"Dave" wrote in message
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"Ralph Mowery" wrote in message
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"Dave" wrote in message
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Hey Ralph, thanks for coming in. I am wondering though if I can't tune
out some of the noise,and eliminate more with a directional antenna
(which I currently don't have.) Would an IF stage not help me here? Or
a second tuning function, on the output? Just wondering.

Do appreciate your comments. If I'm wrong I'm wrong, I was just
thinking these things might help. No? The signal I am trying to clean
up is at 9335 kHz.


Dave you started with a simple whip 40 some inches long. As I mentioned
, no mater how much amplification you have , the local and not so local
noise will limit the ammount of amplification you can use. All you will
amplify is noise. Lets say you have a noise floor of .3 microvolts and a
signal is picked up from the antenna of .4 microvolts. Your signal will
be higher than the noise and you can hear it to some extent. If the
noise is .5 microvolts and you get the same signal , then you will not
hear the signal. If you add an amplifier (one that has no noise of its
own , which is impossiable bu the way) you may get .8 uv of signal, but
you will then have 1.0 uv of noise and you will still not hear the
signal. The amp may add .1 uv of noise so you then get 1.1 uv of noise
and only .8 uv of signal.

You may change the antenna to a tuned loop. Take a couple of sticks
about 3 feet long and make an X out of them and wrap a few turns of wire
around the outside of the X so you have a loop about 3 feet square and
tune it with a capacitor to the frequency you wish to hear and it will be
somewhat directional. That may help.

The main thing is that a 3 foot whip in the house is not going to be a
very good antenna for shortwave.



Huuuuhhhh. Okay, I think I am beginning to understand. At least, when you
put it in those terms.

I had thought about using a loop, but for some reason decided to try the
whip first. I guess 'cause that's what I had handy, and I wasn't sure how
I would mount a loop. Until I can figure that out, I am going to try
tuning the output of the RF amplifier the same way I tune the input. If I
can work out the last detail of doing that.

Your words, and numbers, are much appreciated. And your patience.

Thanks, Ralph.

Dave



Okay, tuning the output along with the input does help, but it's still very
close to what the built in whip on the 7600GR does. The only real
difference between now and before is less noise, which makes the
intelligence more accessible (easier to understand what they're saying.)
Time to try the loop, for directional input. I still wonder if something I
thought about a while back might work, which is to mount a second whip on
the other side of the case and seperate them with coax internally. I had
some numbers in mind at one time, but have forgotten them. Roy Lewellan
suggested I try EZNec, but I haven't been able to dedicate as much time to
it as I thought I would. And someone I met is mailing me a copy of the CD
from the latest ARRL Antenna Handbook. It is my understanding that phased
verticles have been completely re-addressed in this latest copy, which
interests me. For some reason books, even on the computer, speak to me more
easily than applications for modeling given situations. Going to go try
EZNec again.

One thing I realized, to my own benefit. The house has steel siding, and
that degrades the performance of the 'whipped' RF amplifier considerably.
Outside, in the driveway, it works as well as it does inside, off of the
external 110' random wire. Which is a better performance by at least a
factor of 10 when compared to inside, off of the whip. I'm going to keep
squeezing this lemon. One way or another. It keeps improving by
considerable steps, I just have to work the bugs out.

Thanks all, for ideas and feedback. And patience.

Dave