10 Meter US Yagi Stack - Design Modifications

6 May 2004

Old Configuration:

Top 53 ft, Box 45 ft, Bottom 34 ft. This is only 19 feet of spacing between the antennas. 

New Configuration: Top 53 ft, Box 45 ft, Bottom 20 ft. this gives the desired 33 foot spacing, which should provide stacking gain of about 3 dB.

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Feedlines should be equal lengths from the Stackmatch box and an exact electrical half wave.

Coax is Belden 8214, Vf = .78.

246(.78) / 28.200 = 6.80 ft per quarter wavelength.

6.80 * 6 = 40 ft 10 in.

Required length from box to bottom is 25 + 4 foot at antenna + 3 ft top loop = 32 ft.

Decision: fabricate two 10 meter pigtails of 40 ft 10 in each, trimmed to exact electrical length of 1.5 wavelengths at 28.200 with the MFJ-259B.