Frequency Counter Upgrade and GPSDO 

Thanks, Ruel This makes me feel even better about not using the supplied power supply. I am going to do some long term power on testing starting this weekend. I had kicked around doing a band pass filter to smooth it out to a sine wave and I still might have to do that however The Leo Bodnar GPSDO has a feature that I would like to use in the lab it is not locked to 10 Mhz you can set the frequency of the output. Now the 2 outputs have a relationship with each other but nothing says that have to stay at 10 Mhz. This way I can use the Leo GPSDO elsewhere in the lab at different frequencies. Also have the outdoor antenna allows for a much improved signal in to the receiver I never see less then 8 Sats even at night.

@@ZenwizardStudios Excellent. Yes, the ability of the Leo Bodnar unit to generate other frequencies is very handy and you'll probably find uses for it. 😁

That is where it ended up for sure. Especially with this unit running 24/7.

@@ZenwizardStudios genuinely wondering if the EMI from it was causing the GPS issues? 😂

To be honest I never hooked it up seemed a little too..... combustible? to leave on when I was not in the lab. I do have a noise issue in the lab actually a few of them. I need to find a way to do some power line noise filtering I have an energy monitor that uses power line communication that causes all kinds of common mode effects. I would love to isolate the lab and will need to at some point. I am going to need to take some measurements in a Faraday cage. All the computers and monitors that are close by can do some strange things. Especially with some the spectrum analyses. I would love to get an RSA for the lab up to a few Ghz It would be interesting to see the noise spectrum of all the EMI going on.

If the Samsung is unavailable then something that works with the lady heather software would be good that way it can be monitored. Lady heather supports most of the common units. There is a compatibility list at the EEVblog in the lady heather post.

@@ZenwizardStudios What about the Leo Bodnar?

I have the Leo in the lab as well. This video is another one of mine that might have some really useful info in it ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6HZ8CeLFfpU.html I smash the Samsung and the Leo in to a new FS725 Rb unit and make some observations. I have been asked to do more of this testing but I need to upgrade the frequency counter to get the results and numbers I would like so that has been the delay on the more testing. As soon as I can swing the frequency counter I have had lots of requests to leverage the RB unit for testing as they can be cost prohibitive especially in the new market.

@@ZenwizardStudios I was looking at the Leo for this, 10 MHz ch1, and ch2 to dial in audio sampling rates (44.1 kHz / 96 kHz) . . . jitter?

We have had some pretty good rain and storms here and it seems to be holding up fine for the short term but as with all things time will tell.

I have updated since and the amp is relegated to 2nd duty more info is here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6HZ8CeLFfpU.html , I do really want to grab one of the Rohde & Schwarz communications test sets but it will have to wait a bit. Had some other things come up recently. When I did some broadcast work there was a ton of 75 ohm gear seems to be the standard for video.

@@ZenwizardStudios The 75 Ohm connectors on my R&S CMA 180 are for SPDIF (Sony/Philips Digital Interface) input and output. In other words, digital audio.

The antenna was from amazon. This GPSDO can drive an active antenna 5Vdc at the antenna jack. It is a marine antenna. I will admit the price was right. But being active I am getting about 28 Db of gain from the antenna. It really does not have a signal issue. I actually did not calibrate the oven in it. Now that you mention it I probably should. I have a BK frequency counter that I am going to try and mod it for a external reference. On the HP when it detects External Ref and is shown on the front panel I believe it overrides the internal clock. Link here: www.amazon.com/gp/product/B07MYXTVF1/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

Thanks for the support Jennifer!

Andy, for the HP 8657B it calls for 0.2-0.4V RMS in to 50 Ohms. for my particular setup I need a 6Db pad to cut it down. but the HP is now on the GPS as well.

Questions are great no worries there. I guess the real question is the GPSDO “good enough” Having just added Rb to the lab I cant comment on that. However, If a home brew RB standard is the goal. All the 725 is a SRS prs10 in a box with a power supply and distribution amplifiers. A new PRS 10 is still a tall ask some times. There are RB standard on common auction web sites some of the research I did before settling on a solution indicated that not ALL RB standards were created equal. Some did not have the 10 Mhz output and only put out 1pps. The boxes were small and could easily mount somewhere. However, they do tend to run warm. Even the back corner of the SRS unit runs warm to the touch. In my testing the 10 Mhz GPSDO was off at MOST from 10 Mhz 116 uHz (micro hertz) so this is VERY good. A GPSDO is also an “ageless” option as it is self-updating when locked to the satellites. Now for the HP and the RB both output 10 Mhz so there is LOTS of distribution amps The small white box was what I was using for distribution around the lab. Now I had a lot of RF attenuators because that was a 75 Ohm distribution amp so I had to check the signal at all of the devices to make sure I was not overloading the inputs. Some of the signal generators and spectrum analyzers needed -3 or -6 dB of attenuation to keep from overloading the input. Any amp is fine unless the goal is phase correlated measurements. Then it gets REALLY complicated as cable even have to be matched length. ALL that being said I can not speak to the needs of anyone’s lab but my own. If there is interest I could try and home brew a RB reference for the lab as a project. Since I have a known good one to crash it against. That is really the hard part is once it Is working making sure it is working right.

@@ZenwizardStudios You are amazingly kind, what a detailed and great answer1 I am thinking, A build could be amazing! Maybe I could buy it from you, plus shipment? In that way do you make one more interesting video but without expenses, and I get a unit that I know works:-) Only detail is what it would cost?

There is one other big variable that is lamp life. There is a finite time for the Rb lamp. Most of the units on the secondary market are out of cell towers when they were upgraded. They have been running 24/7 for years. It is hard to know how healthy the RB is in the units on the secondary market.

Thanks got it changed.