Terry, I like your numbers better as they use less coax. My series match
program has a flaw that I never noticed in all the years using it: inputting 79
+j.01 gives my numbers and inputting 79-j.01 gives your answers.
Goes to show you can learn something every day!
73,
Gerald K5GW
In a message dated 10/18/2006 3:55:00 P.M. Central Daylight Time,
n6ry@arrl.net writes:
At 01:03 PM 2006-10-18, Phil Clements K5PC wrote:
>I hastily threw together a 30 meter Delta Loop this summer in order to get
>KH8SI in the log for a new one on CW. Using the formula, the resonant point
>came out 10.105 mhz (great, first try!) but the feed-point impedance is 79
>ohms.
>
>What is a good method of matching this antenna to 50 ohm coax? I don't want
>to use ferrites. I'm using a line-flattener in the shack now, but I robbed
>it from another project, and I need to return it.
>
>This antenna is a real "keeper;" I was able to bust the pile-up on 2nd call.
>The apex is a 50 feet on an 80 foot Rohn 25 tower.
A series-section matching arrangement would work well to match to 79
ohms at 10.125 MHz.
Connect 4.83 feet of 50 ohm line to the feedpoint (VF=0.66)
Then follow with 5.99 feet of 75 ohm line (VF=0.66)
Looking into the 75 ohm line it will be 50 ohms.
The bandwidth of the series-matching lines is much greater than the 30m
band.
73, Terry N6RY
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