Murphy A272C valves

[Ever-HMV]

I recently picked up a Murphy A272C as part of an Auction lot.

Unfortunately, ALL of the valves had been removed - something I hadn't checked B4 bidding (Not a mistake I'll make again!)

It's too good to scrap, but some of the valves are hard to get, and expensive. A quick check on Ebay suggests it would be easy to spend £50 just on the valves, which is beyond my budget.

What valve substitutions could I make to use either valves that I have, or easily available alternatives? I am not averse to changing the valve bases to suit, if essential.

For example:

Substitute an ECC84 or a 6BQ7A for the ECC85 (I have stock of these!)

Substitute an EZ80 or EZ81 for the EZ40

Substitute ?? for the 6P1

and so on.

Any suggestions much appreciated!

Rob

[Leon Crampin]

The A272C is an excellent receiver and sounds good on FM with a 10" Celestion 'speaker on what is effectively a large baffle.

Please don't butcher the set - valves for it are not too difficult to get.

The valve for the FM head is an ECC85 - plenty available. A possible substitution which will work is an ECC88 but there's not a lot of point. Don't attempt to rewire the base otherwise alignment will be lost.

The second valve (AM frequency changer) is a 6C9 which is a Mazda special. They are around and long lived, so a second hand valve is a possibility. If pushed, an ECH42 will work here, but the screen resistors will need changing and the set re-aligning.

The IF amplifier is a 6F18 which is similar to the EF89 - but check the screen connections as they differ on pin 1. Re-alignment would again be needed if a change was made.

The detector/AF preamp is an EABC80 - easy to get.

The 6P1 output valve is a "GT" version of the earlier Mazda 6P25 and there's room in the A272C to fit one. Other pin compatible possibilities are an EL33 or a KT61 (which would definitely need a bias change). A 6V6 would also work, but leave the set short of audio gain due to its low slope.

I would look for a 6P25 which is a plug-in replacement whilst you try to find a 6P1 - they are around. Check the bias if you make any other substitutions.

The UU9 rectifier is a straight equivalent for an EZ40. At a push, two silicon diodes and a resistor would do whilst you find one.

There was no screening can fitted to the AM aerial coils - it looks as though it's missing. Don't fit one.

Leon.

Send me a PM if you're stuck and I may be able to help with some of the Mazda specifics - other than the 6P1.

[yestertech]

Hi Rob

have sent you a PM

Andy

[Ever-HMV]

Leon

Thanks for your detailed reply which has illuminated much for me. Perhaps this substitution game is not as easy as I hoped!

I'll check what's available (and at what price) from the BVCF at the weekend - I might be lucky!


Andy

Thanks for your PM - PM sent.

Rob

[Tim]

You'll need to change the base to use an EZ80, but it will work well(have done it on one of these sets).

[John_BS]

Rob:

There were several 6P25's in the collection I gave to the forum c/o Jeremy last year. Also one EZ40 & one ECC85.

I have a NIB Tungstram EF89 if you are still in need!

John

[Leon Crampin]

Rob, I've just had a look at my stock and I have a good used 6C9 - yours for the cost of the postage.

Leon.

[Ever-HMV]

Thanks for all the kind offers.

I'm just in the process of stripping the radio down, to ensure the rest of it is OK, and worth getting valves for; if cobwebs were spun with gold, I'd be a rich man!

Rob