1932 Philips 930A valve equivalents

[howard]

Hello,

Now that I have sorted out a full set of original valves for my 1932 PYE "G" I am now going to try and complete the set of original valves for my Philips 930A Local Station Receiver. The original complement of Mullard valves as marked on the valve bases in the set was ...

484V 484V PM24 1801

The Dutch, Swiss, Czech and Italian built 930As came with these Philips equivalents ....

E438 E438 B443 1801

My 930A came with the following valves, none of which are exact equivalents ...

354V MH4 PM24M U14

I am having a struggle finding these valves, I found a NOS 1801 rectifier for £1 but sadly that's no good, and a NOS E438 (484V equivalent) for £15 which is perfect.

There are several equivalents for the missing 484V so I should be able something suitable eventually, but having tried dealers for an 1801 and a PM24, I'm told that these are really rare valves and are unlikely to work if found.

Does anyone actually have a working 930A with a full complement of original valves ? If not and original valves are extinct then I shall have to find other valves which are more suitable eg: the U14 I'm told is completely wrong ! Any advice would be very welcome. Thanks.

Howard

[petervk2mlg]

Hello Howard,
My Ham Tin came with its original valves apart from the rectifier. In place of the 1801 is an Austraian G470 which might be impossible to find now. Also its heater current is double that of the 1801. Not as heavy as your U14 though, which is really hungry and will stress the transformer.
What about a 506 rectifier although its filament will draw 1 amp. A German RGN504 is identical to the 1801 and might be easier to find.
Peter

[howard]

Thanks Peter,

The RGN504 is a German Telefunken equivalent of the 1801 rectifier, and there are a couple more valves equivalent to the 1801 ...

G504 (German)
VG406 (Austrian)

There are a few valves similar to the 1801 as well including the Dutch Philips 506, but they're all European and will be expensive now that the value of the £ has dropped against the €.

Unfortunately the PM24 is unique .......... but at least there is one still working.

Howard

[petervk2mlg]

Howard,
As you say anything is going to be pricey. BUT you have a valuable set there. What about a German RES174.
Peter

[newlite4]

Howard, finding the PM24 should not present too much difficulty. They are not a rare valve. They are common enough to find at the radio fairs. Just keep looking in the valve trays. I found one for a pound at the Willand event a few years ago.
Neil

[Tim]

Hi Howard
Those valves look to be reasonable equivalents. The circuit is quite simple and should work with a wide range of valves. The ones you have in it are also 30's/40's valves so it's not like someone has stuck an EL84 in there!. MH4's aren't that rare either, nor U14's.354V's(NR52) come up now and again.
If you're stuck or wan't to save your wallet I would keep the ones you have-assuming they're not faulty of course. Hopefully you can get it working on those and then get the "right" valves later on when you have saved up!!

[johnn]

Hello Howard,
regarding the U14, I replaced a worn out 1821 in my 727A set with a MU14,
but I think the heater current was too high. It works.
I have obtained a Mullard DW4/350 & think this is OK. HT voltage was about spot on.
The 1821 was a bit of an old type for a 727A, but it was wired only as half wave. The similar 470A has a much better power supply! STRANGE COMPANY.
I don't think I can help on the other valves therefore.
Regards John.

[PJL]

The heater current of an 1801 is 0.5A and there ain't many like that! The 506K I have here is 1A. The U14 is 2.5A. I would be tempted to substitute with silicon and resistors under the chassis until you can find one.

The PM24 is pretty common.

[Mr Moose]

Hello,
The Mullard valve guide for 1933-4 gives the rectifer as a DW2 (U10, R1 etc). This has a 1A heater which is higher than the 0.5A or 0.6A heater of the 1801 but not as high as the 2.5A heater of the U14.
A later (undated) Mullard valve list gives the equivalents for the PM24 as Cossor 415PT and 410PT, Osram 425PT and Mazda Pen425, although these are probably as rare as the PM24.
You could try a PM24A which is designed for a higher anode voltage than the PM24 and its heater current is 0.275A rather than the 0.15A of the PM24 but not the 1.1A of the PM24M.
Yours, Richard

[Sideband]

The PM24A will work in place of a PM24M but I think the anode impedance is quite different. My 274A has the original PM24M which still works well. As I had a PM24A, I tried it out of interest and it worked well but slightly lower volume I think.

Howard. Be careful when checking the European version of the set. Some of them were fitted with side-contact valves. I noticed that the 836A Continental version which is identical to the 274A circuit-wise is fitted with side-contact types.


Rich.

[howard]

Many thanks all,

for all your suggestions.

It's good to know I can still get a working PM24 which has a side connector (my set has been modified to accomodate a later PM24A - PM24M with no connector). I'm happy that the E438 is an equivalent of the 484V, no side connectors on either of these valves.

That just leaves the 1801 rectifier which looks like it's going to be difficult to replace with something near original, although Telefunken equivalents do come up for sale on eBay and European websites now and then.

It might be a while before my 930A appears in Success Stories .....

Howard

[Mr Moose]

Hello Howard,
There is an untested, used, Philips 1801 on ebay; item no:- 390035393606 (in Collectables/ Radio), the base is held on with tape and it's not cheap.
Yours, Richard