Side Contact Valves

[FrankB]

I acquired a couple of side contact valves, and was wondering, are there always the same number of side contact "pins" on a side contact tube base? Or are there different size side contact bases?

I don't have any literature to refer to, and a search on the net yielded little.
I hope you folks can shed some light on this for me, as we see very few of them here in the States.

Thanks In Advance.

[Peter.N.]

I only know of one type in this country, if they are Mullard valves they will end with a single number e.g. ECH3, the single figure indicating that its a side contact base. They were not in use for very long, I believe they came out in the late '30s.

Peter

[Alf]

There were two types as far as I can remember, the CT5 base and the CT8 base, the CT8 being the most common. The CT5 and the CT8 scroll down to see base.

[Jeremy M0RVB]

Apparently there is a CT4 too, there is a drawing in one of Keith Throwers books. Was CT8 also known as SC8, and also the P-base?

[emeritus]

The Osram 1938-39 catalogue only lists one side contact valve, Type A537, a "Triode for microphones" valve for use with condenser microphones. It has a miniature 4 contact base whose type is not stated, but its dimensions can be deduced from the drawings. PDF of the data sheet attached.

[emeritus]

The Bulgin 1936-7 catalogue only lists side contact bases (valve holders) having 5 and 8 contacts (for valves) and 10 contacts (for CRTs). The catalogue says that these bases are for the "new side-contact valves", suggesting that the valves were probably introduced around 1935-6. PDF attached.

[Peter.N.]

I obviously didn't learn much during my 50 years in the trade.

[ms660]

B12D, used for VCR97 CRT etc:

http://www.r-type.org/exhib/aaj0166.htm

Lawrence.

[Alan Stepney]

The most common ones can be seen at:
http://www.r-type.org/inx/inx00043.htm

The Side Contact was a Philips idea, with the intention that inserting them wiped any oxidisation off the contacts.

[Maarten]

Originally Posted by Peter.N.

I obviously didn't learn much during my 50 years in the trade.

Valves sporting those sockets were in extensive use on the continent in the late 1930's and even immediately after the war, but not so much in the UK.

[ColinTheAmpMan1]

As far as I can tell, the AVO CT160 valve tester had a Philips "P" type, or 8SC holder as the only one using side-contacts. This had eight contacts. It looks to me as though other AVO valve testers were similar, though I could stand corrected. Doesn't this suggest that whatever side-contact valves were available in the UK, they would all fit one type of holder, with perhaps some unneeded contacts missing?
Furthermore, while I can see that inserting a side-contact valve into its holder involves a "wiping" action that could remove any dirt/oxidation on the contacts, don't all of the other insertion methods involve a "wiping" action, with perhaps the exception of wire-ended types?
Colin.

[G6Tanuki]

I've seen 4-pin side-contact bases used on rectifiers: Mullard/Philips seemed to have a thing about directly-heated fullwave rectifiers with 4-volt heaters.

I always thought that one of the big selling-points about side-contact valves was that since the entire valve-base fitted down into the socket they took up less overall height (perhaps an inch) making 'slimline'-style radios easier to design than if traditional pin-base valves [Octals, or the US/British 1930s equivalents) were used.
And being a non-standard [Mullard/Philips specific] thing, they also provided a commercial 'lock-in' for future supply of replacement valves.

The appearance in the late-1930s of Loktal/Bantal, and squat 'GT' valves clearly undermined the reduced-height-benefit argument. Mazda tried the 'vendor lock-in' thing around the same time with their pervertion of the standard Octal base (and again in the immediate post-WWII era with their 8-pin all-glass range which sat uncomfortably between industry-standard B7G and B9A offerings).