EMI 101 scope

[Andrewausfa]

Has anyone any information on an EMI 101 scope please? I've been offered one but can't find anything in it, vertical input but no sweep was the description. I suspect it may be the display/voltmeter service aid as on Jon Evans' site but no idea really.

Thanks - Andrew

[Radio Wrangler]

EMI's oscilloscope division used the name "SE labs" and you may find info under that name.

David

[Andrewausfa]

Thanks David, I'd already searched using 'SE Labs' finding just the '102'. I suppose I better go and pick it up and see what it actually is !

Andrew

[Radio Wrangler]

I had a search and I found only one other hit besides this thread. There was a photo.

It looks very early for SE labs, round tube, angled in the panel, very basic controls, and even SO239 sockets (ugh!) for signal and trigger connections.

EMI made a few boat anchor size valved scopes and I thought SE labs was floated as a brand for transistor based ones, but this could be either given the apparent age.

If you want a good scope for general use, I suspect this isn't it. But if you're looking for something rare, then you've hit one.

David

[glowinganode]

Hi Andy, I think the scope you describe pre-dates SE Labs by 10 years or so.
If you have the offer of one I'd take it as these are not particularly common. Certainly I've never seen one for sale.
Try Luke (mendipviews) over on VRATS, I think he had one a year or so back.
Cheers, Rob.

[Andrewausfa]

Hi Rob, David,

Thanks for the advice, I'll be grabbing it tomorrow after which I'll post some photos of it for future reference.

Thanks _ Andrew

[WME_bill]

EMI 101 scope. Introduced by EMI in 1965/66, priced at £170. They also sold the design to Marconi, who marketed it as the TF2203. A nice portable single beam 15Mhz scope.
Uses a 3 inch EMI tube MX54 which I have never otherwise come upon, but appears very similar indeed to the Sylvania-Thorn SE3A. Uses a number of the uncommon early germanium high frequency surface barrier transistors MDS40. Nearest similar is the Ge drift types such as AF106. A very standard circuit.
The other EMI scope one sees is the EM102, dual beam 30Mhz. EMI took over SE Laboratories much later, in 1966, and marketed their scopes under the SE Labs name. The SM111 (also Marconi TF2204) was a very successful scope, (CT570), and the SM112 100Mhz, much less successful. A high brightness version of the SM111 was the SM113. All about 1971. Product line closed down in 1977.
I will be interested to hear how you find the EMI101. I have information/manuals upon all these models wme-bill M0wpn

[Andrewausfa]

As mentioned here's some photos of the EMI 101 oscilloscope. I wasn't sure what to expect maybe something a little larger but it's roughly the size of an Advance E2 signal generator. The tube has a label on it which says July 1967 so it's not much younger than me. Bill, thanks very much for your information as always.

Externally all the bits are there which is good news. The chap I got it from wasn't there to hand it over but he's said it there's no sweep and the transformer gets very hot after a few minutes. Internally, on first inspection it's been played with a little but not too much, just a few C & Rs. I need to go through the circuit diagram (I've got the TF2203 version from the BAMA site), particularly as it's my first 'scope repair and check everything is there and connected where it should be. I note there's a daisy chain of capacitors and a wire has come adrift of the large 25V electrolytic near the tube. I'm fairly certain I'll be begging for some help and advice on this project in coming days.

I've not applied power yet as obviously the first thing to check over is the power supply.

Andrew

[Andrewausfa]

A few more

[af024]

My word, someone else who had got one of these. Mine had been very lonely until I told it that it now has a mate.

These run of 12Vd.c. too .. that'll the banana connectors at the rear of course.

Now somewhere (goodness knows where) I have some service information for them. It might take me a little while to do a search around the place, but I'll try to come back to you as soon as I can. Even if I scan in just the circuit that should help, no?

I hope it's the same model after all this now. It certainly looks like it from memory though.

Regards,

Andy
PS I seem to remember a little squeal noise (quite normal) upon switch on. There's some sort of neon stabilisation going on too I think.

[af024]

Bingo! It IS an EMI 101 and I DO have the service information. I'll try to scan some of it in for you. If it gets too huge to post here, drop me a PM and I'll have a go at emailing it to you.

Best of luck,

Andy

[af024]

Hello Andew,

I've done the whole thing and it's rather large - nearly 74MB, so it looks like a CD in the post job.

Here is a small taster ...

[Andrewausfa]

Andy,

Thanks for doing this, from the page count it seems to offer much more detail than the 26 page Marconi manual. I will PM you.

I woke up very early this morning so thought what better way to start the day than to do a bit of soldering and give the scope some volts. The trace came up and the transformer(s) didn't seem to be getting hot at all. I'd assumed the previous owner meant the large transformer but there is a smaller one as well. There's no sweep though. Undoubtedly more reports and questions will follow.

Regards - Andrew

[af024]

Last time I ran mine, I seem to remember that the smaller transformer go rater warm. Probably quite normal.

The manual seems to have some mods listed at the start, so I guess that'll need reading in conjunction with the main offering.

CD-ROM on its way.

Best of luck Andrew, a good start by the sound of it.

Regards,

Andy

[WME_bill]

EMI 101 or Marconi TF2203. It is very odd. I have copies of both the EMI and the Marconi versions of the manual. They are identical in content. The size as scanned is between 8.2 and 10.7 Mb. So what has given you that huge file of 74Mb is a puzzle.
The EHT transformer & circuit was slightly modified later. Also the Y bandwidth increased to 20Mhz from 15Mhz.
If the timebase doesn't trigger, then suspect the 5ma tunnel diode D16, a 1N3716. But do not try using an ohm-meter to test it, for that will destroy it. They are no longer made. You will have to pirate from another scope or timebase Plug-in of the the same period: Tek, HP, Dynamco, Solartron. Not Telequipment, SE Labs. Type number doesn't matter, but the 5ma rating does. I have notes upon how to test them, extracted from Wireless World, March 1965, which I attach. Delightfully simple, but uses another scope.
Also the 1965 Marconi Catalogue description, so you know what you have got. wme_Bill

[Andrewausfa]

Andy, thanks for the CD it arrived today. Excellent thank you. Time for some reading.

Thanks for the advice and pdfs Bill. I have another scope or three so will check the tunnel diode after reading the instructions you kindly attached. I can't guarantee anyone else hasn't tried to test this diode!

I've had the scope powered on for a little longer a couple of times. After switch on the +6.3 test point on the power supply board reads 6.6V, the +40v TP reads 43V and remains stable for a few minutes. At around five minutes my centered spot on the CRT starts shrinking, starts a slow descent and disappears, at the same time the 6.3V TP goes to 3V (CRT heater supply?) and the 40V TP heads down to 37V. The transfomer gets quite hot.

I've switched off pronto both times but once the transformer cools the CRT seems fine again.

Andrew

[af024]

You are very welcome Andrew, I am pleased that it has arrived all safe and sound.

The size might simply be down to the resolution that I chose whilst manually scanning, plus the number of A4 scans I did per pull-out circuit (just to make sure that there was good overlap), so I wouldn't read too much into that (unless of course there is genuinely some extra information in there).

Best of luck now.

Regards,

Andy