the BC250L's grid/driver plate
coil is NOT on a bakelite form. It is a ceramic one, 2 1/2 inches in
diameter.
I still get the exact same grid drive on 160 meters as I did on the
broadcast
band. My problem still remains efficiency, and maybe I'll just have to
settle
with 61% and be happy.
Efficiency is often a function of the tank circuit Q.
Lower Q often gives more efficiency.
It can be quite dramatic if you are far off.
Grid bias needs to be way beyond cutoff, and with a
lower Q, efficiency should go up.
I did some experiments on the push pull 812 rig when it was done.
I was
I made a set of interesting measurements with my spectrum analyzer on a
Drake TR-7 driving a L-4 amp. Set the output at 1kw through a W-4
wattmeter into a dummy load. Harmonics looked good, down quite a
ways. Crank the TR-7 up a bit to the L-4 and the power went up to 1100
watts. The
PROTECTED] On Behalf Of Larry Taft
Sent: Wednesday, September 29, 2004 3:19 PM
To: Discussion of AM Radio
Subject: RE: [AMRadio] Re: Gates BC250L efficiency
I made a set of interesting measurements with my spectrum analyzer on a
Drake TR-7 driving a L-4 amp. Set the output at 1kw through a W-4
The measurements were done several years ago with an old HP 851/8551
analyzer and I didn't write down the data. I'll do the tests again with my
Tek 2712 and plot the results. The only question is When?
What I see in my rounds of making the NRSC spectrum plots on AM broadcast
stations is an
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