ARRL

W1VT

Joined: Sat, Apr 4th 1998, 00:00 Roles: N/A Moderates: N/A

Latest Topics

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Antenna analyzer vs feedline type Sep 21st 2012, 14:37 1 1,205 on 21/9/12
USB to Serial Port problems--Prolific Drivers Aug 3rd 2012, 18:27 1 1,469 on 3/8/12
Italian Phishing emails! Dec 13th 2011, 14:20 1 1,276 on 13/12/11
John K0GMO needs help designing SS Amp Nov 17th 2011, 15:53 1 1,157 on 17/11/11
1 Farad Capacitor to Eliminate Headlight Flicker? Oct 19th 2011, 13:14 4 2,003 on 9/11/11
History of Relay Rack Dimensions? Oct 17th 2011, 12:58 2 1,373 on 25/10/11
Miswired Selsyn Oct 13th 2011, 17:51 1 1,223 on 13/10/11
Stealth Antenna wire Sep 12th 2011, 12:51 2 1,767 on 13/9/11
Designing a ham bench Aug 29th 2011, 12:38 2 1,843 on 29/8/11
Can't find recent Hint and Kink Aug 26th 2011, 13:01 1 1,766 on 26/8/11

Latest Posts

Topic Author Posted On
Dipole or loop? KO0Y 3 days, 7 hours ago
Another option may be to put up a wideband 80 meter antenna.

http://rudys.typepad.com/ant/files/antenna_broadband_dipole.pdf
Here is a clever open sleeve design by Rudy, N6LF--that actually covers frequencies above and below the 80M band!
Dipole or loop? KO0Y 5 days ago

You are seeing a resonance shift because of the mismatched feedline.

A shorter length of 300 ohm feedline may move the resonance up and make the impedance at 4.2 MHz easier to match. But, accurate prediction are hard, given the way wire antennas interact with the surroundings.

You may want to experiment between several of the most practical antenna choices for your station--combinations of wire and feedline lengths. Take good notes. Then, go back to the one that works best.

If you have a lot a room, it may make more sense to put up two (or more) antennas to meet your needs.

Zack W1VT
ARRL Senior Lab Engineer


My first antenna questions ... tuulen 1 week, 3 days ago
An OCFD isn't balanced. As a result, no matter how you orient the feedline, the feedline will affect the tuning. This is distinctly different from a center fed dipole--in which bringing down the feedline properly will minimize the tuning interaction.

Typically, one uses an OCFD to eliminate the need for open wire.
Open wire, while an effective way to minimize losses, can create the issue of wide impedance swings that are difficult for a tuner to match without excessive loss or voltage breakdown. So, while open wire can be made to work, you may need to experiment with different line lengths.

At present, nobody has found a good simple all band HF antenna--one that will operate from 80 through 10M with reasonable efficiency on all bands and no need for cut and try. Perhaps the closest is an inverted-L with an autotuner at the feedpoint. But, this antenna needs a radial system with good efficiency, and many hams would prefer to keep all the electronics in the shack.

Zack Lau W1VT
ARRL Senior Lab Engineer

Morse code pocket transceiver? KC9UNY 1 week, 3 days ago
Dave Benson of Small Wonder Labs produced a kit for exactly that--it will even run off a 9V battery that also fits into the Altoids tin.

http://www.w0ch.net/rock-mite/rock-mite.htm

Dave has retired, but kits are still available from another source.

http://www.qrpme.com/

Zack Lau W1VT
ARRL Senior Lab Engineer
random wire antenna WD9DMM 1 week, 4 days ago
http://www.w8ji.com/house_ground_layouts.htm

I'd suggest studying this page to choose the best way to bond your station ground to the service entrance. For lightning protection, you want a quick land easy path for lightning from your service entrance to the shack ground.

Zack W1VT
ARRL Senior Lab Engineer

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