Home brew dipole help

[JDemoret]

I just got my homemade copper pipe dipole up and hooked up. I checked the SWR on the ground before it went up to get it close and had it at 1.5:1. Checked it after it went up and now I have 2:1 on channels 1, 20, and 40. Some issues I'm concerned with:
1: Do I have it high enough...the radiator is above the roof line at the peak of the roof but the counterpoise is below the roof line....is the an issue?
2: I have 100ft. of Tramflex RG-8X that i have the extra looped (about 4ft. loops) up hanging on the wall. I don't want to cut it because I hope to relocate in the near future......is this an issue?

Pictures of the antenna included.....thanks in advance.
John

P.S. would grounding the antenna help any and where should I terminate the ground wire at the antenna.

 

[W5LZ]

John,
What you are running into is fairly common. An antenna 'tuned' at ground level almost never acts the same when it's where it's going to be used (if it isn't in the same place it was tuned), because everything around that antenna is going to affect it. So, up/down a few times is considered normal, sort of.
There are a few things about your installation that are going to affect the antenna's tune that you might want to think about. The first one that sort of 'sticks out' is the metal pole holding the thing up. That's going to affect it. Shouldn't be all that hard to compensate for, but you will have to adjust the tuning to compensate for it. The bottom half being below the roof line is going to make some difference too. But, nothing that you can't do some of that 'compensating' for. How to do that compensating? Good question, and I can't say without more information. Basically it's going to amount to adjusting the length of the antenna. More of that 'up/down' stuff, oh boy, what fun!
The coiled up feed line shouldn't be affecting things much one way or the other. If you want, you can always un-coil it and see. then again, if you want to, you could always use some of that 'un-cut' stuff to put a choke at the antenna. May or may not do any thing constructive.
- 'Doc


(Also noticed those tracks! If you really, really get bored, you might try feeding them as an antenna sometime. No, they aren't ever going to be a 'good' antenna, but it will work, believe it or not. I did say if you got bored, right?)

 

[ron103067]

Like Doc said it is probably a couple different thing first being the feed line you need to keep that away from from your antenna try running down your eves for a little I would try that. Then see what that gets you I know I had to move my coax away when I built mine.

 

[BOOTY MONSTER]

hey 5 , not trying to get my hind parts handed to me but i was of the impression to never loop extra coax into a coil , except as a bauln at the antenna . was told to tie it in the center sorta like a bow tie .

what is that bracket made of ? if its conductive isnt it adding the mast to the ground plane of the antenna ?

 

[JDemoret]

The bracket between the antenna and mast is 1/2 inch plywood coated with a spray on rubber paint.

 

[Highlander_821]

It seems a little strange to me that the SWR stays constant as you go from channel 1 to 20 to 40. One would think that you would see a curve of some sort. If you had such a curve, you might be able to see which way to go with it (shorten or lengthen it.)

 

[JDemoret]

That's why I'm asking if I might have issues because the reading is exactly the same on all channels. I think I'm going to raise it another 5 feet an move that coax around and see what happens.

 

[Marconi]

That's why I'm asking if I might have issues because the reading is exactly the same on all channels. I think I'm going to raise it another 5 feet an move that coax around and see what happens.

Demoret, the feed line really needs to come away from the antenna as far as possible before going down to the ground in this case. As 'Doc says, the metal support pole will affect the tuning some, but with the coax also running along side the two elements going down, you may be effectively having the bottom element not working as it should due to cancellation. With a little work you could fix the support pipe so the feed line could run down inside it far enough to get the feed line past the bottom end of the down element and that might help some.

How long are the elements?

Neat construction though.

Your SWR reading also indicates something is not showing currents as it should. I suspect you want to be vertical, but if the thing was horizontal, it would probably work just fine if the lengths of the elements are OK. The problem with SWR that read any value less than 2.5:1 or less and are about the same from channel 1 to 40 in 11 meters is: you are showing extreme losses to make the bandwidth you are seeing.

That is likely a problem that Homer needs to consider also, but back in Feb Homer said he had a 1.2 on 40 and 1.0 on 1, like he was a little long. I think he was not suggesting he was flat like he suggests now. So, I'm not sure Homer has not made some other changes since then.

 

[HomerBB]

There are smarter folks on this blog than me, but I did mine with a choke at the feed point made of 18' of coax wrapped around a 4" -6" core. I laid the dipole horizontal in place and trimming the ends for length. I have now raised it even higher and laid it at a 45* angle to avoid any influence from the metal mast. The conduit are isolated from the dipole by building the whole thing at the center of PVC. The thing is very widebanded and shows close SWR from ch 1 - ch 40.

See my progress on this thread started by ron103067:
http://www.worldwidedx.com/cb-antennas/32188-conduit-dipole-swr-issues.html

 

[BOOTY MONSTER]

The bracket between the antenna and mast is 1/2 inch plywood coated with a spray on rubber paint.

did you use the under carige spray for cars and trucks ? was thinking of using that when i replace my wire radiator with copper pipe and put it up properly . was gonna spray it over the entire antenna and connections to the coax and its feed point .

how do you like your results with it ?

 

[JDemoret]

Neat construction though.

Thanks.......I raised it 5 feet and moved the coax a little but the SWR went to 3:1 on the whole band. I think the thing needs to be horizontal....won't that make it directional? I'll have to bring it down and rework the design but that's the fun part.

Booty Monster
The paint is that spray on Plasti Dip used for tool handles.....we will see how it is after a few months.

 

[HomerBB]

My SWR remained good after I changed it from horizontal to 45*.

If shifting the coax caused SWR changes it seems you have "common mode current" issues, so I'd suggest you to make a choke like I described above just below the coax connector (feed point) on your antenna to correct that, then adjust the lengths of your two pipes equally until your SWR gets right.

The only reason you might want to move it from vertical is if your mast is causing resonance issues with your dipole, or if you don't wish to use it to talk to other local stations that are vertical. Another reason is if you are wanting it only for talking horizontal DX.

Talking locally is the main reason I switched mine from horizontal to between vertical and horizontal. Now I can communicate with vertical stations