Very interesting. I was given a 475 scope in apparently pristine condition, but it will not trigger. I also have an old Heathkit Transistor Tester that does leakage testing. Transistor leakage tests have saved me a lot of trouble on several occasions, including on an old combo organ I was given because everyone else gave up on trying to fix it.

Why you did not connected common wire from BNC to SG505 in differential mode? Also I see some 60/50Hz spikes in spectrum beginning. Does power supply in SG505 is ok? Filtering caps?

There’s a cottage industry built around courrier laundering broken test equipment through eBay

I ordered a GPSDO that came 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 just it's 5 pins holding it. 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?

Hi, I have a 725 hooked up to a 770; when i turn ON the 770, the red power light comes on, but none of the indicator LED's do not turn on. I purchased brand new RCA's just to be sure, but still no dice. I bought the pair from an ebay seller and he swears up and down that it "was working".... Any advice would be greatly appreciated

is there software to talk to the unit with the usb port?

i have one of those, is a neat unit. manual is online somewhere

The only issue we have had here on test equipment rebuilds is proper service documentation with the more vintage test gear, Great advice on the brightness setting..

I've got an HP 8657 signal generator that I am dreading tearing into. Another "works correctly" purchase off of Ebay. Of course it has low output at lower frequencies. I keep on looking at it with the same enthusiasm I would have for picking up roadside litter on a 10 mile stretch of highway.

dont know what the kit is for but interesting anyway best guess ,is it a dds sig gen thats sync-able with a time base reference? in the uk we dont get access to hp gear

Thanks for the thorough vid. The bathtub cap in my unit is toast. The one thing that I don't like about the TT is the control knobs for Bias and Meter. Specifically, the arrow indicator is too far from the number scale. I like being as precise as possible and you really need to trust your eyesight to get them aligned perfectly. Being a bit nit-picky but comparing with the Hickok, they could have done better in this regard.

Question what was total cost in parts including the CRT?

🙌🏼

I have the older Leo Bodnar single output unit and added some heat sinks to the unit, both internal and external to lower the localised hot spots. If the Leo unit stabalizes over 60seconds and the GPS signal needs to be averaged over 60minutes to gain what the real accuracty is as it cycles to reduce its precission. What precession does the Leo achieve in the 60sec stabalisation time? I'd be interested in the non GPS locked stability figures at 10Mhz. thanks for the testing videos. cheers from Australia

VaLhalla, not Vahalla, or Odin would show no mercy :)

I have had a significant number of Valve equipment power transformers fail over the years due to shorted turns…simply because there are so many turns of fine wire at so few volts per turn at mains frequencies….also had a 950v secondary in a Gould 4035 Oscilloscope that supplies the tube have shorted turns….enough to cause a 200w globe to glow about a quarter bright and a hot smell to eminate from the transformer. In that case I unwound the 6.3v tube heater winding and the 950v was the next winding down…got right “medieval” on it and chomped half of it away…put loads of captan tape over it, rewound the 6.3 on top and voltage doubled off what was left…which was about 415v worth….it worked quite well for about eight months then shorted again. this time I’m ripping it sll off and replacing it with a 25v winding to drive a Royer or Flyback ferrire vored EHT supply for the tube. Do have some valve regulated HV supplies here, two from Sanborn electromedical equioment….but both with just 120v primaries and a multitude of 350v secondaries…two driving a 5U4 locally, but the others went through wiring looms to remote rectifiers in the huge Sanborn 350 racks. As I’m in Australia, I will series the two 120v primaries on the two transformers, then parallel all the 350v secondaries between each to get them to share the load equally so I can run them of our 240v mains. They use 6L6’s as pass regs, 85A2’s as references and 12AT7’s as diff amps. Here, I would pull ALL the valves…including the 5U4 and jst see what the transformer draws on its own with no loads at all. the 5U4 heater draws 3A at 5v, so there is 15W already. When you showed the ripple, every second half cycle looked lower, suggesting a higher source impedance in one of the 5U4’s anodes than the other. I’d be loading down those secondaries with strings of low powered light globes….don’t you have 7.5w, 115v candle lampe over there in the United States? Put four of those in series to get a 30W, 500v resultant load you can test the secondaries wiith…form one end to the centre tap of course, not right across the whole lot. Somewhere I saw a video of a fellow Aussie getting the power transformer of a late 1920’s AWA (Our equivalent of your RCA) TRF radio rewound…yep here it is… nCB-iEllFak. He did happen to know a guy who would tacetly rewind transformers but did not openly advertise the fact. This is certainly a project I would like to complete too…do have a PS from a transmitter that has two 866A’s and two or three 5U4’s followed by regulators…..about four supplies in all of two transformers…and quite a few chokes and oil filled caps with bushings and dodgey dielectric inside….could tuen that into a HV bench supply, but a lot of work to make it safe and goof proof around the terminals!

I’m pretty sure I have one of these and a HP 5245L out in my shed. A few months ago I took the lids of both of them to see how similar they were inside and sort of expecting not that much difference, but I was surprised to fond that they were quite different despite the general layout and specs being similar. Have not found the time to power up either of them yet, but when I do it will be in series with some light globes. Both are fitted with hererodyning fown converters in the left hand plug-in bay and they are in no way interchangable between the units or even similar in interior design apart from containing an adjustable cavitity. Once I have had the time to check them over I will try to remember to come back and make a comment here on what I find.

You stated that this power supply has a full wave bridge rectifier configuration, and you also claim it has 60 Hz ripple, those 2 things do not add up ( it should be 120Hz ripple), something is still faulty or miswired. I would load test that transformer for its AC output without the circuitry before condemning it. The small "transformer" you pointed to on the bottom of the chassis is most likely a choke inline with the output, if that is shorted it will not remove the last of the ripple as well.

Send to Mr Carlson I bet he will fix it :D

To paraphrase: "I've done everything right and it still doesn't work". I don't think your power transformer is bad; transformers don't just start delivering low current. I recommend getting a schematic for the A3A and carefully checking ALL your work. If a rectifier is getting hot then possibly too much current is going through it. With the wrong tube installed (6SH7), it may have been modified; the correct tube may now be a mistake, and other parts may have been changed. BTW, I'm a tech.

Don't give up. Swap in a different transformer from an old radio chassis. Transformers are not critical. You can re-wind that one, too.

Possible leakage from potentiometer/switch casings, wiring, or from the meter already eliminated as a possible fault source? I remember I recently had quite some "fun" fixing an analog multimeter where there was leakage (not even high voltage leakage, it ended up putting the ohms battery in circuit at unexpected times) from movement to meter face to meter mounting screws through some degraded electrical tape below the meter face to the battery contacts.... I'd be tempted to have at every front panel control that is still connected to anything with just the rectifier in with an insulation tester...

Buy a Cesium standard :) 🕰

@25:56 can't be the GPS self correcting, the jitter is faster than 1s...its whatever jittery oscillator the leo unit is using. The fast jitter looks like it's a VCTCXO (eeeek!)

@19:38 they are ALL GPSDOs , yes even the mighty Rubidium. Some GPSDOs use "crappier" oscillators. But if oscillates and its being "disciplined", it's a GPSDO. :)

I’m always shocked when they make it through shipping alive. So risky. People like to launder broken gear through a courier.

Did KZfaq remove the audio, I think I need this repair too! No idea whats going on tho, total silence!

Intel hi-end 13 and 14-gen CPUs are very buggy, why not AMD Ryzen 8 & 7-gen CPUs, which are significantly faster, cheaper and more stable.

Hello, I continue to have problems with the R control board, the bias cannot be adjusted, it remains at 275mV and the VR402 potentiometer does not respond. All transistors have been replaced and the capacitor of the input has also been replaced. I have an audio signal, but bias does not adjust. What am I overlooking? Can you give advice? Icoon voor Geverifieerd door de community

I bought one of these, there is about zero info on them. I'm curious about the tracking led status. Initially the led flashed quite fast. After about a day it slowed to about one flash a second. Then it started to flash fast again. Does anyone know if this is normal. The antenna is outside and in the clear.

I could not find a series on a full repair of a 465 (non-B). Have you done one?

I just got a 577 and repaired the totally messed up PS that had a previously terrible attempted repair . Got it working but have not done a calibration yet. I also have a 575 that I got over a year ago and would love a video on that. I replaced one tube on it and it somewhat works. But i have not dived into deeply into it. Any chance on doing one?

When my old HP GPS time and frequency reference receiver finally kicked the bucket I got a new Stanford Research Systems GPSDO and frequency counter with optional rubidium time base. Best of both worlds, GPS and rubidium. However, you could probably buy a rather large pile of those little GPSDO's for what I paid for the SRS one new. If I only worked on HF/VHF/UHF transceivers one of those little things would probably be fine. In my case I also work on SHF and EHF transceivers. A tiny error in the 10MHz reference to one of the EHF radios can cause a frequency error of hundreds if not thousands of Hertz error.

Battery could be for the GPS receiver module so it can preserve the GPS/GNSS satellite almanac or ephemeris data to improve time-to-first-fix times.

I have three of the 575’s, all the higher voltage Mod122C models. The most expensive one was $350+ shipping. They’re well worth it IMHO. But I’m partial to the old tube 500 series Tektronix stuff.

Nice I have a PACE PRC2000 also known as a Model PPS400 and those Pencil Soldering Irons PS 80/90's etc give out all the time, and they start at like $135.00 each without a tip. Of course in a production or repair center, these tips can go through as many as 20 cycles in a day all week long, and sometimes are on almost 7-8 hours a day for days in a row until the weekend comes. However I just might have to figure what Hakko is doing and adapt them into the PACE Station. One thing I do like about the PACE station Irons is the tips are changeable on the irons without having to unscrew the iron or change it out all together. I also like the Temperature Setback Mode, basically it's an idle mode where you can ask it to keep the tip warm but not hot, like if you go to lunch or the restroom. After you take it off Setback Mode it warms right back up fast. When I went to school for soldering, the basic rule for us was to choose a tip and wattage large enough that you could get a full wet and be on and off the joint in 3 seconds or less. Large ground planes obviously require a larger mass tip and the SMT's with leads attached used the smallest tips. Again the basic idea was the smaller the lead or area, the smaller the tip to keep the iron from transferring to much heat to the board. A really good primer on the video bud. I loved that you talked about the humidity and iron components, I never knew that one. Thanks for sharing, love the channel, you are way under subscribed to that's for sure. Best Wishes & Blessings. Keith Noneya

I'm one of those who love HF tips (Thermaltronics TMT-5000S system) Beneficial is that it throw much more power in short time. Therefore even smaller tips don't need so much mass. (I have experience with JBC, Weller WX system and some Chinese stuff as well) Changing the tips is really necessary only in case of massive thermal mass like big ground planes or power components. And for those I have only one tip. The rest is for low temp only different style depends on type of components. Most used is 3mm chisel after that conical and last sharp tip. What I'm missing in Thermaltronics offer is microwave (chisel tip with small hollow in the center)

Thanks for followup about soldering. I am learning especially in regards to understanding what is a reasonable amount of time expected to heat a joint without damage. Now to master the real art of soldering because we need three hands! Big Clive with his big hands, nonetheles demonstrates real dexterity in soldering.

Good soldering stations, both Hakko and Weller (have both), that will keep up the heat transfer can surprisingly attach a PL-259 or N silver connector to the end of a 100' of LMR400 cable...surprised me the first time I was able to do that. 73 - Dino KLØS

Great Video! Soldering IS an art, I think. I certainly know people that are soldering for decades and still BLOB it on..... Cough*** 12volt vids ****cough.... 😉 And of course we should really talk about the importance of FLUX!! I have been soldering since about 10 or so. My first, and I still have it.. is a Weller gun. Today I cannot imagine using that thing on anything any longer. I have gone from it, to Pace, to Weller, to Hakko, to Metcal. Aaandddd..... stayed with Metcal. The Hakko for me is a close second, and I'd recommend them to anyone. Absolute safe bet. Same for the DE-soldering gun, and absolute MUST if you do a lot of work. But to me, the Metcal is IT. It can push so much power when needed, I just never needed anything else from surface mount to soldering a stud to a metal chassis. BUT.... they are expensive. I got mine used, of course. BTW, try a HOOF tip! Best of both worlds and much nicer for drag soldering. ( And DAMN!! Those old Tek Scopes are works of art! ) 😍

With over 50 years of experience soldering, I found your advice very sound. I particularly agree with the fact that soldering is a bit of an art. Buying some cheap kits and putting them together for practice is a good way to learn. Then try working on that $1,000 transceiver, when you feel confident Two items I would add. 1) The solder is hot enough when it turns shiny. 2) Learn to minimize the amount of solder needed to make a strong joint. Globs of solder are not good. Also get a good de-soldering gun, solder suckers work but get a bit tedious when having to replace multiple parts, such as recapping an old piece of equipment.. That should be a good topic for a follow up video.

I have a 465 with ch 1's 10x indicator burned out. Would be amazing if you have a chance how to get to these bulbs... Hopefully without too much disassembly.

I bought one at a good price. I am thinking of using banana plugs so I can use different cables, however, I see on lines are grounded. Not sure how that will work out. I might test before committing.

I thought I wanted one of these. But after seeing what you did to make it work. I’ll pass.

Do you also have the Leo Bodnar GPS reference? Wondering how they compare. I'm in the UK and should probalby just get LBE-1420 . . .

Measuring GPSDO requires the Allan variance

I have one of these units as well with date code 2020-06-10. I have compared mine against my Rubidium standard and I'm getting similar results to yours using a HP 5371A Frequency and Time Interval Analyzer. I have also characterized the unit using Time Lab, and for the money, it's certainly a very cost effective option than using a Cesium standard. I have had no issues monitoring the unit with Lady Heather.

very interesting video, thank you for making it. do you have some explanations for dummies on what Allen deviation is and how to measure it properly ? in your examples, I see you are changing gate time. what is that about changing the gate time for Allen deviation?

adjust the line voltage everytime after putting different tubes ? thx

Curious where you found the calibration items for the DM44. Have a 465 w/dm44, and the 465 doesn't show anything for it. Is the info in the 475 service manual applicable for the 465 w/dm44? Edit: Nevermind. Found a DM44 service manual. For others, it says "Instruction Manual" on the front, but has calibration data in it. It is a standalone document for the one I found, rather than with the 465.