[AMRadio] AM Transmitter Advice??


Gary Schafer garyschafer at comcast.net
Fri Feb 17 11:36:34 EST 2006


Actually the 10 watt ratting on the CE 10A/B is 10 watts PEP input. That
gives around 5 to 6 watts output PEP for available drive.

73
Gary  K4FMX


> -----Original Message-----
> From: amradio-bounces at mailman.qth.net [mailto:amradio-
> bounces at mailman.qth.net] On Behalf Of Bob Bruhns
> Sent: Friday, February 17, 2006 11:23 AM
> To: Discussion of AM Radio
> Subject: Re: [AMRadio] AM Transmitter Advice??
> 
> 12AX7s have surprised me with their power
> capabilities before, but 20 watts output with 30
> watts input is 67% efficiency, and that means that
> the 20 watts output is the PEP output of the
> 3-12AX7 linear.  I think that the 10W rating with
> a 6AG7 is PEP as well.
> 
>   Bacon, W3WDR
> 
> 
> ----- Original Message -----
> From: "Jim Candela" <jcandela at prodigy.net>
> To: "Discussion of AM Radio"
> <amradio at mailman.qth.net>
> Sent: Friday, February 17, 2006 7:29 AM
> Subject: RE: [AMRadio] AM Transmitter Advice??
> 
> 
> >
> >
> > Hi All,
> >
> >    I recently had a conversation with a ham in
> San
> > Antonio (forgot his call), and he told me that
> he
> > built a unique linear amplifier for his central
> > electronics 10a, and for tubes he chose 3 type
> 12AX7
> > in parallel grounded grid. He said he could run
> 30
> > watts input (300v @ 100ma) with no problems, and
> about
> > 20 watts out. I find it odd though that a 10a
> can do
> > 10 watts with a single 6AG7, and 20 watts is
> only a
> > 3db boost.
> >
> > To my way of thinking, a linear amp needs to
> boost
> > your power at least 6 db (~1 'S' unit) to be
> worth the
> > trouble. For us AM'ers, going from 100 watts to
> 375
> > watts carrier does not meet the 6 db boost
> criteria,
> > and that explains why a good antenna on a DX-100
> is
> > better than a average antenna on a Globe King
> 500.
> >
> > Still, as I once posted last year, a dual 304TL
> > grounded grid linear seems to fit the bill as a
> 6 db
> > 'brick' capable of 400 watts AM carrier output
> with
> > 100 watts AM input, or said another way it takes
> 400
> > watts PEP and boosts it to 1600 watts PEP. There
> was
> > an old W6SAI construction project about this
> (single
> > 304tl GG amp), and I recall that the setup in
> class C
> > could run 1 kw dc input with over 1 kw rf output
> > because of the low gain, and massive amount of
> > feedthrough power from the exciter that finds
> it's way
> > to the output. This was a way around the FCC
> power
> > rules of the day.
> >
> > Regards,
> > Jim
> > WD5JKO
> >
> > --- Donald Chester <k4kyv at hotmail.com> wrote:
> >
> > > >Assuming one is going to build a linear, and
> so
> > > putting aside other issues
> > > >such as linear vs plate modulation, why do
> you
> > > think it makes a difference
> > > >what tube is used? Are you referring to
> running a
> > > linear at greater than
> > > >legal limit?.
> > >
> > > Well, go ahead and try building a legal limit
> linear
> > > that runs a pair of
> > > 807's in the final.
> > >
> > >
> >
> __________________________________________________
> _____________
> > >
> > > This message was typed using the DVORAK
> keyboard
> > > layout.  Try it - you'll
> > > like it.
> > > http://www.mwbrooks.com/dvorak/
> > > http://gigliwood.com/abcd/
> > >
> > >
> > >
> >
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