Thanks for all replies on part number etc,? Will try to find out a german supplier to avoid high shipping cost.

@George G6HIG
Yes, I only need the removable part. Enclosed a picture of the holder to make sure it is same you have. If it fits I would be glad to accept you offer. Of course I will compensate your expenses.

Ernst

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On 4/18/19 7:59 AM, Jeff Kruth via Groups.Io wrote:

I am about to begin the process of scrapping two complete 3330B units
for gold content. Let me know if you dont find what you need.? I gave up
trying to find a home for these.

I don't think I saw that mentioned here. I'm flat broke at the
moment, but would probably have taken you up on that at the time. I'd
love to put together one of those systems.

-Dave

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Dave McGuire, AK4HZ
New Kensington, PA

I got a nice older hp 8558B/182C spectrum analyzer from a friend when he passed away recently. Everything seems to be working, but the large, rear Frequency Span/Div knob (hpn: 08558-20162) is missing.? incredibly, I found the front part of the knob (Resolution Span hpn: 08558-2-161) in my spare parts, so I am halfway there. Does anyone have that rear knob they will sell or trade? I can send a pic if interested.

I also found a factory boxed 8555-60073 attenuator assembly in my spare parts if anybody can use it in that older spec an unit.

saturday's stuff day event was great, we had about 200 visitors, and got rid of a lot of parts and material.
not quite enough to clear out that storage building, but it's getting closer.? many thanks to everybody that came
or got items remotely!

any help appreciated.
all the best,
walter

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Hello,
this is very strange, I had a very similar issue (see my Instagram). Oddly, the device works perfectly ever since - maybe it was indeed related to the GPS time rollover?

Sadly, we probably never will find out as there is no source code available...

Tam

---

With best regards
Tam HANNA (emailing on a BlackBerry PRIV)

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Tam

It has never had any start issue since I got it one year before.

Jack

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Alex,
I would not worry about the full scale gain calibration for the Ohms ranges unless for some reason you need it to be dead on at this time.? The 3468A has a? ONE YEAR spec of 0.016% of reading plus 2 counts.? This works out as follows for expected maximum reading error:

? ? ? ? ? ? ? ? ? Full Scale(FS) reading:? ? ? ?error = 166 ppm? ? ? ? ? ? ? ? ? ? ppm = parts per million
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 2/3 FS reading:? ? ? ?error = 170 ppm?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1/3 FS reading:? ? ? ?error = 180 ppm
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1/6 FS reading:? ? ? ?error = 200 ppm
? ? ? ? ? ? ? ? ? ? ? ? ? ? 1/10 FS reading:? ? ? ?error = 226 ppm

Your readings are out of spec but not that unreasonable for a calibration that may have occurred many years ago.??

The 20K resistor measured 19.9661K in 4W mode (actual value is 19.97140K).? ? ? ? ? ? ??
The 98.975K resistor measured 98.978K in 4W mode (actual value is 99.00352K).?

?Error of 20K in ppm:? ? ? (19.9661 - 19.9714) / 19.9714 X 10^6? =? - 265 ppm?
?Error?of 98.975K in ppm:? ? ? (98.978 - 99.00352) / 99.00352 X 10^6? =? - 258 ppm??

?Measuring 20K is a 2/3 FS? reading on 30K range:? ? ? ? ? ? ? ? ? EXPECTED? max. 2/3 FS error <=? 170 ppm? ? ? ?
?Measuring 98.975K?is a 1/3 FS? reading on 300K range:? ? ? ? ?EXPECTED? max. 1/3 FS error <=? 180 ppm? ? ? ??


Both of your readings are low by about 260 ppm which is out of range.? The Red Devil resistors have a TC of around? [+/- 5 ppm/C]? to? [+/-10 ppm/C]? so 25-50 ppm might be due to temp drift from your environment compared to mine ( a 5C change).?

Of the 260 ppm error,? around 210 ppm is non-temperature related (50 ppm max due to 5C temperature change) which tells me the Ohms reference resistor R201 may have shifted upward by about 210 ppm over time since two ranges seem to be out about the same amount.? This is a bit out of the maximum expected range(170 - 180 ppm) by about 30 - 40 ppm but not worrisome.

You could bring the Ohms into compliance by lowering the 40K Ohms reference resistor, R201, by 210 ppm to 39.9916K Ohm by paralleling it with a 190 Meg Ohm resistor without calibrating the ranges.? It might be interesting to try this.? If all ranges come into compliance, then R201 has shifted.? A huge improvement would be to replace the 40K Dale resistor with a 40K Vishay S102 precision resistor.
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ANSWERS:? ?
?(1)? I am letting the DVM run for about 30 minutes prior to doing the Zero cal procedures, as recommended in the manual. Since you did not mention this not sure it is only needed if further range calibrations would be done, but I assume it won't hurt.

The reason for powering the meter for 30 minutes before calibrating is to insure the internal components reach a stable temperature.? I did not mention it because I just assumed you would be calibrating with the meter having been on a long time.? ?I never turn my meters off -- the references only get better with time while being powered up.

(2)? Since you pointed out earlier in this thread that one cannot calibrate the DVM to both 2W and 4W ohms due to lack of storage space for the constants, I figured I Zero calibrate the 3468 for 4W, and the 3478 for 2W, so I have one of each calibrated measurement modes. . . . Went out of cal mode, and now reading in 4W with both jumpers in, and bridged together still reads 000.000. If I go to 2W I get a reading of 000.059 ohm. I guess this small error is to be expected as the calibration was performed on 4W.

This is really not a good idea.? You should always cal in 4-W mode.? If you insist caling one meter in 2-W and the other in 4-W, cal the 3478 in 4-W since it has one lower range in OHMs - 30mOhm range.? The 2-W offsets due to input wiring and lead resistance in 30mOhm range will be a nuisance.? The offset of 59 mOhm you read between 4-W and 2-W is reasonable.? There is about 75 squares of trace resistance on the PCB plus some wiring to the input terminals from the where the DC voltmeter senses the point where the current from the ohms converter enters the input.? The traces on the PCB are 1oz copper clad 20 mils wide having 0.508 mOhm per square with 74 squares of resistance which results in about 38mOhm of resistance plus the wiring of 3.5" of 20AWG from the PCB to the input terminals (20AWG:? 10.15mOhm/ft.@ 3.5"? =>? 3mOhm).?Therefore, the total resistance unsensed in 2-W mode is about 41mOhm so your reading of 59 mOhm is reasonable for there may be some other offsets due to thermals and contact R.?

(2a)? If you plan on caling the instruments in 2-W Ohms, then do so with your test leads that you intend to use connected to the meter and shorted together at the probe tips to ZERO out the lead resistance.? Nothing is to be gained shorting at the meter inputs and performing a ZERO calibration in 2-W mode.? Your test lead resistance will still show up and be an annoying offset to your readings.? Cal out all the measurement lead resistance and not just the internal residual wiring of the meter.

(3)? In any case would it be possible to use your two resistors to at least get the 30K and 300K ranges more closely calibrated?

Yes you can use those but get as close to 22C as possible with the environment containing both the meter and resistors.? Keep in mind that the 99.975K resistor is caling the instrument at 1/3 FS and the 20K is caling at 2/3 FS so it is more susceptible to errors.? We designed the instrument to cal at FS of 300,000 counts, 2/3 FS at 200,000 counts and 1/3 FS at 100,000 counts keeping in mind there are standards out there for Fluke that has 200% over range and others at the cardinal values of 1.000000 etc.? Our meters 3468A and 3478A have 300% over range reading capability but can be caled at? FS, 2/3 FS, or 1/3 FS to accommodate the various standards out there in the world.

(4)? Pushed in both your jumpers and wrapped around them tightly a shorting wire at about the same position on both jumpers to hopefully force the same potential.

It is not necessary to create a very low ohmic short between the source and sense jumpers.? All that is needed is a jumper between them of reasonably low resistance to force them to the same potential.? No current flows between them so you could even connect them with a 100 ohm resistor and the cal would be good.? Just use a short jumper wire with alligator clips to connect them.

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When HP closed down its component division that made the precision resistors for standards and the instruments, I purchased the remaining inventory of Red Devils and Kelvin resistors.? I just looked over the inventory and decided I can lighten the inventory and will make sets available to viewers in the near future.? I need to inventory all the values and will post them here in the future and offer them at a very low price for what they are.

The video for the design and use of the 3468A / 3478A has stalled but hope to finish it soon. UP to 4 hours now.? I will cover in more detail all that I have discussed in these pages and more regarding the specs and measurement techniques.
Stay tuned.

George? ? April 18,? 2019? ?8:28am

Can you take a look at the fuse holder itself and see if there are any markings or logos or patt numbers on it?
Even take a few photos for us to see.

I've had luck in the past cross referencing fuse holders to standard parts and ordering the inserts from Digikey etc.

Hi,
I just got a 437B power meter with issues at a low price. One thing is a missing (removable) part of the fuse holder. I have the almost complete service manual including schematics but parts list is missing.
So what I need is a supplier of the fuse holder. Maybe someone has one spare in his junk box he could part.

Regards Ernst

Took a peek... this is old I think.
The manuals have been revamped since then.
The "new" ones are available via Keysight and cover the same material.
(updated to reflect new firmware versions)

Have?you tried the link at archive.org? I’ve had some success in the past using that approach.?

I am currently trying to resolve an 07 error in an HP 8662A signal generator. Working on this unit there are power levels shown on the circuit diagrams for the various frequencies generated in the unit. When for example I look at the Service Sheet D? as a starting point the power levels quoted in table 8-218 are measured low when I look at the signal via an Advantest R3465 SA. On the list of test equipment for troubleshooting and calibrating the 8662A it lists an HP power meter and sensor. Also it is obvious that there are other signals at lower power levels detected by the SA take for instance the 10/20 MHz input to A6A4J1. When getting the 10 MHz signal there is a strong but lower magnitude signal at 20 MHz. But when the input is at 20 MHz there is almost nothing at 10 MHz. So my question is when measuring the power levels should I be using my HP 437 power meter to establish the signal level or are the power levels quoted purely for the signal at the frequency being measured. When there are multiple signals present my 437 will obviously read higher than the SA. Any help on this is appreciated.

John Proctor
VK2DLP

I have an excellent 1727A for sale.? This is an older analog storage oscilloscope, bandwidth 275 MHz.

I don't know what it's worth, so am entertaining offers.

It's in Los Angeles.

Thanks for reading, Bob

I don't need the HP 117A VLF Comparator, only the loop.
--
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Whitham D. Reeve
Anchorage, Alaska USA
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Hello,
did you also have the issue that the machine originally didnt start?

Tam

---

With best regards
Tam HANNA (emailing on a BlackBerry PRIV)

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