bit cheaper than that,
but I could be wrong.

The only other thing you might want is a calibration kit, but as the
8754A has no automated correction capability, it would be of limited use
there. Our own Dave Kirkby makes and sells decent calibration kits at
good prices.

I agree about the NanoVNA. I did pick one up recently, though...it
was on sale, and I want to put it next to my HP 8510C for some
side-by-side comparisons. For what it is (a hobbyist toy) it is
surprisingly capable and a very nice piece of work. But a piece of lab
equipment "it ain't".

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Testing dummy loads with a VNA

 

¿ªÔÆÌåÓý


Test port cables and calibration kits to match.?

Welcome to the insanity!

On Mar 8, 2020, at 20:10, Jinxie <paul666@...> wrote:

?Yeah, but I don't like the Nanovna type stuff; it's not a proper VNA in my view. How about I buy the matching S-parameter test set for my VNA? I've been offered one for USD450 Would that solve all my problems? And is there anything else I might need in the future?

Re: Testing dummy loads with a VNA

 

Yeah, but I don't like the Nanovna type stuff; it's not a proper VNA in my view. How about I buy the matching S-parameter test set for my VNA? I've been offered one for USD450 Would that solve all my problems? And is there anything else I might need in the future?
Re: Testing dummy loads with a VNA

 

On 3/8/20 2:09 PM, David C wrote:
You deliberately mis quoted what I said and changed it to:

"the
assertion that they are "intended" to only do thru measurements is
false. Very, very false."

You deliberately took my statement out of context to contradict , censor
and bully

Wont work

I did not say "only"

You invented that.
My mistake; it was not a verbatim quote. But the gist of my statement
remains; your assertion that "VNAs are intended to do "thru'
measurments" (I even included your careless mismatched quotes and
original spelling error!) is still false.

PS youre off topic attacking the messenger and not responding to OP.
I did, in fact, respond to the OP with what I hoped was useful advice
to get his job done. Now about that "inventing"..

Thats not how we conduct ourselves on the Internet.
As if you'd know? Shall we compare net creds? I'd not recommend it.

Drop it. Now.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: 693B sweep oscillator restoration

 

On 3/8/20 2:22 PM, David C wrote:
Moderator, where are you?
Here's one! I'm wearing my moderator hat, and I'm telling you that
you're officially on thin ice. Tone it down and speak respectfully.

And for heaven's sake, PLEASE start checking your facts.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: HP 8662A Verification Tape (08662-10001)

 

On 3/8/20 12:47 PM, Wolfgang Schraml wrote:
I got my hands on an 8662A verification tape. I posted the
booklet/manual that came with it in the files section
(/g/HP-Agilent-Keysight-equipment/files/8662A).
I do not have the 9825 controller to read the tape. It may not be
readable at all due to age. From the outside, it appears to be unused.

Anyways - if anyone has the means to read the tape, please let me know
and I will send it to you (US preferred to limit shipping expense). The
only ask I have is - if feasible - to post the contents/files in this
forum. I do not know whether these programs are stored in a binary
format that will only work for a 9825 or in a higher-level programming
language that could be converted to a different platform (e.g. HP Basic
on HP9000/300).
Wow, it would be really good if this is able to be saved!

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Testing dummy loads with a VNA

 

Jinxie,
As others have noted, you will need at least a splitter and a directional coupler.? I gather you are using an 8754a: It does not have software correction of the test setup, so I think you will be limited to the inherent performance of the directional coupler, particularly its directionality.? Later VNAs like the 8753 series can use an open-short-load calibration to correct these hardware errors.? If you are willing to consider a non-HP solution, you might consider just buying a NanoVNA for about $50.? They work pretty well to 900MHz, and acceptably well for evaluating dummy loads (not lab standards) to 1.5GHz.? ?It has a built in test set and usually comes with open, short and load standards for SMA.? You will need appropriate cabling (and perhaps standards) for the type of connectors your dummy loads use.
--John Gord
Re: Transistor equivalents

 

There's also one of each controlling the cal signal - A5Q4 and A5Q5 - and my cal signal is dead.

2N3904/2N3906 certainly seem like a good idea.

Thanks.

On Sun, Mar 8, 2020 at 3:12 PM saipan59 (Pete) <[email protected]> wrote:
If I spotted the right parts in the manual, they are in the "220 Hz Multivibrator".
I would try pretty much whatever you have on hand, such as 2N3904 and 2N3906.
If they're not already socketed, consider installing plug-in socket pins, such as the 'machined' type of pins found in the better IC sockets.

Pete

Re: Transistor equivalents

 

If I spotted the right parts in the manual, they are in the "220 Hz Multivibrator".
I would try pretty much whatever you have on hand, such as 2N3904 and 2N3906.
If they're not already socketed, consider installing plug-in socket pins, such as the 'machined' type of pins found in the better IC sockets.

Pete
Re: HP 3456A Problem Solved

 

Recently i found the same problem with two HP 3437A system voltmeters that we have. After one of them showed occasional digital errors (e.g. failure of display multiplexer) i looked inside. While the power supply generated 4.9 V at 1.5 A, some corners of the digital board received only 4.73 V or so, with a large part of the loss along the ground network. I just added two wires (Gnd and +5V) from one corner to the opposite one as redundant connection and the losses are less than 20 or 30 mV now. The faults are gone.
The digital boards of that time had very few buffer caps. In the 3437A i measured up to 1 Vpp noise on the +5 V net. When looking at the 3456A digital boards (especially those with CMOS logic) i am missing buffer caps that are so common nowadays, especially near the isolation interface digital receivers.

Regards, Dieter
Transistor equivalents

 

I'm looking for equivalents for:

1853-0459 and 1854-0810

They seem to be fairly generic 40V VCEO 625mW TO92 transistors.? Used in the 438A power meter.

Thanks, Orin.
Re: HP 3456A Problem Solved

 

I think they may be other places, but a web search shows them from this site:



Some links on that page point to the service note files:




As an update, with the boards removed, I took a pair of needle-nose pliers and very gently rotated the ground lugs, every so slightly (just enough to see movement) around each rivet. The resistance appeared to drop to a consistent value for all ground lugs (primarily the lead resistances). I reassembled the boards and when I powered it up, it worked. I measured the +5V at the CPU I measured yesterday and it was back up to 5V as well as the other 5V test points on the other boards.

I'm not convinced that's a very reliable "fix" and still plan to replace the rivets but did find it interesting.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "garp6" <hrgerson@...>
To: [email protected]
Sent: Sunday, March 8, 2020 3:11:44 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 3456A Problem Solved

hi Barry,

Can you post .pdf's of the Service Notes for this ?

thank you,
rick
Re: 693B sweep oscillator restoration

 

¿ªÔÆÌåÓý

Hello,
please, let us be fair to the two contestants.

As my AirBNB hostess pointed out, it is the world woman's day today. So, please, let us all join the two heroes in connecting to our inner feminine side.

Seriously: this makes me understand why the Danaher mailing list is moderated so strictly.

I will, right now, go out and grab a cigar and light up in the ice cold western German winter. If I get I'll, it is all your fault.
With best regards
Tam HANNA (emailing on a BlackBerry PRIV)

Enjoy electronics? Join 14k other followers by visiting the Crazy Electronics Lab at

Am 8. M?rz 2020 21:51:46 MEZ schrieb Chuck Harris <cfharris@...>:

Dave C,

Do you have any idea where you are posting?

This is not a paid industry discussion group, but rather a
bunch of people with varied experience that like HP equipment.

Some of us are engineers, with 40+ years of work experience,
and others are hobbyists that have little or no formal
electronics training.  The only things we all have in common
is we like this stuff, and we are here.

Anyone thinking that a very, very old sweep oscillator, like
the 693B is going to be used in a professional R&D lab is, in
my belief, delusional.

If you want to help, help.  But please, please, leave the chip
on your shoulder stuffed in some closet, far, far away.

If you want to talk about what is really bothering you, feel
free to contact me off group.

-Chuck Harris


David C wrote:
 Pete, understood, but your response is not to OP as is proper on a Forum, and technically inaccurate

 For a reference, youre referring to personal opinion. I refer to 30 plus years of working on more gear than youve seen in 10 lifetimes.

 Electrolytics are SEALED, the local RH has nothing to do with cap life. "Dry out" is not moisture, its electrolyte leakage
 Further,? your advice WAITS till a capacitor or other component fails to then chase the fault down. Thats fine for an old stereo, but
 not for high end test equipment.

 The Context of OPS comment was to bring back to life an old piece of high end test equipment. This is not hobby level work.

 Your approach of waiting till a part fails invites disaster...which apparently you dont have as much experience in as do I with 30 years of doing it.

 Pete, what happens when an electrolytic on the output of a pass regulator breaks down and shorts the regulator?
 Your advice on the resistor on the scope is totally wrong. Realize you are making wildly overgeneralized statements on apiece of gear you know nothing abotu

 Facts are, the resistor does NOT get hot. I checked it with an IR thermometer. You statement to use a buck transformer is false, a XFMR wont physically fit.

 The assertion that the resistor doesnt regulate is false also, NEITHER DOES THE TRANSFORMER. Pete, where do? you buy Magic Transformers that can regulate voltage?

 The on board voltage regulators regulate and the resistor is not relevant.

 Sory, youre lecturing an experienced test bench rider and R& D engineer...that attempt at lecturing was a terrible failure as you know nothing about the topics youre lecturing on

 


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Power Transformer needed for HP1220A (PN 9100-3436)

 

Greetings all,

I have a HP 1220A scope that needs a new power transformer (HP Part Number 9100-3436). I bought a junker basket case HP1222A at a hamfest for parts unfortunately it uses a totally different power transformer.

Thank you and 73,

Sam Reaves
W3OHM
Re: 693B sweep oscillator restoration

 

Dave C,

Do you have any idea where you are posting?

This is not a paid industry discussion group, but rather a
bunch of people with varied experience that like HP equipment.

Some of us are engineers, with 40+ years of work experience,
and others are hobbyists that have little or no formal
electronics training. The only things we all have in common
is we like this stuff, and we are here.

Anyone thinking that a very, very old sweep oscillator, like
the 693B is going to be used in a professional R&D lab is, in
my belief, delusional.

If you want to help, help. But please, please, leave the chip
on your shoulder stuffed in some closet, far, far away.

If you want to talk about what is really bothering you, feel
free to contact me off group.

-Chuck Harris


David C wrote:

Pete, understood, but your response is not to OP as is proper on a Forum, and technically inaccurate

For a reference, youre referring to personal opinion. I refer to 30 plus years of working on more gear than youve seen in 10 lifetimes.

Electrolytics are SEALED, the local RH has nothing to do with cap life. "Dry out" is not moisture, its electrolyte leakage
Further,? your advice WAITS till a capacitor or other component fails to then chase the fault down. Thats fine for an old stereo, but
not for high end test equipment.

The Context of OPS comment was to bring back to life an old piece of high end test equipment. This is not hobby level work.

Your approach of waiting till a part fails invites disaster...which apparently you dont have as much experience in as do I with 30 years of doing it.

Pete, what happens when an electrolytic on the output of a pass regulator breaks down and shorts the regulator?
Your advice on the resistor on the scope is totally wrong. Realize you are making wildly overgeneralized statements on apiece of gear you know nothing abotu

Facts are, the resistor does NOT get hot. I checked it with an IR thermometer. You statement to use a buck transformer is false, a XFMR wont physically fit.

The assertion that the resistor doesnt regulate is false also, NEITHER DOES THE TRANSFORMER. Pete, where do? you buy Magic Transformers that can regulate voltage?

The on board voltage regulators regulate and the resistor is not relevant.

Sory, youre lecturing an experienced test bench rider and R& D engineer...that attempt at lecturing was a terrible failure as you know nothing about the topics youre lecturing on
Re: Testing dummy loads with a VNA

 

¿ªÔÆÌåÓý

I thought the OP said he had an 8754.? Correct me if I'm wrong.?

Jim Ford?



Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------
From: "Stuart Landau via Groups.Io" <stuartl73@...>
Date: 3/7/20 11:06 PM (GMT-08:00)
Subject: Re: [HP-Agilent-Keysight-equipment] Testing dummy loads with a VNA

I think that an honest question regarding measuring SWR or return loss has gone off on a strange tangent. The answer to the question is relatively easy to answer if we know what frequency range is involved, and perhaps the type of connectors will be used and what the person currently has on hand.

What we don't know is what sort of equipment is available to the person who asked the question.

The S11 measurement is a very common one and is not "black magic" to perform. Usually the results are expressed as return loss (in decibels) or as voltage standing wave ratios.

Since there are several ways to make the measurement, what is needed to describe the procedure to the person asking for help, is to know what he currently has available to make the measurement. I assume that he doesn't want to spend a lot of money buying additional equipment.?

He asked for assistance, and that is what I offered. Possibly free advice is worth what you pay for it.

Stuart K6YAZ
Los Angeles, USA

Re: Testing dummy loads with a VNA

 

As a life long "weasel worder", I recognize an
omission of pertinent information.

Omissions, such as yours, are often used by
weasel worders as a method of deceiving the
reader, without actually lying.

When you word a sentence as you did:

"VNAs are intended to do "thru' measur(sic)ments"

You make it seem as though "thru' measur(sic)ments"
are the only acceptable "measur(sic)ments".

This is especially likely to happen, if you follow
such a statement with a diatribe on how to measure
a dummy load using only "thru' measur(sic)ments".

Dave's interpretation of your sentence as
entirely logical.

Instead of accusing others of ulterior motives,
you should perhaps strive to write more clearly.

-Chuck Harris

David C wrote:

Interesing the TROLLING on this forum

Dave, you deliberately misquoted me in order to play Forum Expert and falsely contradict my statement.

Kindly read more carefully and dont put words in my mouth (keyboard) that I didnt say.

Your resposne is dishonest.

Since you didnt read my statement, Ill repeat it:

"VNAs are intended to do "thru' measurments"

You deliberately mis quoted what I said and changed it to:

"the
assertion that they are "intended" to only do thru measurements is
false. Very, very false."

You deliberately took my statement out of context to contradict , censor and bully

Wont work

I did not say "only"

You invented that.

PS youre off topic attacking the messenger and not responding to OP. Thats not how we conduct ourselves on the Internet.
Re: HP 3456A Problem Solved

 

hi Barry,

Can you post .pdf's of the Service Notes for this ?

thank you,
rick
Re: HP 3456A Problem Solved

 

That is precisely why they mention a serial number and below.
HP, and others, were on a process of continuous improvement.

-Chuck Harris

n4buq wrote:

The mod doesn't involve drilling a circuit board. There are header pins that are mounted with a ground lug to the appropriate pin. All the boards are pretty easily removable (the front panel board is a but more effort and most likely doesn't need to be removed for this) so the drilling is done with the boards removed.

I'm still a bit curious as to why that mod mentions a serial number and below. It makes me think they did something different at that point to address this problem.

Thanks,
Barry - N4BUQ
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