The Christmas 2018 High Voltage quiz part one.

[Heatercathodeshort]

I have always liked the appearance of EHT rectifier valves particularly the early types employed in the pre war and early post war periods.

In part one of this quiz and just for a bit of fun, can you identify these EHT rectifiers dating from 1936 to the period immediately after WW2.

In part two I will include the post war types with a few pit falls.

OOO! I have just seen a rare bird in the garden, A Cuckoo..

David, I know you have all the answers but could you hold back until the others have had a chance.

Good luck. John.

[Heatercathodeshort]

The remainder of part one. J

[Sean Williams]

Pic 4 SU 120
Pic 5 HVR2

?

Sean

[ms660]

Photo 4 of the photo's in Post 1.

SU2150A.

Lawrence.

[Argus25]

I have seen a lot of "interesting" vacuum tube EHT rectifiers in my time and the ones in the posts are no exception.

But...it is practically impossible to go past RCA's 2X2A.

It seems this fact was identified in the UK, many projects used them in favor of other rectifiers made by Marconi, and other UK companies, here is the data sheet:

https://frank.pocnet.net/sheets/049/2/2X2A.pdf

There were so many around post war that even Practical Television went nutty over them and used them in the Argus television project. Imagine that, a VCR97 CRT teamed up with an American icon EHT rectifier. Now that really was a transatlantic treaty.

Of course, now you can buy for a few dollars a microwave oven silicon EHT diode with much better ratings and no heater requirement. Despite this, the magic of the 2X2A still lives on , in my mind at least.

[ms660]

Photo 3 of the photo's in Post 1.

U21?

Photo 1 of the photo's in Post 1.

U16?

Photo 2 of the photo's in Post 1.

U17?

Photo 5 of the photo's in Post 1.

SU25?

Photo 1 of the photo's in Post 2.

U35?

Lawrence.

[paulsherwin]

Originally Posted by Argus25

But...it is practically impossible to go past RCA's 2X2A.

It seems this fact was identified in the UK, many projects used them in favor of other rectifiers made by Marconi, and other UK companies, here is the data sheet:

https://frank.pocnet.net/sheets/049/2/2X2A.pdf

There were so many around post war that even Practical Television went nutty over them and used them in the Argus television project.

Remember that huge quantities of American valves were shipped over to the UK during the war years and these were unceremoniously dumped onto the market in the late 40s. Hobbyist projects of the time used all sorts of odd valves, and small manufacturers sprang up building things like signal generators with them.

[ms660]

Photo 4 of the photo's in Post 2.

U24?

Lawrence.

[ms660]

Photo 2 of the photo's in Post 2.

U22?

Lawrence.

[ms660]

Photo 5 of the photo's in Post 2.

Fresh solder.....!!??

Envelope/base swop?

Lawrence.

[Dave Moll]

Originally Posted by Sean Williams

Pic 5 HVR2
?

Sean

I don't think so unless you are referring to the second set. The pin arrangement is rather different from my HVR2:

[FERNSEH]

Valve number 10 is a strange looking thing. The glass bulb appears to be too small for the B5 base. Any ideas what it is?

[ms660]

The glass and innards look similar to a 1B3GT..U41 type.

Lawrence.

[FERNSEH]

It certainly looks like the American 1B3GT. From r-type.org:

http://www.r-type.org/exhib/aas0001.htm

DFWB.

[Heatercathodeshort]

I think some of you would have a problem identifying a fairy light bulb..J.

[Restoration73]

Mains derived EHT pre dates my experience.

I actually have the valve in pic 4 labelled as VU120, probably Cossor. Hand made.

[Argus25]

Originally Posted by paulsherwin

Remember that huge quantities of American valves were shipped over to the UK during the war years and these were unceremoniously dumped onto the market in the late 40s. Hobbyist projects of the time used all sorts of odd valves, and small manufacturers sprang up building things like signal generators with them.

That was a good thing, better than disposing of them any other way.

It would be good to see a photo of the 2X2. I don't have any photos on hand. There were two different types I believe. They changed the way that the anode was attached to the bulb, for vibration resistance. I think that is probably the difference between the 2X2 and 2X2A. I'll have a look and see if I can find some.

[DangerMan]

2X2A can be seen here: http://www.r-type.org/exhib/aaa0506.htm

And 2X2 here: http://www.r-type.org/exhib/aaa1572.htm

The 2X2 certainly looks as though the anode support is quite flimsy for such a large electrode.

Pete

[Heatercathodeshort]

Thanks for having a go and you all did very well.

1 U16 2 U17 3 U21 4 SU2150A 5 SU25

6 U35 7 U22 8/9 U24 10 GY501.

Uploading two pictures of the U24 was a mistake. One shot was of very poor quality requiring a second attempt. Unfortunately both were posted. It should have been the HVR2 in the first shot a picture of which I have posted just for completeness.

The GY501 is a Russian example just pushed into a B4 base to add confusion.
Lawrence nearly got this one but the newly soldered B4 base was simply due to someone making up a test lead with it!

Just a few notes. The U16 was employed in the first EMI and GEC receivers in 1936. Easily recognized by its 'old penny' sized anode with the zig zag filament underneath.

The U17 will be found in the HMV 904/5. It's huge considering what it has to do.

The Mazda U21 is the pre war B4 based rectifier seen in the Murphy A56V and other manufacturers aligned with Mazda.

The Cossor SU2150/SU2150A is the 'saddle anode' rectifier from 1936 and still found in a few post war Cossor models.

The SU25 is the post war, octal based version of the SU2150. This example sports the Emitron badge and could be discovered in the English Electric models.

The U35 first seen in the HMV 1807 and used for a number of years in that chassis and later versions of it.

The U22 is a Mazda BEAST. Used almost exclusively in mains derived EHT systems. It usually failed in a spectacular way with an internal firework display, violent purple flashes and a red hot anode, usually due to a short in the EHT smoothing capacitor or the transformer itself. The fun stopped when the house fuses eventually blew.
EKCO ULTRA and MURPHY can you believe, used two of them in a voltage doubling mains EHT supply to provide 10-11kv for that frightening 15" CRM151 tube.. [Murphy V176 Ekco TC155/165 and the Ultra YE72.]

The U24 was designed for flyback EHT. An awkward thing with it's heater usually supplied from a well insulated winding on the mains transformer.
Most commonly seen in the Ekco TS88 series.

The GY501 25kv EHT rectifier from the first generation colour receivers. Seen in the 'smoke stack' with it's family, PL509 PY500 and PD500. [Not with a B4 base...]

The HVR2 and it's 2V heater version the HVR2A are the very familiar rectifiers from the 1939/48 period. Extremely tough valves that can sustain an EHT short with only a blue glow and a protesting red hot anode. Maybe it's better for a rectifier in a mains system to destroy itself rather than hold out for dear life and burn the EHT transformer out. All the same a truly excellent valve seen most often these days in the dangerous PYE D16T.

Part two will follow. Regards, John.

[Heatercathodeshort]

Please have a go at part two.

Not so easy due to the small size of the B9A and wired in types. Good luck! J.