Explain the counterpoise/ground...

[M0GVZ]

shure..

He's correct. The unmatched feedpoint impedance of a 1/4 wave vertical over real ground is around 37 Ohms. Altering the angle of radials raises or lowers the feedpoint impedance.

 

[Lil'Yeshua]

If you've tied the coax to the metal mast you'll have common mode on the coax and this may affect the SWR reading. Create a RF choke, place it at the antenna socket or as near as possible and bring the coax down keeping it away from the mast.

It'll reduce or hopefully eliminate common mode current, may lower noise and it'll probably have an effect on the SWR.

Thanks for the info. I still have to make a rf choke for my A99. I read that I could make one consisting if eight turns and right inches in diameter.

 

[The Jerk]

Thanks for the info. I still have to make a rf choke for my A99. I read that I could make one consisting if eight turns and right inches in diameter.

Unfortunately I just cut off my rf choke...for this "vertical" install...grrrrrr. No, I haven't looked at it since the other day.

Still thinking about the next step...mainly how I can make something work without spending any $$. I'm thinking of acquiring a piece of channel to build the base for the dipole, then putting up another horizontal. I might need to buy some shorter Firestick-like antennae to avoid it being too long (sidewalk one direction, driveway the other)...

As far as the choke. What I found worked very well was the bottom of a five gallon bucket. Cut it off so you have a "drum" (the height of the drum depends on your coax...I think mine was about eight inches because of the RG-8. You can use the bottom of the bucket as the mount for the choke assembly to the antenna mast or the side of the house. I used zipties to mount the coax to the bucket.

 

[The Jerk]

So I don't have to look it up again, do I need an RF choke on a horizontal dipole? If I do, I might not have enough coax left to make one that is adequate.

 

[Beetle]

So I don't have to look it up again, do I need an RF choke on a horizontal dipole? If I do, I might not have enough coax left to make one that is adequate.

I've used a LOT of dipoles in 50+ years of hamming, and I've never HAD to use a choke or a balun on any of them to get good results. I'd put the antenna up without choke or balun and see how well it works in your particular configuration. If you (and your neighbors) have no problems, then just leave as is and operate.

If you do encounter problems like RF in the shack or in the neighbors' TV, I'd get a good 1:1 current balun and install it in place of the center insulator.

 

[The Jerk]

I'm running stock power and my nearest neighbor is probably 200 feet away...that might be the reason I had one on the last place since I was attached to the neighbor.

Ok, got a game plan...

Sent from my SAMSUNG-SM-G730A using Tapatalk

 

[M0GVZ]

So I don't have to look it up again, do I need an RF choke on a horizontal dipole? If I do, I might not have enough coax left to make one that is adequate.

Unless you can guarantee your antenna is truly balanced you'll have common mode on the coax. How much is anyone's guess and it may or may not be a problem.

I would say given your situation just to keep an eye on things and if you start experiencing TVI or RF on your audio to put one in.

5 turns of RG213 or RG58 on a 4.25" diameter former is what you need and should give you 8k Ohm choking impedance on 26-28MHz.

 

[MSGED2007]

Here you go. Long read, but very, very useful. It explains alot about ground planes and counterpoises in real world experiments.

 

[Beetle]

Unless you can guarantee your antenna is truly balanced you'll have common mode on the coax. How much is anyone's guess and it may or may not be a problem.

I would say given your situation just to keep an eye on things and if you start experiencing TVI or RF on your audio to put one in.

5 turns of RG213 or RG58 on a 4.25" diameter former is what you need and should give you 8k Ohm choking impedance on 26-28MHz.

I wouldn't coil RG-213 or any other 0.405" OD coax into that tight of a bend. Figure at least 8" diameter for that size.

Rule of thumb: bend radius = 10 x coax OD. For RG-213 that would equal 4.05" RADIUS, which would be 8.1" diameter. Close enough to 8".