Author Topic: Found home made rubidium reference that seems to really work well (Read 19477 times)

notfaded1 · « **Reply #125 on:** February 22, 2020, 12:48:27 am »

I couldn't resist... had to feed the BG7TBL GNSSDO 10MHz output into the 53131 extref input and test the unknown Rb. Now if I could just figure out good Time Interval readings I'll be doing ok.

B

notfaded1 · « **Reply #126 on:** February 22, 2020, 01:35:57 am »

Overlaid the Datum 8040 on the other Rb graph. The GNSSDO makes a huge difference in the counters ability to measure. I'm convinced the 53131 has it's HS OCXO set around .4 Hz low.

B

ArthurDent · « **Reply #127 on:** February 22, 2020, 04:04:13 am »

Your 010 option timebase in the HP 53131A should give far better accuracy than .4Hz and it can be recalibrated easily if you connect the GPSDO to channel 1 and carefully follow the steps below. Even calibrated properly the 010 option timebase isn't adequate to calibrate an Rb oscillator and the GPSDO used as an external timebase for the counter must be used. The scope method I described earlier gives good quick results, better than the counter unless you log the data over a long time as you have done previously.

Allow the Counter to warm up for approximately 24 hours before
performing this calibration. This calibration is unlikely to fail, unless
the Counter is not warmed up.

1 Connect the output of a 10 MHz house standard to Channel 1 of
the Counter as shown in Figure 2-5.

2 Press any one of the arrow keys until CAL: TIMEBAS? is displayed.
Note that the timebase choice (CAL: TIMEBAS?) only appears when the
Timebase Option is installed.

3 Press Enter key and follow the instructions in the scrolling
message that appears in the Counter display.

4 Press Enter key after each instruction.
The Counter displays CALIBRATING, and then it should display
TB CAL PASS.

If the fail message is displayed (even after the Counter has been warmed
up for 24 hours), refer to the troubleshooting section in this chapter.
This completes the High Stability Timebase Option Calibration procedure.
If all tests passed, the Counter is now calibrated.

thinkfat · « **Reply #128 on:** February 22, 2020, 11:48:39 am »

I'd take it easy on the number of GNSS constellations enabled. In my experience, more is worse. It degrades the stability of the 1PPS signal. I disabled everything but GPS.

notfaded1 · « **Reply #129 on:** February 23, 2020, 03:47:38 am »

How does this look? I'm reading more of the details about LH. I'm really impressed with it and TL. Big props for the guys that made them both and offer it up for everyone. I need to take this GNSSDO apart and see what it's made of. It would be neat if there's more I can get from LH than just the basic NMEA information with this version of BG7TBL device. IDK what most people do but I edited out the coordinates on the GIF LH produced?

Bill

notfaded1 · « **Reply #130 on:** February 23, 2020, 04:39:21 am »

When I bought my 3458A a couple weeks ago I got the seller to throw in an HP 33120A since I knew I was in search of time as well as the volt. It totally passed all it's built in extended self tests but didn't output anything. I tested the resistance between the center of the BNC and case and it read like it wasn't connected... I started down this road because I wasn't getting any output from it. At first I thought maybe I just didn't know how to operate the frequency generator. I pulled up the service manual and it said the internal output fuse F801 might be open. I opened up the case... put my Fluke 289 on continuity and checked the fuse... yep it was open as could be... NO BEEP! I ordered replacement Littlefuse part 251.500T1 and replaced the fuse today. Hooked it back up and it's all working now again.

I put it on channel two of 53131A while my GNSSDO was feeding as extref and when I set the 33120A on 10MHz it reads 9,999,990.82 Hz. It looks like as with my counters own internal HS reference it too needs some adjustment. Thanks AurthurDent for sending me in the calibration direction for the 53131... I had almost forgotten it can be adjusted without turning screws!

I'm not as worried about 33120A as the counter and it's got a more involved verification/calibration procedure. I'm glad I got it to put out output though. The internal fuse was an easy fix!

Bill

notfaded1 · « **Reply #131 on:** February 23, 2020, 04:53:26 am »

Here's the pic of the fuse I replaced circled in red to fix the frequency generator.

ArthurDent · « **Reply #132 on:** February 23, 2020, 01:48:39 pm »

"IDK what most people do but I edited out the coordinates on the GIF LH produced?"

Removing that info from the top left doesn't help if you're plotting that same data on the graph at the bottom. There is no reason to plot that info because your coordinates/elevation don't change and you generally don't want others to see it. Look at what data is plotted on the graph I posted.

notfaded1 · « **Reply #133 on:** February 23, 2020, 05:44:43 pm »

What setting do you use to get it like yours? Is it possible for me to get same info?

Bill

ArthurDent · « **Reply #134 on:** February 23, 2020, 07:25:03 pm »

Different makes and models of GPSDOs display different data with Lady Heather. The graph I showed was from my NTPB15AA made by Trimble which displays the same basic info as a Trimble Thunderbolt. Your GPSDO is apparently displaying NEMA data and I'm not sure if you could make the graph look exactly like mine but you may be able to get rid of the coordinate/altitude info which isn't necessary. If you're stuck with displaying that data I would use a photo editing program and wipe out the location information so if you post a graph no one can see that your antenna is on the south side of your duplex near the window.

thinkfat · « **Reply #135 on:** February 23, 2020, 08:01:22 pm »

If this GPSDO only outputs positioning data, there is nothing worth showing anyway.

notfaded1 · « **Reply #136 on:** February 23, 2020, 10:16:26 pm »

This is kinda fun... I'm a cold cathode display tube person and have a bunch of nixie tube counters. I hooked the 5MHz Unknown Rb output to my Systron Donner Model 114 that has big nice tubes. I have a decent distribution amp with over 10 outputs on it... it would be cool to hook up all my nixie counters at the same time and take a picture.

Bill

notfaded1 · « **Reply #137 on:** February 23, 2020, 10:17:28 pm »

Quote from: thinkfat on February 23, 2020, 08:01:22 pm

If this GPSDO only outputs positioning data, there is nothing worth showing anyway.

I'm hoping it actually outputs more than just that data... it's heather that defaults to NMEA correct?

notfaded1 · « **Reply #138 on:** February 23, 2020, 10:23:05 pm »

Eldorado Model 225 it's nice and small and has very few controls on it.

notfaded1 · « **Reply #139 on:** February 23, 2020, 10:29:30 pm »

Monsanto Counter-Timer Model 101B

notfaded1 · « **Reply #140 on:** February 23, 2020, 10:37:08 pm »

Yaesu YC-355D - I don't know a lot about these but they were apparently popular with HAMs.

Bill

notfaded1 · « **Reply #141 on:** February 23, 2020, 10:42:26 pm »

On another note I just bought this for a little over 100 British pounds... it's supposed to have the power supply with it.

notfaded1 · « **Reply #142 on:** February 23, 2020, 10:53:33 pm »

This is kinda an affliction I think.

notfaded1 · « **Reply #143 on:** February 24, 2020, 04:04:32 am »

I figured out how to get slightly better screen from lady heather buy using the ublox flag.

All the great code pulled together to make this is awesome!

Bill

notfaded1 · « **Reply #144 on:** February 24, 2020, 04:09:24 am »

The change in the graph at the bottom is pretty helpful I'd say... it's nice to know the nanosecond span 100%.

thinkfat · « **Reply #145 on:** February 24, 2020, 08:59:55 am »

Yes, but it's still only the GPS part. The "DO" part shows up nowhere. No TFOM and FFOM and the 1PPS nanoseconds is just the output of the receiver, no relation to the output of the GPSDO. Also - this doesn't seem to be a timing receiver. Lady Heather would identify it if it was. So, no position hold mode, which is definitely bad for the 1PPS stability.

notfaded1 · « **Reply #146 on:** February 24, 2020, 11:38:29 am »

Quote from: thinkfat on February 24, 2020, 08:59:55 am

Yes, but it's still only the GPS part. The "DO" part shows up nowhere. No TFOM and FFOM and the 1PPS nanoseconds is just the output of the receiver, no relation to the output of the GPSDO. Also - this doesn't seem to be a timing receiver. Lady Heather would identify it if it was. So, no position hold mode, which is definitely bad for the 1PPS stability.

You're right about that. The 10MHz is about as good as you can get but the 1PPS will be adjusted all over the place because it's monitoring the UBlox not the LO. I think the perfect addition for this is a LO that can be monitored by ladyheather too. Which do you recommend @thinkfat?

Thanks,

Bill

thinkfat · « **Reply #147 on:** February 24, 2020, 12:28:29 pm »

Well, if the serial interface output is the only port you can access, the only chance is to see if the GPS module is one of the "Frequency and Time Sync" modules from UBLOX. Those are able to discipline a LO by themselves and if you enable the correct messages, you have enough information for Lady Heather. So, the job is then to modify LH to understand this data.

If the GPS module cannot supply the disciplining data and no other interface is available, your journey ends there, if you don't want to use extra hardware.

What you could do is order a TAPR TICC (it's about $250), which LH supports, and feed it the 1PPS signal from the GPS module and the 10MHz from the LO and see what you get there. No idea if LH can work both with a GPS and the TAPR TICC but it's worth a shot.

notfaded1 · « **Reply #148 on:** February 24, 2020, 12:54:31 pm »

Quote from: thinkfat on February 24, 2020, 12:28:29 pm

Well, if the serial interface output is the only port you can access, the only chance is to see if the GPS module is one of the "Frequency and Time Sync" modules from UBLOX. Those are able to discipline a LO by themselves and if you enable the correct messages, you have enough information for Lady Heather. So, the job is then to modify LH to understand this data.

If the GPS module cannot supply the disciplining data and no other interface is available, your journey ends there, if you don't want to use extra hardware.

What you could do is order a TAPR TICC (it's about $250), which LH supports, and feed it the 1PPS signal from the GPS module and the 10MHz from the LO and see what you get there. No idea if LH can work both with a GPS and the TAPR TICC but it's worth a shot.

What's an alternative GNSSDO that has LO which can be monitored by LH in addition to it's monitoring of the birds? I'm checking out the TAPR TICC.

Thanks,

Bill

thinkfat · « **Reply #149 on:** February 24, 2020, 01:28:32 pm »

Quote from: notfaded1 on February 24, 2020, 12:54:31 pm

Quote from: thinkfat on February 24, 2020, 12:28:29 pm
Well, if the serial interface output is the only port you can access, the only chance is to see if the GPS module is one of the "Frequency and Time Sync" modules from UBLOX. Those are able to discipline a LO by themselves and if you enable the correct messages, you have enough information for Lady Heather. So, the job is then to modify LH to understand this data.

If the GPS module cannot supply the disciplining data and no other interface is available, your journey ends there, if you don't want to use extra hardware.

What you could do is order a TAPR TICC (it's about $250), which LH supports, and feed it the 1PPS signal from the GPS module and the 10MHz from the LO and see what you get there. No idea if LH can work both with a GPS and the TAPR TICC but it's worth a shot.
What's an alternative GNSSDO that has LO which can be monitored by LH in addition to it's monitoring of the birds? I'm checking out the TAPR TICC.

Thanks,

Bill

Lady Heather should have list of GPSDOs it supports somewhere in the documentation.

Regarding the TAPR TICC, I see you have a 53131A. That should be fine, I just don't know if you'd want to dedicate it permanently towards monitoring a GPSDO

Maybe LH supports it already.


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Author Topic: Found home made rubidium reference that seems to really work well (Read 19477 times)

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