Thank you for the replies on this subject of spares.
I suppose that what I would figure to be a part that does fail, the multi-function knob, is not high on the list of failure, which is surprising given its extensive use in navigating.
Side note; Terry Gillard, its nice to see that besides the Kenwood NX-5000 series we also have the HP 892x series in common. :-)
Thanks again,
Alex

Good day, and welcome to this group.

Over the years of working with relays of all kinds, including some very small signal relay like those used in RF test equipment, I've run into several occasions where a relay would develop a "perm."? "Perm" is a term that when associated with relays refers to some residual, permanent magnetism in either the pole piece or the armature.? It doesn't take much in the way of direct contact of the armature to the pole piece to cause a relay to not release when a perm develops.

In the past, and if it was possible to remove the relay, I would pass it slowly through an AC field, such as the type that was used to bulk erase magnetic recording tape.? This would usually cure the problem... for a while.

High quality relays will often have a piece of non-ferrous material in the armature where it contacts the pole piece.? This is to prevent the ferrous portion of the armature from directly contacting the pole piece.? When I first learned about this issue, I was able to put a piece of very thin piece of tape, such as the type of tape used in the olden days of splicing tape used in magnetic tape recording editing, across the pole to prevent the direct contact.? Obviously this can't be done in sealed relays.

The purpose of this epistle is to explain a common problem of why a relay might hang up.

Burt, K6OQK

Hi Alex,

I have heard that the AC / DC Switch on the PSU can be swapped if you only use the set on AC. This forum has excellent Manuals, which you should download and memorize .. or perhaps Print out.

Be very careful when disconnecting the Power Switch from the Rod from the front, I use long nose pliers to hold the switch mechanism and jack the rod from the switch with a 1/4" blade screwdriver. DO NOT just pull on the rod.

I am still working slowly thru My 8921A, I have found Rick at Amtronix is very helpful. He often gives advice on this forum.

Regards

Bill M.??? VK6IC

I've worked on quite a few E8285A, 8935 (E6380 & E6381) & 8924E/C over the years. PSU / Regulator board CAPS are the most prolific failures. CRT/Plasma displays next. Several have had failed measurement units (A19 in 8920). In the same one, Sig Gen Synth A14 had a tantalum cap pop on one of the DC rails. So I replaced all tants in its A19 but it still failed to calibrate. Swapped it out in the end. I've got around 4 dud A19s in the parts box. Another common error is out of lock OO LEDs illuminating which normally is a sure sign something is up with the 40V PSU rail. they are a great analyzer for general analogue radio. The only other I'd ever get would be IFR1900. From same era, does the same things but goes about it quite differently..

Hello to the group,
I have always maintained spare parts for any test equipment that I own, i.e. IFR 1200 SS, Fluke, and the like.
Since I am new to the HP 8920B and have already done the LCD conversion, rebuilt the power supply, backed up the Cal Data, and renewed the memory battery are there any spares to keep an eye out for; such as the multi function dial, cards, or any parts (odd or rare IC's/transistors) that tend to fail with age?
I kept my spare CRT but if anyone needs one I am happy to part ways with it.
Thank you,
Alex, KD6VPH

Welcome.

If the 8920B has the full frequency option (0.4-1000MHz) and thus relay RF module that is possible. Another possibility is a poor coaxial connection.

Robert.

Good morning friends,

Your distribution amp will probably be happier with a sine-wave signal.

I realized that it is not the FS730 I have but rather the smaller one FS710:

Thanks Rick. ?

?

My 8920A works perfectly fine and runs through all the diags for the various modules without errors and all measurements I have checked are within specs.

It is only the SA module that shows approx 3 dB to low (if I remember it correctly) which is sliiiightly lower than the specs +/- 2.5dB.

Global user key..

The following files and folders have been uploaded to the Files area of the [email protected] group.

• /1Separate miscellaneous files/HP AN200 Fundamentals of the Electronic Counters.pdf

By: Hank Riley <n1ltv@...>

Description:
The basic principles and some advanced techniques for getting the best results from a frequency counter. 44 pages

开云体育

Wow,? $1400 for a calibration is outlandish. If you run all your diagnostics, chances are your 8920 is working okay but may be off frequency, etc.. If your doing commercial work requiring a cal, you may need it. Just to let all know, the calibration on the 8920 units involve running the internal diagnostics then the "percal" program to adjust the 8920 internal frequency standard, voltage standard and audio levels and a few other minor things. Then the power meter and DC offset are zeroed from the front panel. After that, we run the performance evaluation. This checks most all of the AM, FM, rf in/out levels, audio, power meter, receive and generate and spectrum levels, spurious levels, etc. This is an automated test that produces some 20 pages of performance data. The performance evaluation insures that the 8920 is accurate and tests much more than the internal diagnostic program. Sometimes, the performance evaluation reveals faulty modules or hardware failures that the diagnostics don't show. I hope this helps....Rick

?

Great! Thx for all input.??

Will build my own 10MHz low pass filter as per the article Robert linked to or just take the easy way out and purchase the one on eBay.
I'll dig through my storage boxes first though, I might actually have a 10MHz low pass filter from Mini Circuits that would work in that case.

I have used this one from ebay - about 3 dB insertion loss, about $10.50 - eBay item number:385415398319

Yes.
I'd put it through a low pass filter though. The 8920 input is sensitive enough. Here is one example:

looks like same design with stripline and SMD components.

?

Fully agree even though I have not used Ricks services for actual repairs or mods but only for advice as well as Rick's excellent posts here in the group.

I just wish we would have a similar workshop here in Sweden (or within Europe) that has the same experience and knowledge that Rick and his Amtronix has.
I am located in Sweden so shipping my 8920A back and forth to USA is just to expensive.

I would like to get my spectrum analyzer module calibrated and Agilent in Sweden would charge me 1400 USD to calibrate my 8920A (which would be a full calibration and not just the SA module).
It would also be nice to upgrade from 60W input module to the high power option 100W.

I have a Spectracom GPS clock 8183A as my 10MHz frequence reference in my lab to my various instruments.

I am interested in testing the Leo Bodnar Electronics?Precision GPS Reference Clock:


However it seems that it only produces a square wave with 10MHz so my question is if the reference input on the HP 8920A accepts a square wave or does it only work with a 10MHz sine wave?

I have read through the user manual and on page 531 (in the version I have of the user manual) I find the paragraph "10 MHz REF INPUT" which does not state sinus wave only.
It just says:

=========

10 MHz REF INPUT??