On April 27, 2020 at 11:58 AM Dave McGuire <mcguire@...> wrote:


On 4/27/20 10:02 AM, Reginald Beardsley via groups.io wrote:

Occulus, Thanks. Yahoo changed the interface so that it doesn't show unread messages in the SPAM bin :-(

As a consequence I've been forgetting to check and empty it as I used to do every day.

I do wish that "developers" would realize that people do *not* want the UI to change constantly.

Actaully I think it's what a lot of the kids DO want. If it looks the
same as it did yesterday, it's not "FRESH!"

I worked with some developers a few years ago that were of that
mindset. They were doing the web app and back end that talked to
firmware I was writing. The lead developer was unbelievable; his stated
position was that any API (yes, API!) that hasn't changed in the past
few weeks "isn't being updated" and is therefore "dead". Believe it or
not, it actually went downhill from there.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

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On April 27, 2020 at 11:52 AM [email protected] wrote:

Yeah, complete UI/UX changes with web services seem to be par for the course these days. Farcebook is a leading example. But I digress...

Another thing to keep in mind with the Tek curve tracers is some of them develop HV transformer difficulties (lots of info about this+repair strategies on TekScopes); however, they are indispensable if you need to characterize high power parts. The 575 with a particular special option (name and number escapes me) is even better for this. I'd personally like to find a good one with that option as it would be a great curve tracer and would satisfy the itch to have one glowing Tek with vacuum tubes and ceramic strip construction. :o) It doesn't have blanking though, so things like families of curves will show retrace unlike a 577 or 576. The 577 also has the advantage of basically being made of standard 5000 series oscilloscope parts, unlike the 576 which is large and more complicated with the fiber optics to light the display annunciators. You can also get the 577 with a storage crt, but whether that crt will have any life left is questionable most likely.

As I understand it, the semiconductor parameter analyzer that HP marketed was really more intended to be an analytical lab instrument mainly focused on characterizing lower-power parts, while Tek curve tracers often were used on production lines for matching components and stuff like that. This at least partially explains why a lot of 577 and 576 curve tracers that come up for sale are beat up pretty badly. And as you observed, good condition examples command high prices.

I understand where you are coming from wanting to be able to do whatever measurement you need. I'm working to build up to that and also be able to calibrate my own stuff. Perhaps we can have a discussion offline about what you've found indispensable, as I believe our interests align quite a bit in the microwave realm.


Cheers!

Sean

On Mon, Apr 27, 2020 at 07:02 AM, Reginald Beardsley wrote:

Occulus, Thanks. Yahoo changed the interface so that it doesn't show unread messages in the SPAM bin :-(

As a consequence I've been forgetting to check and empty it as I used to do every day.

I do wish that "developers" would realize that people do *not* want the UI to change constantly.

Keysight didn't have much on their stuff on the website, but I eventually found copies of the manuals at some of the repair shops. It appears that a 4145B is what I want (i.e. is cheap enough I can afford it ). Perhaps augmented by a Tek 576 or 577, but those look rather expensive and hard to find.

In general I want to be able to make pretty much any test I might need. At the time I was most active designing and building stuff all I had was a 5 MHz recurrent sweep single channel scope (banana plug input), a VOM and a DMM. All my other test gear was DIY. Trying to build radios from scratch with that is pretty much a lost cause. But I was in my early 30's on my 2nd pass through grad school. So I had no budget for things other than books. Those were very expensive, though now it appears to be worse.

Reg

Occulus, Thanks. Yahoo changed the interface so that it doesn't show unread messages in the SPAM bin :-(

As a consequence I've been forgetting to check and empty it as I used to do every day.

I do wish that "developers" would realize that people do *not* want the UI to change constantly.

Keysight didn't have much on their stuff on the website, but I eventually found copies of the manuals at some of the repair shops. It appears that a 4145B is what I want (i.e. is cheap enough I can afford it ). Perhaps augmented by a Tek 576 or 577, but those look rather expensive and hard to find.

In general I want to be able to make pretty much any test I might need. At the time I was most active designing and building stuff all I had was a 5 MHz recurrent sweep single channel scope (banana plug input), a VOM and a DMM. All my other test gear was DIY. Trying to build radios from scratch with that is pretty much a lost cause. But I was in my early 30's on my 2nd pass through grad school. So I had no budget for things other than books. Those were very expensive, though now it appears to be worse.

Reg

First, make sure the Rb standard is locked. Second, couple the output of the Rb to a receiver and check it against WWV. ?Adjust the coupling so that the Rb signal is about the same strength as WWV. You should be able to detect errors of a few Hz pretty easily. Even without a recent cal the Rb standard, if locked, should be better than 1Hz at 10 MHz. ?If the standard checks out you can then adjust the ref oscillator in each counter to read exactly 10 MHz on the counter.
However, I'm betting there is a problem with the standard, since all the counters show the same error.
Remember all these Rb standards were pulled because they were pretty worn out. I had one stop locking, and now have two, checked against a GPSDO. ?I can set mine to about .001 Hz against the GPSDO.
Finally, after using the Rb for a while I realized that none of the internal ref oscillators are as stable as the Rb, so I just feed the counter the Rb as a reference. Since I got my Rb reference GPSDO have gotten a lot less expensive, so if your Rb is misbehaving I'd suggest buying one of those.

Ed. W2EMN


On Apr 26, 2020, at 10:34 PM, Terry Maurice <ve3xtm@... <mailto:ve3xtm@...>> wrote:

I have two of these units, one has the oven the other does not.? The two units do not read exactly the same value when fed with a signal from a 10MHz FE-5680A, rubidium frequency standard.? I am monitoring the frequency standard with the two HP units and my Siglent SSA 3021X spectrum analyzer, all units being fed from the rubidium standard through a Downeast Microwave 10-4, 10MHz amplifier and filtered 4-way divider. The units have been on for about 5 hours before taking the readings below.

Unit A (with crystal oven) reads 9,999,828 Hz, +/- 2 Hz; unit B reads 9,999,830 Hz, +/-2 Hz and my spectrum analyzer reads 9,999,826 Hz.? Are these values within the expected values for these older frequency counters?? Is the FE-5680A correct? I checked both HP 5342As with their internal references and both show 10MHz.? How can I know, which unit(s) are correct, or do I assume my rubidium frequency standard is off by about 170 Hz?

The FE-5680A does generate some heat when left on for prolonged periods, however, It is mounted on an aluminum heatsink and sealed inside a solid metal box, but the metal case is only slightly warm to the touch.? On my oscilloscope, the output of the rubidium standard shows a distorted wave, but once it passes through the DEM 10-4 it is a clean sine curve.

Any help or comments would be much appreciated.

Terry

I have two of these units, one has the oven the other does not.? The two units do not read exactly the same value when fed with a signal from a 10MHz FE-5680A, rubidium frequency standard.? I am monitoring the frequency standard with the two HP units and my Siglent SSA 3021X spectrum analyzer, all units being fed from the rubidium standard through a Downeast Microwave 10-4, 10MHz amplifier and filtered 4-way divider.? The units have been on for about 5 hours before taking the readings below.?

Unit A (with crystal oven) reads 9,999,828 Hz, +/- 2 Hz; unit B reads 9,999,830 Hz, +/-2 Hz and my spectrum analyzer reads 9,999,826 Hz.? Are these values within the expected values for these older frequency counters?? Is the FE-5680A correct? I checked both HP 5342As with their internal references and both show 10MHz.? How can I know, which unit(s) are correct, or do I assume my rubidium frequency standard is off by about 170 Hz?

The FE-5680A does generate some heat when left on for prolonged periods, however, It is mounted on an aluminum heatsink and sealed inside a solid metal box, but the metal case is only slightly warm to the touch.? On my oscilloscope, the output of the rubidium standard shows a distorted wave, but once it passes through the DEM 10-4 it is a clean sine curve. ?

Any help or comments would be much appreciated.

Terry?

Atomic references are in general, short lived. Cs beam's run
out of vacuum, or out of Cs (some debate about that!). Rb
references plate out the Rb metal on the lamp's glass bulb,
and get to a point where not enough light can get past the
plated out Rb metal film for the detector to operate.

The Rb can very often be fixed when the lamp goes dark by using
a heat gun to evaporate the Rb on the inside of the bulb where
the light is emitted, and let it plate out somewhere else.

The biggest problem is gaining access to the Rb bulb. Many
of the compact units are essentially assemble only devices.

When either a Cs beam standard, or a Rb reference runs out of
"physics" to operate, its disciplined VCXO will end up against
its rails too high, or too low in frequency (depending on how
it was designed).

Also, crystal ovens are a reliability problem. They are
electrically heated devices, and as such must be protected
against thermal runaway situations... lest they catch fire.

[I have seen oven failures where the entire oscillator board
melted its solder, and parts dropped out.]

In many cases, the thermal fuses installed inside of the oven
will fail, even though there is nothing otherwise wrong with
the oven. But again, they are usually assemble only devices,
and replacing the fuse will require serious removal efforts.

-Chuck Harris

Dr. Frank wrote:

I fully agree to Ed Breya. Your Rb standard very probably is not locked, 17ppm off is a typical sign for that.
All such OCXOs (10544 or 10811) can never be out that far, if they are operating correctly (i.e. getting warm, please check).
As both OCXO agree to each other, they seem to be working.
Please check the LOCK signal of your Rb clock.

After you identified the root cause, further hints how to correctly adjusti either of your clocks can be given.

Frank

I fully agree to Ed Breya. Your Rb standard very probably is not locked, 17ppm off is a typical sign for that.
All such OCXOs (10544 or 10811) can never be out that far, if they are operating correctly (i.e. getting warm, please check).
As both OCXO agree to each other, they seem to be working.
Please check the LOCK signal of your Rb clock.

After you identified the root cause, further hints how to correctly adjusti either of your clocks can be given.

Frank