[Amps] Transformer guess?

[Carl]

That Philco transformer is part of their "Universal" series and the 1952 
catalog only goes to the -6 version. I'll check my later Radio Masters when 
I return after some errands.

Carl
KM1H


----- Original Message ----- 
From: "Ian White GM3SEK" <gm3sek at ifwtech.co.uk>
To: <amps at contesting.com>
Sent: Monday, August 27, 2012 3:18 AM
Subject: Re: [Amps] Transformer guess?


> Manfred Mornhinweg wrote:
>>Vic,
>>
>>> What I want to know is how much DC I can draw from the HV winding
>>> with a full-wave CT circuit.
>>
>>A simple rule for small transformers is that they are designed to have a
>>voltage drop of close to 5% in each winding (10% total). This figure can
>>vary a little, but not very much. At least it gives a reasonably close
>>idea. So, take out your multimeter, measure the resistance of the
>>windings, and apply Ohm's Law, using 5% of each winding's voltage. That
>>will give you the approximate current rating of each winding.
>>
>>It might be good to measure both the primary and secondary windings,
>>calculate the current for each, and see how well the two power ratings
>>match. They should be very close, of course. If there is a large
>>difference, you either have made a mistake, or the transformer is poorly
>>designed!
>>
> Or it's a multi-winding transformer, which is exactly the case here.
>
> Also, in windings that are rated for a very low current, the
> manufacturer may use over-sized wire to help avoid breakages, so the
> real-life current rating may be higher than the value specified.
>
> If Vic is not proposing to use the heater/filament windings, he may be
> able to increase the current in the 380V winding without overheating.
>
> As Carl says, the only valid test is to try it on load (and I think I
> know what the load may be :-)   Use the actual rectifiers and smoothing
> capacitors, with dummy load resistors of the correct calculated value.
>
>
>
> -- 
>
> 73 from Ian GM3SEK
> http://www.ifwtech.co.uk/g3sek
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