correctiin, 15750 Hz

On Tue, Jul 9, 2024 at 12:41 PM, <fpgadaemon@...> wrote:

5086-7842

That part is replaced by the 33321YT so it probably has the same pin-out as the 33321Sx range. Voltage is another question may be 5V or 15V It may or may not have auxilary contacts to disconnect the coil after it has latched. If not you must puse the signal. I use the attached circuit to test these. It uses a pair of BCD thumbwheel switches to select all options. Set required attenuation and press the momentary switch.

Common fail in old TV receivers. Shorted main winding usually damages transistor driver.

Always diffucult to diagnose.

Try, with power off to excite the main winding with RF oscillator. May be several KHz frequency. Does it resonate? See a voltage waveform for the driver, it may help indicate the frequency.

In TV it was 15,750 KHz.

Hi, I've recently purchased a 5086-7842 attenuator from a radio amateur, with the intent of making a stand alone adjustable attenuator. However, I am unable to find a datasheet for this attenuator, and am curious about the following:

1) Whether the DIP pinout might be the same as attenuators of a similar form factor, such as the 33323K?
2) What the maximum input power might be.

Any advice, or suggestion of resources to check, would be appreciated. I've tried googling, but only come across other units for sale on Ebay.

Regards, John.

3754A is for Telco FDM baseband test access in a central office. 3 level higherarchy. Controlled by hp3755a via twisted pair or coax. Probably no use to you.
Bill Lauchlan

Hello, All,?

I am happy to report a successful repair! By a stroke of pure luck, I found a parts 8566B locally for a very attractive price. It was missing the entire A11 section, and the 2nd converter, but was otherwise in-tact.?

I wound up replacing the A6A12 YTX driver card with one from the donor unit. This was a partial success, as it would finally display a meaningful signal, albeit 30 dB low and not 90 dB low. By performing a factory reset of the YTX current (SHIFT, PRESEL PEAK) the error improved to -20 dB, and by adjusting the DAC control (SHIFT, GHz) I was able to get a full amplitude signal, although it was non-linear as I changed the input frequency.?

Ok, so on the right path, but something is still off.?

During this time I found R106 was burned on my original A6A12. Concerned this could have been caused by a damaged coil in the YTX, I decided the next logical step was replacing the YTX with one from the donor unit. Success! I was able to achieve a full amplitude signal across all tested frequencies.?

TLDR for those reading this from the future, looking for help with their 8566B. The conclusion is a failed coil in the YTX that overloaded the A6A12 driver card. Replacing the YTX and A6A12 solved the issue. R106 could likely be replaced, but as I had a spare card, and one that was tuned to the YTX, I elected not to repair the original.?

Thank you everyone for all of your help and advice!?

Not entirely sure.? There must have been some ATE need they designed this to satisfy at the time.

I have one of these in the pile. I have read the manual, and apart from the fact you can stack these 10 channel witches so you can access 1000 RF signals. what good are these. Only good to 25 MHz. Any thoughts, anyone? Need space here. Jeff Kruth

For the rear bezel, go on eBay for decent reproduction parts. I do that quite a bit since many come through with broken rear bezels.

For issues on the front bezel, I have used service cement (if you can still obtain it). I have found CA accelerator to soften the abs and use it very sparingly.

hi Bruce,

I realize you are asking for "Repair" instead of "Calibration", ... but the Cal aspect will come shortly thereafter:

? So, you might also reach out to the two North American?? National Measurement Standards?? groups, to see if a technician there *might* have any technical information, suggestions, tips,? or repair/refurbishment info on your particular Resistance Standard.
( ... Or if in the EU, then try NPL, PTB, BIPM ).?
These orgs have publications freely available on the Web concerning all types of Calibration measurements.

Either or both of? NIST (US)
? or NRC (MSS?? - was INMS ) in Canada:

rick
(electron/photon & Time-Volt? nut)
**
a)? NIST:


?Refs (? or? possible bedtime reading ) :








b)? NRC Canada ( MSS or was called INMS ) :
{ typically faster turn around Calibration times, at typically a cheaper price }




Refs:






Also,
?? for measurement guidelines, have a peek at:

and? its derivative:

开云体育

The volt-nuts@... list is still alive and kicking, with about 400 subscribers, though traffic has been very low for the last few years. I think the eevblog metrology forum has become the more popular place.

time-nuts (with about 1800 subscribers) is also still running.

All the publicly-available febo lists are shown at


John
----

Ping John Ackerman, he used to run the Febo servers that hosted
both volt-nuts, and time-nuts, and others.

I think he got out of the business, so it may be hosted in a
different way.

-Chuck Harris


On Mon, 8 Jul 2024 23:50:43 -0400 "Dave McGuire"
<mcguire@...> wrote:

Unfortunately there hasn't been so much as a peep on that list in
many months. :-(

-Dave

On 7/8/24 22:32, Jeff AC0C wrote:

volt-nuts@...

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 7/8/2024 9:07 PM, Bruce wrote:

Thanks, but I cant find Volt-nuts (or most variations) using the
search tool.? Am I missing something?

Adrian,
I was exactly having the same thought and your answer helps.
What fw version of 8510C were you using? And did you ever update the firmware of your 8341B?

From what I have read a v7.xx of 8510C requires 1992 version of 8341B. I am therefore interested in hearing your answer.

Dave, thanks for the advise on using the IO-trace, it helped me see what was going on on the bus.

A little update, it turns out that there is a problem with GPIB on my A60 board which was causing this. It, as far as I can see, works otherwise. If someone has a spare that they are willing to sell for a fair price please contact me offline, its part no. is 08340-60299.

Regards
Saevar

I will say that these are built like a tank - out of this group of eight, only one had an out of tolerance value on one of it's decades (-2.255%, lim: +- 2%)? Considering the abuse these things probably took over the last 50 or 60 years that is, to me, pretty amazing.

Hal

Thank you all!

@David M - I should have just kept looking; that was one of the first places I looked but I didn't go back far enough - I was thinking that they were introduced in the late 50's / early 60's or so.

@Stephen Croom - Thanks but, well:



This has been the last couple of weekend's project. I've been cherry picking some of the inexpensive ones (bad cosmetic shape) over the last several years to refurbish, calibrate and sell - they kinda built up due to lack of time to work on them.

Hal