Adding external antenna to clock radio?

[Todd K.]

I have a clock radio that gets lousy reception in my office at work.
I want to experiment with adding external antennas to it. Maybe a
half-wave looped dipole for FM and a small external loop for AM.

My question is how to add the external connection.

The radio has a loopstick ferrite antenna (I presume for only AM) The
loopstick has 4 connection points. 2 of them are on the same circuit
trace which only goes between these two points and nowhere else (what
might this be for?). The other two, one goes to DC ground and the
other goes off into the circuitry of the radio. If I solder leads to
these four points, is that my external connection for only AM or both
AM and FM?

I presume the FM antenna is the power cord because that is commonly
done in radios of this type and adjusting the shape of the power cord
just right picks up my FM station in question, 88.7 MHz. How can I
add an external connection in this case?

TIA,

Todd K.

[Pawel Stobinski]

Post by Todd K.
I have a clock radio that gets lousy reception in my office at work.
I want to experiment with adding external antennas to it. Maybe a
half-wave looped dipole for FM and a small external loop for AM.
My question is how to add the external connection.
The radio has a loopstick ferrite antenna (I presume for only AM) The
loopstick has 4 connection points. 2 of them are on the same circuit
trace which only goes between these two points and nowhere else (what
might this be for?). The other two, one goes to DC ground and the
other goes off into the circuitry of the radio. If I solder leads to
these four points, is that my external connection for only AM or both
AM and FM?

LW/MW AM bands usually look similar in popular medium-class radios. It's a
resonat circuit tuned with a variable capacitor, the inductor is just the
ferrite-rod antenna. 4 wires you've found are proably used for 2 bands: LW
and SW. Find two of them leading to ground, the left two are these, which
are connected to rotors of variable caps. Connect a wire through a 100pF
capacitor, that should improve reception a bit. In case you come across
troubles with noise level or other distortions, try winding some insulated
wire round the ferrite rod and then connect the ends to a loop.
The last thing you could do is to connect a variable capacitor to the loop
in parallel, tuning for best reception.

Post by Todd K.
I presume the FM antenna is the power cord because that is commonly
done in radios of this type and adjusting the shape of the power cord
just right picks up my FM station in question, 88.7 MHz. How can I
add an external connection in this case?

First you've got to do is to isolate an FM aerial signal inlet, somewhere
close to the FM tuner circuitry. There might be a series coil for aerial
lenghtening and insulating circuit, beware of high voltage on caps from AC
decoupling. Once you've got FM tuner input, the only thing is to connect
external wire. Besides, having a schematic diagram, there oughtn't to be any
problems about it.


--
Pawel Stobinski
Republic of Poland

[Cecil Moore]

Post by Todd K.
My question is how to add the external connection.
The radio has a loopstick ferrite antenna (I presume for only AM) The
loopstick has 4 connection points.

What has worked for me is to wrap a good number of turns
of #30 insulated wire around the loopstick. Ground one end
and tie the other end to an external jack. Run a long wire
antenna from the jack to wherever works best.
--
73, Cecil, W5DXP

[Viðarr]

One way to add an external FM antenna is to create a folded dipole out of
some twinlead. Use another length of twinlead for the feedline.
"Terminate" the other end of the feedline by connecting the two conductors
with a 330 Ohm resistor, leaving one of the leads long. Use that lead to
attach the antenna to either the whip antenna that comes with the radio, or
the connector on the back. (This worked well enough in my college dorm room
'way back when.)

What W5DXP said for the AM problem. Wrapping some wire around the radio
itself (assuming a plastic case) sometimes works too, but not quite as well.

NØKF

Post by Cecil Moore

Post by Todd K.
My question is how to add the external connection.
The radio has a loopstick ferrite antenna (I presume for only AM) The
loopstick has 4 connection points.

What has worked for me is to wrap a good number of turns
of #30 insulated wire around the loopstick. Ground one end
and tie the other end to an external jack. Run a long wire
antenna from the jack to wherever works best.
--
73, Cecil, W5DXP