Like a few others here, watching the diagnosis without seeing the actual repair at the end is a bit like missing the conclusion of a detective thriller, leaving the watcher with a sense of anticlimax. I still love watching your videos though.

Would have liked to have seen how you decided to add the flexible epoxy to the attenuator assembly but great repair as usual! Thanks for sharing!

Shariar saved me many hours and $$ I don't have by leading this horse to water. I opened the attenuator and watched the solenoids operating. They are basically 10dB steps. The middle solenoid was stuck open, leaving 40dB attenuation stuck in place. The cause was loss of the rubber ring but for a different reason. Without the ring on the side facing the coil, the plunger makes metal to metal contact. These relays are pulsed to save energy and have a magnet. They are pulsed to open and pulsed to close. When metal to metal contact was present, the coil is not strong enough to force a release. I simply put a small square of polyester graphic overlay material with 3m 427 adhesive on one side and let it stick to the core of the solenoid. This introduced a gap close in size to that which the normal section see from the upper rubber ring. Works perfectly ! !

My wife just asked me last night: "The smart guy hasn't done a video in a while? I haven't seen you watching him." Boom...today new video!

It would have been nice to have seen the actual repair of the rubber dampers or at the very least a picture of the final repair. What did you finally make the dampers out of? Did you use rubberized epoxy as mentioned in the video or something else?

Thank you very much for this video. I have learned a lot regarding the inside of the attenuation block assembly. now I know whats wrong with my Marconi RF signal Generator. Next I will view all the rest of your videos

Ah, rubber rings, a curse left over from HP. This is the main reason for failure of tuned YIG (SYTF) in the old 859x, 856x series spectrum analyzers. The YIG spheres were suspended and adjusted with the rubber donuts to hold the setting, then hit with epoxy. Over the years and heat of the SYTF magnet, things shift and the SYTF can end up with high losses. I broke one, fixed the next one and never want to touch another one 😝 In this case, I may machine small donuts from nylon or a softer material if I can lathe turn it. Remove the old ones with an end cutting xacto blade ground narrow for a plunging motion, the snip each donut to remove an arc of the donut, making it sort of like an E clip.

They look like simple O-rings above and below the plate that actuates the plastic rods. Maybe they are rubber, which usually hardens and cracks with age.

@uploadJ

5 жыл бұрын

Wow ...that Agilent gear was front-line test equipment back in - 2005 ... amazing to see the little idiosyncrasies like crumbling, drying rubber O-rings bringing it to its knees 13 years later!

@gordonwedman3179

5 жыл бұрын

If they are just O rings could you not make one cut, slip it over the rod and they put a dab of super-glue on the cut?

@vadimbellous8313

5 жыл бұрын

@@gordonwedman3179 That's exactly what they are. I fixed a few of them before using micro rubber bands that orthodontists use for braces. I had to find the high-quality ones that are not from China because the Chinese ones were irregular shaped and I'm sure inferior material. With some double tweezer work and a lot of patients they can be maneuvered into place plus the rubber is so durable that you can stretch it out to make it thin and slip it down the bottom

Thanks Shariar, excellent video. As usual, I have generally no idea what all this High Frequency stuff is about, but I find these videos fascinating, absorbing, and I actually do get some useful tips on general fault finding techniques that can be applied for us mere mortals :-). Many thanks... look forward to the next one...

Arent those washers at 16:00 just rubber o-rings so they absorb the impacts... would be easy to fit.

@vadimbellous8313

5 жыл бұрын

That's exactly what they are. I fixed a few of them before using micro rubber bands that orthodontists use for braces. I had to find the high-quality ones that are not from China because the Chinese ones were irregular shaped and I'm sure inferior material.

@jonka1

5 жыл бұрын

I agree but that would require taking the relay apart which he didn't want to do.

The best EE channel in youtube. You're great bro. Congrats!

Wow... what a lab!

Really interesting! These devices are like dark waters to me. They are so different from "ordinary" electronics. Thanks

Useful video 👍

Excellent video! Like many others I would have liked to have seen the repair - at least the outcome. I had just completed the repair of my much, much older HP 8657B Synthesized Signal Generator so I found this video particularly interesting. My generator also had an issue with the attenuator but was a bit more difficult to troubleshoot as it was not making contact on the "through" side. The output at 2 GHz looked almost correct but rolled off badly as the frequency was lowered - I suspect capacitive coupling through the almost closed contacts caused my confusion. It looked to me as if the body of the attenuator could be marked with a scribe and the solenoids/pushrods could be removed and reinstalled without any problem.

you can buy tiny O-rings....

Excellent video! It would be very interesting to see a tutorial about high frequency oscillators, talking 50GHz and above, I'm talking magnetrons, Gunn diodes etc

Check out the Dewalt DCF682N1 Gyroscopic screwdriver. It doesn't have the same kind of torque control but has some pre-set limits that seem to work just fine. At first I really thought it was going to be gimmicky but its actually pretty intuitive and has since become our favorite electric screwdriver.

The rings are off-the-shelf o-rings, you can get them in all shapes and sizes. Easy repair!

I charge a regular syringe with acidy sanitary silicone ... that bites super well into a lot of stuff ... never had issues with it corroding stuff but ... yeah - good ventilation while it dries doesn’t hurt

Shahriar, I just repaired an HP 8663A generator yesterday (1995 date code) with the exact same attenuator failure. There are tiny o-rings or rubber grommets that sit in a groove on those plastic pins. I used 5 minute epoxy to fill the gap left when the o-ring disintegrated. The o-rings obviously absorb shock when the selenoid switches. We should compare notes to see if epoxy or silicone lasts longer. I will also see if I can source those tiny o-rings so this can be repaired to OEM specs. So much for no user serviceable parts inside these attenuator assemblies...

Does the RPPU discriminate between reflected power and forward power? Or does it simply monitor the level at that point and shutdown if it exceeds a limit?

Which video has the teardown and analysis of attenuators like that?

If you were able to get the solenoids out it would be pretty trivial to get replacement orings. I can just about guarantee they are a standard size and readily available.

I've enjoyed every one of your videos, especially ones which allowed me to immediately fix an instrument. One concern however, is what happens to these repaired units, whether by you or other owners? I do not want to buy one off ebay that has had been bandaided (although your bandaid here is clever and great for an owner). I guess such is used equipment. Unless you buy from a company you know has had it in constant use until retirement, it's a crap shoot.

is the transmission line between the VR300 and VR301 works as an SWR that you talked AT 19:38

Great video,can I ask how much this cost and how much once repaired is it worth ,cheers

Would have been nice to see the actual repair.

Hi Shariar, I own a 4438c. It’s reverse power protection has been activated 4 times. I discovery that the problem is that when it’s set for a high output power the reverse power is activated by the signal generated. I’m trying to figure out a way to solve this issue. Maybe I will buy a new module. Do you know if it is possible to reset the counter of reverse power trips?

Metabo HPT DB3DL2 Seems to be the replacement model according to listing

Question. I was able to obtain a few of the Agilent E4433b, E4437B, E4438c signal generators from a local estate sale. I am working on the output board from the E4437b and I found at least 1 shorted HFET labeled "H1". What I came up with is that is actually a part number of the "H1" is actually an SHF-0189 from Sirenza Microdevices or RFMD. Since this is such a high failure part What is your opinion in replacing with the SHF-0189 with a SHF-0289. The spec sheets are easily found online. Thanks in advance.

Screwdriver: I have a Panasonic EY7410 which looks almost identical. I saw mikelectricstuff using a similar model as well. I believe it's a bit too heavy and powerful for such light work. A few years ago I bought a small Kawasaki K-AK for 10E but gave it away; it was OK for light work and had torque limiting.

If I'm not mistaken that VSA is made locally in Wichita by what used to be IFR Systems.

@duggerd

5 жыл бұрын

Usually the UK division (Marconi heritage) develops the cellular test gear like this and Wichita (IFR heritage) handles the LMR test gear.

My budget doesn't quite stretch that far... I tend to limit myself to about US$600 when buying broken gear to fix for my channel.

I would think those must be rubber o-rings. Too bad you did not show the result of gluing.

@Thesignalpath

5 жыл бұрын

I really didn't think it was all exciting to see a tiny blob of glue. :)

@shifter65

5 жыл бұрын

@@Thesignalpath Ah, how mistaken you are! I have watched Dave water sponges and regretted not a second of it.

Fwiw Hitachi shows a discontinued. The new brand names are in eu, hikoki or in us metabo htp not to be confused with metabo.

Could you make video of troubleshooting RS Fsiq26?

👍👍

Shahriar, could you help me out and tell me what tables your using to place your test instruments on? I'm setting up a lab and can't find a good size to use.

@Thesignalpath

5 жыл бұрын

They are from U-Haul.

@Drforbin941

5 жыл бұрын

@@Thesignalpath Hi, could you supply a link? I can't seem to find any reference to them.

@Drforbin941

5 жыл бұрын

@@Thesignalpath I looked on U-haul website and could not find anything. Any guidance?

@Thesignalpath

5 жыл бұрын

That is because I accidentally told you U-Haul! I meant to say U-Line! Sorry. Here is the link: www.uline.com/Grp_264/Packing-Tables

HI All, I am wanting to learn about QAM, I have found an Agilent E4433B ESG-D 250KHz to 4GHz with I/Q modual, I am playing with QAM over sound waves at 17Khz. Not knowing too much about this subject, hence wanting to learn, E4433B I/Q baseband can go from DC to 40 MHz. Would this be a good teaching tool for me and will it be useful for 17KhZ QAM? Thanks.

Pre Vid View comment. I'm here as much to see the electronic knowledge demonstrated as I am to see Pooch :) He better be here ! Also , I think I get to say "First"

Wait, so you're not gonna show you put the epoxy =o

A wall of money.

Nice video, but could you use less abbreviations (RPP, PLL, LO etc) so that a not so experienced person (like me) can easier follow your explanations. Nevertheless great video!

@BruceNitroxpro

5 жыл бұрын

Lars 0 1, I think he talks so fast that you wouldn't actually notice the difference! LOL

Instead of using glue I wonder if you could have used a 3D printer with a flexible filament to make some semi-circular rings to replace the old and cracked ones in the attenuator.

all that, and no repair shots..

Showed anything but the actual repair.