Strange valves?

[CambridgeWorks]

Whilst sorting through my valves for a 6L7G for someone (didn't find one) I found this pair of UY-807A and also an EBL31 octal plugged into a side contact adapter. Never knew those adapters existed.
Can't find info on the UY-807A either. Maybe a more modern alternative to 807?
As yet, no tests done.
Any ideas?
Rob

[paulsherwin]

The UY-807A appears to be a Japanese 807 equivalent/copy from the late 30s. Maybe they turned up on the surplus market at some stage.

[CambridgeWorks]

Yes, all I found were pictures of some sold boxes Toshiba ones. Radiomusem turns up my number but with dimensions of the common 807. That's what made me ask.
Regarding the EBL31 adapter. Any adapter usually refers to removing the side contact base and/ or adapting to an octal. Strange mine does the opposite. Must admit, I never knew I had this, otherwise would have tried it as octal in my A22.
Rob

[paulsherwin]

Presumably they started off as the coke bottle shape but were squeezed into a GT profile in the 50s, as happened to many prewar types.

[David G4EBT]

Originally Posted by CambridgeWorks

Regarding the EBL31 adapter. Any adapter usually refers to removing the side contact base and/ or adapting to an octal. Strange mine does the opposite. Must admit, I never knew I had this, otherwise would have tried it as octal in my A22.
Rob

That side contact adaptor converts the EBL31 into an EBL1 as they're electrically identical, apart from the bases and the fact that the EBL1 has a 3/8" top can and the EBL31 a 1/4" top cap. Seems a bit odd really, why there was a need to backwards convert an EBL31 to an EBL1, in that for decades now, NOS EBL1s have been/still are more plentiful than EBL31s.

All so-called EBL31s on sale from UK dealers for many years have been EBL1s, still with their 3/8" top cap, the side-contact base left in place and an octal socket glued over it making the valve an inch or so taller. As many A22 owners have discovered, myself included, while these 'imposters' work fine in radios with enough headroom, and they work fine in an A22, if you want to leave the back panel off.

Can't you just unplug the valve from the adaptor and try it in your A22?

If you're lucky Rob, it might still have mileage in it.

Pic 1: EBL1 Side Contact base to EBL31 Octal base wiring diagram.

[CambridgeWorks]

Paul, I just feel this design may be quite rare over here, considering maybe millions of "traditional" 807 were possibly made.

Yes David, that is a possibility.
Currently my A22 is pride of place on our lounge sideboard.
Next time I wish to check it over I will try the EBL31.
Just thought it a strange conversoion, from a rare type to common.
Rob

[paulsherwin]

I've never seen them. There are mentions of them being scavenged from WW2 Japanese equipment by occupying American troops.

As you suggest, there were an awful lot of basic 807s floating around in Europe and the US after the war, so there was little incentive to bother about obscure Japanese versions.

[CambridgeWorks]

The EBL31 adapter fooled me. it was just various wires soldered to the EBL31 octal pins and then connected very neatly into the side contact base. Not loose at all, as it took a bit of removing.
Pleased to say I now have another good EBL31 for my A22.
One of the 807s shows a tiny trace of gas when testing, the other is faulty.

Rob