Dave wrote:
It's a 43 inch collapsable antenna (7 segments.) Maybe I just need more
amplification...

For maximum power transfer from the antenna to the
receiving load, you need a matching network, i.e.
a low-loss antenna tuner. What is the dynamic gain
range of the receiving load device?
--
73, Cecil http://www.w5dxp.com

Hello Cecil,

Thank you for the interest, and the question. Last time I had the RF
amplier on the scope and sig generator, it was giving me approximately 100
mV output with something that *looked* like a millivolt or two input
(possibly at much as 5 mV but no more), at 5 and again at 10 MHz. Now, I am
enough of an RF newbie that I *think* this is what you are asking, but if
not then please enlighten me. I think I understand the need for a low-loss
antenna tuner, which I am trying to improvise with a 25 ohm wire-wound pot
acting as an autotransformer, ala The Miracle Whip (QST, July 2001 PP
32-35.) And it seems to be working to some extent, just not in the ideal
way I need. I am able to pick up Radio Nederlands on 6145 kHz (I *think*
that's the frequency) off of the whip, but not BBC Africa on 7160 kHz, even
if the radio stops there and seems to realize that there is something going
on, but just can't pull it out of the mud. I am able to pull in BBC Africa
on 7160 kHz with the external 110' random-wire antenna, and that with a bare
minumun of noise. The whip however, just gives me the noise. I am about to
do some more experimenting with different WW pots to see if I can get
anything better. If all of this sounds totally bat-****, please forgive.
It does seem to work at least half as good as I need however, and I am
hoping to tease out the rest.

Please let me know if I am headed up the wrong creek with my answers. Hate
to say it, but am honestly making this up as I go along (obviously).

Thanks again,

Dave

"Cecil Moore" wrote in message
...
Dave wrote:
It's a 43 inch collapsable antenna (7 segments.) Maybe I just need more
amplification...

For maximum power transfer from the antenna to the
receiving load, you need a matching network, i.e.
a low-loss antenna tuner. What is the dynamic gain
range of the receiving load device?
--
73, Cecil http://www.w5dxp.com

Update: replaced the 25 ohm WW pot with a 1 ohm 4 watt WW potentiometer,
with surprisingly good results. Am now able to pull in BBC Africa on 7160
kHz, although there is a somewhat faint high-pitch whine behind it. Still,
it is definetly intelligable. At least 1000% better than it was. When
attached to the external antenna, it is downright incredible. The only
thing I have trouble picking up with the whip is WWV at 5 MHz (and 2.5 MHz
is out of the question). With the external antenna however, these come
through like gangbusters. The acid test will come at 1300 UTC when I try
to pick up Voice of Korea. If I can pull that out of the noise, I will be
ecstatic. That is what I have been working towards since I started this
project. Oh, and it helps if all your wires are connected, and the one
carrying the RF to the input of the first amplifier stage is not hanging
loose, near it's intended connectionpoint, due to a broken solder joint.
Found that while installing the 1 ohm pot and had to go back and see how the
25 ohm pot performed once the wire was reconnected. Better, but still not
ideal by any means. Then installed the 1 ohm pot, and got surprised. If
you want to see the schematic, I can post it to
alt.binaries.schematics.electronic.

Hoping to hear from you again on how to improve reception further.

Thanks,

Dave

"Dave" wrote in message
...
Hello Cecil,

Thank you for the interest, and the question. Last time I had the RF
amplier on the scope and sig generator, it was giving me approximately 100
mV output with something that *looked* like a millivolt or two input
(possibly at much as 5 mV but no more), at 5 and again at 10 MHz. Now, I
am enough of an RF newbie that I *think* this is what you are asking, but
if not then please enlighten me. I think I understand the need for a
low-loss antenna tuner, which I am trying to improvise with a 25 ohm
wire-wound pot acting as an autotransformer, ala The Miracle Whip (QST,
July 2001 PP 32-35.) And it seems to be working to some extent, just not
in the ideal way I need. I am able to pick up Radio Nederlands on 6145
kHz (I *think* that's the frequency) off of the whip, but not BBC Africa
on 7160 kHz, even if the radio stops there and seems to realize that there
is something going on, but just can't pull it out of the mud. I am able
to pull in BBC Africa on 7160 kHz with the external 110' random-wire
antenna, and that with a bare minumun of noise. The whip however, just
gives me the noise. I am about to do some more experimenting with
different WW pots to see if I can get anything better. If all of this
sounds totally bat-****, please forgive. It does seem to work at least
half as good as I need however, and I am hoping to tease out the rest.

Please let me know if I am headed up the wrong creek with my answers.
Hate to say it, but am honestly making this up as I go along (obviously).

Thanks again,

Dave

"Cecil Moore" wrote in message
...
Dave wrote:
It's a 43 inch collapsable antenna (7 segments.) Maybe I just need more
amplification...

For maximum power transfer from the antenna to the
receiving load, you need a matching network, i.e.
a low-loss antenna tuner. What is the dynamic gain
range of the receiving load device?
--
73, Cecil http://www.w5dxp.com

Dave,
In a nut-shell, a larger antenna will tend to be more 'receptive'
at lower frequencies. Then you can think about matching the
impedances of the antenna system and receiver.
Larger antennas have the 'problem' of being 'larger', as in where
do you put the thing? Reducing the size of an antenna can be more
practical mechanically, but tends to be less practical electrically
(noise, less 'receptive', etc, etc.). Your 'best' bet would be to
find a reasonable compromise between the two kinds of 'practical'
thingys (mechanical/electrical). Usually easier if you can make it
bigger, sort of.
- 'Doc

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

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
hard to compete with a successful commercial product. Still, I have at
least reached the level of performance with the RF amp that the preamp in my
7600GR already offered, with the exception of a little additional background
noise.

Hope I didn't discourage Cecil from trying to help. Sorry if I did. I
don't mean to be ignorant, and it is something I am trying to change.

73 and good DX

Dave

wrote in message
ups.com...
Dave,
In a nut-shell, a larger antenna will tend to be more 'receptive'
at lower frequencies. Then you can think about matching the
impedances of the antenna system and receiver.
Larger antennas have the 'problem' of being 'larger', as in where
do you put the thing? Reducing the size of an antenna can be more
practical mechanically, but tends to be less practical electrically
(noise, less 'receptive', etc, etc.). Your 'best' bet would be to
find a reasonable compromise between the two kinds of 'practical'
thingys (mechanical/electrical). Usually easier if you can make it
bigger, sort of.
- 'Doc

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

"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

wrote in message
ups.com...
Dave,
In a nut-shell, a larger antenna will tend to be more 'receptive'
at lower frequencies.

Agree. Years ago I was an avid broadcast band (BCB) DX'er, usually getting
what I wanted late at night. However, when I installed about a 50-foot
dipole wrapped around the inside of my garage, I found an exciting number of
distant stations available during the day. It seems old hat today, but the
experience was valid, I think.

"Sal M. Onella" wrote in message
news

wrote in message
ups.com...
Dave,
In a nut-shell, a larger antenna will tend to be more 'receptive'
at lower frequencies.

Agree. Years ago I was an avid broadcast band (BCB) DX'er, usually
getting
what I wanted late at night. However, when I installed about a 50-foot
dipole wrapped around the inside of my garage, I found an exciting number
of
distant stations available during the day. It seems old hat today, but
the
experience was valid, I think.



Oh, I understand that a larger antenna is much more receptive. And I have a
110' random wire that does wonders. I am just wanting some sort of
reception booster to take with me if we have to bug out for a hurricane
again. That, and the challange interests me.

Dave

On Tue, 13 Nov 2007 07:31:14 -0600, "Dave" wrote:

I am just wanting some sort of
reception booster to take with me if we have to bug out for a hurricane
again.

Hi Dave,

Was my successful experience of adding 4 meters of wire height too
simple? Didn't it cost enough? Was it too low tech?

That, and the challange interests me.

It would seem the bar is especially low as it is - that or this
appeals to some notion of having a wrist SW radio a la Dick Tracy.

There have been lots of special challenges posted here in the past
that outperform. One might be instructive that several regulars here
might remember: Pound a nail into a tree and connect your whip
antenna to that. Reports would suggest DX opportunities abound.

73's
Richard Clark, KB7QHC