Test Equipment Anonymous (TEA) group therapy thread

[TERRA Operative]

Looks like the forum image bug is biting again.

Flare, when you post images, ignore the first slot and start uploading your images from the second slot. There's a bug in the forum software that messes up the images if you use the first upload slot.

[THDplusN_bad]

Switch Question :

I took apart that old TE below, a strange kind of RF gen., from the (60's looks like, though it's solid state inside somehow.

I salvaged all the switches from output step attenuator.

They look like beefy things, that would normally switch big mains loads but... since they are used to switch delicate RF signal, I fear they must be specialized in conveying RF signals, and are not capable, despite they big size, of safely switching mains with a high current ? 

There is no part number on them so I can't pull a datasheet for them. Only marking on them is at the back, it reads " KAY " , which appears to be the name of the manufacturer of that TE, if I believe the front panel of the instrument, located in Pine Brook New Jersey, US of A.

Wow, that's quite a beefy unit from a specialized company. Some information about the "Kay Electric company" can be found here:
http://waywiser.fas.harvard.edu/people/8990/kay-electric-company
The switches in the unit's step attenuator assembly are special as they have a special substrate. They also switch a resistor network as visible from your photos - but as the generator's max. frequency was 120 MHz and most likely the flatness specs for its output signal were not very good, the large geometries did not hurt back then. At least, that's my theory to it...

Cheers,

THDplusN_bad

[Flare]

Looks like the forum image bug is biting again.

Flare, when you post images, ignore the first slot and start uploading your images from the second slot. There's a bug in the forum software that messes up the images if you use the first upload slot.

Thanks, I was questioning my sanity.

[factory]

After I was announced this:


I got an email today announcing the delivery of my hp 5370B time interval counter to me today! 

...snip...

Full story here.

Shame the pictures & more than half the forum are hidden for non members and no I don't want to join another forum, don't have enough time to contribute to three I use.

David

Edit: Apologies to anyone that misunderstood this post, it was a general comment about the TEA forum and not aimed at anyone.

[Robert763]

Switch Question :

I took apart that old TE below, a strange kind of RF gen., from the (60's looks like, though it's solid state inside somehow.

I salvaged all the switches from output step attenuator.

They look like beefy things, that would normally switch big mains loads but... since they are used to switch delicate RF signal, I fear they must be specialized in conveying RF signals, and are not capable, despite they big size, of safely switching mains with a high current ? 

There is no part number on them so I can't pull a datasheet for them. Only marking on them is at the back, it reads " KAY " , which appears to be the name of the manufacturer of that TE, if I believe the front panel of the instrument, located in Pine Brook New Jersey, US of A.

Oh Vince,
Why did you do that? Those switches, resistors and housing made a very nice switched RF atttenuator and you broke it up 
Ok you might have had to cut out the section of front panel but it would have been worth it.
The generatoe was good for CW as wel as pulse. What coverage did it have? VHF at least but it looked multiband.

No, the switches are no good for power, just low level signals and RF. I looks like KAY bought standard tpggle mechanisms and put their own RF contacts and insulators on the back. You will have to check but they may ground a terminal to the bush in one position.

Robert.

[m k]

E,
due to hiccup the reply is moved to future.

[Vince]

Oh Vince,
Why did you do that? Those switches, resistors and housing made a very nice switched RF atttenuator and you broke it up 
Ok you might have had to cut out the section of front panel but it would have been worth it.
The generatoe was good for CW as wel as pulse. What coverage did it have? VHF at least but it looked multiband.

No, the switches are no good for power, just low level signals and RF. I looks like KAY bought standard tpggle mechanisms and put their own RF contacts and insulators on the back. You will have to check but they may ground a terminal to the bush in one position.

Robert.

Thanks THD and Robert for the replies. I shall make sure I don't mix these switches with the rest, and label them appropriately...

Robert I understand you are into RF so must have felt heartbroken.... I apologize for that 
But I am not into RF at all and never will be if just because it's a niche domain that will never fit my buying power.
So to me an attenuator had no practical interest... but switches being a general purpose kind of part, I saved them.
I am more into general "slow" electronics, where 100MHz is like TeraHertz for an RF guy...

To make it worse, and twist the knife in the wound, I would add that keeping the attenuator assembly in one piece would have been easy... no need to disc cut the cabinet... the attenuator just falls in your hand once you have just removed the retaining nut on all the switches, that's all...but removing those switches from the die cast alloy housing was actually very difficult and painful.

OK I will stop there.

Again I apologize for the pain I caused to your RF guy heart, I really do.  I hope I will somehow earn your pardon further down the line when I eventually do something good in the lab, one day, who knows... you just can't rule it out, never say never....

OK, now please excuse me but I need to go back to the bench to dismantle some more stuff.... no don't worry, no more TE... just random consumer junk friends have been giving me this week.
A flat TV, a coffee machine with an open circuit heating element and the manufacturer won't sell any parts so as to make sure you buy a new one rather than fix the old one, and some 2 wheel electric gizmo Segway style, and also an electric pruning shear. The latter I didn't even know existed... but there you go, I learned something. They managed to shove an electric motor and gearbox into the top handle, and the battery into the lower handle. I was stunned....

I did manage to fix something though. Friend who passed the coffee machine also gave to fix the 20 year old Philips stereo system of his old man. CD player would not work.. he got lucky, I had already fixed the same problem on the exact same stereo.... from my dad, 2 years ago. So took me only 2 minutes to establish the diagnosis (tired laser as always, need to replace the complete transport), and 2 hours instead of XXX to take it apart and fix it and put it all back together.

So this one will run for a few more years, I helped the environment, it's not gonna be an e-waste just yet...

See ? I can make good sometimes.... just sometimes 

[m k]

If you have a 3D printer, I made a 3D printable version that might help you out..

https://www.thingiverse.com/thing:3606417

Every now and then authentic spares are also available.
Unfortunately prices can also be pretty authentic.

[Neomys Sapiens]

I've bought an ANGENG SZ20 as a comfort purchase  , the level of TE drought is terrible, anyways someone around Mannheim with a reasonable calibrator who wants to do a quick check/characterization ?

Cheers,
DC1MC

For risk takers:
https://www.aliexpress.com/item/1005005201649970.html

I haven't made it to a 'reasonable  calibrator', but you could use my 'DMMcheck'.

[m k]

So you opened it.

Was it a regular pot on top of not so regular something?

I originally opened the back in situ in the hope I could repair it in place, as I'm pretty sure that the technically correct way to remove it is to remove that PCB, desolder the entire Horizontal timing assembly and then remove it from that. In the end there was just enough tolerance to get it out leaving the rest in place.
I've attached a picture of the insides, as you can see the crack fully separated. The wiper assembly actuates the switch on the rear which is inside the same casing. Also attached is a picture showing that due to it being switched, it doesn't have a regular track, the latched area of the switch is solid metal instead of carbon, for negligible resistance (I assume this is normal for switched pots).
If anyone has the service manual it would be great, I've just gotten the operating manual from Iwatsu Europe which I think I'll upload to Electrotanya as it's too large to host here.

Dang, I was hoping it's a two in one style but it's more like two thirds and three halves.

Maybe you'll be more vice if you mangle the rivet a bit and remove the switch part from the pot.
With luck you can swap the switch part from old to new, but that probably requires that both are from the same source.

Last change would be adding a switch circuit that recognizes the resistance.

Old Tek uses the style where end side is switching but I guess those are usually less packed and more stacked, and possibly not electrical.

[factory]

Not done much on my TE this weekend, been helping deal with woodworm eaten shelving in the workshop.

Got the Marconi signal generator setup again to test the 500MHz input boards in the two HP 5327B counters, they are both dead as expected, fuses check out OK, but the bias voltages are a problem on both units, I'm hoping this is dead RCA CA3046 trannystor arrays and not the custom ICs. The CA3046 is of course no longer made, but should be easier to obtain.

P.S. the Marconi TF2008 has another fault with the counter display, it shows a 002000 when the CW is switch off and some numbers don't light, I suspect another Nasty Semi display decoder IC is dieing. 


Two got replaced last time, one was completely dead, the other had a dim 7 lit all the time, still have three left.


P.S. Mouser order placed, including the parts for Vince.

David

[m k]

But since you're now internationally recognized nasty semi IC maker it's just few rotations and done.

E,
no hiccups.

[factory]

OK, now please excuse me but I need to go back to the bench to dismantle some more stuff.... no don't worry, no more TE... just random consumer junk friends have been giving me this week.
A flat TV, a coffee machine with an open circuit heating element and the manufacturer won't sell any parts so as to make sure you buy a new one rather than fix the old one, and some 2 wheel electric gizmo Segway style, and also an electric pruning shear. The latter I didn't even know existed... but there you go, I learned something. They managed to shove an electric motor and gearbox into the top handle, and the battery into the lower handle. I was stunned....

I did manage to fix something though. Friend who passed the coffee machine also gave to fix the 20 year old Philips stereo system of his old man. CD player would not work.. he got lucky, I had already fixed the same problem on the exact same stereo.... from my dad, 2 years ago. So took me only 2 minutes to establish the diagnosis (tired laser as always, need to replace the complete transport), and 2 hours instead of XXX to take it apart and fix it and put it all back together.

So this one will run for a few more years, I helped the environment, it's not gonna be an e-waste just yet...

See ? I can make good sometimes.... just sometimes 

I wasn't aware that electric pruners existed either, until I was reminded of AVE in another thread recently, they look quite dangerous IMO, do not copy what he does with the DeWilt & a Li-Boom unless you like fire escaping everywhere, the Duracell Duraleak was of course a complete disappointment, as per usual.

As this was a bit OT, here is something more relevant for the page, not just any old HP 5340A, but number 00067, possibly (not confirmed) used by the project manager mentioned in the April 1973 HP journal.




David

[TERRA Operative]

Oh 5340 day! Did I miss it?....

@Factory, I probably have some parts if you need any to complete yours. I'm certain to have those two missing cards in the aluminium box, and maybe a HP logo too. 

[TERRA Operative]

Whoops, I did it again baby.

Just bought a Tek THS720P scope, paid roughtly US$120 for it, screen looks good but no accessories (I already have a bag and charger from my THS720STD anyway)

[DC1MC]

I've bought an ANGENG SZ20 as a comfort purchase  , the level of TE drought is terrible, anyways someone around Mannheim with a reasonable calibrator who wants to do a quick check/characterization ?

Cheers,
DC1MC

For risk takers:
https://www.aliexpress.com/item/1005005201649970.html

I haven't made it to a 'reasonable  calibrator', but you could use my 'DMMcheck'.

Is most welcome, as least for a basic check, but I'm really curios about linearity and the stuff that can be determined with a variable calibrator, I still remember the Chinese precision scales that were showing perfect values for known calibration weights.

 Cheers,
 DC1MC

[Flare]

So you opened it.

Was it a regular pot on top of not so regular something?

I originally opened the back in situ in the hope I could repair it in place, as I'm pretty sure that the technically correct way to remove it is to remove that PCB, desolder the entire Horizontal timing assembly and then remove it from that. In the end there was just enough tolerance to get it out leaving the rest in place.
I've attached a picture of the insides, as you can see the crack fully separated. The wiper assembly actuates the switch on the rear which is inside the same casing. Also attached is a picture showing that due to it being switched, it doesn't have a regular track, the latched area of the switch is solid metal instead of carbon, for negligible resistance (I assume this is normal for switched pots).
If anyone has the service manual it would be great, I've just gotten the operating manual from Iwatsu Europe which I think I'll upload to Electrotanya as it's too large to host here.

Dang, I was hoping it's a two in one style but it's more like two thirds and three halves.

Maybe you'll be more vice if you mangle the rivet a bit and remove the switch part from the pot.
With luck you can swap the switch part from old to new, but that probably requires that both are from the same source.

Last change would be adding a switch circuit that recognizes the resistance.

Old Tek uses the style where end side is switching but I guess those are usually less packed and more stacked, and possibly not electrical.

I'd thought of trying to re-rivet (with pliers) the switch actuating part onto another 50k pot. Like you say it would probably have to be the same design, and as it would just be a regular pot track I'm not sure the switch would hold it in zero resistance like the original.
I've thought about using a circuit to switch the LED, but I think that without a switch or detent on the pot it may be turned by the delay time knob as the shaft sits inside that shaft. I'll give it a test though thanks.

[M0HZH]

A rather rare Marconi 2026B Multisource Generator arrived in my lab last week. This is a fantastic beast, includes two low phase noise signal generators (2.51Ghz, -140 to +24dBm (!)) and a combiner, excellent for receiver or transmit amplifier IMD tests. Also has the OCXO option.



From my research these didn't really sell in the UK; there are some Marconi 2026B out there but they were mostly sold in the US as IFR 2026B. The unit has some hand written notes inside on various modules, there's additional wiring inside, unit serial number in software is ..00001 (but that can be changed I think). Possibly a development / evaluation unit that got out when Marconi closed down sites around the UK.

Came with 2 errors related to generator B which went away after running the self-calibration routine. I also calibrated the frequency against the GPS-aligned counter, but getting the ch. A output level right took a bit more time (so many calibration points); output level still has some variation after warming up so I might have to open it up.

Also, PSU makes some funny noises when cold so I should probably recap it soon. All in all, I'm very happy with it.

Anyone needs a Rohde & Schwarz SMPD that I never got to fix?

[AVGresponding]

THS710 can become a THS720 (I did this to mine), but not a THS720P, on the other side a THS710A/THS720A may be easily modified to become a THS720P. Nice trick with the C cells, I splurged 17EUR and got one "original" for mine.

 Cheers,
 DC1MC

Interesting, how's that then?

[TERRA Operative]

Here you go:

https://www.eevblog.com/forum/testgear/tek-ths720a-portable-scope-teardowndiscussion/msg1073777/#msg1073777

https://www.eevblog.com/forum/testgear/tek-ths720a-portable-scope-teardowndiscussion/msg1074016/#msg1074016

[Neomys Sapiens]

I've got another Megger probe delivered - but this time not as a spare for the Megger. I think that I can modify it to work as a data hold probe with the UDL44. It is not exactly the most elegant solution, but it should give me an idea whether I want to use this function more often or not.
For this, I need to cut the three-pole connector off and fit a banana plug to the probe tip line and connect the two switch lines to a 3.5mm tip/ring connector using a short pigtail.

[TERRA Operative]

So, got a delivery from PCBWay today.....

I needed some new faceplates for some of my TM500 modules and I thought I'd give their CNC service a go. All up they cost about US$45 a piece (I was sponsored for a youtube video so I paid nothing, full disclosure... )

They came out realllllyyyy nice. 

I got them machined in aluminium, then bead blasted and clear anodized. So far the DM502 is assembled as shown (I made a few inconsequential modifications to the 3D file if anyone else decides to get one made) and I'll assemble the SG504 and PG506 later.

Files will be uploaded to Tekwiki etc later.






Boy do I love well machined parts. 

[TERRA Operative]

In other news, I have figured out how to replace the isolated BNC jacks in the THS700 series portable scopes. Details (and a video of course) to come.

[srb1954]

So, got a delivery from PCBWay today.....

I needed some new faceplates for some of my TM500 modules and I thought I'd give their CNC service a go. All up they cost about US$45 a piece (I was sponsored for a youtube video so I paid nothing, full disclosure... )

They came out realllllyyyy nice. 

I got them machined in aluminium, then bead blasted and clear anodized. So far the DM502 is assembled as shown (I made a few inconsequential modifications to the 3D file if anyone else decides to get one made) and I'll assemble the SG504 and PG506 later.

Files will be uploaded to Tekwiki etc later.






Boy do I love well machined parts. 

Very nice outcome.

Did you get new versions of the printed face plates done as well or are they just the old versions?

I find that on many of my TM500 modules the red printing on the face plates has faded almost to the point of invisibility and it would be nice to have some process to restore or replace them.

[TERRA Operative]

I'm using the old faceplates for now. I haven't found a place that can do printed anodizing (but I haven't looked too hard...)
Maybe screenprinting could be used, or mylar stickers like in the later modules.

One day I might look into it, but one step at a time.   


In other news........ Got my THS720P delivered this morning. Seems to work perfectly and has the last firmware revision (I will have to put it through its paces on the leveled sinewave generator and AC and DC calibrators to see if it needs a run through the adjustment procedure).
It came with no accessories but has the original battery which is going through a series if charge/discharge cycles to see how much capacity is left, but I'll probably rebuild it with Ni-MH cells soon anyway.
It also has the usual broken battery door which I'll repair with JB Weld as I just did with the THS720STD I'm currently working on.

I have a new LCD on the way from China too. I think I'll end up putting it into the 720P, and taking the screen from the 720P to put in the 720STD.
That way the 720STD gets a working screen and the 720P gets the shiny new one as the 720P is gonna be the one I keep.