[TowerTalk] Broken Alpha Spid

[Steve Maki]

That's what we did (on a small scale) with our 4 high 10 meter stack of 
4L yagis. The yagis at 40' & 60' rotate together and are treated as one 
antenna in the stack switch. And likewise the pair at 80' & 100'.

300° of rotation is fine as long as you have at least one antenna that 
can rotate the full 360°.

Our 20' masts are only 1-7/8" OD water pipe, which is perfectly adequate 
for this little system. The thrust collars are short pieces of 2" ID 
water pipe. I wouldn't hesitate to scale this up for larger antennas, up 
to a point, depending on tower strength.

Everything is welded except for the antenna mast clamp. Very cheap to make.

Here's a couple shots:

https://app.box.com/s/fkft820hkiukr3ms4n909t16wz1d8hw3

-Steve K8LX



On 2/26/2020 11:49 PM, Grant Saviers wrote:

> K0XG rings meet the bill, seven on my Rohn 65.  Some startup fixesand 
> then no problems 5 years.  see my QRZ page.  A huge complex project though.
> 
> Would I do it again - no.  I'd go with swing arms with 20ft masts,top 
> and bottom supports, 2 yagis per.  It's rare I need fully independent 
> beams and almost never 360 degrees for me.  I did the CAD work forthese 
> swing arms. Some CNC plasma cutting of 1/4" steel plate and welding 
> needed for a fraction of the cost.  Uses a standard mount rotator,eg 
> Orion 2800, etc for rotation.
> 
> Grant KZ1W