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Wartime Minicsope oscilloscope , any info/sources ?

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Made for ultra portability fits in an 8x11x 2.5 inch case when the thyratron and vibrator are removed from the chassis and stowed near the hinge. What war time use was there for such a small 'scope, with in-the-field 12V supply capability? War finish presumably means the off white enamel rather than black crackle finish. Plate on the brown casing lid Miniscope Miniature C/R oscilloscope Pattern No 58259

Stencilled labels on the case are R.L. 4 and No 1

Presumably somewhere would have info on the pattern number. Even using "-dr who" googling does not find anything on Miniscope or that pattern number, plenty on the 6K25 thyratron but nothing on 9 pin VR91,

10E/92 voltage regulator? or 9 pin CRT VCR 522, 10E/787, Design Inspected CRT 4 (shattered probably when the shoulder carrying strap broke and corner brace broke off and split occured in the "suitcase" ) no other valves, also Masteradio G650 12V vibrator, military trident symbol in a couple of places , after an A on the VR91 and before a Z on the CRT side panels missing, someone has crudely bodged in pot .

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specs etc on hinge-down, prop-up plate
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-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook
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VR91 would seem a pentode

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CRTm some info

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-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

Well that's certainly a clever bit of kit.

Keep us posted if you find out anything about it.

Jeff

Reply to
Jeffrey D Angus

What a neat piece of history! Never seen one before so can't add any info. Pity about the broken CRT - is it replaceable? Also, I love the words "time base" on the label - takes me back to those days of yesteryear!

BTW, the VR91/EF50 is an RF pentode - I once had an old TRF, one channel TV (Pye 19T) that used several of them in the RF strip. One of my first "serious" tube(valve) proejcts was to build an ITV converter from scrap WW2 parts to convert circa 180 MHz ITV to the circa 42.5 MHz (vision) and 41.5 MHz (sound) antenna input of the Pye 19T (I forget the actual frequencies.) Cheers, Roger

Reply to
engineer

equivalent EF50 (often red coating) was used a lot in early TRF televisions.

Bit of info on the 6K25 - probably used for a timebase:-

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--
Geo
Reply to
Geo

info.

"time

TV

WW2

frequencies.)

I picked it up at a "silent key" disposal at a carboot sale. Inheritors had no knowldege about it. The valves etc may not be what was originally in there of course.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

Looks like a "Malvern" variant from this page:

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Reply to
Mike

had

Thanks for that I've used or repaired nearly all those on bottom 3 rows and a few of the earlier

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GEC one looks very similar externally, especially the prop plate The chassis dimensions are similar, this one 8 x 6.5 x 2.25 inches but valves and internals are look earlier.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

VR91 / EF50 was used in many wartime radios and early radar units (PPI and pulse position). I owned a '1392 ex RAF vhf control tower receiver for many years, and that was full of them.

Arfa

Reply to
Arfa Daily

Yep, it looks like an earlier version of the GEC unit. Maybe a prototype?

Reply to
Mike

What

crackle

that

of

many

I downloaded the GEC schematic from

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but substantially different, except 4V and 6.3V heaters agree with VCR 522 and VR91. Looks as though I'll have to get/derive the CRT VCR 722/ CV1522 or related E4103/B/4 / CV320 / CV967 / CV335 pinout and maybe de-topologize for the schematic. But I'd really like to find out what sort of use it was put to, most likely tech museum or forum to try ? Very large print , 1 inch high letters "R.L.4" = radio location unit 4 ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

Of course a broken CRT makes it easy to determine pinning. As broke unpowered the heater is still there, all 4 X,Y plates exposed and A3 so just leaves A2 and grid undetermined without destroying the envelope more.

155mm long, 1.5 in diam, and 7 out of 9 pins agrees with GEC 4103/B/4 with 1.1KV pda and 4V heater. And I have the pinning for the 6K25 and pentode. I may scan in the board edges, as is with added valve pin labels , and multi-photo before undoing and trying to unravel the schematic while trying to find out about its likely in service use.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

d
e
h

ng

Would someone at the, if I remember from a visit to London 10 years ago, British War Museum be able to help you?

Reply to
hrhofmann

trying

on

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Would someone at the, if I remember from a visit to London 10 years ago, British War Museum be able to help you?

******

I'd thought of contacting Kew ,PRO, national archives, but the Imperial War Museum makes sense as well. I'm a bit concerned with the use of the word pattern before the number 53259 in that it may relate to the "samsonite" case rather than scope although etched on to the metal plate refering to C/R oscilloscope, I will take another pic later . Perhaps there is a GEC archive somewhere other than Kew and the war museum.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

trying

on

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Would someone at the, if I remember from a visit to London 10 years ago, British War Museum be able to help you?

*****

GEC/Marconi archives site

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seems to be defunct

I will try contacting

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and am aware of a very active retired members branch around Portsmouth
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who may be able to help as I seem to remember GEC had a site in Pompey

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

I've put a page together on

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with a pic of the case top with the "R.L.4" stencil

and will add to when I've found out any more

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

I don't know if you found this page or not, but it may be of help. There's a claim to a service manual for (some model of) the GEC miniscope, among other details. I have no idea if it's the same basic design or not, but they do look at least related.

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Presumably it's the civilian finish for the one on that page, what with fancier knobs and such.

--
Andrew Erickson

"He is no fool who gives what he cannot keep to gain that which he cannot
lose."  -- Jim Elliot
Reply to
Andrew Erickson

CUTE, I want one!!! I sold my Jackson 1" 'scope a few years ago and regret it.

John H.

Reply to
HagstAr

at

kle

at

of

d

ny

VR91/EF50 High gain pentode. Many of them were painted red. Some were manufactured in the USA for Britain (I have one marked Sylvania'). They have a special 9 pin base. AIUI tube was based on a Dutch Philips design. Had always assumed they were a non-variable mu RF or IF pentode, which were also used in some early mid-war aircraft radar receiver plug-in units labelled RF24 through RF27 available on the surplus market after WWII. But in a discussion some years ago on a group such as this, one poster found the characteristics and pointed out that the tube did not have a sharp control grid cut-off. Cheers for 2009

Reply to
terry

Assuming that it's military, I think the "R" would stand for Radio. The "L" would stand for Laboratory (test & calibration).

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Reply to
Mike

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