HP calibration resistor out of spec

You might try baking it to see if the resistor has adsorbed some moisture.

--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Hello Michael,

Good idea. But first I have to get it open. Which means I have to build myself a custom-fitted wrench :-(

Regards, Joerg

If moisture can get in, it can get out. Just don't get it too hot.

BTW. I made some fairly accurate 50 ohm BNC terminators by using 49.9 ohm metal film resistors and a small brass disk that was soldered over the cable nut. All of them measured between 49.9 and 50.0 ohms. They were more accurate than some that Microdyne purchased.

--
     Subject:  Re: Try ``this``
        Date:  Tue, 05 Jul 2005 14:04:00 GMT
        From:  "Steven Dinius" 
Organization:  Ispeed Wireless Inc. (srvinet.com)
  Newsgroups:  rec.antiques.radio+phono
  References:  1 , 2 , 3 , 4 , 5 , 6

I complained to this church of yours that you haven\'t been very
"Christian"
in response to a genuine want to help your case. You should feel
ashamed. I
feel disgusted.

Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Hello Michael,

True. I'll try that. Wood stove season is over (thank God) but I can let it bake for days in the kindling bin which is now empty. It gets very toasty in there, you can dry wood chunks in less than week.

I can even calibrate with those because the analyzer has an SMT clamping device. That only is only certified to 500MHz but I don't need more anyway.

But I've got a whole other issue at hand. The whole HP4191A seems to be sick. It takes forever for the display to come on and then it measures erratically. The service manual just says to check the power supply which looks clean. I asked at s.e.equipment whether anyone had that happen but no takers yet. Oh man...

Regards, Joerg

"Michael A. Terrell" wrote in news: snipped-for-privacy@earthlink.net:

If you used SMD resistors,you probably achieved a decent VSWR,too.

some of TEK's terminations used MF chip resistors inside a nice housing,or were built on double-clad PCB material.

--
Jim Yanik
jyanik
at
kua.net

They were axial leads, but they looked very good on the network analyzer, to 1 GHz.

I did use SMD caps to build DC blocks. The brass box and rod gave me

50.5 ohms, according to the ratio of the diameters, and a small stack of caps were soldered between the ends of the rods, in the center of the box. Even without the bottom cover soldered on the VSWR was excellent, and the insertion loss was flat to under .5 dB from 50 KHz to over 480 MHz. I didn't get a chance to retest them after the bottom was soldered to the box. I used some thin double sided PC board so that it could be removed with a sharp pick, if they were damaged.

--
     Subject:  Re: Try ``this``
        Date:  Tue, 05 Jul 2005 14:04:00 GMT
        From:  "Steven Dinius" 
Organization:  Ispeed Wireless Inc. (srvinet.com)
  Newsgroups:  rec.antiques.radio+phono
  References:  1 , 2 , 3 , 4 , 5 , 6

I complained to this church of yours that you haven\'t been very
"Christian"
in response to a genuine want to help your case. You should feel
ashamed. I
feel disgusted.

Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On Tue, 25 Apr 2006 21:08:51 -0700, John Larkin Gave us:

I just got a new job and I go through 100 of these a day.

My rack modules will be testing jets.

It looks real simple on the schematic, but HF components all have to be canned and rugged, so actual implementation of what's on the schematic entails a lot of RF piping and physically large components that don't appear to be when looking at the schematic. Filters, amps, power splitters... a menagerie of microwave circuit elements.

Since it is a one shot deal (not a manufacturing run) custom, I get to build them, then I get to test them, then I get to integrate them into their racks, and then I have to pipe all those together and test the final rack.

By the time I am finished, I won't want to see an SMA fitting for a LONG time.

All of my attenuators attenuate.

On Wed, 26 Apr 2006 09:58:11 GMT, Fred Bloggs Gave us:

That's the right call.

On Wed, 26 Apr 2006 16:44:21 GMT, Michael Gave us:

More like ebbing and flowing, man... (Donald Sutherland inflection)

On Wed, 26 Apr 2006 20:45:29 GMT, Joerg Gave us:

Your appeal has been denied... like you knew it would be...

"Joerg" a écrit dans le message de news:jWQ3g.70021$ snipped-for-privacy@newssvr13.news.prodigy.com...

values

Hmmm, that's pretty strange, unless it (strangely) considers the load to be

50 ohms. On the 4195A, I have a menu entry where I can set the short/open/load values and parasitics, which are then used into calcs. Then obvioulsy when I measure the cal load, as a check, it's spot on the entered values. I guess it should be so with the 4191 too.

--
Thanks,
Fred.

"carneyke" wrote in news: snipped-for-privacy@i40g2000cwc.googlegroups.com:

Using a 4-terminal measurement? (to eliminate lead resistance) Or just a coupla probes across the termination?

--
Jim Yanik
jyanik
at
kua.net

"carneyke" wrote in news: snipped-for-privacy@g10g2000cwb.googlegroups.com:

You would be surprised at how many "pros" make such errors. however,I meant no insult.

where's your lab?

--
Jim Yanik
jyanik
at
kua.net

Hello Fred,

I'll have to read up on that when I found the other problem with its hardware (bad reset handling, hoping that's the only one). But the 4191 is much older and AFAIK does not allow any entries other than frequency and bias voltage ranges.

The RF circuitry in there is very elaborate and impressive but the controller is rather basic. The did a neat thing with it: You can flip the controller section up like the trunk of a car, take the back cover off and work on it at an ergonomically correct height and posture. Cool.

Regards, Joerg

Hello Roy,

:-)

Right now the cal resistor is the least of my worried. The analyzer's hardware is sick. Doing surgery on it today.

Regards, Joerg

Hello Kevin,

Well, just checked again. It is a 909A. It came in the HP4191A accessory kit. :-)

BTW, since you work in a cal lab: Besides those NiCds in the units there is another thing that needs to be watched but probably you know. The foam in those accessory kits begins to disintegrate and clump. I had to spend considerable time cleaning that gunk out of some of the probe fixtures that I had kept in there. I'll probably build a nice wood box with posh looking felt in there. That would be more proper for HP equipment than those chintzy plastic cases where the molded hinges always break. Somehow these boxes always had a Heathkit feel (nothing against Heathkit though).

Regards, Joerg