Sirio 3 element SWR Question

[fourstringburn]

Nice, glad you got it!

Those looked like some sort of twist lock on those elements where you just slide them out to length. That would have been more convenient especially since you got few chances to cut elements and get it right.

Nice set up you have with that rotor. I run a 3 element Maco using the same rotor with a hy-gain YRC-1 rotor controller that lets me use any two of my rig control software programs to easily point and click where I want the beam heading.

Pointed west right now but nothing heard. I'll give you a shout if I do.

Good DX to you!

73

 

[BJ radionut]

So for anybody else benefit:
What were the final lengths on the elements??

 

[freecell]

well sirio was kind enough to give us the length of the reflector @ 5740 mm. from the manufacturer (if not altered) that puts the reflector @ a length of 18.832 feet.

since we know that the typical increase in length for the reflector over the driven element is 5% we can work backwards from the reflector to determine the length of the driven element.

driven element = 18.832 X 0.95 = 17.890 feet.

now given the driven element length and knowing that the typical decrease in director length referenced to the driven element is also 5%.

director element = 17.890 X 0.95 = 16.995 feet.

the operating frequency of the driven element is approximately 27.500 mhz
.

 

[DXcarpenter]

Nice, glad you got it!

Those looked like some sort of twist lock on those elements where you just slide them out to length. That would have been more convenient especially since you got few chances to cut elements and get it right.

Nice set up you have with that rotor. I run a 3 element Maco using the same rotor with a hy-gain YRC-1 rotor controller that lets me use any two of my rig control software programs to easily point and click where I want the beam heading.

Pointed west right now but nothing heard. I'll give you a shout if I do.

Good DX to you!

73

Thank you for the compliments... Yeah the elements should have some sort of telescopic tuning in them.... I think they just run them proud knowing there long and need to be cut for higher bands.. Man, I was a little nervous checking match after cutting and reassembling.. lol I got lucky.. Conditions fell out around 12:30 PST Made some good contacts prior. WI, AL, ILL, MI..
Hope to catch up with you on the band...
73's

 

[Robb]

Hey guys... Having a cup of coffee and reading replies.... Thank you for the info... One thing I didn't check was the length of the 8mm end pieces.... Reflector, driven, director.. As you can see in tuning table chart.... Just a little nervous cutting elements... I did set gamma for 27.5 specs but not the end elements.. Its up on mast now.... Looks like I'll be taking it down today to get her dialed in... I'm usually on 27.385.. And sometimes go above ch 40.... the mm to inches is a pain, but it is what it is.. At least we got sunny weather today.....

That antenna does NOT need to be trimmed - right out of the box. Not for CB anyway; 10m - yes. Be careful! You can't put it back on, lol.

I would just make SURE that the assembled dimensions are correct to the instructions. Helps if you have/use a tape mesure that also shows the mm/cm scale. I went out and bought a tape measure to be sure.

 

[DXcarpenter]

So for anybody else benefit:
What were the final lengths on the elements??

Didn't see your post till right now...Well this is what I came up with..
Gamma tuning" L1 37 1/2" L2 20 3/8"
A (Reflector) 31 3/4"
B (Driven) 21 1/16'
C Director) 18 11/16'
73's

 

[DXcarpenter]

That antenna does NOT need to be trimmed - right out of the box. Not for CB anyway; 10m - yes. Be careful! You can't put it back on, lol.

I would just make SURE that the assembled dimensions are correct to the instructions. Helps if you have/use a tape mesure that also shows the mm/cm scale. I went out and bought a tape measure to be sure.

Yes sir... I used a mm to inches calculator and a decimal to fraction conversion tool.... Thats what I thought too is it would be ready to rock on citizen band besides tha gamma tuning.... All good.... We seem to get lucky today.....
Thabks for the advice..
73's

 

[Staybolt]

*Take the antenna down (sorry!)
*Place the reflector side on the ground and then point the beam straight up in the air supported by a 2x4 or something similar.
*Keep it away from any other metal for at least 25-30 ft.
*Tune the gamma match with an antenna analyzer right at the feed point with a VERY short (1 ft/less) jumper.
*Tune for lowest SWR @ ch 20 (27.205Mhz).

Should be good to go. Had the same problem you had with the 4 element version and was told by an old salt that is the best way to tune a Yagi beam. The old salt was right, as usual . . .

EXACTLY how i tuned my Maco 5 element.