Test Equipment Anonymous

Posted: **Sun Oct 01, 2023 4:11 am**

Well, you guys have motivated me to get cracking on this thing again. My failed RTV dams are visible here (the moveable foot is on the bench; took it off for the evaporust soak)

My laziness last week paid off - meant to put this laundry detergent container out with the recycling and didn't; it's a good size to let this thing soak.

Coaxed the boiler into operation and filled it with #2 fuel oil from the pump bleed valve. Took some juggling to get as much as possible from the bleeder without extinguishing the burner - there's a fine line betwixt barely anything coming out and no fire.

Now to cover it and forget it's there for a few months...

-Pat

Posted: **Sun Oct 01, 2023 6:45 am**

Cubdriver wrote: ↑Sun Oct 01, 2023 4:11 am Well, you guys have motivated me to get cracking on this thing again.

Very nice! Happy to help with triggering actions.

I found this marketing film while googling. Full of the period style language, a fair dollop of "benevolent misogyny" ("You can come here, be employed, perform some parts of the work, but don't expect to be treated equal, just as a peculiar resource") and lots of boasting. But if viewed critically still an interesting document.

Posted: **Thu Oct 05, 2023 6:38 pm**

The car stereo ended up being the inadvertent test equipment for this one.

I was driving to work on Tuesday morning and listening to music streamed from my phone to an aftermarkert Carplay device on the dashboard of my truck which RF modulates it onto an unused FM frequency in the area. The quality isn't the greatest but the truck's stereo doesn't have any kind of USB or line in so that's all there is to work with. Everything was working fine until this nasty cycle of repeating interference started up while I was about three quarters of the way in on the highway and it followed the same rotating pattern.

Eventually I noticed this service truck with a big idiotic amber and white light bar flashing away for no reason while he was driving along in one of the other lanes had the same pattern but it was out of phase so the interference was only present when the LEDs in the light bar were off. The controller or it's power supply was blasting off RF garbage into the surrounding area when unloaded.

The confirmation came when the various lanes on the highway moved at different speeds and the gap between the truck with the absolutely stupid lightbar on the top and mine varied and the strength of the interference with it. I was surprised how much interference this thing was throwing off. Unreal.

Posted: **Thu Oct 05, 2023 9:22 pm**

It reminds me of a story I heard when discussing problem solving.

There was an office where the computer died every Friday afternoon at 4:30pm. I recall it was a PDP11. DEC engineers came out and could find nothing wrong, but it died at 4:30pm on a Friday when they were there. After it rebooted and ran without hitch.

The office was in a port. The master problem solver appeared on the scene and realised it corresponded with the arrival of a ship, every Friday afternoon. The ship had a particularly powerful radar, and the signals were bouncing off a filing cabinet, hitting the computer and causing it to die. The solution was to move the filing cabinet.

Dunno. It could be true.

Posted: **Thu Oct 05, 2023 9:44 pm**

Never forget: http://catb.org/jargon/html/magic-story.html

mnem
"When in doubt, dike it out!" ~old man Kirsch

Posted: **Thu Oct 05, 2023 11:52 pm**

25 CPS wrote: ↑Thu Oct 05, 2023 6:38 pm The car stereo ended up being the inadvertent test equipment for this one.

I was driving to work on Tuesday morning and listening to music streamed from my phone to an aftermarkert Carplay device on the dashboard of my truck which RF modulates it onto an unused FM frequency in the area. The quality isn't the greatest but the truck's stereo doesn't have any kind of USB or line in so that's all there is to work with. Everything was working fine until this nasty cycle of repeating interference started up while I was about three quarters of the way in on the highway and it followed the same rotating pattern.

Eventually I noticed this service truck with a big idiotic amber and white light bar flashing away for no reason while he was driving along in one of the other lanes had the same pattern but it was out of phase so the interference was only present when the LEDs in the light bar were off. The controller or it's power supply was blasting off RF garbage into the surrounding area when unloaded.

The confirmation came when the various lanes on the highway moved at different speeds and the gap between the truck with the absolutely stupid lightbar on the top and mine varied and the strength of the interference with it. I was surprised how much interference this thing was throwing off. Unreal.

Yep some are really bad. Our Larry Minor uses them on his digger and tractor and some are so bad you can't use radio muffs nearby.
But many are awakening to this and only buy/fit those that are verified/guaranteed low RFI.

Posted: **Fri Oct 06, 2023 4:50 am**

Cubdriver wrote: ↑Sun Oct 01, 2023 4:11 am Well, you guys have motivated me to get cracking on this thing again.

Mine just arrived. Turns freely, all parts present, could do with a bit of a clean and some paint, but in essence would work if bolted to the bench right now. A bargain.

Posted: **Fri Oct 06, 2023 2:13 pm**

Any of the tube-lickers here want this? Rescued it from work today:

toob.jpg

It's an ITT 16STE L102/2K regulator. The filaments measure just over 68 and 69 ohms respectively. The pins are a bit bent, I'm not going to risk trying to bend them back. Appears to be NOS from 1974 (pins show no sign of insertion marks).

Posted: **Fri Oct 06, 2023 6:18 pm**

Umm a Barretter. You don't see a lot of those these days.
I do know of one current application. It's in the ignition circuit of some Pratt & Whitney Canada PT6A turboprop engines. These have glow plugs rather then the more common high energy discharge system. Each of the two glowplugs is in series with two large barretters in parallel. PWC call the ballasts. They allow fast heating of the glow plugs regardless of ambient temperature. The glow plugs look like an old fashoned car electric cigarette lighter elements.
https://www.aviationpros.com/home/artic ... 6-ignition

Robert.

Posted: **Mon Oct 09, 2023 11:45 am**

Latest project? Might be. Thinking it over. It's a 150 mile (240km) round trip.

https://newjersey.craigslist.org/ele/d/ ... 65817.html

Posted: **Mon Oct 09, 2023 2:59 pm**

Go for it, Mike - that’s a cute little scope!

-Pat

Posted: **Mon Oct 09, 2023 3:06 pm**

Does anyone here owns a Philips/Fluke PM2525 multimeter?

I had a strange current ranging effect and just before opening it I found the fuse with 630mA to be blown. Of course the meter works again after replacing the fuse, but the manual states, that all ranges (not the high current ranges 1A and 10A with the separate input) are protected by that fuse against 250Vrms input voltage. As the smaller ranges were just fine, there is a chance either the manual is wrong or someone has been in before.
The input resistance of the lowest ranges is abt. 100R, but works even without fuse. According to the principle of operation , it is a I-V converter with an Opamp and a feedback resistor. I can confirm that the 100R are not "real", as they disappear when powering the meter down. I have my doubts that Opamp will withstand 250Vrms at its input...

Posted: **Mon Oct 09, 2023 3:09 pm**

Cubdriver wrote: ↑Mon Oct 09, 2023 2:59 pm Go for it, Mike - that’s a cute little scope!

-Pat

It's the same footprint as my Type 503 which is slightly smaller than the Type 535/545/547/etc.

Still mulling it over. He is including a nice stash of probes.

Posted: **Mon Oct 09, 2023 6:34 pm**

dl6lr wrote: ↑Mon Oct 09, 2023 3:06 pm Does anyone here owns a Philips/Fluke PM2525 multimeter?

I had a strange current ranging effect and just before opening it I found the fuse with 630mA to be blown. Of course the meter works again after replacing the fuse, but the manual states, that all ranges (not the high current ranges 1A and 10A with the separate input) are protected by that fuse against 250Vrms input voltage. As the smaller ranges were just fine, there is a chance either the manual is wrong or someone has been in before.
The input resistance of the lowest ranges is abt. 100R, but works even without fuse. According to the principle of operation , it is a I-V converter with an Opamp and a feedback resistor. I can confirm that the 100R are not "real", as they disappear when powering the meter down. I have my doubts that Opamp will withstand 250Vrms at its input...

The 2525 has that motorised range switch. I can't provide comparison measurements as I only have a 2503 and 2521 in my weird Philips section...

Posted: **Mon Oct 09, 2023 7:09 pm**

MED6753 wrote: ↑Mon Oct 09, 2023 3:09 pm
Cubdriver wrote: ↑Mon Oct 09, 2023 2:59 pm Go for it, Mike - that’s a cute little scope!

-Pat
It's the same footprint as my Type 503 which is slightly smaller than the Type 535/545/547/etc.

Still mulling it over. He is including a nice stash of probes.

That's a nice package deal with the scope, the probes, and the scope shown in pretty much working condition. The vertical amplifiers are passing signals and the timebase is functioning along with the CRT and the high voltage so it's not like you'd be travelling only to encounter something that's a totally DOA turd like that disgusting 575 curve tracer I said no thanks to last summer. If you can roll one or two other things into the trip and make that drive worthwhile, go for it!

On a totally unrelated note, happy Thanksgiving to the Canadians who hang out here.

Posted: **Tue Oct 10, 2023 3:43 pm**

AVGresponding wrote: ↑Mon Oct 09, 2023 6:34 pm The 2525 has that motorised range switch. I can't provide comparison measurements as I only have a 2503 and 2521 in my weird Philips section...

Thanks, that helped me a lot

The service manual for the 2521 has a more detailed circuit diagram of the I-V converter in Fig. 25. I suspect it to be quite similar to the PM2525, as they share almost the same ranges and specs despite the manual vs. motorized knob. It has no fuse in front of the I-V converter, so this could be identical to my PM2525.

Posted: **Tue Oct 10, 2023 5:20 pm**

dl6lr wrote: ↑Tue Oct 10, 2023 3:43 pm
AVGresponding wrote: ↑Mon Oct 09, 2023 6:34 pm The 2525 has that motorised range switch. I can't provide comparison measurements as I only have a 2503 and 2521 in my weird Philips section...
Thanks, that helped me a lot The service manual for the 2521 has a more detailed circuit diagram of the I-V converter in Fig. 25. I suspect it to be quite similar to the PM2525, as they share almost the same ranges and specs despite the manual vs. motorized knob. It has no fuse in front of the I-V converter, so this could be identical to my PM2525.

It does appear to be protected by a MOV/NTC resistor though. The schematic is a bit all over the place...

Posted: **Tue Oct 10, 2023 7:04 pm**

AVGresponding wrote: ↑Tue Oct 10, 2023 5:20 pm It does appear to be protected by a MOV/NTC resistor though. The schematic is a bit all over the place...

NTC? I suspect R221 is a PTC. In combination with the Zeners at the output of the Opamp it will limit the current. Quite interesting they use a PTC in the feedback loop of the Opamp, as this resistor defines the I-V ratio. And then they protect the ADC input to the +/-10V by clamping it to the power supply with V207..V210.

Posted: **Wed Oct 11, 2023 4:46 pm**

Displaytube rapist and TE destroyer in UK trying to sell of kit he hasn't wrecked yet:
https://www.ebay.co.uk/itm/115939571612?
Even then he is cheating by listing the collection at a silly price and then offering individual items for collection...

Posted: **Wed Oct 11, 2023 6:06 pm**

dl6lr wrote: ↑Tue Oct 10, 2023 7:04 pm
AVGresponding wrote: ↑Tue Oct 10, 2023 5:20 pm It does appear to be protected by a MOV/NTC resistor though. The schematic is a bit all over the place...
NTC? I suspect R221 is a PTC. In combination with the Zeners at the output of the Opamp it will limit the current. Quite interesting they use a PTC in the feedback loop of the Opamp, as this resistor defines the I-V ratio. And then they protect the ADC input to the +/-10V by clamping it to the power supply with V207..V210.

R223 has to be an NTC/MOV, given its placement.

Is Discord down for anyone else?

Posted: **Wed Oct 11, 2023 7:06 pm**

AVGresponding wrote: ↑Wed Oct 11, 2023 6:06 pm R223 has to be an NTC/MOV, given its placement.

Is Discord down for anyone else?

Hmm, I don't think R223 is a NTC either. Both have the same symbol with +Theta, I would expect -Theta for an NTC. And if its an NTC/MOV, the traces to it will explode with powerful +250Vrms fed into it.

Posted: **Wed Oct 11, 2023 7:19 pm**

Robert wrote: ↑Wed Oct 11, 2023 4:46 pm Displaytube rapist and TE destroyer in UK trying to sell of kit he hasn't wrecked yet:
https://www.ebay.co.uk/itm/115939571612?
Even then he is cheating by listing the collection at a silly price and then offering individual items for collection...

Wonder what he would ask/get at a hamfest

Posted: **Wed Oct 11, 2023 8:01 pm**

A good swift kick in the balls if there were any justice in this world...

mnem
so-o-o-o-o-o tired...

Posted: **Wed Oct 11, 2023 8:08 pm**

Dad is home. Entire last week has been a series of one "get this, fix that, install the other" task after another.

He's in good spirits.

Hopefully this time with the correct hip immobilizer prosthetic (as opposed to the first two go-rounds with a leg splint cuz cheaper

) will result in him healing properly and back to his normal state of "getting around better than me".

mnem
dinnertime...

Posted: **Wed Oct 11, 2023 9:51 pm**

Fingers crossed. Now if you can just get him to stop trying to pick things up off the floor for the time being…

Test Equipment Anonymous

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