Yagi balance point
I have two yagis that I need to mount a little off center and wanted to put a little weight on the back of the antenna as a counter balance.
Assuming the counterbalance will need to go in front of the rearmost reflector, does it matter if the counter balance is metallic (i.e. some fishing weights)? Should I isolate it from the boom? Should I use something ceramic instead?
73
David
K6CDW
As a practical matter, I'd use the fishing weights tucked in as close to the boom as possible to keep the additional wind load down. In fact if the boom is hollow, you could stick the weights inside and not increase the wind load at all. As long as the metallic counterbalance is not actually touching any elements you will be fine.
-Joe KM1P
How about putting them inside the boom?
Joe Fitzgerald wrote:
As a practical matter, I'd use the fishing weights tucked in as close to the boom as possible to keep the additional wind load down. In fact if the boom is hollow, you could stick the weights inside and not increase the wind load at all. As long as the metallic counterbalance is not actually touching any elements you will be fine.
-Joe KM1P
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Inside the boom is a great idea but unfortunately I think it would be a bit difficult as the rearmost reflector is only 1 inch from the end of the boom and it goes right through the boom.
It could be done but I don't think the wind loading reduction would out weight the "pain in the butt" factor.
Appreciate the suggestion though!
73, David
-----Original Message----- From: Nigel Gunn G8IFF/W8IFF [mailto:nigel@ngunn.net] Sent: Tuesday, November 10, 2009 10:57 AM To: Joe Fitzgerald Cc: David Wing; amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: Yagi balance point
How about putting them inside the boom?
Joe Fitzgerald wrote:
As a practical matter, I'd use the fishing weights tucked in as close to the boom as possible to keep the additional wind load down. In fact if the boom is hollow, you could stick the weights inside and not increase the wind load at all. As long as the metallic counterbalance is not actually touching any elements you will be fine.
-Joe KM1P
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
What "pain in the butt factor"? Remove the rear element, fit the ballast, refit the rear element.
If the elements are not removable from the boom and the beam isn't already reasonably balanced then perhaps it was a lousy choice of antenna.
David Wing wrote:
Inside the boom is a great idea but unfortunately I think it would be a bit difficult as the rearmost reflector is only 1 inch from the end of the boom and it goes right through the boom.
----- Original Message ----- From: "David Wing" david@cdwing.com To: amsat-bb@amsat.org Sent: Tuesday, November 10, 2009 7:09 PM Subject: [amsat-bb] Yagi balance point
I have two yagis that I need to mount a little off center and wanted to
put
a little weight on the back of the antenna as a counter balance.
Assuming the counterbalance will need to go in front of the rearmost reflector, does it matter if the counter balance is metallic (i.e. some fishing weights)? Should I isolate it from the boom? Should I use something ceramic instead?
73
David
K6CDW
Hi David, K6CDW
Both for the KLM 2M-14C and KLM 2M-22C I suggest you to remove the rear reflector and put into the boom a counterweight made with a long piece of steel rod or lead rod if you prefere having the same inside diameter of the boom and the right weight to balance the antenna. The lenght of the boom between the rear reflector and the rear dipole is more than enough to get the needed counterweight. Drill a hole into the boom and slip into it a bolt passing through the conterweight and put again the reflector into the original hole.
73" de
i8CVS Domenico
----- Original Message ----- From: "David Wing" david@cdwing.com To: amsat-bb@amsat.org Sent: Tuesday, November 10, 2009 7:09 PM Subject: [amsat-bb] Yagi balance point
I have two yagis that I need to mount a little off center and wanted to
put
a little weight on the back of the antenna as a counter balance.
Assuming the counterbalance will need to go in front of the rearmost reflector, does it matter if the counter balance is metallic (i.e. some fishing weights)? Should I isolate it from the boom? Should I use something ceramic instead?
73
David
K6CDW
Hi David,
If you have the better part of an inch of boom sticking out behind the reflector, there should be ample metal to attach something off the end, maybe supported by a slightly smaller piece of tubing that just slips into the boom. After all, the farther back the weight is, the less of it you will need, and the less weight you will be adding to the overall structure.
Greg KO6TH
_________________________________________________________________ Bing brings you maps, menus, and reviews organized in one place. http://www.bing.com/search?q=restaurants&form=MFESRP&publ=WLHMTAG&am...
participants (5)
-
David Wing -
Greg D. -
i8cvs -
Joe Fitzgerald -
Nigel Gunn G8IFF/W8IFF