Id say you are good to go as received John considering that the 76 was
shipped worldwide and used in contests and DXpeditions. If you have the
Hypersil transformer option even better.
The blower runs at reduced voltage thru a bucking winding in the transformer
to reduce noise, you can bypass that if you wish. At 400W you can probably
have the wheel almost at a standstill and have sufficient cooling (-;
A transformer rewinder will have no problem with that sealant, its easy to
remove for those shops but I doubt you will need their services.
Enjoy it. I have the 3 tube version on the 2nd station.
Carl
KM1H
----- Original Message -----
From: "John E. Cleeve" <g3jvc@jcleeve.idps.co.uk>
To: <amps@contesting.com>
Sent: Friday, April 23, 2010 8:24 PM
Subject: [Amps] Transformer 50/60hz
> Thank you Carl K1MH, Vic K2VCO and VK3PA for their response to my
> question.
>
>
>
> The transformer fitted to this example of the 76PA is the more efficient
> option that was on offer at the time of manufacture. Should the
> transformer
> fail, I do not think it could be rewound because it has a thick black
> coating, it has most likely been impregnated and then dipped. In the UK
> the
> amplifier will not be run at more than 400w and so the power supply will
> not
> be stressed, but the losses within the transformer, manifesting as heat
> are
> of concern to me. But I had realised that the fan would turn slower when
> running on the 50hz supply and part of my refurbishment plan is to change
> the fan to a DC unit with the equivalent or greater air flow, which may
> help
> with the transformer heating.
>
>
>
> However, I think that my first experiment will be to power up the
> transformer on its own, before installing it into the amplifier, and see
> just how hot it becomes, keeping a close check on it, say every 15
> minutes,
> if it gets warm to the touch, but no warmer, and remains that way, then I
> will install it into the amplifier. But, if it gradually gets hotter, to
> the
> point where you could "fry and egg on it", that would mean I will have to
> obtain the 50hz replacement.
>
>
>
> Thank you once again for your advice, sincerely, John. G3JVC.
>
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