Wartime Minicsope oscilloscope , any info/sources ?

I have to disagree. No laboratory equipment would be made deliberately too small, requiring the removal of parts before placing in a protective housing. This was made to be ultra-portable, the smallest possible carrying case for discretion, airbourne use, or covert reason, I would suggest. Routine military equiptment is not made for the effete to carry around. Come to think of it wartime airbourne radios etc were not made deliberately light or compact.

Drawing out the preliminary circuit topology is half complete, i will place on the page

when nearer complete, before unravelling for the intermediary schematic.

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regret

"Condition unknown, NOT been powered up" very wise Anyone know of an E4103/B/4 or compatible CRT around the UK ? I quite often see similar at radio rallies.

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regret

"Condition unknown, NOT been powered up" very wise Anyone know of an E4103/B/4 or compatible CRT around the UK ? I quite often see similar at radio rallies.

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

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I agree with you Nigel. The fact it runs on 12VDC [the GEC Miniscope does not] would indicate it was for mobile or field use where where 'mains' power was unavailable. I was thinking the RL might be 'radio location' where it could be used for timing compaison or phasing check as ground mobile. The transit case and the external vibrator smack of a 'modified' unit for temporary applications. I get the impression that the GEC uses a horizontal multivibator so the thyratron may also be a mod for some special requirement. Since it looks to be able to operate from mains and aircraft power as well, the application was likely broadly used. Also could be for adjusting or troubleshooting high speed data circuits [teletype].

Neil S.

for

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I agree with you Nigel. The fact it runs on 12VDC [the GEC Miniscope does not] would indicate it was for mobile or field use where where 'mains' power was unavailable. I was thinking the RL might be 'radio location' where it could be used for timing compaison or phasing check as ground mobile. The transit case and the external vibrator smack of a 'modified' unit for temporary applications. I get the impression that the GEC uses a horizontal multivibator so the thyratron may also be a mod for some special requirement. Since it looks to be able to operate from mains and aircraft power as well, the application was likely broadly used. Also could be for adjusting or troubleshooting high speed data circuits [teletype].

Neil S.

******

There was no original probes just some home-brew croc-lead things from the

60s or 70s , of much the same date as the bodged pot. I will test the 6K25 and the VR91 as EF50 settings, heaters are ok

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An email response from the guy at the valvepage site

Yes that GEC is internally quite different to mine, and the use of bigger valves suggests an earlier design.

The catch on that case looks very un-military-like as it and the case look so fragile.

Maybe the crt broke when the chap in the aircraft got fed up and threw the darn thing out of the aircraft - the shaped controls on mine are still fiddly, yet the controls on the front of yours would I think be impossible to use with gloves on !

Also, where on earth do the valves go ? There doesn't seem to be any space, and I also can't spot any ht rectifier.

I've seen quite a few of the GEC scopes like mine but not encountered any like yours before so I can't really add any information. Perhaps you could let me know if you find out more. Also, could I scrounge a couple of pics for my website ? Just a small pic of the front and one of the side, just enough so if a visitor sees my page they'll think "that looks just like mine" and they can then follow a link to your page.

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Now starting at £25.00

AH, but I'm in Vermont, USA. No shipping offered to here, and shipping is quite pricey anyway. Thanks though!

John H.

I found 2 unlabelled black painted glass Si diodes of the 70s , not original for the added reason that 2 solder points were to wires and not tag board tags. Se rectifiers been around since earlier than 1933 but where was there space for any. Even if the vibrator was originally synchronous type , would it be possible to use such a vibrator to rectifierless feed mains in , via the transformer to such a vibrator, to allow 12V and 180/230V ac use? The mains cable seems to go to the output side of the vibrator, with no mechanical interlock to lockout other than someone remembering to unplug the vibrastor, or does it matter ?. For the 4 pin vibrator, that came with it, gum on Masteradio label is bad and original un-re-badged label under is Mallory G650 Indianapolis Ind Made in USA

Anyone have specs for the G650 ? or even whether synchronous types could be in only 4 pin format

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The only reference I found was a google cached page which include this info on a PSU:-

"The Power Supply Unit is running from a 6 V car battery using a Vibrator or from the mains at 110, 150 or 220 Vca 50 Hz. The Vibrator is of the "nonsycronous" 4 pins type (B MKII or Mallory 650) The mains voltage value can be changed by a switching system on the front. A valve 6X5G is used like rectifier. When the set is to be used on the mains, the vibrator must be removed to prevent burning up. "

--
Geo

info on a

or

prevent

What i suspected. I happened to have rebuilt the contacts of a synchronous one last year and that was 7 pins. At the moment I'm bogged down with confusing cap colour codes.

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FWIW, Nigel, we used to use caps not unlike the ones in your 'scope and until the early '60s they were identified by 'bin numbers' which were simply assigned as new values were needed. Since there were less than 1000 values in use, a 3 colour code sufficed. Unless you had the 'rosetta stone' to co-relate the bin number to value, the colour coding meant nothing. I am sure a similar scheme was used by many manufacturers in the '30s-'50s. I know CGE/RCA/Westighouse in Canada used a 3 digit numeric code on some of their paper caps during that period.

Neil S.

This is the preliminary node map for the scope

Scanner does not like full A4 useage. Letters E, K and C along the top

2 tag boards running vertical, numbered from bottom S (16) and R (16) then P (11) and Q (11), colours match major component pinning numbers to node numbers. ground lines not added and some components around the front panel pots, switches and 2 3.5 mm i/p sockets (feintly marked as worn off , maybe read INVERT and GAIN not readable on the earlier pics) not transcribed. Some unplaced loose wires and 2 caps covered in laquered cloth so left in place as unknown values and puffy cap values are assumed , ignoring the green and yellow "multiplier" dots that are probably temp or tolerance values. polarised caps marked with a - . QQ is unkown function as knob missing and other Q pot functions as letters on the knobs, as found. There are bound to be still more errors, I've just noticed the 22K resistor apparently going to doubley N/C K6, maybe used as a tag. M & VIB wiring and power select shorting plug arrangement is probably much like the valvepage schematic including the vib, for the later miniscope. Power cable wiring Y,R,B is the same in both cases Next intermediary schematic is placing the valves etc into the optimum coloured nodes and un-knotting to a certain extent. Nothing powered up so far, a few volts from variac may resolve a few problems, and valves not tested yet. Primary of M is probably ok , selecting 230V is 129 ohm and 180V is 75 ohm

The socket for the vib is badly fixed , one bolt is skew as it interferes with something else on the chassis. So maybe not original vib type but I don't see how a synchronous type could have made it Si diode rectifierless. What were the smallest Se rectifiers available in the 1940s for this sort of application ?

page devoted to this project

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Anyone care to decode the knob legends Vc,Vf,F,C,A,S

Vc was on the 6 way timebase switch, I am assuming it was moved from the least used or easiest to turn without a knob Gueses S for Sync, A for attenuation, F for Fine, C for Coarse , Vf for focus but Vc ?

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Vc is cathode voltage - probably the brilliance control Agree Vf for focus. F could be (timebase) Frequency?

--
Geo

I have a CV320 tube that has a pale green screen and might possibly work as a replacement for your tube. I have not checked the filament for continuity, but the tube 'looks' fine...

John :-#)# Vancouver, Canada.

N_Cook wrote:

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thyratron

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crackle

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of

I would be interested, different pinning, no problem, otherwise much the same specs

is your valid email address really spam and then the things sharks and pinball m/cs have .com

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