paulears
Member
I have one of these J-poles - built into a tube
https://www.ebay.co.uk/itm/Sirio-CX...033719?hash=item441c355677:g:m28AAMXQS6pRyUbo
It works, but isn't any better than a dipole, despite the lower radiation angle. As for slim Jims - all the local older hams around here had one a Fred's Slim Jims. He knocked them up for everyone as he only lived a few miles away near Cantley. He built most of the non-metal hardware from. offcuts of perspex - a good insulator. I helped put quite a few up as most of the fellas then were not really up top doing ladders. NONE were grounded in any way other than the coax in the shack. Fred also built a few for the local fishermen who used them on boats, again - simply cabled to the radio, with no metal work to ground. He bent the aluminium *(much of it second hand and scavenged from old VHF low band TV antennas) on a former, and the coax was attached with solder tags, secured with self-tappers or pop rivets. Adjustment of the one he gave me was a bit off - 2:1 VSWR was the best - and he told me it was the length of coax. His solution was two small jubilee clips - small versions of the car hose types, and these had the coax slipped under them, slid up and down the tube till the VSWR was lowest and then tightened and varnished to waterproof it. Mine lasted 6 months before water got in. I never found them good antennas, but they did the job and were cheap to build. A stuck up a dual band Jaybeam which was hugely better and worked on both bands.
Despite all the G2's and G3's on the early morning net using them, us youngsters didn't like them.
Fred was very knowledgeable but not the easiest person to have a discussion with. I didn't find him receptive to questions at all.
https://www.ebay.co.uk/itm/Sirio-CX...033719?hash=item441c355677:g:m28AAMXQS6pRyUbo
It works, but isn't any better than a dipole, despite the lower radiation angle. As for slim Jims - all the local older hams around here had one a Fred's Slim Jims. He knocked them up for everyone as he only lived a few miles away near Cantley. He built most of the non-metal hardware from. offcuts of perspex - a good insulator. I helped put quite a few up as most of the fellas then were not really up top doing ladders. NONE were grounded in any way other than the coax in the shack. Fred also built a few for the local fishermen who used them on boats, again - simply cabled to the radio, with no metal work to ground. He bent the aluminium *(much of it second hand and scavenged from old VHF low band TV antennas) on a former, and the coax was attached with solder tags, secured with self-tappers or pop rivets. Adjustment of the one he gave me was a bit off - 2:1 VSWR was the best - and he told me it was the length of coax. His solution was two small jubilee clips - small versions of the car hose types, and these had the coax slipped under them, slid up and down the tube till the VSWR was lowest and then tightened and varnished to waterproof it. Mine lasted 6 months before water got in. I never found them good antennas, but they did the job and were cheap to build. A stuck up a dual band Jaybeam which was hugely better and worked on both bands.
Despite all the G2's and G3's on the early morning net using them, us youngsters didn't like them.
Fred was very knowledgeable but not the easiest person to have a discussion with. I didn't find him receptive to questions at all.
is used to designate wavelength. So, λ/2 is half of the wavelength.
