I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have used
long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to even
48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?

On Wed, 09 May 2007 17:35:31 GMT, "no spam" wrote:

I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have used
long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to even
48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?


The simplest would be to find a variable capacitor from a derelict
radio. The tuning range and size will force you to build the right
size coil - which is vastly simpler to building the coil first and
then finding the right variable capacitor. Using a cap from a
derelict radio will give you the right minimum to maximum range
variation (often with a max in the region of 360 pF just in case you
cannot find a derelict radio). With the capacitor in its maximum mesh
(or nearly so), you wind the box antenna until you find enough
windings to peak the lowest frequency signal. The upper frequency
signal should also peak when you open up the meshed plates. Mark the
two peaks' positions of the variable cap's knob setting.

To couple to the antenna, construct, or simple extend the existing
loop of your current radio to fit inside the box antenna.

73's
Richard Clark, KB7QHC

"no spam" wrote in message
news
I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used long wires but they are not very directional.

"not very directional"
A loop will have figure 8 pattern with sharp nulls on axis (both sides)

I have found some fairly good plans online

How about posting the URL.

for what looks like wire wound around a box but all of them seem to have
potentiometer in the mix somewhere. It would be very little problem to
build an aimable 18 to even 48 inch frame.

"seem to have potentiometer in the mix somewhere."
I think you mean a variable capacitor.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?
A tap could be done but I think it would be difficult to find the proper
position.
A better way would be to use a switch with two different tuning capacitors.
You
could have the smaller value fixed in the circuit (for 1440) then close a
switch
to put the second larger value in parallel to tune 690 khz.
If the stations are 90 degrees from each other at your location, you might
find one station
in the null of you antenna.
Mike

On May 9, 11:35 am, "no spam" wrote:
I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have used
long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to even
48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?


Like Richard says, it's easier to find an old cap, and build the loop
around the cap. The old analog dial stereo receivers have some of
the best variables for this purpose. Most are multi gang caps, which
often can approach 1000 pf or more if you tie all the gangs together.
This can be handy for wide freq use as you can use switches and
switch gangs in or out of the circuit to change freq coverage.
Most stereo caps also had a few small gangs with low pf values,
which are good for extending the coverage higher in frequency.
Most old AM radios used dual 365pf caps, which would total 730 pf
tied together. This will work ok, but not as switchable as using a
several gang cap.
The cap on my 44 inch per side loop is 5 gangs total, and I have a
switch.
You can also "tack" fixed caps in parallel with the variable to drop
in frequency. For that matter, once you determined the amount of
capacitance for the two frequencies, you could switch between two
fixed caps, but who wants to be limited to two freqs? Once you
start playing with a good loop, you'll probably want to dial around
a bit..
Also, using your present loop as the coupling loop to the bigger
loop would be the easiest route. No actual connection is made.
You just hold the present small loop within, or closely in front of
the bigger loop, and vary distance for max signal. You will notice
the sensitivity vary greatly as you move the loop around. Just
find the "hot spot" and nail it down...
Here is one PVC design I've used.. It's about as simple as I could
conjur up, and all parts can be found at any hardware, home depot,
etc..
http://web.wt.net/~nm5k/loop5.jpg
My big loop is even more simple.. It's just a mast of about 2 inch
PVC, and the cross arm is regular 3/4 inch PVC which I drove
through a drilled hole on the 2 inch PVC. I drilled wire holes
directly in the 2 inch PVC at the top and bottom, and used "T's
on the ends of the 3/4 inch PVC. Same as the one in the jpg...
It sit's on a stand in the room here, and rotates.
If you can't find any old variable caps, they can be bought on the
web...Maybe not real cheap, but they can be had.
Myself, I butcher them out of old analog dial stereos...
BTW, I feed my loops with coax, and have a single wire coupling
loop within the bigger main loop, but I built one of the "jpg" loops
for a guy on the shortwave group, and he used his antenna in the
radio as the coupling loop. He just found the hot spot, and
rigged a mount so he could place the radio in that location
on a little stand or whatever..
MK

"no spam" wrote in message
news
I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to
even 48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?


690 used to be for WAPE a clear channel 50KW station on Jacksonvile FL. I
understand it a 10kw talk radio station now. Is this the 690 you are
refering to.

I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to
even 48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and
one for 1440 then just connect one or the other the radio? How long
would be wires need to be and how would I feed it into the connections on
the radio (coax)?


690 used to be for WAPE a clear channel 50KW station on Jacksonvile FL. I
understand it a 10kw talk radio station now. Is this the 690 you are
refering to.


Yes, 690 out of Jax and 1440 out of Brunswick.

"Richard Clark" wrote in message
...
On Wed, 09 May 2007 17:35:31 GMT, "no spam" wrote:

I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used
long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to
even
48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the radio
(coax)?


The simplest would be to find a variable capacitor from a derelict
radio. The tuning range and size will force you to build the right
size coil - which is vastly simpler to building the coil first and
then finding the right variable capacitor. Using a cap from a
derelict radio will give you the right minimum to maximum range
variation (often with a max in the region of 360 pF just in case you
cannot find a derelict radio). With the capacitor in its maximum mesh
(or nearly so), you wind the box antenna until you find enough
windings to peak the lowest frequency signal. The upper frequency
signal should also peak when you open up the meshed plates. Mark the
two peaks' positions of the variable cap's knob setting.

Simple for you. My electronic education is limited to some high school and
college physics and some 'playing' on my on. IOW, I know a cap isn't
something you wear on your head but 'maximum mesh' sounds like either the
gears in your transmission are working very well or your girl friend is
wearing something sexy.

I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used long wires but they are not very directional.

"not very directional"
A loop will have figure 8 pattern with sharp nulls on axis (both sides)

Long wires aren not very directional.


I have found some fairly good plans online

How about posting the URL.

In no particular order. . .

http://www.mindspring.com/~loop_antenna/
http://www.dxzone.com/catalog/Antennas/Loop/
http://www.mtmscientific.com/loop.html
http://www.frontiernet.net/~jadale/Loop.htm
http://www.dxzone.com/catalog/Antennas/Shortwave/
http://www.schmarder.com/radios/misc-stuff/loops.htm



for what looks like wire wound around a box but all of them seem to have
potentiometer in the mix somewhere. It would be very little problem to
build an aimable 18 to even 48 inch frame.

"seem to have potentiometer in the mix somewhere."
I think you mean a variable capacitor.

One or the other depending on the plans


I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and
one for 1440 then just connect one or the other the radio? How long
would be wires need to be and how would I feed it into the connections on
the radio (coax)?
A tap could be done but I think it would be difficult to find the proper
position.
A better way would be to use a switch with two different tuning
capacitors. You
could have the smaller value fixed in the circuit (for 1440) then close a
switch
to put the second larger value in parallel to tune 690 khz.
If the stations are 90 degrees from each other at your location, you
might find one station
in the null of you antenna.

I think a simple measurement would do it. For 690KHz you could tap it at
1425 feet or at any fraction thereof. For 1440KHz you just use 919 feet.

That was my original plan. To take a 4 foot square frame and put 22 winds
of wire on it. That would give me about 1/4 of a wavelenght of 690. I
could put a tap at the 14th winding to give me a 1/4 wavelenght for 1440.

Mike

I'm looking for plans for a simple AM antenna to connect to my stereo to
replace the little loop antenna that came with it. In the past I have
used
long wires but they are not very directional.

I have found some fairly good plans online for what looks like wire wound
around a box but all of them seem to have potentiometer in the mix
somewhere. It would be very little problem to build an aimable 18 to
even
48 inch frame.

I only have two AM stations I'd like to come in clearer (690 KHz and 1440
KHz). Would it be possible to make a 'box' with one 'tap' for 690 and
one
for 1440 then just connect one or the other the radio? How long would be
wires need to be and how would I feed it into the connections on the
radio
(coax)?


Like Richard says, it's easier to find an old cap, and build the loop
around the cap. The old analog dial stereo receivers have some of
the best variables for this purpose. Most are multi gang caps, which
often can approach 1000 pf or more if you tie all the gangs together.
This can be handy for wide freq use as you can use switches and
switch gangs in or out of the circuit to change freq coverage.
Most stereo caps also had a few small gangs with low pf values,

good stuff cut)

Almost anything is easy if you know how to do it. I was looking for
something really simple w/o any electronic parts in it. I posted several
URLs with plans for building a loop like the one you are talking about. I
naively thought I might just be able to take piece of wire that was a
fraction of the wavelength of the freq and wrap it around a frame and aim it
in the correct direction. But I didn't want to do all the work only to find
out it wouldn't work.

no spam wrote:
Long wires aren't not very directional.

From Wikipedia: "The Beverage Antenna is an inexpensive
*long wire* receiving antenna ... Beverage antennas are
*highly directional.*
--
73, Cecil, w5dxp.com