Building my first antena

[Roscoe1961]

I'm just getting back into scanner listening and I am trying to improve my 2 old analog scanners reception. (RS pro 66 and pro 2040). I'm located 5 miles north of Lindsay On. and I'm afraid there's not a lot to listen to. As I ease back into the hobbie I will buy some better equipment.
I have looked onsite here and going to attempt a Off Center Fed Dipole. The question is; I have lots of RG 58U coax the OHMs are not printed on the cable. I understand that I should be using 50 OHMs cable. If this is 75 OHMs will there be a significant loss?

I have thicker coax but the only markings on it are TFC T10. Would thicker mean less OHMs or more?

I also have this splitter, would I loose 3.5 db to each scanner if I was to use this?

Sorry for the size of the picture.
Thanks for the help!!
I

 

[prcguy]

Yes you will loose a good 3.5dB or more than half of your signal feeding it through that splitter. The OCFD antenna project on RR (which I'm not a fan of) would use a TV type 75 to 300 ohm matching transformer and 75 ohm coaxial cable. RG-58 is very lossy at VHF/UHF if your coax run is very long.

 

[Roscoe1961]

Thanks for your quick reply. I can ditch the splitter and use one radio at a time or make a couple of different antennas. I'll look for a matching transformer. I can keep my run less than 100'.

 

[jim202]

For what it's worth, the connectors on your spliter look like type F connectors. The normal cable that TV and cable feeds use is RG6. You can get the connectors in a crimp style or screw on. The crimp connectors require a special crimp tool. This tool pushes the ends together and not crimping the rear round connector like most people do with some of the coax connectors on the market.

 

[mmckenna]

Size of the cable doesn't dictate it's impedance. The impedance is determined by the spacing between the inner conductor and the outer shield.

In most cases, larger cable is going to have less loss. Less loss means more signal gets from your antenna to your radio.
But chasing a small improvement often isn't worth it if you have a strong enough signal outside your house.

In addition:
Cable will be rated as a certain amount of loss per foot (or 100 feet) at a given frequency.
As length goes up, so does the losses.
As frequency goes up, so does the losses.

Unless your cable run is really short (like 20 feet or less) you really want to use better cable.

For the Off Center Fed dipole, regular cable TV/TV antenna RG-6 can work well. It's fairly low loss at most frequencies that scanner listeners are interested in. The F connectors are easy to install and will match up with your splitter. Best of all it's cheap.


If you are 'getting back into the hobby' and will be building your own antennas, it may be beneficial to buy a bunch of RG-6 at a bulk discount and set yourself up with the tools necessary to put connectors on:

Amazon.com : F connector kit

No, it's not the "best" cable, but it's good enough for most scanner hobbyists.
Before you ask...
No, you cannot afford the "best".
Do the best you can within your budget and capabilities.

 

[kb9hgi]

I have a St-2 antenna with RG-6 coax and runs into a 3 way Time warner cable tv splitter and I hear stuff 50 miles away. Work good enough for me. Actually that antenna system works better then my discone that is fed to 1 scanner

 

[ladn]

I've made several variants of the RR OCFD antenna (some out of anodized tubing and others out of wire). I've been generally pleased with the results. I've found it fairly adequate for California Highway Patrol (around 42-49 MHz), but not great. Same for 800 MHz L.A. City Fire. For the most part I'm monitoring repeaters or base stations on these frequencies. I'm pleased with the performance on VHF (air, ham and commercial) as well as UHF (milair, ham, commercial) up to about 512. I use decent quality RG-6 cable with F-connectors and a jumper/adapter as needed at the scanner end.

Your results with vary.

 

[a417]

Before you ask...
No, you cannot afford the "best".
Do the best you can within your budget and capabilities.

I fear you are going to get a repetitive stress injury.

Before you ask...

• "Just drill the damn hole."
• "No, you cannot afford the 'best', do what you can within your budget and capabilities"

 

[mmckenna]

Good idea:

 

[Roscoe1961]

Thanks for everyones feedback.
I have accumulated the parts and pieces to build an 18/48 Off Center Fed Dipole.
I also have a tig welder and lots of 1/8" stainless filler wire. I will try a disc cone like below.