I'm trying to create a largish ferrite receiver antenna tuned
exclusively to the 457khz range. I was going to get the ferrite rod
from he

http://www.stormwise.com/page26.htm

As I only need the single frequency I was wondering if it was more
effective to make a self-resonant antenna?, or does a capacitor not
decrease quality of the single?

Secondlly, I have very little experience in the radio world, and was
considering following am radio plans similar to this to attach my
antenna to:
http://www.stormwise.com/page56.htm

Just swapping the variable capacitor for a fixed one tuned to my
frequency.

Is this the optimal way to get the strongest signal? Can anyone point
me in a direction to get more information on how to build such a
receiver? Most important is the range of the antenna in picking up
very weak signals.

Thanks,
Chris

On Dec 11, 9:18 am, cmor wrote:
I'm trying to create a largish ferrite receiver antenna tuned
exclusively to the 457khz range. I was going to get the ferrite rod
from he

http://www.stormwise.com/page26.htm

As I only need the single frequency I was wondering if it was more
effective to make a self-resonant antenna?, or does a capacitor not
decrease quality of the single?

Secondlly, I have very little experience in the radio world, and was
considering following am radio plans similar to this to attach my
antenna to:http://www.stormwise.com/page56.htm

Just swapping the variable capacitor for a fixed one tuned to my
frequency.

Is this the optimal way to get the strongest signal? Can anyone point
me in a direction to get more information on how to build such a
receiver? Most important is the range of the antenna in picking up
very weak signals.

Thanks,
Chris

Are you trying to build a better avalanche receiver or what? The
trancievers available today seem to be pretty good.

Paul, KD7HB

Are you trying to build a better avalanche receiver or what? The
trancievers available today seem to be pretty good.

Paul, KD7HB

I am, but I'm trying to build a longer range receiving antenna for
specialized purposes, possibly for use in a heli...

On Dec 11, 9:18 am, cmor wrote:
I'm trying to create a largish ferrite receiver antenna tuned
exclusively to the 457khz range. I was going to get the ferrite rod
from he

http://www.stormwise.com/page26.htm

As I only need the single frequency I was wondering if it was more
effective to make a self-resonant antenna?, or does a capacitor not
decrease quality of the single?

Secondlly, I have very little experience in the radio world, and was
considering following am radio plans similar to this to attach my
antenna to:http://www.stormwise.com/page56.htm

Just swapping the variable capacitor for a fixed one tuned to my
frequency.

Is this the optimal way to get the strongest signal? Can anyone point
me in a direction to get more information on how to build such a
receiver? Most important is the range of the antenna in picking up
very weak signals.

Thanks,
Chris

What specific kind of signals are you trying to pick up, and what is
it that will prevent you from hearing them? That is, if the signals
are buried in atmospheric noise, a more "sensitive" antenna that also
picks up more noise as well as more signal isn't going to help the
signal-to-noise ratio. For that, you may need to use some additional
knowledge about the signal that you can use to differentiate it from
the noise. At 457kHz, atmospheric noise is very high amplitude, and
it doesn't take much of an antenna plus receiver to get all the signal
that will do you any good.

On the other hand, if the thing that keeps you from hearing the
desired signal is an interfering signal, the null of a loop (or
ferrite rod) antenna can be used to get rid of that signal that comes
from one direction (which lets you listen more easily to the desired
signal, provided your desired signal isn't coming from the same
direction).

Cheers,
Tom

What specific kind of signals are you trying to pick up, and what is
it that will prevent you from hearing them? That is, if the signals
are buried in atmospheric noise, a more "sensitive" antenna that also
picks up more noise as well as more signal isn't going to help the
signal-to-noise ratio. For that, you may need to use some additional
knowledge about the signal that you can use to differentiate it from
the noise. At 457kHz, atmospheric noise is very high amplitude, and
it doesn't take much of an antenna plus receiver to get all the signal
that will do you any good.

On the other hand, if the thing that keeps you from hearing the
desired signal is an interfering signal, the null of a loop (or
ferrite rod) antenna can be used to get rid of that signal that comes
from one direction (which lets you listen more easily to the desired
signal, provided your desired signal isn't coming from the same
direction).

Cheers,
Tom


The signal itself is coming from an avalanche transceiver ( a pulse at
457khz every second or so) which has a relatively small antenna and
the signal attenuates quickly , most receivers only have about a 25m
straight line range and I'm trying to improve on that. I thought the
small range was due to the weakness of the signal, I'm a bit clueless
as to how much of the problem would be from radiant noise, although
these posts are starting to give me some insight. Thanks for the help
thus far.

-Chris

cmor wrote:

The signal itself is coming from an avalanche transceiver ( a pulse at
457khz every second or so) which has a relatively small antenna and
the signal attenuates quickly , most receivers only have about a 25m
straight line range and I'm trying to improve on that. I thought the
small range was due to the weakness of the signal, I'm a bit clueless
as to how much of the problem would be from radiant noise, although
these posts are starting to give me some insight. Thanks for the help
thus far.

-Chris

As Tom says, once your antenna is good enough to make atmospheric noise
louder than receiver noise, you can't do anything to further improve the
S/N ratio unless you can null out some noise from a single direction (or
opposite directions). And it doesn't take much of an antenna or receiver
to do that at this frequency.

The only way to improve range, then, is to make the transmitted signal
stronger with respect to the atmospheric noise. To do that, you'll need
to increase the strength of the transmitted signal by increasing
transmit power or improving the efficiency of the transmitter antenna.

Roy Lewallen, W7EL

cmor wrote:

...
Thanks,
Chris

Don't worry about the noise.

Construct the best possible setup you can. Pay close attention to
matching the impedance to the receiver. Use quality/high-freq
semiconductors, even better than required/stated--if possible, keep
those noise figures low. Remove the antenna away from any potential
noise source as you possibly can. Keep the antenna as high as you
possibly can. Place the antenna where it will get the largest possible
view of the heavens/horizon. Use as Hi-Q coil/cap as you can, to narrow
the bandwidth as much as can be logically tolerated. Keep the
coax/feeder as short as is logically possible and the run away from
noise sources. Etc. ...

Now, worry about what you can do to help with noise reduction ... if you
find you have too much gain, drop a gain control in ... filters?

Regards,
JS

John Smith wrote:

[his normal chit]

Oh yeah, and by the way, 10-4 'gud buddy! ROFLOL

Just remember, 26-27mhz is radio too! :-)

Regards,
JS

cmor wrote:

...
Thanks,
Chris

Oh yeah, somethin' Roy said, making the antenna "directional."

Lucky you, that ~1ft. long ferrite rod is a dream for it, use aluminum
foil shielding!

Just place some foil on the side(s) of the rod you have no interest in
getting a signal from.

If you doubt the effectiveness of this, wrap a 1ft. "circle" of foil
around the darn ferrite antenna (DON'T short the ends of the foil--so as
to complete a "shorted turn." And, you'll get a lot of silence with
this shield ... you might even find it works rather well. :-)

These guys, most likely, consider you a "slow cousin." Heck, I'll give
'ya the benefit of the doubt--you'll figure it all out--and, probably,
and most likely, quickly!

I like your questions, makes me remember when I played around with
similar stuff ... good luck!

Regards,
JS

Great thought on making it directional, hopefully even the slow cousin
can figure out how to wrap foil.

As for the receiver would a simple MK484 based one suffice? Or would a
Superheterodyne provide better performance?

Lastly is their a cheap commercially available receiver I could plug
my antenna into to compare the performance to my home built one?

Thanks,
Chris