On (02 Jul 96) Steve Eizenberg wrote to Ray Wade...
-> SE> is there anyone that can solve my ant problem? my problem is i
-> SE> can't put up any outside ant's in the apt building i live in so
-> SE> I put up a  horizontally polarized inverted V ant in my radio
-> SE> shack. it is 21 feet  each side. it is the best that i can think
-> To calculate the length (in feet) of each half of a dipole you divide
-> the freq in Mhz into 468. Your antenna dimensions would be suitable
-> for 22.285 Mhz. Is that where you are trying to operate? There is no
-> ham band there.......
 SE> i lenghtened the ant to 23' each side and i have a mfj 900 ant tuner.
 SE> also i founded the source of the rfi it was the cable tv box tn my
 SE> shack but i still have the problem with weak sig. i have messed around
 SE> with
 SE> all kinds feed lines in atempt to make it work better with no luck.
What band(s) are you trying to operate on?
What class of license do you have? (all bands are not available to all
license classes)
What kind of feed line are you using?
You keep calling your antenna an "inverted V". An inverted V is a
"drooping dipole". The center is supported at the highest point
(typically a tower or a pole or a tree etc) and the "legs" taper down
from the center, thus forming an inverted "V" shape. If you are
truely trying to erect an antenna inside a structure (your apartment)
then I fail to understand how it can be (or you would want it to be) an
"inverted V".
Is it an inverted V or is it not? If not, it is a dipole!
The simplest antenna you can use is a (horizontal, not drooping) dipole
fed with 52 ohm coax and *no* tuner. To get the maximum signal in/out
the antenna should be resonate. So, considering the maximum length
possible of your dipole is 23 feet each side (I assume you have put it
in the attic or on the ceiling and the longest straight run available is
46 feet total) the bands you can use are:
15 meters (22.02 feet each side for a center frequency of 21.250 Mhz)
12 meters (19.5                d i t t o                  24 Mhz    )
10 meters (16.42               d i t t o                  28.5      )
Get some sort of center insulator to isolate each side.
Solder the center conductor of the coax to one side of the dipole and
the shield (braid) to the other. RG58 and RG8 are both 52 ohm coax. RG58
is cheap and will work fine for up to 1000 watts or so, even on 10
meters.
Suspend the antenna somehow (tape it to the ceiling of your apartment?).
Do not use nails or wire. Keep it as far as you can from any other wires
(like electrical wires in the attic) or metal conductors (like the metal
supports on a suspended ceiling) running *in line* with the antenna. If
you *must* be near some conductor, put the antenna "crossways" to it.
Put (solder) a PL 259 connector on the bottom end of the coax feed line.
Run the feed line *straight away from the antenna (90 degrees)* for the
longest distance possible (put your radio right in the center of the
room?)
Screw the connector onto your radio coax connector.
Tune to the frequency you made the dipole for.
What you hear is the *best* that you are going to hear with *any*
antenna you can put up, other than a "gain" antenna (like a beam).
The antenna should "load" (take power) with very little reflected
power. It should work for frequencies each side of the center frequency
for about 2% of the center freq, with less than 2 to 1 reflected power.
No tuner needed!
... Why give her diamonds? She won't LIVE forever...
--- PPoint 2.00
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