antenna expirement flops
 

I just wanted to share the results an antenna experiment I did tonight. In
the rain, no less.

The antenna was simple. 300 feet of solid core 20 gauge copper wire. I ran
it from the 500 ohm connector of my R-75, out of the shack and all the way
into the back yard. The yard extends about 200 feet, so I had to double the
wire back in the direction of the shack for 100 feet.

No mater what I tune the dial to, I'm getting splashed from the local 50
kilowatt am stations. The preselector doesn't clean it up either.

Every time I exceed 200 feet of wire, I have the same problem.

Weird...

Michael

It's a wonder you didn't get hit by lightning fooling around with all of
that wire out there in all that rain. www.lightningstorm.com
cuhulin

"Michael" wrote in message
...

No mater what I tune the dial to, I'm getting splashed from the local 50
kilowatt am stations. The preselector doesn't clean it up either.

Every time I exceed 200 feet of wire, I have the same problem.

Sounds like your front end is being overloaded by the AM stations. I guess
the simple solution would be to not exceed 200 feet of wire. A 200' random
wire should work well, I'd think. But if you have local 50 KW stations,
then it's not unusual to get a lot of imaging and intermod with a long
antenna.

--
Tom Sevart N2UHC
Frontenac, KS
http://www.geocities.com/n2uhc

What do you mean by "splash"?

I have Beverage antennas of 450 and 700 feet, oriented toward my desired
targets *and* (unfortunately) a number of 50kw MW stations in the
Seattle/Tacoma area. I also have a 1 kw station 1.4 miles off the end of one
of the antennas. I have a number of S-9+65db stations on the dial, but my
R-75 and IC-756Pro handle them well. However, I'm not using the hi-Z input
but the 50-ohm unbalanced input via a Beverage matching transformer and
grounded, double-shielded coax.

Have you tried adding a transformer and the 50-ohm input?

Guy Atkins
Puyallup, WA USA


"Michael" wrote in message
...
I just wanted to share the results an antenna experiment I did tonight. In
the rain, no less.

The antenna was simple. 300 feet of solid core 20 gauge copper wire. I
ran it from the 500 ohm connector of my R-75, out of the shack and all the
way into the back yard. The yard extends about 200 feet, so I had to
double the wire back in the direction of the shack for 100 feet.

No mater what I tune the dial to, I'm getting splashed from the local 50
kilowatt am stations. The preselector doesn't clean it up either.

Every time I exceed 200 feet of wire, I have the same problem.

Weird...

Michael

MICHAEL,

"Guy Atkins" wrote in message
...
What do you mean by "splash"?

I have Beverage antennas of 450 and 700 feet, oriented toward my desired
targets *and* (unfortunately) a number of 50kw MW stations in the
Seattle/Tacoma area. I also have a 1 kw station 1.4 miles off the end of
one of the antennas. I have a number of S-9+65db stations on the dial, but
my R-75 and IC-756Pro handle them well. However, I'm not using the hi-Z
input but the 50-ohm unbalanced input via a Beverage matching transformer
and grounded, double-shielded coax.

Have you tried adding a transformer and the 50-ohm input?

Guy Atkins
Puyallup, WA USA

Hiya, Guy.... That is exactly what I already have currently with one of my
roof antennas, the 200' "Frankenstein. That antenna is ideal !!!! A great
DX'ing antenna. Detailed info is on my web page. See the link in my
signature. I just decided to try the 300' wire with no additional dressings
like transformers or coax feeds. The end result... The local AM flame
throwers are strong enough to overload the front end even on an R-75.

--
Respectfully,

Michael

Location: New Jersey
Primary Receiver: R-75 with full Kiwa mods
Antennas: G5RV, 200ft "Frankenstein" roof wire
Additional Radios: 7600GR,KA-1101,KA-1102
PL-550, KA-989, Info-Mate 837, GE-SR III
Westinghouse H-104 (seven tube)
Web Site: http://md_dxing.tripod.com

"RHF" wrote in message
ups.com...
MICHAEL,
.
First make sure that you have both of your
Icom IC-R75's Pre-Amplifiers turned OFF.

I did and I tried the att also. Even with the att switched on, the local AM
stations still overload the radio. It is just too much wire for my
location. North NJ is the king of the MW transmitters. Lots of ground
water and excellent conductivity. I just cant use that much wire.

Michael


TRY A LOOP ANTENNA :
Re-run the Wire as a Loop-On-the-Ground (LOG) Antenna.
Try to have the Out-Leg of the Loop separated as
much as possible from the Back-Leg of the Loop.
Use the Two HI-Z Terminals of your Icom IC-R75
for the input for this Loop Antenna.
.
USE AN "EXTERNAL" ATTENUATOR :
Build the GIZMO Box and use the built-in Attenuator
to reduce the Signal Levels.
READ - Portable AM/FM Shortwave Radio-to-Antenna
"GIZMOE" Connector Box
http://groups.yahoo.com/group/Shortw...a/message/2070
NOTE - If you use the NE-2 Lite-Bulb and on a 'normal day'
the Bulb is always Glowing or Blinking; then Trim your
Antenna by 25 Feet and check it again - repeat as needed.
.
USE A MATCHING TRANSFORMER AND GROUND :
Continue to use your 200+ Feet Long Wire Antenna
and Build a Voltage Step-Down Transformer :
Use a Ferrite Core with a 25:1 or 36:1 Turns Ratio.
* 25:1 Ratio = Thirty-Five (35) Turns and Seven (7) Turns
* 36:1 Ratio = Thirty-Six (36) Turns and Six (6) Turns
Use a Ground Rod and Wire with this Matching Transformer.
.
CUT THE SIZE OF THE ANTENNA DOWN BY . . . . . . . . .
* Cut the Size of the Antenna from 300 Feet to 250 Feet
and use 50 Feet of Coax Cable as a Feed-in-Line.
* Cut the Size of the Antenna from 300 Feet to 200 Feet
and use 100 Feet of Coax Cable as a Feed-in-Line.
Plus use a Matching Transformer and a Ground Rod at the
junction of the Antenna Wire Element and the Coax Cable.
.
TIP - In the Future - Pick a Dry and Warm Sunny Day 'to do'
your Out-Side Antenna Work :o)
.
.
iane ~ RHF
.
All are WELCOME and "Invited to Join" the
Shortwave Listener (SWL) Antenna eGroup on YAHOO !
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortw...na/message/502
.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
With a Shortwave Listener SWL Antenna of your own making.
"If You Build It {SWL Antenna} You Will Hear Them !"
.
.

wrote in message
ups.com...

Michael:

1: - What 50 watt station ??

2: What kind of Pre selector are you using?
I have a MFJ - 1046 pre selector; It's very good

Dan / NYC

Dan... I hear 66, and 77. My preselector is an MFJ-1048. Same as you have
but you can use it to transmit too. 300 feet is just too much wire here, I
think. My 200 foot antenna is OK, but 300 feet at ground level is just too
much wire. Given the ground conductivity here, I'm not sure if the antenna
was just soaking the signal up MW signals right from the ground.

Check out my two antennas on my web site. Both of these work great. 300
feet was just too much. The link to my web site is in my signature.

--
Respectfully,

Michael

Location: New Jersey
Primary Receiver: R-75 with full Kiwa mods
Antennas: G5RV, 200ft "Frankenstein" roof wire
Additional Radios: 7600GR,KA-1101,KA-1102
PL-550, KA-989, Info-Mate 837, GE-SR III
Westinghouse H-104 (seven tube)
Web Site: http://md_dxing.tripod.com

"Guy Atkins" wrote in message
...
What do you mean by "splash"?

Intermod...

Michael

"Telamon" wrote in message
...
In article ,
"Michael" wrote:

I just wanted to share the results an antenna experiment I did tonight.
In
the rain, no less.

The antenna was simple. 300 feet of solid core 20 gauge copper wire. I
ran
it from the 500 ohm connector of my R-75, out of the shack and all the
way
into the back yard. The yard extends about 200 feet, so I had to double
the
wire back in the direction of the shack for 100 feet.


I used a similar solution with my roof wire. It is folded in a unique
manner. It is debatable whether or not that half the length of the 200'
receiving wire is nulled out because of the way it is folded.

--
Respectfully,

Michael

Location: New Jersey
Primary Receiver: R-75 with full Kiwa mods
Antennas: G5RV, 200ft "Frankenstein" roof wire
Additional Radios: 7600GR,KA-1101,KA-1102
PL-550, KA-989, Info-Mate 837, GE-SR III
Westinghouse H-104 (seven tube)
Web Site: http://md_dxing.tripod.com

what you want to build is a bandpass/reject tunable filter.you can tune it
to notch out the offending bcb station while letting everything else through

--
My Family Website--
http://mysite.verizon.net/res868sp/t...ily/index.html My
Amatuer Radio Website-- http://www.qsl.net/kb9ygd/index.html
http://dx.qsl.net/logs ---Search My Logbook
"Michael Lawson" wrote in message
...

"Michael" wrote in message
...
I just wanted to share the results an antenna experiment I did
tonight. In
the rain, no less.

The antenna was simple. 300 feet of solid core 20 gauge copper wire.
I ran
it from the 500 ohm connector of my R-75, out of the shack and all
the way
into the back yard. The yard extends about 200 feet, so I had to
double the
wire back in the direction of the shack for 100 feet.

No mater what I tune the dial to, I'm getting splashed from the
local 50
kilowatt am stations. The preselector doesn't clean it up either.

Every time I exceed 200 feet of wire, I have the same problem.

Weird...

You might want to put a high pass filter in place between
the longwire and the preselector, nulling out the AM band
as much as possible before the preselector. When I lived
closer to the antenna for WCKY 1530, I homebrewed one
that got rid of the AM BCB band. You can find the schematics
for one in the ARRL handbook or one of Joe Carr's Tech Notes
on DXing.com: http://www.dxing.com/tnotes/tnote06.pdf

--Mike L.


--Mike L.

Wrapping the antenna wire back on itself as you do with "Frankenstein"
or forming the G5RV into a quasi-rectangle is liable to result in an
antenna that performs no better than a single wire as long as the
maximum dimension, especially in directions in the plane of the shape
and perpendicular to the longest side. However, I have heard people
extol the virtues of a bedspring as an antenna - an extreme example of
winding on itself. Of course, the more wrapping about you do, the more
the wire approaches a solid, the limiting condition. Looking at
Frankenstein, I'm reminded of a fat dipole, something like the
"butterfly" antenna element frequently used at UHF. If you connect the
free end and all the criss-crosses to the feed point, it certainly
would be. With an overall length of 82 ft per the diagram, it would
probably have a major lobe pointing straight up around 6 MHz. Height
above ground will control the gain at lower elevation angles while the
slight inverted Vee shape will broaden the lobe towards the narrow
ends. At higher frequencies, the major lobe will divide into smaller
lobes at lower elevations. The fatness factor will moderate the
impedance range of the antenna around its 6 MHz resonant frequency.

I rather doubt that either your G5RV or the Frankenstein are great DX
antennas, the way they are laid out. Both are liable to favour short to
medium distances below 10MHz and are unlikely to provide the necessary
low elevation angle sensitivity for really long DX in all desired
directions at any frequency. I think you would be better off with less
wire, laid out straight to take advantage of directional properties.
Three mutually orthogonal antennas with a switch would be great. Attach
a vertical antenna, say a CB whip or longer, to your chimney, as high
as possible, for one. Run two independent dipoles in a cross pattern,
even an X like you have would be a good compromise, from the chimney.
Then you can switch among them for best reception - often one will
stand out above the others because of direction, polarisation,
frequency, and arrival angle of the incoming signal will best match one
antenna.

Regards,
Tom