Відео

The equipment on display is no less "scientific" than the 20 year old X-ray machine in the local hospital is. It may not have that 'new car' smell to it but dollars to donuts you could send them out to be calibrated and they would still be in calibration.

You might want to look into those MOSTEK ROMs on the main board. These are known to fail over time getting corrupt bits. If any ROM has incorrect contents the processor will most likely crash and go into an endless loop. This unit appears to have a 6800 family microprocessor and these typically go into an endless loop cycling through the whole address space reading each memory location sequentially. Probing the address lines with a scope can check this with each address line having a square wave on it halving in frequency for each successive address line from A0 through to A15.

If you hook the serial port up to a computer, you can download and run “Lady Heather” which can talk to and control a wide variety of GPSDOs. It shows a lot of useful information, plots maps of the satellite coverage, produces graphs of lots of data and much more. One thing to check once you’ve got the antenna fixed is whether the GPS has gone into 2D position fixed mode as this gives the best timing accuracy. You can trigger a self-survey which can run for 24 hours and averages out the position errors and then use the resulting position as the fixed “truth”

I'm a simple man. I see a video on a GPS Disciplined Oscillator (no clue what the fuck it is) I click.

Repairing equipment is a lot like solving a crime. Except it is a lot messy! My dishwasher was giving problems recently and after a lengthy faultfinding, I realised that the hose connecting the pressure sensor was leaking because of a bad hose-clamp. No sensors... not the relay on the control board which I replaced... nothing sinister in the software... a plain old cheap hose-clamp! Great repair video, thanks Gary! Let's hope no.3 will be the last one for this instrument! Good luck!

At 5:20, you should be saying to yourself, “That’s when he realized, he F’ed up.”

A biquad filter is very sharp. The ringing can sometimes be irritating.

Thanks for the video. Suggestions: Because you used the exact same battery as the original, you may want to add a note inside the unit that says that the battery has been replaced and the installation date. For the springs that pop out... You might secure the outer end of the spring to the switch body with a flexible glue. I suggest a tiny dab of Shoe Goo. Hot glue would not be appropriate for this use. HTH.

The HP 3314A is a really nice function generator. A common fault in these units is the bottom entry Molex (Series 4455) connectors used to connect the power supply series pass transistors to the circuit board - they overheat, corrode and go open circuit. TIP41 and TIP42 transitors work well should you need to replace the existing transistors. The output cable connector you showed is actually type SMB, it has a round outer shell and is a push-on connector, type SMC has a hex shell and is a screw-on connector. To get the most from the "Easter egg" you'll need an amplifier and speaker. Regards, David

Nice ! seem to do its job, can you do a Bandwith test of the distribution amplifier to se if it is capabel of up to say 30 MHz or higher ? , then it could be used as shortwave signals to several receivers, maybe there is a bandpass or lowpass filter on the outputs but it would be nice to know also if it is 50 ohm on all outputs ?

Beck to the 70´s then when Lab coat was popular haha

"C'mon Baby!" I am so glad that I am not the only one who speaks to his test equipment! 😆 What a bargain to buy such a great instrument for the price of a battery! Those Lithium Thionyl batteries can be expensive, but well worth it given their longevity. Great video, thank you Gary! Can wait for Part 2! (ps. That white lab coat does look good on you!)

Up vote for the succinct unboxing video.

Thanks for sharing! Take care.

I got one something like this from Aliexpress but it's rather disappointing. On the display it just says "10.000 Mhz GPSDO" for a while then changes to say "PPB -2.3" and "PWM31077" but there are no instructions at all so I have no idea what that means. Pushing in the knob gets into a menu where I can select Contrast, Offset, PWM Set and Exit but that's all. It never displays the time like they show in some photos and there's no way to even tell if it's picking up any satellites or working at all! I opened it up and inside it has an Arduino STM32 and NEO-6M module plugged into the main board with a 5 volt regulator and LCD. The main board also has a 10.000 Mhz OSCO on it and outputs on the back for 1PPM and 10 Mhz.. With the top off I can at least see the LED blinking on the NEO-6M so I guess it's working to some extent but they should have put the LED on the front. Since there are no instructions can you tell me what PPB -2.3 and PWM31077 mean and how to use the settings for Offset, PWM Set? The PPB value goes down to just a fraction after it's been on a while so I assume that is some indication of the amount of error?

❤❤❤ ...what a nice collection! Congratulations. Regarding the spurs in the original board, I suggest to check Phase Detector and OPAMP Loop Filter in the main loop. You are right: there is an undesidered modulation there... A good strategy could be to test first of all passive elements for aging issues and than exchange the semicinductors with new parts. Good luck and keep us informed. Regards from Italy.

If you have the opportunity measure two GPSDOs, and then have a look at the Lissajous curve! I designed a GPSDO as my thesis, I had measured it, and I think the comparison would be interesting for you as well!

Hello, not sure how much services you have done to your HP 3585A, but I recommend you replace all them electrolytes in the power supply area. I have the same unit, them caps are dry and stresses the power transformer! also make sure you apply new thermal compound on the power transistors! otherwise this will run HOT! thanks!

Brother of my 3582A.

I LOVE your collection! I think that the multiplexing effect looks really cool on camera. I see it a lot on some of the airplane videos I watch. I love how they have the circuit traces on the same side of the board as the ic's. Cool video and nice jacket too.

Wow, I didn't know such thing was available. It definitely has advantages to "discipline" cheaper gear that doesn't come with vcxo option

What web site did you use to calculate the component values?

👍👍👍

I also have a 3325A and it is located exactly as yours, just above my bench. I'll be checking the spurious noise level as well and will report back!

You can use that serial port to set up a stratum 1 NTP server. All you need is a cheap computer and Linux. I run pfSense on a mini PC for my firewall/router and it supports a GPS connection. If you really want accurate time, you could also add a Facebook atomic clock PCI card.

Been meaning to get one of these myself. I looked at one of these when I bought my GPS reference but never followed up with the purchase. I have also seen others repurpose video distribution amplifiers but I would rather use something purpose built. I do recommend terminating all unused ports with 50 ohm loads to minimize leakage and any unforeseen issues that may arise from unterminated outputs.

This is a complete failure if you want to keep your modern frequency reference source a secret you should not publish a video revealing it.

A question Gary. Should the unused ports of the distribution amplifier be terminated in 50 ohms, to prevent reflections back into the amplifiers? Not sure if this would cause problems. By the look of it probably not...

A nice unit - I like the build quality here.

Good stuff. I bought a GPSDO a year or so ago, but instead of buying a purpose built distribution amplifier I bought a used video distribution amplifier off of somebody on Ebay. This was on the advice of some folks on the EEVBlog forums, who were saying that if you just change some resistors to switch the impedance from 75 ohm to 50 ohm, those repurposed video amplifiers work great for this purpose - and they're cheap. I haven't actually gotten around to switching the resistors in my amplifier yet though. One more project for the backlog. *sigh* Too many things to do, not enough time. 🙂

May we please have the link to these two exact units?

Awesome channel Gary . Regarding finding somewhere to mount the Distribution Amplifier and GPSDO...I have a disused HP 5061A Cesium Beam Frequency Standard. The Cesium is exhausted, but I'll install the GPSDO inside the HP 5061A for now incase another Cesium bottle comes along. The HP 5061A has a built in LED clock option, so the GPSDO 1 PPS output will be useful to keep the clock going. Well done. Kind regards.

Your channel is very interesting. Thanks for sharing your love for our hobby.

A lab coat to wear in the lab, very cool! I was wondering if you tried the DAC Offset (para. 5-8) and Analog Phase Interpolation alignment procedure (para. 5-10) on your original A21 board. API alignment removes or minimizes spurious output from the VCO output. I ask because I recently repaired a 3325A and ran the entire alignment procedure. Regards, David

Nice, I also have a 3325A and just did this test myself. I used a HP 70K series SA and discovered using the same parameters of CF 1MHz, Span 1MHz, RBW 300Hz and 1kHz VBW my 3325A @ 1MHz, 0dB out measures -89 to -88.42dB @ 400kHz from the carrier. I have also measured the phase noise performance of the 3325A that I have and have discovered that it is well within the specifications listed in the service manual. These instruments will last seemingly forever if properly cared for. *edit* Guess I'm going to have to get a "lab coat" now. :)

Thanks for your presentation. If you look at the circuit closely you will see that the two heater/thermistor pairs are connected back to back in the feedback loop of the op-amp - this is not for improving sensitivity as you state. This connection accomplishes the AC to DC conversion and nulls out any common mode errors due to ambient temperature changes etc. Jim Williams was a big fan of this instrument, its elegant operating principle was used in an IC he had a hand in designing.

great video, usefull and simple idea. Just a note: to have the same polarity on both channels use the low side of the transformer(0V) as common ground and the black probe/1k union as Y out.

Nicely built! I really like it. Got a curve tracer in my old Hameg 204 scope. I also gutted an old single-channel scope and repurposed it as a curve tracer among other things, using schematics from Paul Carlson.

Probably the best unboxing video .....EVER! 🤣

Hameg zawsze miał taki tester elementów wbudowany.

Oh I Love this! I first learned how to unbox things at the age of two on Christmas day...

piękne mierniki.

Ciekawa maszyna i ciekawie zbudowana. Który to rok wykonania jej ? . Pięknie zaprojektowana jest.

Ładny sprzęt. Wykonanie tradycyjne a nie SMD wszechobecne. Maszyna ma swój urok. Pozdrawiam.

I used to perform electronics repairs 35 years ago; when a customer would bring in a stereo with one dead channel, my curve tracer was the fastest way to identify bad or weakend components in the dead channel, simply by comparing the traces of the two channels. A very handy tool.

Those things are awesome, Hameg scopes had them built in, they made me a fortune as a repair tech, once you have a little understanding of what they show you and you're used to the shapes you see it's so fast and easy to sprint through analogue components in power supplies, amps, monitors, TVs, all sorts of stuff, you can spot leaky caps, failed diodes, transistors, FETs and all sorts of semiconductors almost instantly

I miss the old scopes. Even though the new digital scopes are far more capable, there's something about looking at a nice blue/green trace that's directly connected to the signal instead of what is effectively just another image on a pc screen. Oh, and you didn't have to listen to a constantly whining fan. Plus they've done away with the Z input.

Sir, can use it with a digital Oscilloscope...??