Coax cable to use? And other antenna building suggestions!

Status
Not open for further replies.

Firetxmi

Member
Joined
Oct 15, 2005
Messages
310
So I am thinking I am going to build this antenna: http://cykf.net/Liveatc/Antenna.htm

Background info: I have a pro-96 and this will be used to monitor Commercial Aircraft (108-136 mhz) band- thus the elements will be cut for this (23 inches each). The scanner will be about 50 ft (max) away from the antenna. The antenna will be placed in the attic.

I want to get ya'lls advice on some materials:

A) What should I use for the wire lengths and where can I get it?

B) What RadioShack coax cable should I use, as I want the best reception?

C) Do you think the reception will be decent (I mean, I am pretty sure it will be better than the rubber duck that the Pro-96 comes with)?

Thanks guys! Can't wait for some suggestions as this is my first antenna build!
 

pddispatcher

Member
Premium Subscriber
Joined
Nov 8, 2004
Messages
18
Your question answered.

RG-213
RG-8X Is Borderline OK depending on frequency
LMR400
RG-6

Just don't buy a real offbrand name of coaxial cable as the old saying " You Get What You Pay For "

Times Microwave is the best LMR400 coax

Or better yet get yourself a Scantenna or the $25.00 RS Antenna

And Please - Don't get Radio Shack Coax - Junk!

Since your antenna will be in the attic it should be ok as in stability wise. If you ever decide to mount it outside I'm concerned about the stability and the strength of this design.

If your going to mount it in the attic you should be ok but don't count on putting it outside as it won't stand up to mother nature depending on where you are and weather conditions.
 
Last edited:

Firetxmi

Member
Joined
Oct 15, 2005
Messages
310
pddispatcher said:
RG-213
RG-8X Is Borderline OK depending on frequency
LMR400
RG-6

Just don't buy a real offbrand name of coaxial cable as the old saying " You Get What You Pay For "

Times Microwave is the best LMR400 coax

Or better yet get yourself a Scantenna or the $25.00 RS Antenna

And Please - Don't get Radio Shack Coax - Junk!

Since your antenna will be in the attic it should be ok as in stability wise. If you ever decide to mount it outside I'm concerned about the stability and the strength of this design.

If your going to mount it in the attic you should be ok but don't count on putting it outside as it won't stand up to mother nature depending on where you are and weather conditions.

Yeah, thats why I'm thinking I'd mount it in the attic.

Do you think the $25 RS Antenna has decent reception?
 

scan_nepal

Member
Joined
Dec 17, 2007
Messages
69
Location
NEPAL
Sorry if I brought the old thread back (didn't want to start new thread).
But just have a quick question about connecting two coaxial cables.
Is it a good idea to solder braids & tip of coaxials rather than to use connectors?
How much signal loss there will be if I do that?
I am thinking of adding two 20 ft. coaxials (RG-58).
Thanks.
 

pddispatcher

Member
Premium Subscriber
Joined
Nov 8, 2004
Messages
18
You need to get something better than RG-58 - Its lossy.

When you add any type of barrel connector or anything to connect more coax other than the 1 long piece that your currently using you start getting lossy.

RG-58 with a barrel connector is not recommended.

Get you some RG-6 Regular or Quad Shield whatever you can afford in one long piece and avoid the whole RG-58/Barrel Connector all together.
 

kb2vxa

Completely Banned for the Greater Good
Banned
Joined
Mar 22, 2005
Messages
6,100
Location
Point Pleasant Beach, N.J.
Hi Fire and all,

Ah the old familiar ground plane, I've made more than I can count. I've used an SO-239 flanged chassis mount connector and 5 pieces of 1/16" diameter non fluxed brazing rod as it's stiff and won't turn into a pretzel in the wind. The article says coat hangers but they rusted quickly although this doesn't matter with an indoor installation. Outdoors it's advisable to waterproof the center insulator with a big gob of silicone bathtub caulk and wrap the connector assembly tightly with cheap black vinyl tape, the "quality" stuff doesn't stretch well and won't wrap tightly for a good moisture seal.

A note on final assembly and soldering, put a 90 degree bend at the radial ends so they fit properly into the holes in the flange. Fasten the connector and radial temporarily but firmly, it shouldn't move during soldering or you'll get a poor connection. A dab of liquid or paste rosin flux (not acid as used for plumbing) will facilitate the operation. Use a big horse's leg iron that won't cool when it contacts the work so it goes faster and you won't overheat the work. I don't recommend a soldering gun, those things are pretty useless because the tip cools and tends to stick to the work or you have to hold it on so long it overheats the work. The key is speed, if it takes longer than two seconds to form the joint you've messed it up. When the soldering is done turn it upside down, put it in a vise and file the tips and excess solder off nearly flat leaving just enough to hold things together.

Outdoors an ordinary TV antenna mast is a good way to go, shove the coax and PL-259 up through the center before final assembly and the antenna sits nicely on top. Indoors it's own radials will support it rather well unless you use copper wire, not recommended in any case.

Last but not least for receiving only it doesn't matter if the radials are 90 or 45 degrees off axis, that only affects the impedance and SWR slightly on transmit. If you choose 45 degrees of course you'll have to hook the radial ends accordingly before soldering.

My two cents worth on the coax is avoid Rat Shack like the man said. As for the type, avoid RG-58, RG-59 and RG-8X being they're too lossy for VHF and up. Otherwise it needs no special consideration for "normal" runs around 50' or maybe a little longer, more than 100' you start to get into hard line and gain antennas.

OOPS! I almost overlooked the guy with the RG-6U quad shield! The trouble with that is it requires a special F connector which means a rather uncommon crimping die to put it on. More than that you'll have to use adapters which all in all isn't really a bad idea but more involved than necessary. It's better to use RG-8U type 1/2" cable for the PL-259 and an adapter on the receiver end to fit whatever is on it, probably the usual BNC female. You may consider a short flexible jumper of RG-58U there with a PL-259 on one end and a BNC male on the other to avoid straining and damaging the connector.

WHEW! I hope I didn't forget anything, my fingers are tired. (;->)

Good luck, it's nice to see a builder/experimenter for a change!
 
Last edited:
Status
Not open for further replies.
Top