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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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18th Jul 2007, 8:08 pm | #1 |
Heptode
Join Date: Aug 2006
Location: Sheffield, South Yorkshire, UK
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Murphy U144 - Alternative Valve Types?
I'm having trouble finding replacement valves for my Murphy U144 portable
Does anyone know of any equivalent types that could be substituted instead? The original types specified for this set are; V1 - 10C1 V2 - 10F9 V3 - 10LD11 V4 - 10P13 V5 - U404 |
18th Jul 2007, 8:30 pm | #2 |
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Re: Murphy U144 - Alternative Valve Types?
This is a standard 4 valve + rectifier superhet using B8A valves.
V1 - 10C1 - frequency changer V2 - 10F9 - IF amp V3 - 10LD11 - recitifier / agc diodes + audio amp V4 - 10P13 - audio output V5 - U404 = half wave rectifier There are no direct equivalents for these valves, but the appropriate Mullard 'U' series valves are near equivalents. You may need to make minor wiring and component changes to use them. V1 - 10C1 - UCH42 V2 - 10F9 - UF41 V3 - 10LD11 - UBC41 V4 - 10P13 - UL41 V5 - U404 - UY41 The original Mazda types are often cheaper than the Mullard alternatives, particularly the 10P13. Paul |
18th Jul 2007, 10:29 pm | #3 |
Dekatron
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Re: Murphy U144 - Alternative Valve Types?
I would agree with Paul's comments above, but please bear in mind the 10P13 has a maximum anode current of 29mA, so the output transformer may be designed for this lowish anode current. The UL41 may need "limiting" to near that figure.
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19th Jul 2007, 1:30 am | #4 |
Heptode
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Re: Murphy U144 - Alternative Valve Types?
Thanks for the replies Paul and Tim
I just wondered if there were any direct equivalents to the Mazda types that were more readily available, obviously not But thanks for the list of near equivalent Mullard types. Its something to fall back on if I can't locate the original Mazda valves, much appreciated Paul |
19th Jul 2007, 9:01 am | #5 |
Pentode
Join Date: Sep 2005
Location: West Midlands, UK.
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Re: Murphy U144 - Alternative Valve Types?
Hi,
You would be very unlucky to need to replace all the valves. Jim Fish of Wilson Valves has large stocks of valves and can probably help you, his on-line list is here http://www.flashbacksales.co.uk/wils...es/wvindex.htm Phil. |
19th Jul 2007, 10:38 am | #6 | |
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Re: Murphy U144 - Alternative Valve Types?
Quote:
As Tim said, the 10P13 has lower current handling than the UL41 so you would need to check the current being drawn and possibly increase the cathode resistor. This is often a good idea anyway since a reduction in the output valve current will result in it running cooler and lasting longer. Even halving the OP valve current will make a barely audible difference to maximum volume. Paul |
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19th Jul 2007, 12:19 pm | #7 |
Retired Dormant Member
Join Date: Oct 2004
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Re: Murphy U144 - Alternative Valve Types?
There are Marconi valves which are direct equivalents, according the the WW data book.
V1 - 10C1 - X118,X145 V2 - 10F9 - W118,W145 V3 - 10LD11 - DL145 V4 - 10P13 - N118, N145 V5 - U404 - U118, U145 Maybe not too helpful except in that it gives you a slightly wider target to aim at. I'd have a go at finding the right valve types before mucking about with the circuit to adapt it to near equivalents. Pete. |
19th Jul 2007, 4:00 pm | #8 |
Heptode
Join Date: Aug 2006
Location: Sheffield, South Yorkshire, UK
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Re: Murphy U144 - Alternative Valve Types?
Thanks for all the replies, much appreciated
No don't need to replace all the valves. I've had the set about a fortnight and it is working in a fashion, the audio is a little muffled and distorting slightly. Haven't investigated the cause yet, it probably needs several capacitors replacing and/or some of the valves are a bit tired. But in any case I always to try and obtain a spare set of valves as a back-up for my sets, hence my original request. |
19th Jul 2007, 4:53 pm | #9 |
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Re: Murphy U144 - Alternative Valve Types?
Murphies of this era are normally full of 'Orrible 'Unts and require a recap, especially That Capacitor. Don't run the set without changing That Capacitor or the 10P13 will lose emission by being overrun and will need replacing - like UL41s they aren't cheap valves, though conversion to another output valve is possible.
Paul |
19th Jul 2007, 5:18 pm | #10 | |
Retired Dormant Member
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Re: Murphy U144 - Alternative Valve Types?
Quote:
Pete. |
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19th Jul 2007, 6:52 pm | #11 |
Heptode
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Re: Murphy U144 - Alternative Valve Types?
Good phrase Paul, I like it! Very appropriate!
Thanks for the advice Paul and Pete, but I haven't actually run the set at all. I know enough not to risk powering it up until I've checked things out and replaced what needs replacing. The chap I bought the set from was the last to plug it in, in order to demonstrate his claim that it was in a working condition. It was at that time I noticed the condition of the audio and got him to turn it off again fairly quickly! Obviously its not a major problem (famous last words! ) and cosmetically the set was in such a very good condition, that I went ahead and bought it! |