It certainly does complicate things. Modulation transformers are constructed
differently also so they can function with that DC in both windings.
Im going to have to dig out my ancient Terman and other tomes of antiquity
and relearn all this AM witchcraft.
Peter might have something there with the choke feed of the RF amp HV and a
blocking cap to the modulation xfmr. If memory serves it was referred to as
"modified Heising". The last time I used true Heising modulation was around
1958 on a homebrew 2E26 2M rig.
Carl
KM1H
----- Original Message -----
From: "David G4FTC" <g4ftc@hotmail.com>
To: <amps@contesting.com>
Sent: Sunday, November 11, 2007 2:50 AM
Subject: Re: [Amps] operating a transformer in oil
>
>> > Has anyone tried extending the power capability by placing one in oil?
>> > Im
>> > aware of the flux density, core size and all that but just curious how
>> >much leeway there is.
>> > Right now Im contemplating 500W of AB2 out of a 300W CCS modulation
>> >xfmr. It is not potted and the end bells are removable.
>> > > > Only a scope will tell me when Ive exceeded the saturation limit
>> > > The flux density is set by the excitation voltage and not load
>> > > current - if
> you are running the transformer from the correct supply voltage, the flux
> density will be OK.
>> > What you will get is increased I^2*R losses in the windings due to the
> higher load current - this will result in increased temperatures and it is
> this
> which can ruin the transformer.
>>
> Oops - the word "modulation" didn't register. As per the other reponses
> the dc bias complicates things.
>
> Next time re-read question before hitting the send button.
>
> David
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