G0VQO

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2 Element 5 Band Spider Quad

After my 2 element Lightning bolt quad was damaged in storms I decided to build a 2 element spider quad. I used a qtenna  hub that I modified to hold an extra fibre glass tube to support the feeders
The spreaders from the lightning bolt where still good so I used these, However they were not long enough due to the spreaders been at an angle so I extended then using some UPVC tube, in order to protect the spreader where they are clamped on the hub I slid some hose over the fibre glass tube, the spreader was secured to the hub using hose clips.
I originally cut all the elements to the same lengths as my old lightning bolt quad and feed each band with a 1/4 wave matching stubs made from RG11, The SWR was OK however there was room for improvement , I also ended up removing the matching stub on 15m as the impedance was only 25 ohms with the stub fitted and the SWR would not go below 1.8 to 1. So I fed it directly with RG213 which gave 50ohms at resonance. To make the matching stubs you can use RG11 or RG59 the length will vary depending on the velocity factor of the coax. fit a PL259 to one end and trim down until X = 0 on your analyzer at the centre frequency of the band then fit another PL259 to the other end. For a guide you can use the lengths below for matching stubs. I have now also removed the matching stub on 10m and fed directly with 50 ohm coax with a 1:1 balun at the feed point and the match is much better,

                           RG59
10 Meters 6 Ft. 8 3/4″——— (205.105) CM                                                                   
12 Meters 7 Ft. 8 1/4″——— (234.315) CM
15 Meters 9 Ft. 0″————– (274.320) CM
17 Meters 10 Ft. 7″———— (322.580) CM
20 Meters 13Ft. 6″————- (411.480) CM

                            RG11
10 Meters 5 Ft. 8″——-(172.720) CM
12 Meters 6 Ft. 6″——-(198.120) CM
15 Meters 7 Ft 7″——–(231.140) CM
17 Meters 8 Ft. 11″——(271.780) CM
20 Meters 11 Ft. 5″——(347.980) CM

These are the final  dimensions of my quad

Driven Element
20m 70 ft 9 inches
17m 55 ft 3 inches
15m 46 ft 9 inches
12m 40 ft 1 inch
10m 34 ft 11 inches

Reflector 
20m 72 ft 6 inches plus a 6 inch tuning stub, total length  73 ft
17m 56 ft 8 1/2 inches plus a 6 inch tuning stub, total length 57 ft  2 1/2 inches
15m 48 ft 2 inches plus a 6 inch tuning stub, total length 48 ft 8 inches
12m 41 ft 4 inches plus a 5 inch tuning stub, total length 41 ft 9 inches
10m 35 ft 6 inches plus a 4 inch tuning stub, total length 35 ft 10 inches

These dimensions I had the following SWR