[Amps] Re: Big HV Transformer for Sale

[Gary Schafer]

Richard wrote:

> >Definitely not multi band or even multi frequency. Single frequency only.
> >From what I understand they were a real pain to keep tuned properly.
>
> I heard the same thing.
>
> >Advantage was high level modulation and class C efficiency without the usual
> >big high level  modulator.
> >
> A Class AB1grid-driven,  or AB2 g-g linear amplifier is typically 60%
> efficient.  Class C may be 78% efficient but the difference would be
> virtually not noticeable at the Rx end or on the utilities bill.
>
> cheers, Gary

With AM though the carrier efficiency is only about 30% with a linear amp. The
amp needs to be tuned at and able to handle 4 times the carrier power to handle
the audio peaks for 100% modulation. Most stations run upwards of 120% positive
peak modulation making the amp PEP power handling requirement even greater than 4
times carrier. Efficiency will be even less in that case. Lots of heat to get any
kind of real power on AM with a linear amp.

73
Gary  K4FMX