17-01-2018, 08:30 PM
G'day Hayden,
No worries on the upside down photos
I'm still learning the subject, so no expert by any means....
More cores at the feedpoint would be best, then route the coax straight back in line with the boom (straight over the middle of the reflector element) then loop it around and forward on the underside of the boom. That keeps it symmetrical - if that makes sense?
A Fully Symmetrical Coaxial Balun may be the best option, it uses two pieces of coax, one 1/4 wave length and the other 3/4 wave length in a configuration like this example half way down the page - http://www.g0ksc.co.uk/creatingabalun.html but it introduces other problems like more joints for water to get into etc...
An example of a Pawsey Stub is on the same page.
I 'think' the screw in the middle of the far end of the driven element (at the zero volts point) is simply for static bleed off. I've used the same LFA with and without the screw there and didn't notice and difference in performance, although I don't have a super test gear setup.
Back on ferrites, these are the part numbers I've bought for the 6m LFA, 2m OWL and 70cm LFA
http://www.fair-rite.com/product/round-c...631101902/
http://www.fair-rite.com/product/round-c...643101902/
http://www.fair-rite.com/product/round-c...661102002/
I plan on using 4 on 70cm, 6 on 2m and a heap on 6m
Let us know how you go, building antennas is super interesting!
No worries on the upside down photos
I'm still learning the subject, so no expert by any means....
More cores at the feedpoint would be best, then route the coax straight back in line with the boom (straight over the middle of the reflector element) then loop it around and forward on the underside of the boom. That keeps it symmetrical - if that makes sense?
A Fully Symmetrical Coaxial Balun may be the best option, it uses two pieces of coax, one 1/4 wave length and the other 3/4 wave length in a configuration like this example half way down the page - http://www.g0ksc.co.uk/creatingabalun.html but it introduces other problems like more joints for water to get into etc...
An example of a Pawsey Stub is on the same page.
I 'think' the screw in the middle of the far end of the driven element (at the zero volts point) is simply for static bleed off. I've used the same LFA with and without the screw there and didn't notice and difference in performance, although I don't have a super test gear setup.
Back on ferrites, these are the part numbers I've bought for the 6m LFA, 2m OWL and 70cm LFA
http://www.fair-rite.com/product/round-c...631101902/
http://www.fair-rite.com/product/round-c...643101902/
http://www.fair-rite.com/product/round-c...661102002/
I plan on using 4 on 70cm, 6 on 2m and a heap on 6m
Let us know how you go, building antennas is super interesting!