Labgear "Viewing Unit" - UK Vintage Radio Repair and Restoration Discussion Forum

buggies · 24th Oct 2017, 2:28 pm

Old Labgear "Viewing Unit" about 12.5 deep x 6.5 wide x 5.5 high.
No timebase or Y amplifier just a U16 2 volt valve rectifier with EHT about 1kv.
Y sensitivity is stated as 1.5 volt per mm.

The sweep is simply the live mains connected to the HOR input terminal via a 0.1mF capacitor. This produces a sweep sufficient to overscan.

Images show the front panel, side views and crt etc
There are 5 x 0.1 mF 450v capacitors which are leaking. My question is should I just replace with modern types naked or stuff them in the original cases?

buggies · 24th Oct 2017, 2:34 pm

Forgot to mention, there is a typed instruction manual which helpfully warns about the mains appearing on the front panel terminal when 50 c/s sweep selected!

HamishBoxer · 24th Oct 2017, 4:26 pm

Well I love it! And as I have not seen one before I would re stuff or at the very least keep the old caps having changed them.

M0FYA Andy · 24th Oct 2017, 4:32 pm

I agree, try to keep it looking original. But I'm aware there are many on here who will disagree and say simply use modern parts. There's no definitive answer!
Andy

G6Tanuki · 24th Oct 2017, 4:57 pm

That's rather nice: I recall something similar being used by a G3-plus-2-letter ham of my acquaintance back in the 1960s, to produce a #'trapezium' display of his AM modulation-envelope.

1100 man · 24th Oct 2017, 9:54 pm

Interesting unit!
I did smile at the instructions though. "Now, what precautions are we going to take to prevent the user being zapped with 700 Volts on the front panel terminals? I know: we'll just tell them not to touch it, that'll work!!"

Cheers
Nick

dseymo1 · 24th Oct 2017, 10:26 pm

When fully-fledged scopes were very expensive, this would still provide a lot of information about what was going on, presumably at a much lower price. Just as a high impedence voltmeter it would be pretty handy. As they say, it could later be extended with a proper timebase (and Y amp, I suppose). I wonder if they sold a suitable TB, or just expected that anyone with a use for one could design and build their own?

M0FYA Andy · 25th Oct 2017, 8:55 am

Quote:

Originally Posted by 1100 man

I did smile at the instructions though. "Now, what precautions are we going to take to prevent the user being zapped with 700 Volts on the front panel terminals? I know: we'll just tell them not to touch it, that'll work!!"

In the past that would have been quite sufficient, when common-sense was err..... common!
Andy

buggies · 25th Oct 2017, 3:47 pm

Thanks for all the replies - I will stuff the new caps inside the original cardboard sleeves. Not sure if there will be sufficient old tar to use to seal the ends but I suppose beeswax would do?

I think the unit was probably produced in the late 40s as Labgear apparently liquidated in 1951 (according to google) and their name taken was by Philex.

I obtained it from Harry, GM2TW around 1980. He probably did use it for modulation setting as described in the instruction manual. I used a couple of signal transformers to step up the voltage from a teleprinter two tone filter. Each tone was applied to the respective X/Y input to obtain a cross display to aid tuning on HF.

There is a bulgin 5A plug (male pins) behind a plate on the rear panel which is connected to the switched live. The flexible wiring is all white pvc and I suspect this may have replaced rubber covered wires at some point so the wiring may not be correct. The mains cable was rubber and completely rigid.

Rough sketch of circuit attached - I will redraw in Orcad when I have made some components and checked values and connections.
The scanned instruction manual (7 pages) as a pdf file is too large to attach but should be available here:-
https://www.dropbox.com/s/6xm9w6ose7w47x7/instruct.pdf

Refugee · 25th Oct 2017, 11:33 pm

That mains lead looks awful.
I bet the plug is still all right though.

CambridgeWorks · 26th Oct 2017, 6:24 pm

Surely Labgear were still going in the 1960s, maybe even 70s? Thinking of loads of amateur radio gear from the 60s. LG300, Low pass filters, mains filters, tv test gear etc.and I have a 160M tx by them.
Looks a nice, simple piece of kit though.
Rob

Andrewausfa · 26th Oct 2017, 7:00 pm

Pye bought them in 1951. Still going today. Still making TV aerials.

I looked into them, as a local firm, when I saw a Radio Fault Locator unit they did. Their former home Willow Place has gone I was interested to find out where exactly it was. Under what is the Grafton Centre now!

Andrew

Radio Wrangler · 26th Oct 2017, 8:46 pm

wasn't there a name associated with Labgear.... Sant Karbana or something like that?

David

ms660 · 26th Oct 2017, 8:54 pm

Sant Kharbanda, was the technical director at some point apparently.

Lawrence.

G6Tanuki · 26th Oct 2017, 9:16 pm

Yep: he held the callsign G2PU. A quick search shows he had at least one TV-related patent in his name: https://patentimages.storage.googlea.../US2550821.pdf

Seems he died in January 2000.

24th Oct 2017, 2:28 pm	#1
buggies Heptode Join Date: Jan 2009 Location: West Lothian, UK. Posts: 761	Labgear "Viewing Unit" Old Labgear "Viewing Unit" about 12.5 deep x 6.5 wide x 5.5 high. No timebase or Y amplifier just a U16 2 volt valve rectifier with EHT about 1kv. Y sensitivity is stated as 1.5 volt per mm. The sweep is simply the live mains connected to the HOR input terminal via a 0.1mF capacitor. This produces a sweep sufficient to overscan. Images show the front panel, side views and crt etc There are 5 x 0.1 mF 450v capacitors which are leaking. My question is should I just replace with modern types naked or stuff them in the original cases? Attached Thumbnails __________________ George

24th Oct 2017, 2:34 pm	#2
buggies Heptode Join Date: Jan 2009 Location: West Lothian, UK. Posts: 761	Re: Labgear "Viewing Unit" Forgot to mention, there is a typed instruction manual which helpfully warns about the mains appearing on the front panel terminal when 50 c/s sweep selected! Attached Thumbnails __________________ George

24th Oct 2017, 4:26 pm	#3
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: Labgear "Viewing Unit" Well I love it! And as I have not seen one before I would re stuff or at the very least keep the old caps having changed them. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

24th Oct 2017, 4:32 pm	#4
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: Labgear "Viewing Unit" I agree, try to keep it looking original. But I'm aware there are many on here who will disagree and say simply use modern parts. There's no definitive answer! Andy

24th Oct 2017, 4:57 pm	#5
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Labgear "Viewing Unit" That's rather nice: I recall something similar being used by a G3-plus-2-letter ham of my acquaintance back in the 1960s, to produce a #'trapezium' display of his AM modulation-envelope.

24th Oct 2017, 9:54 pm	#6
1100 man Octode Join Date: Apr 2016 Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK. Posts: 1,377	Re: Labgear "Viewing Unit" Interesting unit! I did smile at the instructions though. "Now, what precautions are we going to take to prevent the user being zapped with 700 Volts on the front panel terminals? I know: we'll just tell them not to touch it, that'll work!!" Cheers Nick

24th Oct 2017, 10:26 pm	#7
dseymo1 Retired Dormant Member Join Date: Dec 2007 Location: Shropshire, UK. Posts: 3,051	Re: Labgear "Viewing Unit" When fully-fledged scopes were very expensive, this would still provide a lot of information about what was going on, presumably at a much lower price. Just as a high impedence voltmeter it would be pretty handy. As they say, it could later be extended with a proper timebase (and Y amp, I suppose). I wonder if they sold a suitable TB, or just expected that anyone with a use for one could design and build their own?

25th Oct 2017, 3:47 pm	#9
buggies Heptode Join Date: Jan 2009 Location: West Lothian, UK. Posts: 761	Re: Labgear "Viewing Unit" Thanks for all the replies - I will stuff the new caps inside the original cardboard sleeves. Not sure if there will be sufficient old tar to use to seal the ends but I suppose beeswax would do? I think the unit was probably produced in the late 40s as Labgear apparently liquidated in 1951 (according to google) and their name taken was by Philex. I obtained it from Harry, GM2TW around 1980. He probably did use it for modulation setting as described in the instruction manual. I used a couple of signal transformers to step up the voltage from a teleprinter two tone filter. Each tone was applied to the respective X/Y input to obtain a cross display to aid tuning on HF. There is a bulgin 5A plug (male pins) behind a plate on the rear panel which is connected to the switched live. The flexible wiring is all white pvc and I suspect this may have replaced rubber covered wires at some point so the wiring may not be correct. The mains cable was rubber and completely rigid. Rough sketch of circuit attached - I will redraw in Orcad when I have made some components and checked values and connections. The scanned instruction manual (7 pages) as a pdf file is too large to attach but should be available here:- https://www.dropbox.com/s/6xm9w6ose7w47x7/instruct.pdf Attached Thumbnails __________________ George

25th Oct 2017, 11:33 pm	#10
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,553	Re: Labgear "Viewing Unit" That mains lead looks awful. I bet the plug is still all right though.

26th Oct 2017, 6:24 pm	#11
CambridgeWorks Nonode Join Date: Jun 2010 Location: Spalding, Peterborough, Cambridgeshire, UK. Posts: 2,859	Re: Labgear "Viewing Unit" Surely Labgear were still going in the 1960s, maybe even 70s? Thinking of loads of amateur radio gear from the 60s. LG300, Low pass filters, mains filters, tv test gear etc.and I have a 160M tx by them. Looks a nice, simple piece of kit though. Rob __________________ Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd

26th Oct 2017, 7:00 pm	#12
Andrewausfa Octode Join Date: Dec 2010 Location: St Ives, Cambridgeshire, UK. Posts: 1,180	Re: Labgear "Viewing Unit" Pye bought them in 1951. Still going today. Still making TV aerials. I looked into them, as a local firm, when I saw a Radio Fault Locator unit they did. Their former home Willow Place has gone I was interested to find out where exactly it was. Under what is the Grafton Centre now! Andrew __________________ Invisible airwaves crackle with life. Or they should do. BVWS Member

26th Oct 2017, 8:46 pm	#13
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,872	Re: Labgear "Viewing Unit" wasn't there a name associated with Labgear.... Sant Karbana or something like that? David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

26th Oct 2017, 8:54 pm	#14
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Labgear "Viewing Unit" Sant Kharbanda, was the technical director at some point apparently. Lawrence.

26th Oct 2017, 9:16 pm	#15
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Labgear "Viewing Unit" Yep: he held the callsign G2PU. A quick search shows he had at least one TV-related patent in his name: https://patentimages.storage.googlea.../US2550821.pdf Seems he died in January 2000.