On 07/10/2012 22:09, Hal W5GHZ wrote:
Whats is the point? Your friend is wanting a linear amplifier that has a
narrow tuning range of 200 KHz, 14.150 MHz to 14.350 MHz., assuming he is
an Extra. Why does he want to eliminate the lower portion of the band?
He could purchase an Ameritron 500 watt solid state amp and leave the
band select switch in the 20 meter position. He could then reduce the
drive to the point that he only gets 300 watts out. Then when he finds
out that he is frying his brain operating with that much power only two
feet from his head, He can sell the amp to someone that can make more
use of it. His money would be better spent on improving the efficiency
of his antenna. I have always thought that a small trailer a few feet
behind the bike with an antenna mounted in the center would give me a
taller antenna with slightly more ground plane. It would also reduce my
exposure to RF. It would also improve reception. One could also put
more batteries in the
trailer and have more operating time at the camp site if he were going
on a trip. Then he could string out a dipole and run 500 watts and maybe
40 meter DX at night. Now that makes much more sense.
However, if he really wants to spend the extra money for a custom made,
single-band linear amplifier, I would be happy to design and build him
one at a premium price.
I assume that by "simple", your friend means cheap. If that is the case,
then I suggest he find a bootleg CB amp at the required power output.
These amps are broadband 40-10 meter amplifiers with no filtering
(cheap). He would have to reduce the drive so as not to burn up the amp.
They have no filtering so they might not meet FCC specs., however he can
always build a 20 meter output filter if he values his license. There
are plenty of filter designs in the ARRL handbook. I would think about
putting a fan on an amp like this.
Hal W5GHZ
I find myself looking for the [Like] button to click ;-)
Yep, turning one of those CB amps into a relatively clean ham monobander is
very easy. By "clean" I mean around the same poor mid to high -20's IMD of
any 12V SS transceiver or legitimate ham amp.
With one of those its GIGO+
Carl
KM1H
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