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Something about radios for once.

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Bill Baka

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Nov 21, 2009, 4:41:20 PM11/21/09
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I would like to start a thread about antennas, like how to build some
oddball indoors types, outdoors, matching networks, and any other pet
projects involving the front end of a radio and what you can feed it for
the best DX'ing. This is receive only so nothing too fancy should be needed.
Indoors;
3 loops around the radio room, 1 around the ceiling, 1 around a wall
from floor to ceiling, and another on the other wall. A switch and some
kind of matching network should work well.
1 big wire in the attic (If you have one).
Your turn.

Outdoors;
Single long wire with stake in ground for earth side. Wire is looped
through trees at my house, all trees and no clear spot.
Multiple long wires at different angles with switches to select the one
with best signal.

General;
Antenna tuners, not MFJ or whatever those toy boxes are.
Noise blankers for us with a noisy neighborhood, or mobile.
R.F. amps, tuned or not, tuned preferred.
I have one for B.C. band 540 to 1800 KHz.
It has better 'Q' than the radios I hook it up to.
I built it with a JFET for the amplifier bottom then ran it's output to
a 2N3904's emitter and use the output of the 3904 to drive a loop around
the usual old tube clock radio I am playing with. The tuned circuit sees
no resistance except the wire so the 'Q' is insane.
D.C. to about 30 MHz is where I play most of the time.
Projects or politics and I am tired of the latter.

Bill Baka

dave

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Nov 21, 2009, 4:58:24 PM11/21/09
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You have to have a radio that can handle a lot of millivolts if you're
going to use big antennas. I'd avoid using an amp like that; it's
likely to cause intermods. What's wrong with MFJ?

Bill Baka

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Nov 21, 2009, 5:15:12 PM11/21/09
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I only have one AM station to worry about and that is another subject,
like how to use a tuned circuit to notch it out and get power from it.
There were some articles in the past about using this technique to get
some good use out of the free power for your amplifier stage.
MFJ has been described to me, by a Ham, as Mighty Fine Junk.
I want to roll my own, so to speak, just to keep a bored mind busy.
My pile of parts has a military antenna tuner with some *big* variable
caps and a roller inductor.
I want to build something out of this mess, not just buy more junk,
which by now is probably made in China anyway.

Bill Baka

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