[AMRadio] AM Transmitter Advice??


Rev. Don Sanders innatehealing at bigplanet.com
Sat Feb 18 14:06:34 EST 2006


I like my 100 watt linear with four 6AG7"s.

Healthfully yours,
                          DON W4BWS
----- Original Message ----- 
From: "Brian Carling" <bcarling at cfl.rr.com>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Friday, February 17, 2006 6:41 AM
Subject: RE: [AMRadio] AM Transmitter Advice??


> I bet you a BC610 will out-peg a DX100 any day!
> Don't care what the numbers say...
> 
> Grin!
> 
> That 12AX7 linear amplifier sounds like more of a FUN project 
> than a useful station accessory! Just WAIT until the experts 
> start telling you it can't be done, you will only get 30% 
> efficiency and all that jazz! LOL.
> 
> 73 de AF4K, Bry
> 
> On 17 Feb 2006 at 4:29, Jim Candela wrote:
> 
> > 
> > 
> > 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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