Bent boom on 70cm yagi...

[mr_fx]

I have a M2 432-9wl, 28 element, 20 foot boom, 70cm yagi that was recently given to me.

http://www.m2inc.com/index.php?ax=amateur&pg=104

HOWEVER when you look down the book it becomes obvious that the boom is bent

If you try a string to the front side (director) and pull the string straight toward the back side (reflector/driven) there is nearly 1.5 inches of difference...

I have tired to straighten it out but it is not working...

How bad will this hurt the antenna's operation?

 

[binrat]

I would try it as is.

 

[FatHam]

Are you planning on running it horizontal or vertical? I only ask because I run an 18 element M2 44o beam vertically and it has about an inch of "sag" over it's length. If you plan to mount it vertical, try it with the bow "up" at the ends (like a smile) and it's liable to lay straight when bolted to the mast.

If you're going horizontal, I'd talk to M2 about it. Their online customer service is fast to respond. If they can't direct you on straightening it, I would bet they could get you a replacement section of boom and a handful of element retainers (you're liable to wreck the old ones getting it apart) for $30-$40.

http://www.m2inc.com/index.php?ax=contact

 

[Captain Kilowatt]

Typical boom sag. That antenna was likely mounted vertically and the boom sagged over time. Typical really. If it was horizontal then it must had been in one hell of a wind.If you are mounting this with the elements vertical then mount it so the bend is up and gravity will make it straight again. If not then you can try and straighten it. It is only aluminum and can be fixed quite easily. You need to mount the middle of the boom to a solid point like a mast or in a vise and s-l-o-w-l-y bend each end of the boom beyond the straight point to apply stress in the opposite direction. Aluminum is springy but will take a set when stressed enough. Try it a few times and see but do not man-handle the thing and break it. You really have to be an idiot to break it mind you and common sense applies when stressing aluminum tubing. I have straightened many booms and elements this way over the years. No big deal really.If you really do not want to do it leave it as it is. Again I suggest for vertical operation mount it with the bend UP so gravity will correct it.

 

[Captain Kilowatt]

Are you planning on running it horizontal or vertical? I only ask because I run an 18 element M2 44o beam vertically and it has about an inch of "sag" over it's length. If you plan to mount it vertical, try it with the bow "up" at the ends (like a smile) and it's liable to lay straight when bolted to the mast.

If you're going horizontal, I'd talk to M2 about it. Their online customer service is fast to respond. If they can't direct you on straightening it, I would bet they could get you a replacement section of boom and a handful of element retainers (you're liable to wreck the old ones getting it apart) for $30-$40.

http://www.m2inc.com/index.php?ax=contact

We doubled.

 

[FatHam]

We doubled.

Story of my life. lol

 

[mr_fx]

I am planning to mount it horizontal

M2 wants about $65 shipped to my door for the boom section... I really dont care to do that...

I think the previous owner did have it mounted vertically...

 

[Moleculo]

I really doubt it will skew the pattern very much even mounted horizontally. I'd just run it and see what happens.