The 90% efficiency thing actually make some sense from
a weight standpoint if you consider amps intended for
DXpedition style operation. Of course this assumes that all
of the circuitry needed to linearize the amplifier can be made
to weigh much less than the transformer weight that its
replacing.
One of the operators from the C5Z multi-multi team showed me
his spreadsheet where he tabulated the weight of everything
he took (down to the toothbrush). Their air carrier - Ghana airlines
had a 2 bag x 70lb/bag/passenger weight limit. As it turns out
an Alpha 78 weighs just a hair under 70lbs :):)
73 de Mike, W4EF.....................................
----- Original Message -----
From: <amps-bounces@contesting.com>
To: "Dr. William J. Schmidt, II" <bill@wjschmidt.com>; " AMPS"
<amps@contesting.com>
Sent: Wednesday, December 17, 2003 1:52 AM
Subject: Re: [Amps] Big Solid State Power Amplifiers
> ** I have yet to hear a Ham station on SSB who is getting 90% efficiency
> from his/her linear amplifier. My SB-220 linear amplifier probably uses
> c. $1.20 worth of electricity per month. Going to 90% efficiency to save
> a quarter a month would not make economic sense.
>
> Thank you, Dr Schmidt
>
> >Well, lets look at this logically.... and for the sake of argument use a
> >real example... the Harris DAX series. This box uses the digital
adaptive
> >(phasing) modulation circuitry. The AM wave form in the exciter is
> >digitally generated and non-linear. BUT every ham on the planet knows
you
> >CANNOT use this form of modulation in the ham bands... so toss the
exciter
> >and phase correcting module out the door as step one. What's left is
group
> >of very linear very wide band Mosfet amps. By terminating the combiner
to
> >replace the modulation phaser, you now have a wonderful high performance
SS
> >linear to use with your favorite radio.
> >
> >Its been done before.
> >
> >Sincerely,
> >
> >Dr. William J. Schmidt, II K9HZ
> >Trustee of the North American QRO - Central Division Club - K9ZC
> >
> >"Collector of Edison Wind-up Phonographs... Do you have one for me?"
> >Email: bill@wjschmidt.com
> >Alternate Email: wmschmidt@charter.net
> >WebPage: www.wjschmidt.com
> >
> >
> >
> >----- Original Message -----
> >From: "R. Measures" <r@somis.org>
> >To: "Dr. William J. Schmidt, II" <bill@wjschmidt.com>; " AMPS"
> ><amps@contesting.com>
> >Sent: Tuesday, December 16, 2003 4:21 AM
> >Subject: Re: [Amps] Big Solid State Power Amplifiers
> >
> >
> >>
> >>
> >> >This couldn't be farther from the truth...
> >>
> >> ** Dr. Schmidt. Please explain why high-efficiency BC-type designs
are
> >> suitable for applications where linear operation over a range of
> >> frequencies is required. Tnx
> >> >
> >> >Sincerely,
> >> >
> >> >Dr. William J. Schmidt, II K9HZ
> >> >Trustee of the North American QRO - Central Division Club - K9ZC
> >> >
> >> >"Collector of Edison Wind-up Phonographs... Do you have one for me?"
> >> >Email: bill@wjschmidt.com
> >> >Alternate Email: wmschmidt@charter.net
> >> >WebPage: www.wjschmidt.com
> >> >
> >> >
> >> >
> >> >----- Original Message -----
> >> >From: "R.Measures" <r@somis.org>
> >> >To: <gw4dgu@blaenffos.org>; " AMPS" <amps@contesting.com>
> >> >Sent: Monday, December 15, 2003 10:25 AM
> >> >Subject: Re: [Amps] Big Solid State Power Amplifiers
> >> >
> >> >
> >> >>
> >> >>
> >> >> >I don't know what designs you are familiar with, but combiner
losses
> >> >don't
> >> >> >usually impact significantly on efficiency. That's why they are
used
> >in
> >> >> >high-efficiency AM BC transmitters...
> >> >> >
> >> >> **High-efficiency BC-type designs are not suitable for applications
> >where
> >> >> linear operation over a range of frequencies is required.
> >> >> _______________________________________________
> >> >> Amps mailing list
> >> >> Amps@contesting.com
> >> >> http://lists.contesting.com/mailman/listinfo/amps
> >> >
> >> >
> >
> >
> _______________________________________________
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