ARRL

AG6CX

Joined: Sat, Apr 4th 1998, 00:00 Roles: N/A Moderates: N/A

Latest Topics

Topic Created Posts Views Last Activity
Common mode Choke for Balanced Parallel Feed Line Aug 26th, 19:57 6 67 4 days, 3 hours ago
Off Center Fed Dipoles Feb 4th 2014, 19:28 5 1,157 on 6/2/14

Latest Posts

Topic Author Posted On
Common mode Choke for Balanced Parallel Feed Line AG6CX 4 days, 3 hours ago
Sadly have encountered the paywall and the general arrogance of the wall keeper.

Thanks.

73
AG6CX
Common mode Choke for Balanced Parallel Feed Line AG6CX 4 days, 4 hours ago
Thanks for prompt reply Zack.

Was thinking of using Balun Designs model 1171 balun between open wire and balanced link-coupled tuner as common mode choke. Will this not enhance minimization of CMC without impairing efficiency?


Common mode Choke for Balanced Parallel Feed Line AG6CX 4 days, 5 hours ago
Zach:

Cannot seem to find any references in the literature to the use of CMC in parallel feed operation, say with 135 ft doublet fed with open wire to a link coupled tuner. Can you direct me to some resources or articles on the topic. Lots of stuff on coax fed CMC but nothing for parallel feed lines.

Thanks,

AG6CX
Off Center Fed Dipoles AG6CX on 5/2/14
Thanks for your observations Zack.

I guess I have to read your Mar 2001 article QEX (Pg. 55)
Making Off-Center Fed Dipoles Work (RF). I remain perplexed that the article download is not available to members, but would appreciate a copy if you can spare one, or request TIS to scan and send to edwmccann@aol.com. Happy to pay whatever is needed.

In any event, my basic question remains unanswered and I can find no answer: If the OCF antenna is supposed to be resonant on even harmonics, why isn't such an OCF antenna cut for Fo = 3.55 MHz resonant on 6xFo = 21.3 MHz ? (We can worry about the impedance with a balun).

Odd harmonics are 3,5,7,9, etc. So the 40m dipole works on 3x7.0=21.6MHz, as has been known.

Even harmonics would be 2,4,6,8,10, 12, wouldn't they? So wouldn't one expect the OCF Dipole to be resonant at the 6th, 8th. 10th, and 12th harmonics? Or are the 6th, 10th, 14th harmonics not as"even" as we think, being twice the 3rd, 5th, and 7th harmonics?

I look forward to your article to shed some more light on the matter.

73
AG6CX


Off Center Fed Dipoles AG6CX on 5/2/14
Thanks for your observations Zack.

I guess I have to read your Mar 2001 article QEX (Pg. 55)
Making Off-Center Fed Dipoles Work (RF). I remain perplexed that the article download is not available to members, but would appreciate a copy if you can spare one, or request TIS to scan and send to edwmccann@aol.com. Happy to pay whatever is needed.

In any event, my basic question remains unanswered and I can find no answer: If the OCF antenna is supposed to be resonant on even harmonics, why isn't such an OCF antenna cut for Fo = 3.55 MHz resonant on 6xFo = 21.3 MHz ? (We can worry about the impedance with a balun).

Odd harmonics are 3,5,7,9, etc. So the 40m dipole works on 3x7.0=21.6MHz, as has been known.

Even harmonics would be 2,4,6,8,10, 12, wouldn't they? So wouldn't one expect the OCF Dipole to be resonant at the 6th, 8th. 10th, and 12th harmonics? Or are the 6th, 10th, 14th harmonics not as"even" as we think, being twice the 3rd, 5th, and 7th harmonics?

I look forward to your article to shed some more light on the matter.

73
AG6CX


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