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best antenna for 9040mfj qrp rig

Dec 13th 2012, 01:06

WD9DMM

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I am limited for space.Not enough room for the 66 ft wire
suggested with 33 ft of ladder line etc.Maybe someone can tell
me another way.With only 5 watts Icant afford to loose much power.
Many thanks---Matt Furlong wd9dmm
Dec 13th 2012, 18:11

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

A vertical over a salt marsh is the best that I've seen in my several decades as a ham.

A vertical will fit in a smaller space, but most hams need to put in a good radial system to reduce system losses. A small vertical, shorter than 1/4 wavelength, will need some method of measuring and tuning the system to resonance. An antenna analyzer would be ideal for tuning an antenna system.

A Four-band "Tree" Vertical
QST November 1995, pp. 69-70
http://www.arrl.org/files/file/protected/Group/Members/Technology/tis/info/pdf/9511071.pdf
If the thought of a high-visibility HF antenna leaves you cold, it's time to branch out and get to the root of the problem...

A transmitting loop is another small space option, but the costs rise as you use better parts, such as copper tubing instead of wire, to keep losses low. It can also be a hassle to tune--not like a full size dipole, which I've found to work well as a "plug and play" antenna.

Here is a design by Chris Trask N7ZWY
http://home.earthlink.net/~christrask/Transmitting20Antenna.pdf

Zack Lau W1VT
ARRL Senior Lab Engineer
Jan 21st 2013, 16:10

NN4RH

Joined: Nov 12th 2002, 07:47
Total Topics: 0
Total Posts: 0
Quote by WD9DMM
I am limited for space.Not enough room for the 66 ft wire


How much room DO you have?

A simple ground-mounted vertical with a bunch of radials around it would do fine on 40 meters. If it's ground mounted, you don't need 66 feet for the radials - just fit in whatever will fit. No salt marsh needed. I don't remember there being a lot of salt marshes in Illinois when I lived there . . .

The Hustler BTV series of verticals or the Butternut HF verticals with ground radials would give you multiband capability.

If you're feeding with window-line and you have a wide ranging manual tuner such as an MFJ 949E, you can still work 40 meters even if the dipole isn't 66 feet long. 50 feet should work.

Other options might be linear loaded or inductively loaded dipoles which can be designed to fit in shorter spaces.
Jan 22nd 2013, 09:02

K5ITM

Joined: Jan 18th 2013, 04:56
Total Topics: 0
Total Posts: 0
I have had excellent results with the Alex Walkham loop... right from my living room couch even. :)

http://www.eham.net/reviews/detail/9012
Jan 26th 2013, 04:08

KE4LJH

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
There is an interesting antenna for qrp I found on YouTube.com
once there type the following into the YouTube search:
20/40 m END FED ANTENNA - PFR 3A Demo
This is a vertical antenna thrown up into a tree for support.
It's 34 feet of insulated wire and uses a banana plug to insert into the back of a radio or tuner if available. A half wavelength of wire will repeat the impedance of the transceiver if cut to the right length so no tuner is required if not available. This antenna is also a quarter wavelength vertical on 40m. Steve KE4LJH
Jan 26th 2013, 04:27

KE4LJH

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Here is another nice antenna project I found on YouTube. Type into the YouTube search: Portable Field Antenna Project
It's a 3 band "Lambda" antenna. Made from nothing but wire. Very simple. Steve Sherer KE4LJH

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