The valve line up is exactly the same as the Ekco A22.
Hopefully the EBL31 will be OK, because if not, they're both difficult to get hold of, and expensive (£25 - £30). Furthermore, none of those that are on offer from valve dealers are genuine EBL31s - they're impostors - EBL1s, which was a side contact valve, which have been adapted by fitting an octal valve-base over the 7-pin base. Though that's been neatly done (you can see the tell tale join), the valve then becomes too tall to fit in an A22, s the valves lies horizontally and protrudes too far to fit the back on. Apart from that giveaway, the other indication of a non-genuine EBL31 is that the converted EBL1s have a 3/8th top cap (grid), whereas a genuine EBL31 has a 1/4" top cap. It's a double diode pentode, with the diodes taking care of the AVC and detection, and the pentode, the AF amp.
The additional height of the converted EBL1s wouldn't matter in your Pennie set Joe as you have the height, but would need to change the top cap clip to 3/8".
When I needed an EBL31 for an A22 I was restoring for my son, I couldn't get a genuine one anywhere, so I made an adaptor using an octal valve base, a B9A valveholder, two germanium diodes and cross-wired the octal valve base to suit an EL84 to create a 'virtual EBL31' that would fit in the A322 till I eventually found a genuine EBL31, as I did. The adaptor with an EL84 perched on top looks ridiculous in comparison, but it worked well, and had the merit of requiring no alterations to the wiring of the valveholder on the radio. The details were published in the BVWS Bulletin some time ago, but I've attached a pic of a genuine EBL31, a 'pretend' EBL31 (converted EBL1 as sold by dealers), and the EL84 adaptor.The EL84 is close enough in characteristics to the pentode section of the EBL31 for it to work as a reasonable substitute, with the two germanium diodes in the adapator base. On the side of the adaptor, is the 'top cap' connector.
I've since obtained two EBL1s, and have converted one properly, by cutting off the 7-pin base with careful surgery (or you cut through the metalising connection) and fitting an octal base, (as well as removing th 3/8" top cap and fitting a 1/4" one). Very tricky and not for the faint hearted as you must label every connection before lifting off the 7pin valve base. The wires inside otherwise spring out, and aren't in a circle but in a line in the glass pinch, so apart from the heater, you haven't a clue which wire is which.
I've also set about trying to fit an octal base directly over the 7-pin base EBL1 base but at a lower height than those 'pretend' EBL31s offer from dealers, to make it a simpler job to convert an EBL1 for A22 owners who may not be adept at cutting off the valve base with a Dremel, but that project stalled due to other priorities. (Another potential Bulletin article that didn't make it to Carl Glover).
From left to right in the picture is the EL84/EBL31 style adaptor that I designed, a genine EBL31, and a so called EBL31 (converted EBL1) as offered for sale by valve dealers. The two clues that give the converted valve away are the larger top cap, the increased height due to the octal base glued over the 7pin EBL1 base, and the joint on the valve base.
Sorry to take this thread a bit off track Joe.
Best of luck with the Pennie 'Scout' - with a large speaker in a large compartment and if the EBL31 is up to it, it should sound great!
Hopefully the EBL31 will be OK, because if not, they're both difficult to get hold of, and expensive (£25 - £30). Furthermore, none of those that are on offer from valve dealers are genuine EBL31s - they're impostors - EBL1s, which was a side contact valve, which have been adapted by fitting an octal valve-base over the 7-pin base. Though that's been neatly done (you can see the tell tale join), the valve then becomes too tall to fit in an A22, s the valves lies horizontally and protrudes too far to fit the back on. Apart from that giveaway, the other indication of a non-genuine EBL31 is that the converted EBL1s have a 3/8th top cap (grid), whereas a genuine EBL31 has a 1/4" top cap. It's a double diode pentode, with the diodes taking care of the AVC and detection, and the pentode, the AF amp.
The additional height of the converted EBL1s wouldn't matter in your Pennie set Joe as you have the height, but would need to change the top cap clip to 3/8".
When I needed an EBL31 for an A22 I was restoring for my son, I couldn't get a genuine one anywhere, so I made an adaptor using an octal valve base, a B9A valveholder, two germanium diodes and cross-wired the octal valve base to suit an EL84 to create a 'virtual EBL31' that would fit in the A322 till I eventually found a genuine EBL31, as I did. The adaptor with an EL84 perched on top looks ridiculous in comparison, but it worked well, and had the merit of requiring no alterations to the wiring of the valveholder on the radio. The details were published in the BVWS Bulletin some time ago, but I've attached a pic of a genuine EBL31, a 'pretend' EBL31 (converted EBL1 as sold by dealers), and the EL84 adaptor.The EL84 is close enough in characteristics to the pentode section of the EBL31 for it to work as a reasonable substitute, with the two germanium diodes in the adapator base. On the side of the adaptor, is the 'top cap' connector.
I've since obtained two EBL1s, and have converted one properly, by cutting off the 7-pin base with careful surgery (or you cut through the metalising connection) and fitting an octal base, (as well as removing th 3/8" top cap and fitting a 1/4" one). Very tricky and not for the faint hearted as you must label every connection before lifting off the 7pin valve base. The wires inside otherwise spring out, and aren't in a circle but in a line in the glass pinch, so apart from the heater, you haven't a clue which wire is which.
I've also set about trying to fit an octal base directly over the 7-pin base EBL1 base but at a lower height than those 'pretend' EBL31s offer from dealers, to make it a simpler job to convert an EBL1 for A22 owners who may not be adept at cutting off the valve base with a Dremel, but that project stalled due to other priorities. (Another potential Bulletin article that didn't make it to Carl Glover).
From left to right in the picture is the EL84/EBL31 style adaptor that I designed, a genine EBL31, and a so called EBL31 (converted EBL1) as offered for sale by valve dealers. The two clues that give the converted valve away are the larger top cap, the increased height due to the octal base glued over the 7pin EBL1 base, and the joint on the valve base.
Sorry to take this thread a bit off track Joe.
Best of luck with the Pennie 'Scout' - with a large speaker in a large compartment and if the EBL31 is up to it, it should sound great!
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
