A longwire or inverted-L doesn't have to be noisier than balanced
antennas such as a dipole. It's matter of how the coax shield is
grounded/decoupled from the antenna. Here's one way to do it:

http://www.anarc.org/naswa/badx/ante...e_antenna.html




Maximus wrote:

If you don't mind the extra noise, I'd go with a longwire.

"Arthur Harris" wrote in message
. net...
"Lenny" wrote:
I've had my R75 for about 2 years now.
I purchased an Antenna Supermarket dipole, the one with the sealed
traps,

The traps make the dipole resonant at specific frequencies. On those
frequencies the dipole will exhibit the normal broadside pattern. Trap
dipoles tend to have narrow resonant bandwidths at the lower frequencies

Last night was absolutely horrible for listening to foreign stations.
Only
received a few of the strongest ones that were beamed at N. America.

Probably just propagation.

I took a piece of speaker wire, about 25' long, twisted the 2
wires together at each end, stuck
snip
I switched back and forth from the wire to the dipole
and no difference. Hmmmm, strange!
I tuned in a few other stations that were weaker and again, no
difference.

Quantify that. No difference in what your ears heard or no difference on
the
"S" meter.

If the "S" meter reads the same on the dipole as on the 25' low wire,
something is wrong. Check you coax connections.

However, it's not unusual for a poor antenna to produe a similar
"sounding"
signal as a good antenna. Your dipole should be picking up more signal
than
the short wire, but it's also picking up more noise. So the
"signal-to-noise
ratio" your ears hear will often be the same.

Did I waste my money on the Dipole antenna? I can't imagine what 200'
of
wire strung up 25' high in my trees
will sound like.
Now I'm wondering if the Dipole has any advantages over the long wire.
Could some kind soul please explain what is happening?

The trap dipole will have a predictable pattern on its resonant
frequencies.
A 200' wire will have different patterns on different frequencies (not
necessarily a bad thing). I personally don't think it makes sense to spend
a
lot of money on a commercial trap dipole for SWL'ing. A random wire
(doesn't
have to be 200' long) is a very good choice. Signal-to-noise ratio is what
determines readability, not absolute signal pickup.

Art Harris N2AH


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