Wednesday, 11 October 2017

40mtr vertical antenna

after taking down a 2 ele yagi for 40 and replacing it with the OP-DES 14mhz yagi I needed another 40mtr antenna. I decided to put up a quarter wave vertical. I had thought of a 2 ele array switchable, end fire and broadside.
after looking at the logistics and control required, compared to gain, I just went with a single quarter wave radiator.
I had already 120 10mter radials for a 40mtr vertical in the shed.
I made the radiator from 2" aluminium rubing 7mtr's, then a fiberglass fish pole to make up the remainder with #12 copper wire taped to the outside of it.

I installed a 100x100x2.6mtr post to hold the radiator, buried 4ft in the ground.
the copper pipe bus bar was already made.
stauff clamps purchased from antenna engineering. not sure if this company is still trading.
#18 single wire radials.

after installing and testing with MFJ259, resonance was to high. so I lengthened the radiator 0.4mtr to drop resonance to 7.120mhz.
1.1:1 from 7.06 to 7.170. no higher than 1.2:1 between 7.0 and 7.2mhz.
happy with that.

some photos below

73. si......

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