[Amps] Class A fo AM

[Gary Schafer]

Clamp tube modulation is a form of controlled carrier modulation which is a
hybrid screen modulation. With controlled carrier modulation power input
does change some unlike straight screen modulation where the input power
remains constant. With controlled carrier modulation input power changes and
efficiency changes also.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of zl1aih at ihug.co.nz
> Sent: Wednesday, November 15, 2006 2:09 AM
> To: amps at contesting.com
> Subject: Re: [Amps] Class A fo AM
> 
> Hi all,
> Please forgive my failing memory, but was not
> "efficiency modulation" (in the time before SSB)
> taken to it's extreme with 'clamp tube' operation of
> tetrodes e.g. 807s?
> 
> As a young (16 year-old) ham, I tried clamp-tube
> modulation because I couldn't afford a big
> modulation transformer etc.
> 
> It got a bad rep because AM ops didn't switch off
> their receiver's AGC - in those days, they were either
> CW or Phone ops (has anything changed?).
> 
> In the '60's, a Marconi "Kestrel" marine transmitter
> (two 6146s) used a modified form of "controlled
> carrier" on AM that worked very well - some of the
> plate modulator output was rectified and used to
> supplement a lowered standing screen voltage.
> 
> I don't know who copied whom, but there was a
> similar circuit published in CQ Magazine around the
> same time.<G>
> 
> 73, Ken ZL1AIH
> 
> 
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