"Dave" wrote in message
...
Hey Doc,

Thanks for the input. I overslept for the 1300 UTC broadcast of VOK, but
did pick up the 1500 broadcast. Unfortunately the RF amp offers nothing
over the whip that comes with (and already attached to) my Sony 7600GR
portable. More work to be done. Need to tease out the secrets of
impedance matching, as well as add a boatload of additonal amplification.
Damn it's

No mater how much amplification you have, if the antenna is not big enough
or the proprgation is not good you will not pick up a station. There is a
limit as to how much you can amplify a signal before the noise floor takes
over. For signals below 15 to 30 mhz or so the noise floor is very high so
not too much amplification can be used to help with the reception.

"Ralph Mowery" wrote in message
...

"Dave" wrote in message
...
Hey Doc,

Thanks for the input. I overslept for the 1300 UTC broadcast of VOK, but
did pick up the 1500 broadcast. Unfortunately the RF amp offers nothing
over the whip that comes with (and already attached to) my Sony 7600GR
portable. More work to be done. Need to tease out the secrets of
impedance matching, as well as add a boatload of additonal amplification.
Damn it's

No mater how much amplification you have, if the antenna is not big enough
or the proprgation is not good you will not pick up a station. There is a
limit as to how much you can amplify a signal before the noise floor takes
over. For signals below 15 to 30 mhz or so the noise floor is very high
so not too much amplification can be used to help with the reception.



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

Dave,
Would another 'IF' stage, or filtering, or 'nulling', or whatever you
want to call it, help? Sure. But then you start running into the
'practical' thingy again. It can get sort of complicated deciding
what is 'noise' and what is desired signal. DSP does a lot of that
when told how to do it by the controlling algorithms (or is that 'Al-
Gore-isms'? sorry, I know better, just can't help it). The mainest
problem is the time it takes to do that, it is not instantaneous. And
if you are going to make that controlling algorithm variable, the time
it takes makes things even more time consuming, not to mention
difficult. Keeping in mind that simply making the antenna larger/
longer can do about the same thing at less expense (time/work/$$$),
why not? Easy to do with a recording (sort of), very difficult in
real time. Manually doing all that is almost impossible. How do you
decide what to 'do' before it's too late? There are limits with
today's technology. So, put it off till 'tomorrow', right?
- 'Doc

(all puns intended, even the ones I didn't intend)

Hmmm. Yeah. sigh Point taken. I guess this is just my hobby, and I
really don't have anything better to do (other than housework.) I don't
know what to say. Guess I just have to prove to myself that everything that
can be done has been done, or that it's not worth the effort for the
outcome. sigh again.

I do appreciate all of the feedback, and the patience with my ignorance. I
am trying to make this thing work off of a whip for portability's sake, and
am just not willing to accept defeat yet. May not be much longer though...
It does work great on the external antenna, I just want it to work better
off of the whip.

Thank you, all of you who replied. And thank you, doc, for the final simple
analysis. I don't mean to be stubborn, I just have to try everything to
prove to myself that it is as good as it can be. Sorry. Guess I am
stubborn after all.

The hand-holding is appreciated. Sorry if I frustrated you guys. Thanks
again for your patience.

Dave

wrote in message
oups.com...
Dave,
Would another 'IF' stage, or filtering, or 'nulling', or whatever you
want to call it, help? Sure. But then you start running into the
'practical' thingy again. It can get sort of complicated deciding
what is 'noise' and what is desired signal. DSP does a lot of that
when told how to do it by the controlling algorithms (or is that 'Al-
Gore-isms'? sorry, I know better, just can't help it). The mainest
problem is the time it takes to do that, it is not instantaneous. And
if you are going to make that controlling algorithm variable, the time
it takes makes things even more time consuming, not to mention
difficult. Keeping in mind that simply making the antenna larger/
longer can do about the same thing at less expense (time/work/$$$),
why not? Easy to do with a recording (sort of), very difficult in
real time. Manually doing all that is almost impossible. How do you
decide what to 'do' before it's too late? There are limits with
today's technology. So, put it off till 'tomorrow', right?
- 'Doc

(all puns intended, even the ones I didn't intend)

Dave wrote:
I do appreciate all of the feedback, and the patience with my ignorance.

Have you considered a screwdriver antenna? Many hams
try a whip with an autotuner, are dissatisfied, and
wind up with a screwdriver antenna for a 12 dB
improvement, at least on 3.8 MHz.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Dave wrote:
I do appreciate all of the feedback, and the patience with my ignorance.

Have you considered a screwdriver antenna? Many hams
try a whip with an autotuner, are dissatisfied, and
wind up with a screwdriver antenna for a 12 dB
improvement, at least on 3.8 MHz.


-----------


(Spoken in Columbo's voice and mannerisms)"Uh, podden me, Cec, butta,
12db improvement compared to what?"

A 108" whip tuned with an electronic autotuner at the base, on the
trailer hitch attached to an average car should be just as (was gonna
use the words efficient and effective - but thought better of it) as a
short little whip mounted in PVC pipe at the same location, but using a
mechanical tuner (screwdriver) instead of an electronic autotuner such
as an AH-4.

Yes, I have considered a screwdriver antenna, just don't know where to
put it on my minivan(s).

As you can tell, I'm coming in late on this one. Thanks for your patience.


Ed, NM2K

On Mon, 12 Nov 2007 10:51:58 -0500, Ed Cregger
wrote:

A 108" whip tuned with an electronic autotuner at the base, on the
trailer hitch attached to an average car should be just as (was gonna
use the words efficient and effective - but thought better of it) as a
short little whip mounted in PVC pipe at the same location, but using a
mechanical tuner (screwdriver) instead of an electronic autotuner such
as an AH-4.

Hi Ed,

This is a bit garbled, but the sense is there.

You are comparing a bad installation to a bad installation - yes one
will be as efficient/effective as the other.

The tuner at the base of the whip has invested resonance in the wrong
place. A coil at the base of a whip also invests resonance in the
wrong place. A coil higher in the whip invests resonance in the
better places by degree.

Ostensibly, the premium degree of coil placement is one half to two
thirds the way up the whip. A screwdriver antenna attempts to make
this resonance investment. If you will note, the coil section falls
between a lower tube and an upper whip.

There is a world of discussion as to why it is better that I will
leave to others to fill in.

73's
Richard Clark, KB7QHC

Ed Cregger wrote:
Cecil Moore wrote:
Have you considered a screwdriver antenna? Many hams
try a whip with an autotuner, are dissatisfied, and
wind up with a screwdriver antenna for a 12 dB
improvement, at least on 3.8 MHz.

(Spoken in Columbo's voice and mannerisms)"Uh, podden me, Cec, butta,
12db improvement compared to what?"

Compared to the aforementioned "whip with an autotuner".
--
73, Cecil http://www.w5dxp.com

"Dave" wrote in message
...

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.

"Ralph Mowery" wrote in message
...

"Dave" wrote in message
...

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