[AMRadio] AM Transmitter Advice??


Brian Carling bcarling at cfl.rr.com
Fri Feb 17 07:41:55 EST 2006


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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