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Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


    Dynatuner FM-3 PB-012 vs PA509 Transformer

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    Stannie79

    Posts : 3
    Join date : 2020-10-28

    Dynatuner FM-3 PB-012 vs PA509 Transformer Empty Dynatuner FM-3 PB-012 vs PA509 Transformer

    Post by Stannie79 on Thu Oct 29, 2020 12:15 pm

    Hey all, Bob sent me here for my questions about a Dynatuner FM3.

    Recently I bought an old Dynatuner FM-3, supposedly in good working condition although it looks like it spent the past few decades on an attic somewhere.
    This FM3, once cleaned up and properly revised, would go perfectly with my previously restored ST-70 and PAS3, however there is one major problem:
    It has the original PA509 power transformer instead of the optional PB-012 that can be wired for 240V operation, and I live in Belgium where we have a 240V/50Hz powergrid. Clearly I didn't do the proper research upfront as I was under the impression that the FM3 could simply be switched to 240V operation without any additional requirements.
    Those PB-012 seem quite impossible to source. I checked on dynakitparts, dynacodesigns, triodeelectronics, Ebay, ... but can hardly find any reference to it ever having been available. I do know they exist, as these FM-3's do popup in Europe every now and then.

    So my questions:
    - Does anyone know of a viable replacement for the PA509 that operates on 240V, or is there a way to rewire the PA509 to do so?
    - Or do you know of a source that might have a PB-012 laying around?
    - Does anyone have the specs on the PA509/PB012? If I know better what to search for, I might be able to find a suitable replacement online.
    - One option I've been thinking of is to have my PA509 professionally rewound for 240V operation, but I honestly don't know how much that would set me back.

    I'm picking up 230VAC-110VAC convertor tomorrow, which should work just fine, but eventually I'd like to hook it up directly on an outlet on my PAS3, just as I do with my ST70.
    peterh
    peterh

    Posts : 1457
    Join date : 2012-12-25
    Location : gothenburg, sweden

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    Post by peterh on Thu Oct 29, 2020 12:59 pm

    The transformer seems to be quite common, the B+ should be 200+200volt The B+ draws 60mA
    the filament 6.3V 4A

    A transformer supplying 100mA at 200+200Volt and 6.3V 5A should do.
    Hammond 260E might be a replacement https://www.hammfg.com/electronics/transformers/classic/260
    ( 260E delivers 3A @6.3V but leaving the 5V unused probably compensates.
    To copy with a slight higher B+ R36 could be increased.

    Stannie79 likes this post

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    Stannie79

    Posts : 3
    Join date : 2020-10-28

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    Post by Stannie79 on Fri Oct 30, 2020 6:09 am

    Thanks Peter!

    This helps a lot - that 260E might indeed be a good replacement candidate, and it's in stock at Mouser.
    I'll do some double-checking when I've got the 230-110 convertor later today, and search for any other alternatives in the meantime now that I know better what to look for.

    I started out working on vintage audio equipment only a couple of years ago, as a hobby with only basic electronics knowledge, and it seems I still have a lot to learn Smile

    Cheers,
    Tom
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    Hops

    Posts : 55
    Join date : 2019-09-21
    Location : South Detroit, Michigan

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    Post by Hops on Fri Oct 30, 2020 7:26 pm

    You could always use a Variac to lower the voltage. Not ideal, but doable.
    avatar
    Stannie79

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    Join date : 2020-10-28

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    Post by Stannie79 on Fri Oct 30, 2020 8:08 pm

    Using a variac as a permanent solution would be a bit overkill no? Wink I have a 230-110 transformer as a temporary solution, but I'm looking into options for a permanent integrated solution.
    Would this be a better fit than the Hammond you think?
    https: sklep.avt.pl/transformator-el-tsl200-001-2x195v-2x0-39a-27v-0-1a-2x3-15v-2x7-5a.html
    (Sorry, not allowed to post links as a newbie)
    Or would it be a bad idea to combine the two 3,15V secondaries into a 6,3V? It's also not a HV 400, but the 390 it delivers I guess would make an almost negligible difference, on the safe side.

    There's also this one:
    https: sklep.avt.pl/transformator-el-tsl40-002-2x200v-2x0-06a-9v-0-04a-6-3v-2-15a.html
    Correct secondary voltages, but only rated at 2,15A for the filament, which is probably way too risky.
    I'll contact Sklep tomorrow. Supposedly they also make custom transformers on order.

    peterh
    peterh

    Posts : 1457
    Join date : 2012-12-25
    Location : gothenburg, sweden

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    Post by peterh on Sat Oct 31, 2020 2:04 am

    Stannie79 wrote:Using a variac as a permanent solution would be a bit overkill no? Wink I have a 230-110 transformer as a temporary solution, but I'm looking into options for a permanent integrated solution.
    Would this be a better fit than the Hammond you think?
    https: sklep.avt.pl/transformator-el-tsl200-001-2x195v-2x0-39a-27v-0-1a-2x3-15v-2x7-5a.html
    (Sorry, not allowed to post links as a newbie)
    Or would it be a bad idea to combine the two 3,15V secondaries into a 6,3V? It's also not a HV 400, but the 390 it delivers I guess would make an almost negligible difference, on the safe side.

    There's also this one:
    https: sklep.avt.pl/transformator-el-tsl40-002-2x200v-2x0-06a-9v-0-04a-6-3v-2-15a.html
    Correct secondary voltages, but only rated at 2,15A for the filament, which is probably way too risky.
    I'll contact Sklep tomorrow. Supposedly they also make custom transformers on order.

    The first one ( 2*195Volt) seems to be a fine fit. reasonable price too and within EU
    thus no extra cost.


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