Thanks, Bruce and Lou.I figured as long as the units were powered up
everything should be OK.? Just paranoid I guess.JimSent from my
Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Lou Blasco
<vk3alb@...> Date: 4/12/20 9:02 PM (GMT-08:00) To:
[email protected] Subject: Re:
[HP-Agilent-Keysight-equipment] GPSDO connected to external ref
inputs Agree with Bruce,Been running my 10 MHz 24x7 into a HP-5342A,
HP-8901B and Fluke 6060A/AN for years with no ill
effects.RegardsLouVK3ALB

From: "Dave Wise" <david_wise@...>
To: [email protected]
Sent: Monday, April 13, 2020 11:01:03 AM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 334A Balance Pots

That's good news, Barry. I didn't mean to advocate drilling except as a last
resort. In my case the track was bad, with high end-to-end resistance.
Please report in a year; I'd like to know how well the cleaning persists.

Dave Wise
________________________________________
From: [email protected]
<[email protected]> on behalf of n4buq via groups.io
<n4buq@...>
Sent: Sunday, April 12, 2020 3:03 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 334A Balance Pots

I'm happy to report that I was able to disassemble the noisy pot, clean out
the carbon dust, put a couple of drops of DeoxiT on the moving parts (wish I
had FaderLub but...) and reassembled it. It works so well now! Glad I
decided to do that.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Barry" <n4buq@...>
To: [email protected]
Sent: Friday, April 10, 2020 2:22:53 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 334A Balance Pots

I may try prying them open as well so as to be a bit more careful about how
I'm cleaning things in there.

Thanks,
Barry - N4BUQ

----- Original Message -----

From: "Richard Knoppow" <dickburk@...>
To: [email protected]
Sent: Friday, April 10, 2020 1:45:25 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 334A Balance Pots

I have had some luck by prying the covers off for cleaning
and then crimping the tabs back. Can't be done where the pots are
stacked. AB were the best of the bunch are a pain to clean.
Ohmite sold these same pots under their own name. Same for fixed
composition resistors, Ohmite and AB are actually all AB. Ohmite
actually says this in some of its early advertising. I have no
idea what the story behind this was.

On 4/10/2020 11:30 AM, ebrucehunter via groups.io wrote:

Barry,

I have one of these instruments, but it is too buried to easily
allow inspection to determine what type of pots were used.

If the values are above 1k, they are probably not wire-wound.
If they happen to be Allen-Bradley (AB) pots, an age old remedy
is to take a 1/16-inch drill bit and drill a hole in the cover
- in the outer crevice - at the bottom of the pot away from the
terminals. The snout of a can of contact cleaner can then be
inserted in the drilled hole to blast the interior of the pot.
This cleaning will typically last for two or three years and
then you might have to do it again. The access hole remains
available. In drilling the hole, metal chips seem to be pulled
outward and are unlikely to enter the pot. But be careful so
that when the drill bit breaks through, that it does not enter
and damage the pot.

Often these pots can be cleaned by pulling outward on the shaft
-- it will move about 1/16-inch -- while quickly turning the
knob from end to end.

Bruce, KG6OJI

On Sun, Apr 12, 2020 at 02:05 PM, Maurice Smulders wrote:

What is the safest way to pull the keytops of a Bill West keyboard? I have
a 3325A and 8131A with sticky keys I want to fix...

AT

From 3:10 to 5:08... Curious Mark pulls the caps off a 3325A Bill West keyboard... and shows cleaning and lubing (with DeoxiT... which I think, DeoxiT is mostly bunkum). There is a shot of the tool he is using (looks like a small nail puller) at exactly 4.03/15:18.

Seems a bit brutal... He tore the plunger out of the 7 key's frame! (...you can see that if you watch closely.)
If you look in the comments you'll see? Raymond Domp Frank's? recommendations (...same as he has posted in this thread.)
Best regards and wishes.
Roy

Hi all,

?

I have a rather bizarre problem with a 5343A counter. Observed symptoms are that the high frequency input works reliably up to about 250MHz, reads garbage from around 250MHz-800MHz, and then seems to work fine from 800MHz upward through 1GHz (I only have an 8640B handy atm so can't really test higher than that). Cranking up the input power a bunch seems to reduce the dead band to closer to 400MHz-600MHz.

?

The counter initially failed troubleshooting step 4 in the service manual. That was resolved by replacing the A10 board (from another counter with a blown sampler). It now passes step 5 and is marginal on step 6 (sensitivity is a little lower than it ought to be but it seems to work).

?

The one other observation I've made is the IF amplitude into and out of A11 drops off rapidly if an input is tuned into the range of frequencies that it's insensitive to, but I'm struggling to find a plausible explanation for why that could occur given my understanding of the counter design (that wouldn't also make higher frequencies not be detected).

?

If anyone has any thoughts or has run into this before, suggestions would be appreciated.

?

Thanks,

Daniel, KC1EPN

On 13 Apr 2020, at 13:13, george edmonds via groups.io <G6HIG@...> wrote:

?

Hi Colin

CLIP stands for Component Layout Information Package, HP speak for circuit diagrams and board layouts. When you get a service manual for later HP kit it is the text only, the interesting stuff is in the CLIP.

Kind regards

George G6HIG

On Monday, 13 April 2020, 11:28:34 BST, Colin Smithers <colin@...> wrote:

Hi George,

?

Now were motoring! I was unaware of Amtronix, thanks. Clearly they must know and perhaps might help.

?

You will have to inlighten me as to what the CLIP is, please?

?

Kind regards

?

Colin

?

From: [email protected] [mailto:[email protected]]On Behalf Of george edmonds via groups.io
Sent: 13 April 2020 10:32
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8920A spectrum analyser amplitude calibration

?

Hi Colin

I do not understand the posting about making manual adjustments, I can see that using the suggested approach for fault finding is valid, but not for adjusting the calibration given that the 8920A is software calibrated only. The calibration constants are held in none volatile memory in each module which are read into main ram on power up.

As far as I remember the Cal switch just enables and disables the ability to carry out a calibration via the GPIB port.

Prior to 1999 all 8920A's had a mechanical attenuator, which your appears to have. It then became option 055 with the PIN diode attenuator as option 009.

The only remaining commercial support for the 8920A is provided by Amtronix in the US, who do provide full repair and calibration facilities for them.

Are you aware of the information at Amtronix.com/diagnostic/htm?

Do you have the CLIP for the 8920A, I do if you need it.

Regards

George G6HIG

On Monday, 13 April 2020, 07:25:14 BST, Colin Smithers <colin@...> wrote:

?

?

Hi George,

?

Just measured, the unit is substantially flat (+/-0.2dB) across the range from 1MHz -500MHz, but with the Main input around -2.2dB and Ant input -2.6dB. But these back my point that for a subsidiary function this Spec An is very good indeed.

?

The Main input shows >-25dB return loss, I am yet to measure the Ant input.

?

Looking at the Spec An block diagram two things stick out:-

?

-?????????A signal switch near the front with a Cal setting

-?????????A 4-in-1 DAC which seems to control variable gain amp as well as IF filters

?

So I remain thinking that ?I’m on the hunt for a deeply buried Cal routine. Fiddling with loss internally is clearly possible (from another rreply), but only finding the routine would be future proof.

?

Thanks for info about that HP IEEE 488 program. My Win95 machine does still boot up…??J Gonna have to find an IEEE488 card though. Or info on what the code drives.

?

Rgds

?

Colin

?

From: [email protected] [mailto:[email protected]]On Behalf Of george edmonds via groups.io
Sent: 13 April 2020 00:37
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8920A spectrum analyser amplitude calibration

?

Hi Colin

I have also seen your posting on the HP8924 group which has additional information in it.

First it is very important to say at what frequencies you are experiencing the errors, the main reason for this is that the front panel on a HP8920A gives the operating range as 400KHz to 1GHz. This is ONLY true for the original electromechanical attenuator version, all the ones that I have seen in the UK have had the PIN diode attenuator fitted which in my experience cannot be trusted below 50MHz. HP claimed 10MHz in their dreams.

Most of these test sets were purchased in the UK for analogue cellular use so the use of a PIN diode attenuator was not an issue.

I would first check to see if the input load measures 50 ohms at the N port, if it does then check and re torque the internal hard line SMA's using a torque spanner, this is very important to avoid damage to the SMA's. There were a number of optimal power handling input loads available, it is not unknown for excess RF power to damage them.

I have not had to work on a 8920A for some years, but as I recall the calibration/adjustment was carried out via the GPIB port using dedicated HP software that would not run on anything later than Windows 95 or possibly 98.

Hope that this helps

George G6HIG

On Sunday, 12 April 2020, 22:18:40 BST, Colin Smithers <colin@...> wrote:

?

?

Hi all,

I have an 8920A and the spectrum analyser amplitude level is 3dB out. I have read enough to understand that calibrating this is a bit of a secret. Does anyone know it please?

Similarly for calibrating the power meter.

I have asked the same question on the 8924-series group.

Kind regards

Colin Smithers G4CWH

?

?

Hi George,

?

Now were motoring! I was unaware of Amtronix, thanks. Clearly they must know and perhaps might help.

?

You will have to inlighten me as to what the CLIP is, please?

?

Kind regards

?

Colin

?

From: [email protected] [mailto:[email protected]] On Behalf Of george edmonds via groups.io
Sent: 13 April 2020 10:32
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8920A spectrum analyser amplitude calibration

?

?

?

On Mon, 13 Apr 2020 at 04:57, Jared Cabot via <jaredcabot=[email protected]> wrote:

Hi David.

?

Where did you get the BNC connectors for your open and short?
Were they taken from test fixtures or can they be purchased separately?

Thanks!

?

You can get them on eBay. Search for BNC levers or BNC handles. One does need to cut some BNC plugs up to make these, as you only want the inner part of the plug. I use a grinder and hacksaw.?

?

HP do make some fixtures with 4 levers, and some with none. Two is a compromise.

?

I want to make a fixture that allows one to apply a DC offset of up to 30 kV. That will be a challenge. I will probably restrict its use to a lower specification LCR meter I have, as I wrote not want to risk damaging these. At 30 kV, some precautions will be necessary.?

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom

I have a 3567A Logging Multimeter here that I picked up cheap but it is missing the printer module.

Does anyone have a printer module they are willing to sell and send to Japan?

?

Thanks!

?