[AMRadio] Minature Mobile Transmitter


Bob Bruhns bbruhns at erols.com
Mon Oct 3 00:39:58 EDT 2005


That's amazing.  Can't argue with success.  And
the 7.5W-300V-16K p-p adds up.  The published
12AX7 plate dissipation spec must be overly
conservative, and the cathode must be pretty
efficient.

I always thought of the12AX7 as an audio preamp
tube.

   Bacon, WA3WDR



----- Original Message ----- 
From: "Mike Dorworth,K4XM" <k4xm at arczip.com>
To: "Discussion of AM Radio"
<amradio at mailman.qth.net>
Sent: Sunday, October 02, 2005 5:20 PM
Subject: [AMRadio] Minature Mobile Transmitter


> >From QST, September, 1952 Class B modulator.
The 12AX7 modulator tube
> delivers approximately 6 watts output.
>
> >From QST, November, 1951  A Deluxe Mobile
Transmitter for 14 and 28 Mc. Two
> 12AX7s- each tube having similar elements in
parallel- operate at zero-bias
> in Class B modulator circuit which delivers
approximately 15 watts output.
> (300 volts)
>
> ARRL Mobile Manual 1st edition, page 178, The
modulator employs a type 12AX7
> tube and delivers approximately 7 watts output.
> 280 volts resting 10 ma, peak 30 ma.
>
> QST, December 1956 . 10-12 watts input 50 mc
mobile transmitter designed to
> operate on the most INEXPENSIVE power supply
readily available (for mobile)
> . The modulator tube is a type 12AX7.....the
modulator plate current should
> jump 20 to 25 ma above the no-signal value of 6
ma.
>
> >From ARRL Handbook, 1960,  37th edition, page
V17,  12AX7, 300 volts, 0
> volts grid bias load resistance 16 k ohms output
power 7.5 watts.
>
>
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