[Boatanchors] PLATE XFMR

[Carl]

There have been several different grades of transformer iron made since the 
20's with each new one being more efficient.

You can trust the ARRL to be a step behind.

Ive used the dummy load method many times to monitor temperature rise when 
an open frame xfmr makes it easy. OTOH, those cast iron end bells take ages 
to absorb the heat and the windings could be toast by the time you realize 
it. And you never know what is inside a sealed unit.

The problem with old design high impedance windings is that a choke input is 
necessary to get any reasonable regulation under changing loads. You could 
do it with a lot of C only but that requires a lot of wasted bleeder 
current. Best keep the old iron with Class C amps and modulators.

Carl
KM1H



----- Original Message ----- 
From: "J. Forster" <jfor at quik.com>
To: "Bill and Liz McHugh" <magoo at isp.ca>
Cc: <boatanchors at mailman.qth.net>
Sent: Monday, April 04, 2011 1:57 PM
Subject: Re: [Boatanchors] PLATE XFMR


> Roughly 40 watts/pount at 60 Hz for a transformer made with standard
> (cheap) iron.
>
> -John
>
> ===============
>
>
>
>> Some time ago I recall someone providing a "rule of thumb" one might use
>> to estimate the current capacity of a plate transformer based on weight
>> and dimensions.
>>
>> I have a Hammond with an REL number which is not in any catalog and would
>> like to be able to use it in a supply for an 813 rig I am building.
>>
>> Anyone have that "rule of thumb" at hand?
>>
>> Bill VE3NH
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