Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

[EC8010]

Not as far as I thought, then. You must have a museum; I can't imagine your dubbing suite uses the Marconi-Stille (after all, it doesn't have time code). I expect the quadruplex machine is used to transfer historical stuff and is probably a rentable facility for people with old material. Keeping that going must be a trial. Many years ago, I was in BBC Engineering, then I taught broadcast engineering, then I changed direction and designed instruments for measuring ionising radiation.

[bd139]

Mine is currently helping a friend get rid of her friend's ex-husband's stuff so I'm good until tomorrow .

Can I send mine over to help? For some reason she's being a grumpy PITA today.

Ha. No

[bd139]

Wow! I've just looked up Curta (having never previously heard of such a thing). Lovely. I can see why you would want one. It's a jewel. Many years ago, I turned down the offer of a Nagra SN for £250 https://www.cryptomuseum.com/covert/rec ... /index.htm. It's a beautiful thing, but £250 was an awful lot of money to me in 1995 and I just couldn't afford it.

Add in where the inventor was when he invented it, and the amazement grows.

I could afford one if I really wanted it, but somehow thinking and dreaming about geegaws can be as pleasurable as having a geegaw stuffed on a shelf. It is a variant of the old concept that a journey is (and arguably should be) more important than the destination.

P.S. clearly you need to visit TNMoC. It is a short journey from the Dunstable Downs Rally on May 17th

On TNMoC, a couple of interesting things...

Due to the success of the Bletchey Park trip I organised (pictured below), there is a huge amount of interest in going back for TNMoC so I'm going to run another trip to there probably in June. No not doing Dunstable at the same time - need a car for that and I don't have one. Actually bd140 has a car

Secondly, my middle one actually had a college trip to TNMoC on Wednesday. She absolutely loved it.

Upcoming stuff we're doing of interest perhaps: TNMoC, This Museum Is Not Obsolete, Kelvedon Hatch Secret Nuclear Bunker and trying to persuade someone I know to do a private tour of NPL in Teddington.

IMG_3490.jpeg

[bd139]

Edit: add a couple for tggzzz

Ooh, you tease, you.

I keep trying to buy a Curta, but my offers are rejected.

An Otis King is on farcebook. I said I'd buy it at the asking price, but no response. I believe that is par for the course on farcebook.

I haven't found a reasonably priced one yet. I suspect that will never change.

[tggzzz]

Secondly, my middle one actually had a college trip to TNMoC on Wednesday. She absolutely loved it.

Was there anything in particular (an exhibit, general atmosphere/attitude, ...) that she liked?

Upcoming stuff we're doing of interest perhaps: TNMoC, This Museum Is Not Obsolete, Kelvedon Hatch Secret Nuclear Bunker and trying to persuade someone I know to do a private tour of NPL in Teddington.

Having been there twice, I can recommend this secret bunker, designated as a regional seat of government. It contains lots of hard information, in the form of exhibits and contemporary posters (and is thus the antithesis of my pet hate, https://en.wikipedia.org/wiki/M_Shed ).
https://www.hackgreen.co.uk/
Worth seeing if you are doing other things in the area, but not worth making a long trip. I feel the same about "This Museum Is Not Obsolete".

[tggzzz]

Edit: add a couple for tggzzz

Ooh, you tease, you.

I keep trying to buy a Curta, but my offers are rejected.

An Otis King is on farcebook. I said I'd buy it at the asking price, but no response. I believe that is par for the course on farcebook.

I haven't found a reasonably priced one yet. I suspect that will never change.

Depends on your definition of "reasonable" and how long you are prepared to wait. I'm thrifty and patient

Otis Kings are an order of magnitude more reasonable than Curtas

[Zenith]

Having been there twice, I can recommend this secret bunker, designated as a regional seat of government. It contains lots of hard information, in the form of exhibits and contemporary posters (and is thus the antithesis of my pet hate, https://en.wikipedia.org/wiki/M_Shed ).
https://www.hackgreen.co.uk/
Worth seeing if you are doing other things in the area, but not worth making a long trip. I feel the same about "This Museum Is Not Obsolete".

Hack Green *Secret* Nuclear Bunker is well done and definitely worth seeing, but I agree that it's not worth a special long trip to see. There is a radio rally on the same site. It used to be held twice a year, spring and autumn. It was held in March this year, it's not clear whether they'll also hold it this autumn. I've been to it once and thought it was not as good as my local, fairly small ones; Weston-super-Mare, Newport and Chippenham. But if you were tempted to see the bunker and like radio rallies, it would be an idea to combine the two. There are a few other things to see in the general area, such as RAF Cosford.

[25 CPS]

I'm at home and the only picture on my phone is this which I took as a gag for some friends a few years ago. Head drum was 14400 RPM in NTSC land.

Edited to add: And a reel of quad tape.

[EC8010]

That reel in its box is heavy. I saw a mains extension lead wound on a 2" reel one day at Television Centre and empty 2" reels were also screwed to walls for hanging leads on. I liked both ideas, so I have a couple of (sawn-in-half) 2" reels on the lab walls for mains leads and two 2" reels each with a 4 x 13A socket bolted to them as extension leads.

Once upon a time I could have calculated the required quadruplex drum speed for 60Hz NTSC.

[MED6753]

You know what NTSC stood for?

"Never Twice the Same Color"

[EC8010]

Which referred to the problem of passing the signal through a vision mixer (for example) and reinserting the burst incorrectly. NTSC televisions needed a user-tweakable hue control.

Conversely, with PAL (Pale And Lurid) phase errors didn't disturb the hue but gently reduced saturation, so they didn't need that hue control. (PAL = Phase Alternate Line that inverted colour phase on alternate lines, but that tiny tweak made the signal wildly more complex.)

The French SECAM system was entirely different (System Entirely Contrary to the American Method) and used frequency modulation and sequential colour information, requiring one line of video memory (as did delay line PAL). The French system was properly called SystemE Couleur A Memoire. Probably with some accents that I can't type. It wasn't done because the French wanted something entirely different to the rosbifs, oh no, it was because with a large hilly country and low population density, frequency modulation was needed beacuse it was more resistant to multipath reception. But you can't pass SECAM through a vision mixer, so their studio centres were all PAL, then they transcoded to SECAM for transmission. The Russians adopted PAL because it prevented their citizens from watching colour pictures from neighbouring countries.

PAL was an improvement on NTSC largely down to Dr Bruch. No doubt he would have liked it to have been called the Bruch colour system, but he had to settle for his name being applied to Bruch blanking which is the complex sequence of blanking the colour burst differently on different fields and that leads to the eight field sequence. Once upon a time, I was extremely au fait with that. Dr Bruch was also responsible for German guided missiles in WWII having television cameras in their nose. The pilot of the launching aircraft would simultaneously fly their plane and the missile. Wow! But the (analogue) TV system was VHF and suffered from reflections just as the missile came close to the ground (where the target was), so it didn't work as well as hoped. Clever though, and done more successfully later.

[Robert]

I bought some items from a cuple of the recent PP auctions. Finaly got my mitts on them this week. Two are automatic tapping heads for the mill so not relevant here. The others two were a PYE low range decade box and a HW Sulivan 100:1 instrument transformer.

Pye-decade-2.jpg

Pye-decade-1.jpg

This is not as big as some and as Mr Fluke confirms, is working perfectly. Residual resistance is around 50 milliohms thanks to the PYE instrument switches.
The transformer is an odity for when Sulivn were owned by AVO . The connectors are MUSA and unfortuntly potted in place.

HWS-100-1-1.jpg

HWS-100-1-2.jpg

Anyone got any spare MUSA females? Or the old style U links that I can modify? They seem to be scarce on ebay. I can get new "metrology" grade ones from Canford Audio at abot £50 each and MOQ f 250 so wont be doing that. MUSA to BNC adaptors would be even better.

Robert.

[tggzzz]

What's so special about MUSA connectors? Could you replace those connectors with BNC bulkheads?

Did you visit Aunby or use a company to pack and send?

[EC8010]

Twenty five years ago I had MUSAs coming out of my ears, but I didn't know then what I know now, so I didn't bother keeping any. (Unlike crimp BNCs. MUSAs are reusable.) I believe the central pin is solid silver, so the scrappies like them, hence their poor survival rate. The integrity of the electrical connection would be much better than the BNCs I use on my screened measurements because the contacts are much longer, and that's probably why they are thought to be very good for metrology. Recommended on page 46 in here: https://shop.theiet.org/coaxial-elect-circuits.

Useless but possibly interesting geekery: MUSAs are the video equivalent of Post Office jacks (PO316). They could be assembled on a jack field at roughly the same density of PO316 and were used for the same reason; they allowed circuits to be quickly plugged up and broken down as circumstances required. They were developed at Post Office exchange Museum A, hence the name. At the time, the Post Office had a monopoly on telecommunications, so if a broadcaster wanted a temporary vision circuit, they hired it from the Post Office. There were some places that were highly likely to attract cameras and Outide Broadcast vehicles, so they were served by the London Coax (LoCo).

[Robert]

What's so special about MUSA connectors? Could you replace those connectors with BNC bulkheads?

Did you visit Aunby or use a company to pack and send?

EC8010 has covered MUSA advantages. They were designed specifically for switching elements on phased array radar antennas before being picked up by Telecoms etc. Some SDI digital video systems used them too.

I can't easily replace them with BNCs, or better TNCs because of the potting. I don't want to go digging into that if I can help it.

Robert.

[EC8010]

I have heard that phase array story too. I was told the origin of the MUSA shortly after I joined the BBC. I worked in Communications Department at the time and we dealt with all the London exchanges (including Museum A), so I wonder about the phased array story. The name ties in with the Post Office story better than the phased array story, but it would be nice to have incontrovertible proof either way. And yes, SDI went through MUSAs quite happily.

Don't blame you for not wanting to disturb that potting.

[Robert]

I have heard that phase array story too. I was told the origin of the MUSA shortly after I joined the BBC. I worked in Communications Department at the time and we dealt with all the London exchanges (including Museum A), so I wonder about the phased array story. The name ties in with the Post Office story better than the phased array story, but it would be nice to have incontrovertible proof either way. And yes, SDI went through MUSAs quite happily.

Don't blame you for not wanting to disturb that potting.

OK you sent me on chase for contempary information or at least with references.
There will always be a crossover because so much work was done by the GPO research labs on radio and radar as well as telegraph and telephone. They used common parts across all areas.
I was wrong in calling it radar, it's a DF or diversity HF radio system. I found a reference in this document:
https://vtda.org/pubs/BSTJ/vol19-1940/a ... -2-306.pdf see PDF pages 6 and 7. It accurately describes MUSA panels an the solid U jumpers.

There is also a IRE/IEEE paper Proc. IRE, vol. 25, no. 7 (avalable here : https://www.worldradiohistory.com/Archi ... 937-07.pdf ) That actually talks about "special jack strips" and patch cords.

So I think it really did start with radio and moved to telephones and video later. Coaxial (FDM) telephone systems didn't start until after the war.

[EC8010]

The description in the first document certainly fits a MUSA connector, although it's not definitive. The IRE document initially seemed to be at odds because it talks about 1" diameter copper pipe transmission lines (pp855). However, Figure 17 (pp863) has some leads that look suspiciously as if they have MUSA connectors at the end. It's a pity there's nothing absolutely definitive. However, it is documentation of the time whereas what I had was effectively hearsay. Looks like the Multiple Unit Steerable Array is the likely source of the MUSA connector, not MUSeum A.

Thanks for digging that out.

[Robert]

I found some modern MUSA patch bay links on ebay
www.ebay.co.uk/itm/236426841099
They were cheap enough to take a chance to see if they can be used as the basis of adaptors.

[EC8010]

MUSA jackfields occasionally turn up at radio rallies, along with Betacam machines.

[bd139]

Secondly, my middle one actually had a college trip to TNMoC on Wednesday. She absolutely loved it.

Was there anything in particular (an exhibit, general atmosphere/attitude, ...) that she liked?

Not a huge amount of comments made as that's just not her but there was a short discussion on the size and complexity of computers now versus then. And I caught her reading something after that discussion on early computer architecture as in how they worked at register/memory level. Quietly impressed. May have pulled a few strings in her mind.

Upcoming stuff we're doing of interest perhaps: TNMoC, This Museum Is Not Obsolete, Kelvedon Hatch Secret Nuclear Bunker and trying to persuade someone I know to do a private tour of NPL in Teddington.

Having been there twice, I can recommend this secret bunker, designated as a regional seat of government. It contains lots of hard information, in the form of exhibits and contemporary posters (and is thus the antithesis of my pet hate, https://en.wikipedia.org/wiki/M_Shed ).
https://www.hackgreen.co.uk/
Worth seeing if you are doing other things in the area, but not worth making a long trip. I feel the same about "This Museum Is Not Obsolete".

I may be going past that later in the year. Will dip in and have a look!

Yeah the trip I am organising to This Museum is Not Obsolete is combined with both the computer museum next door and a 10km walk

[tggzzz]

Quietly impressed. May have pulled a few strings in her mind.

And that is a prime indicator of a good establishment (of whatever kind). The lack is also why I vociferously dislike "my auntie had one but she gave it away" and "I wonder what that is" type places.

Contrariwise, if somewhere doesn't change your mind/mentality even a little bit, was it worth going there?

Yeah the trip I am organising to This Museum is Not Obsolete is combined with both the computer museum next door and a 10km walk

Report is expected and awaited

If it is good enough, then I may go there again. I haven't been to Kent for 30 years, and it appears to have changed for the better. For example, it seems there are food places it is worth a (short) trip to try.

[bd139]

Quietly impressed. May have pulled a few strings in her mind.

And that is a prime indicator of a good establishment (of whatever kind). The lack is also why I vociferously dislike "my auntie had one but she gave it away" and "I wonder what that is" type places.

Contrariwise, if somewhere doesn't change your mind/mentality even a little bit, was it worth going there?

Indeed.

Also to note, that is why we run this Meetup group. Been to a lot of disparate and very interesting things which have sparked a lot of new thoughts and ideas.

Yeah the trip I am organising to This Museum is Not Obsolete is combined with both the computer museum next door and a 10km walk

Report is expected and awaited

If it is good enough, then I may go there again. I haven't been to Kent for 30 years, and it appears to have changed for the better. For example, it seems there are food places it is worth a (short) trip to try.

Report will be provided.

I assume by that you're not referring to the largest Wetherspoons in the world?

----

Right off out with bd140 for the evening in Pimlico (she lives there at taxpayers expense ). I have been informed that this is mostly going to involve booing loudly at the Sunday night bluegrass band.

[tggzzz]

I assume by that you're not referring to the largest Wetherspoons in the world?

Daughter's first job was behind the bar at a local Wetherspoons. It financed her "Dad I've just bought a plane ticket to Australia for 6 months" trip, and she learned a lot, e.g. how to "control" sozzled men.

Anyway, nowhere's perfect. Doubly so "deown frm Lundn" places and social services overspill sumps.

These are bookmarked in case I ever go that way...
https://www.thewellingtonmargate.co.uk/
https://www.bottegacaruso.com/
https://www.divemargate.com/
https://www.morellisgelato.com/ Broadstairs, Whistable, Margate, Dubai, Tashkent, Dallas, Philippines, registered office in Finchley Rd. Seriously; seem to be channelling Del Boy.

[mansaxel]

Not as far as I thought, then. You must have a museum; I can't imagine your dubbing suite uses the Marconi-Stille (after all, it doesn't have time code). I expect the quadruplex machine is used to transfer historical stuff and is probably a rentable facility for people with old material. Keeping that going must be a trial. Many years ago, I was in BBC Engineering, then I taught broadcast engineering, then I changed direction and designed instruments for measuring ionising radiation.

Yes, in the museum. We're all file based these days . Still some 16mm black/white news footage to do, of course.