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A Dipole for your CB Base Station?
- Thread starter Robb
- Start date
Yes, this does look very promising, however I should mention that I am using RG6QS for the coax. I am aware that it is 75ohms while the CB is 50ohms so there will be mismatch so I will have
bit higher SWR but will still be in a acceptable range. I decided to use the RG6 because I've read that while it may not be the optimal set-up, it works rather well. Plus it was on sell; $3.00 for a hundred feet.
Now....how do I figure out the length of the air choke I need to use with RG6 or will I need it at all?
Secondly, can I bend the vertical dipole in the middle and run it as an inverted V ?
No problem using 75ohm cable if that is what you have, Yes you can run it as inverted V but the impedance will be closer to 50 ohm. Dipole high in the clear is 70 ohm anyway so you get a good match at the antenna, mismatch will be at the tx end.Still no problem getting the swr down to 1.3 or 1.5 though . have a look at the first part of my thread http://www.worldwidedx.com/threads/homebrew-t2lt-dipole-and-3el-skypper-beam.181876/ The pics show the T2lt as a vertical , horizontal and a inverted V with the ant analyzer readings. No the airchoke measurements will work as is, the difference between rg6 size and rg 58 is very small anyway.
Update on the RG6....
I've decided to stop using the RG6. Everything except the TX worked great. I got a low SWR with nice receive, however I think it has too much loss. Makes a good dummy load though or tv cable. WIll be working with regular RG58 from now on.
The antenna situation for work hasn't been sorted out yet but I'm leaning on using two mobile fiberglass antennas mounted vertically (dipole) for the warehouse.
For work, I just got two handhelds, Midland 75-785 which for the front desk and a Realistic TRC-216 placed at the back daycare. I'm just waiting on mics so I can mount the radios. The dipole will be connected to the TRC 216 eventually. We were using FRS radios and they worked great but no body wanted to deal with recharging the batteries. I've used several different radios and none actually worked with the power hooked up, some just did not work and others had a horrible hum on TX. Now, at least the walkies can be left on so no one needs to bother with batteries. Another issue was radios breaking all the time from dogs jumping on attendants and knocking the radios off or chewing though the ear/mic cord....the list goes on.
I work with staff who don't like dealing with the radio and instead prefer to walk 100 ft to communicate. I figure once the radios are mounted, it's easy enough for anyone to simply pick up the mic and talk. But....when dealing with people anything is possible.
The renew interest into CB was really a result of people just being too lazy to fiddle with the batteries on a daily basis at work. Maybe it will peak the interest of others, I certainly hope so.
I've decided to stop using the RG6. Everything except the TX worked great. I got a low SWR with nice receive, however I think it has too much loss. Makes a good dummy load though or tv cable. WIll be working with regular RG58 from now on.
The antenna situation for work hasn't been sorted out yet but I'm leaning on using two mobile fiberglass antennas mounted vertically (dipole) for the warehouse.
For work, I just got two handhelds, Midland 75-785 which for the front desk and a Realistic TRC-216 placed at the back daycare. I'm just waiting on mics so I can mount the radios. The dipole will be connected to the TRC 216 eventually. We were using FRS radios and they worked great but no body wanted to deal with recharging the batteries. I've used several different radios and none actually worked with the power hooked up, some just did not work and others had a horrible hum on TX. Now, at least the walkies can be left on so no one needs to bother with batteries. Another issue was radios breaking all the time from dogs jumping on attendants and knocking the radios off or chewing though the ear/mic cord....the list goes on.
I work with staff who don't like dealing with the radio and instead prefer to walk 100 ft to communicate. I figure once the radios are mounted, it's easy enough for anyone to simply pick up the mic and talk. But....when dealing with people anything is possible.
The renew interest into CB was really a result of people just being too lazy to fiddle with the batteries on a daily basis at work. Maybe it will peak the interest of others, I certainly hope so.
I usually use Belden RG-11. Same basic coax as LMR-400 but in 75Ω and with a little smaller gauge solid copper center conductor.
I use a 1/2 wave horizontal dipole for 11 meter SSB/DX on my balcony. About 8'6" per each element. I initially put one up with a SO-239 connector. I had to wind an air choke with the coax right at the SO-239 feed point, otherwise my SWR were variable based upon how the coax was place in relation to the radio. I used 8 coils of coax at about 5 1/2 inches. This stabilized the SWR and ensured the antenna elements were radiating my signal. It works great for me but the ends of the elements do not transmit much signal, so if you mount it say one end north the other south, it transmits east and west. The second antenna I made performed even better because I didn't use a SO-239 connector but just soldered the elements directly to the feedline coax center and shield. Again, I used the coax air choke. Maybe it works a bit better because there is no connector, I don't know. They work good horizontal for DX, not too good local. All this was by trial and error and asking people with knowledge on another site the correct questions. After trimming the ends a bit my SWR is about flat, maybe 1.0 on 40 and 1.2 or channel 1 or vice versa, I forget.
Dipole question:
I know the feed-line needs to be perpendicular to the antenna for the first several feet. In the case of a horizontal dipole, does the feed-line have to go straight down?
For example, for a dipole strung at 17', can the feed-line be routed directly to an 8' house eave as long as the angle between the antenna and feed-line is 90 degrees?
Am talking about a standard half-wave wire dipole, not an end fed.
I know the feed-line needs to be perpendicular to the antenna for the first several feet. In the case of a horizontal dipole, does the feed-line have to go straight down?
For example, for a dipole strung at 17', can the feed-line be routed directly to an 8' house eave as long as the angle between the antenna and feed-line is 90 degrees?
Am talking about a standard half-wave wire dipole, not an end fed.
Beetle,
Is that a "no" to my first question and a "yes" to my second? Not sure how ro interpret your response. Sorry.
Does anyone else have any thoughts on the subject?
Thanks.
I use a 1:! current balun at the feed point, RG6 quad for coax 75 ohm into my inverted V and delta loops, they work fine.
Route your coax as you need to, put an RF choke or a 1:1 current balun at the feed point and have fun making contacts.
Route your coax as you need to, put an RF choke or a 1:1 current balun at the feed point and have fun making contacts.
I use a Dr. Dipole 1:1 balun and some insulated wire. Just hung a dipole up this weekend. Set up horizontally. It is about 40ft in the air. Maybe a little more. Coax is LMR240, a 60ft piece. Tuned for 27.400. It works well. Even though there hasn't been much DX on 11m. I have it set up for N/S, about 8-10 degrees east of North. Could be why. It was easier than putting my Sirio vector 4K back up just to talk. I can hear all my locals out to about 8-10 miles away and am able to make contact with all of them. So it worked out well for me. The wires for the legs are 8.54ft or 102.47". And be careful when hanging it not to stretch your wiring out as it will definitely throw off the tuning of the antenna, or where there resonant frequency is!! Live and learn! Anyways. I may also hbd a second one up facing E/W as well. Anyhow, they are great antennas for a quick means of making DX contacts and also talking very locally. Orientation will have a lot to do with how well it will work locally. But I like mine setup horizontally as the floor noise is much less and I have plenty of trees to hang up in between!! Here are a couple of pics. Have since moved the ends out a little more away from the tree branches. Anyhow. It works and I can also use it for other bands as well for just receiving. Hope this might help someone that is thinking of placing one up. Easy antenna to make, and they do work well for what they are!!!
Attachments
Nice setup Sean, and up there high where a dipole likes to fly. Hope you don't mind the questions, I'm just curious.
Is it directional enough to detect?
How do you keep from stretching the wire as the wind blows the tree limbs around?
What did you decide to do with your NV4K?
How does the new dipole compare to the Sirio Vector?
Is it directional enough to detect?
How do you keep from stretching the wire as the wind blows the tree limbs around?
What did you decide to do with your NV4K?
How does the new dipole compare to the Sirio Vector?
Wavrider, thanks for info!
222, dadgum! I wish I had your trees! How the heck did you hang that thing? If you paid a neighbor boy to climb up there, I hope you paid him good.
Beetle, thanks for the reply. I was hoping that was the case. Will make it easier and save me some length on my coax if I decide to go that route.
Thanks again, everyone.
222, dadgum! I wish I had your trees! How the heck did you hang that thing? If you paid a neighbor boy to climb up there, I hope you paid him good.
Beetle, thanks for the reply. I was hoping that was the case. Will make it easier and save me some length on my coax if I decide to go that route.
Thanks again, everyone.