Valve replacement

[Ewan fane]

The radio is an Irish model type BI 21 it was built in 1941 but the guy repairing it has never worked on one as old as that.( his current oldest being in 1950s) unfortunately there is no-one else that I know of that can repair it anywhere near me. I live in Cork, Ireland. He is the best I have, he asked me to source the valve EZ40 as he has no internet access to buy one himself. After I called him he said it was just the EZ40 that needs to be replaced. He replaced the EL41 himself because it had collapsed as he had a new one in his workshop. I was on the phone to him just there. The only other question I had was if someone could identify the valve in the back left. Thanks.

[G8UWM-MildMartin]

The back left one is a 6C9 frequency changer (usually by Mazda or Ediswan, but that one has been re-branded by Haltron.)
I don't think the B8A/rimlock valves were released until 1947

[Herald1360]

An ask here:


https://www.vintage-radio.net/forum/...splay.php?f=28


May get you a decent secondhand or even new one. Otherwise Ebay will offer as will suppliers like Langrex.

https://www.langrex.co.uk/products/e...xed-valvetube/


If the EL41 has "collapsed" it sounds like it has suffered from a leaky coupling capacitor and taken out the EZ40 on the way. Hopefully the output transformer hasn't gone too!

[Nuvistor]

If he has worked on 1950’s valve radios this shouldn’t cause him any problems. I have used Langrex in the past and they gave a good service.

He can fix your radio, you help him sort out the internet, perhaps join the forum.

[ekjdm14]

Agreed, if by collapsed he means it's melted internally then probably been cooked by the grid coupling cap leaking. Would be wise for your man to check the audio output transformer before spending on valves.

[Mike. Watterson]

I can't believe someone involved in repair work that has no Internet.
It does sound like the capacitor to grid of EL41 needs checked and all the other PSU, Audio out parts and capacitors.

It's AT LEAST a 1947 radio, likely 1948 or later with those valves. It can't be earlier.

I'm in Limerick. See it says so below my name.

[crackle]

A quick trip up to Limerick and you could get a proper repair job.

Mike

[paulsherwin]

Agreed Mike W, it's impossible that this radio was built in 1941. 1951 maybe. The fact that this wasn't obvious to the repairer is concerning.

[Mike. Watterson]

Maybe.
We'll see.

[kalee20]

Originally Posted by paulsherwin

Agreed Mike W, it's impossible that this radio was built in 1941. 1951 maybe. The fact that this wasn't obvious to the repairer is concerning.

Ewan doesn't say it was the repairer that dated it as 1941, perhaps it was just a family legend date which was misremembered?

For Ewan's benefit, 1941 was when the war was hotting up, and this spurred valve development and miniaturisation. Pre-war valves were all big and bulbous. During the war, new valves were in short supply as production was mopped up by the Forces. But afterwards, the benefits of smaller, easier-to-make valves such as the button-base, all-glass types such as those in the photos were quickly developed and became available to the consumer market.

This dates the valves as definitely post-war. The Radio Museum website lists the B8A base valves (which are the type in the photos) as launched 1947 so by the time manufacturer's had designed new radios to use them it would have been 1948 when they hit the market. 1951 is quite a reasonable date!

[paulsherwin]

I'm not casting any aspersions here, we just don't have enough info.

[Mike. Watterson]

Though the B7G, from the USA point of view was a pre-war valve!
Many sets released before Pearl Harbour. The B7G valves were imported only for military / covert radio production in the UK. The Romac in 1946 and Vidor CN353 1947 were the first two UK battery valve sets to use the imported valves.
Post WWII to 1950 for mains sets in the UK was mostly Octal.
Hearing aids and Japanese pocket sets were the first users of the very miniature crimped base 1.4V and 0.7V filament types used in WWII allied shell & bomb proximity fuzes (a primitive type of radar).
The 1930s Acorn valve was very small, but too costly to mass produce so was only used in low volume UHF equipment.
The Germans had the low profile large diameter Y8 base battery valves from about 1941.

[peter_sol]

6C9 is a substitute for the ECH41 which is OK.
You need to ask what is supposed to be wrong with the EZ40. Unless all the waxed paper capacitors are replaced the voltages all be low. so may not be needed.

[Silicon]

The EZ40 could be replaced by a pair of UF4007 silicon diodes and a resistor to get the radio working.

If the radio proves to be reliable and perform OK after the repair work, you could then invest in an EZ40 rectifier valve.

[Mike. Watterson]

I'd not do that before checking everything else!

[HamishBoxer]

£6.90 for an EZ40 on Ebay, if needed and a very common valve.