G'day Justin, great video, thank you for the detailed description. A question about mounting the 1/4 stub balun - once the stub balun is heat shrunk to the feed coax, can they both be then zip tied to the boom, or should they be kept away from the boom for at least the length of the stub (like what you recommend when using the ferrite chokes)?
Thank you for the video. I did a bit of dabbling on 6 meters in 2024. Using an oblong loop and a hf loop. The makeshift antennas were just good enough to pique my interest, So I am ready to improve on it. You can tell when other local stations are running the LFA Yagi because they always do well. This is great timing, because I would like to learn how to build one for 6 meters. Please keep the RUclips videos coming. 73, K1QS. P.S. I really am interested in that Balun. Can that be used for other types of antennas?
Thanks for excellent video, I would like further explanation on baluns. It was clear how to determine the 1/4w stub length but what is it actually doing? 70cms next please
hi, I did cover this in the video, worth re viewing it. The stub is reversed to the feed line so the outer sleeve of the stub is connected to the inner core at the feed point so on the stub is the 'hot' side of the coax, on the sleeve of the feed line the cold side. therefore, this 1/4wl section is like a balanced line feeder with each side 180 degrees out of phase with the other and therefore, as in a balanced line feeder, radiation is cancelled out.
@ correct. The rf choke prevent common mode currents from travelling back down your coax, this does exactly the same but unlike a choke which ideally need to be measured, this will work fine
@@hamradioguy-g0ksc96 This sounds too simple to be true, I do believe you! Can this 1/4 W Stub arrangement be used on ALL antennas including unbalanced ones (EFHW or OCFD), or just balance antennas (yagi & centre fed dipoles)?
@@gregwmanning An EFHW being an end feed wire need a huge ratio impedance transformer, hence the power power input/poor efficiency. besides this, the stub has a very narrow bandwidth not 10'sMHz long an EHHW. you can use on a OCFD where you are only slightly iff and shifting the centre feed point to one side of centre to achieve a 50Ohm impedance rather than the native 70ohm of a dipole. I do this on my 20m rotating dipole
yes it is possible although for HF and VHF not required as I have calculated the % based correction needed for this to be perfect. it just adds extra time needed for no reason. infact, AN-SOF is an ideal package to do this modelling if you wished to do it. the reason is, it is more sophisticated and can model square and round tube
G'day Justin, great video, thank you for the detailed description. A question about mounting the 1/4 stub balun - once the stub balun is heat shrunk to the feed coax, can they both be then zip tied to the boom, or should they be kept away from the boom for at least the length of the stub (like what you recommend when using the ferrite chokes)?
Great video - thanks. But your web page server has some troubles with redirections. Next I would like to see 144MHz beam modeled
in NEC-5
Sorry about that, bad timing in changing the DNS server - 24 hours and all should be OK
Thank you for the video. I did a bit of dabbling on 6 meters in 2024. Using an oblong loop and a hf loop. The makeshift antennas were just good enough to pique my interest, So I am ready to improve on it. You can tell when other local stations are running the LFA Yagi because they always do well. This is great timing, because I would like to learn how to build one for 6 meters. Please keep the RUclips videos coming. 73, K1QS.
P.S. I really am interested in that Balun. Can that be used for other types of antennas?
Thanks for the 'flowers' on the video and LFA, yes that balun can be used on any Yagi just cut to size for the respective band 73
Thanks for excellent video, I would like further explanation on baluns. It was clear how to determine the 1/4w stub length but what is it actually doing? 70cms next please
hi, I did cover this in the video, worth re viewing it. The stub is reversed to the feed line so the outer sleeve of the stub is connected to the inner core at the feed point so on the stub is the 'hot' side of the coax, on the sleeve of the feed line the cold side. therefore, this 1/4wl section is like a balanced line feeder with each side 180 degrees out of phase with the other and therefore, as in a balanced line feeder, radiation is cancelled out.
@@hamradioguy-g0ksc96 The 1/4w Stub acting as a "balanced line" does that mean an RF choke is no longer required?
@ correct. The rf choke prevent common mode currents from travelling back down your coax, this does exactly the same but unlike a choke which ideally need to be measured, this will work fine
@@hamradioguy-g0ksc96 This sounds too simple to be true, I do believe you!
Can this 1/4 W Stub arrangement be used on ALL antennas including unbalanced ones (EFHW or OCFD), or just balance antennas (yagi & centre fed dipoles)?
@@gregwmanning An EFHW being an end feed wire need a huge ratio impedance transformer, hence the power power input/poor efficiency. besides this, the stub has a very narrow bandwidth not 10'sMHz long an EHHW. you can use on a OCFD where you are only slightly iff and shifting the centre feed point to one side of centre to achieve a 50Ohm impedance rather than the native 70ohm of a dipole. I do this on my 20m rotating dipole
Hello Justin, please. do you have a schematic for 15 meters LFA!?
I will cover for each band different antennas and will do LFA and OP-DES for the HF Bands
@@hamradioguy-g0ksc96 Oh my god! tks to answer me, do you have an ideia when?!
Would it be possible to model antenna with boom and through hole mounts with NEC-5 ?
yes it is possible although for HF and VHF not required as I have calculated the % based correction needed for this to be perfect. it just adds extra time needed for no reason. infact, AN-SOF is an ideal package to do this modelling if you wished to do it. the reason is, it is more sophisticated and can model square and round tube
Hi Justin I tried to go to your G0KSC web page with the link you put in the info it just not working many thanks 73
@@Andy2e0ree sorry Andy, bad timing with a DNS change which is taking a little longer than expected. Give it 24 hours and should be there