Re: How to make an antenna for receiving (only) broadcast AM

On Wed, 09 May 2007 17:35:31 GMT, "no spam" <no@xxxxxxxx> 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
.

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