In article ,
flipper wrote:
Okay, so I like to make up cutesy names 
I wanted to do 'something' with a 6ME8 so I tried using it for an AM
transmitter and the first prototype works rather well. Bandwidth is
'too much', less than 1 dB down at 18 KHz, but we'll worry about that
later.
This is a 'dollar days' special, 2 whole bucks worth of tubes, and L2
is a UHF converter coil scramble rewound, so that was 'free'. Power
supply is from the same converter and if the remaining issues get
worked out it'll probably end up in that cabinet as well (but where to
put the air variable?).
The schematic is rough, but should be rather self explanatory, and the
ganged tuning hasn't been fleshed out yet. I'm still using separate
caps while jiggling things around.
Orphaned web page, not yet ready for prime time, has a recording of it
playing through a table radio.
http://flipperhome.dyndns.org/Beamus.htm
Hi Flipper,
This transmitter has been bouncing around in the back of my head for the past
week because something didn't seem quite right but I couldn't put my finger on
it until this morning when I jumped out of bed.
The problem is that there is nothing wrong with the transmitter concept, except
that it doesn't take advantage of the 6ME8 in the way one might have hoped based
on your previous comments on the tube.
Applying the modulation to G1 doesn't take advantage of the beam deflection
capabilities of the tube and instead uses it in a way that a more ordinary tube,
like a dual control pentode, could serve.
Why not connect the 6ME8 cathode-grid circuit as a Hartley oscillator circuit,
as I think you have suggested in earlier posts, and connect the modulation
signal to the beam deflection plates? I suppose the downside of this scheme is
that it would require a balanced push pull RF output transformer to achieve full
modulation, and building such an RF transformer could be a non trivial project
in itself.
I forgot where you are buying your 6ME8s for a dollar apiece, could you refresh
my memory?
--
Regards,
John Byrns
Surf my web pages at,
http://fmamradios.com/