I am building a 1/4 wave vertical for 30 and 40 meters with a coax trap. In order to do the initial measurements, can anyone tell me if the 30 meter length includes the trap or if the 30 meter length
about 32 feet depending on the diameter of the vertical. The larger the diameter of the vertical the shorter for a given frequency. The length above the trap to resonate on 30 Meters will depend on
Author: "David J. Sourdis - HK1A" <hk1kxa@hotmail.com>
Date: Mon, 19 Apr 2010 00:16:42 -0500
Tell me if I am wrong: The trap should be for 30m band, 10,1 MHz, not for 7MHzFrom the bottom of the vertical to the bottom of the 30m trap is around 1/4WL at 10.1 Mhz. NOT AT 7 MHz.At 7 MHz the RF i
You forgot to mention that the full length on 40 is reduced because the trap acts as a loading call. IE, full length will be less than 33 feet. This also reduces the drive impedance on 40 to less tha
The trap should be a 30 meter trap located about 24 feet up. Rick N6RK _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk
Rick, you are correct, I was in a rush and had my thinking backwards. depending on conductor diameter. The trap should be resonant at about 10 MHZ. It is better to error on the low side. On 40 meters
David You are correct Dan Schaaf K3ZXL "In the Beginning there was Spark Gap" www.k3zxl.com -- Original Message -- From: "David J. Sourdis - HK1A" <hk1kxa@hotmail.com> To: <towertalk@contesting.com>
Forget the trap idea. Put a 1/4-wavelength of 75-ohm coax between your 50-ohm feedline and the feedpoint. The antenna will work on both bands if you use a tuner at the rig. Don't ask me why, but I've
The antenna is designed and built and ready to raise. It was just a simple question about if the trap is included in the resonant length or not. I have worked 308 countries on 30 meters with trap ver
Don, My friend W5EW used a Carolina 80 Windom that he could only get 40 feet up in the center and the ends were a mere 12 feet off the ground. Not satisfied with the results on 30 he looked at all th
I am replacing the 6 BTV with this antenna for low bands. 80 meters on the 6BTV has a way too narrow bandwidth. And, short verticals just don't cut it for long haul in my experience. I could not work
Even better solution - put variable capacitor at the base of antenna to shorten it electrically for 30m band, and add a relay to shorten capacitor when antenna is used on 40m band! After you find the
Yes, I used to have a vertical like that in the early days of 30m. Worked perfectly. No tuner needed. Rick N6RK _______________________________________________ _______________________________________
Of course, the trap doesn't have to be resonant in-band. In fact trap losses are highest when the trap is resonant at the operating frequency. 73, Steve G3TXQ ________________________________________