In article ,
"HankG" no_one@invalid wrote:

"Telamon" wrote in message
..
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In article ,
"HankG" no_one@invalid wrote:

My primary antenna is a 33 ft folded dipole made from 300 ohm twin
lead and is mounted in my roof. It is coupled by a 300 to 75 ohm tv
transformer to 75 ohm coax. The antenna is described in message 2471
of the Yahoo Rx-320 group and works fairly well.

Recently, I acquired 3 rolls (40 ft each) of indoor 300 ohm coax, a
closeout at Radio Shack. On checking my house diagram (drawing), I
determined that I could run another antenna which could run about 100
feet if I include my garage. This is measured from left rear roof,
through a wall, diagonally to front right garage (plus a 20 ft wrap
on each end).

I'd welcome any suggestions from the group on an antenna
configuration such as dipole, folded dipole, twinlead converted to
long wire (doubled back on itself), etc. This would be for SW
reception, but MW would be a plus. Thanks.

You could take two of those 40 foot pieces and make a 80 foot folded
dipole antenna.

Yes. The resonant frequency of an (un)folded dipole of 80 ft would be about
5.85 Mhz. My current antenna (resonant at 14.18 Mhz) uses a twinlead stub
which supposedly confers a broader bandwidth. I have used it to monitor 160
meters and works fairly well in the single digits. Is there a formula for
calculating stub length to give this 80 footer greater bandwidth?

According to a Joe Carr antenna book I have this:
In meters
A - 141.8 / F MHz - Over all length or distance between outer shorts
B - 122 / F MHz - distance between inner shorts

In addition you could leave the outer shorts open then it would be:
A - 142 / F MHz - Over all length or distance between outer ends
B - 122 / F MHz - distance between inner shorts

Example for 9.75 MHz is
A = 14.56 meters
B = 12.51 meters

Some of the Radio Shack 300 / 75 ohm transformers are not much good
below 10MHz.

Interestingly, I acquired the transformers (2 on a card) at the local dollar
store. Works fine.

Well, it depends on which one you got your hands on. On some the S21
falls off below 10MHz and you were talking about a lower frequency
antenna so just watch out for that.

--
Telamon
Ventura, California