Build or buy?

[Raptor05121]

I need a new 2m antenna for my Kenwood TK-7180. I currently have a dual-bander on a 30' pole that I got from my grandpa, but two of the three radials have snapped off (I have them in my posession) and the PL-259 on the bottom is rusted so bad I cannot get it off after sitting in PB blaster for two days. The coax's rubber insulation is pulled down an inch or two off the connector revealing the shielding underneath. Weirdly, I have a 1.1-1.2 SWR on hitting both the local (15 miles, 32 miles) repeaters with little or no static. The fact that its old and rusty has me cringing. I'd rather put something new up there.

Now, would it be cheaper to build ( Build a 2 Meter Vertical Antenna ) or buy a single-band (2m only) antenna? And what kind of antenna coax is best? I'm getting RG-6 TV coax when I try to search.

 

[n5ims]

I need a new 2m antenna for my Kenwood TK-7180. I currently have a dual-bander on a 30' pole that I got from my grandpa, but two of the three radials have snapped off (I have them in my posession) and the PL-259 on the bottom is rusted so bad I cannot get it off after sitting in PB blaster for two days. The coax's rubber insulation is pulled down an inch or two off the connector revealing the shielding underneath. Weirdly, I have a 1.1-1.2 SWR on hitting both the local (15 miles, 32 miles) repeaters with little or no static. The fact that its old and rusty has me cringing. I'd rather put something new up there.

Now, would it be cheaper to build ( Build a 2 Meter Vertical Antenna ) or buy a single-band (2m only) antenna? And what kind of antenna coax is best? I'm getting RG-6 TV coax when I try to search.

They're not all that hard to build, but if you buy you'll generally get better construction (depending on just how handy you are) and higher gain. The link you posted is a unity gain antenna and may do the job, but the dual-bander probably has more gain so it's hard to guess which will work better.

"And what kind of antenna coax is best?" Is really setting the bar quite high. The "Best" coax gets really costly real fast and since you're asking if you should buy or build your antenna you probably don't want to spend that much on the coax. RG-6 probably isn't what you want since your radio transmits and you're indicating that you're hitting some local repeaters.

Under the assumption that "best" really isn't what you're looking for, but rather "what will work for this application" is probably more like it, I'd recommend a good grade of RG-8 (not a cheap brand or somebody's old junk - new junk maybe, but not old junk). Please note that I said RG-8 and not RG-8X, which is no where near the same. Better would be some RG-213 (RG-8 size, style, and connectors, but a bit lower loss). For a bit more cost, LMR-400 will also work fine.

 

[K9WG]

Yes, it would be cheaper to build. But would it be worth the time and effort? You can get some pretty good VHF antennas for a reasonable price ($38 from R&L)

RG6 will work quite well at VHF and even though it is 75ohm the difference will not be great enough for any issues. (You will need a RG6 reducer for the PL259). I use the commercial satellite grade coax for both VHF/UHF and HF.

 

[Nap]

These charts will help you select a cable:

Coaxial Cable Attenuation Chart

The most popular ones are RG-8, RG-58 and RG-213/214.

If you want to do 440MHz then RG-213/214 is highly recommended.

Also note that for installing PL-259 connectors on RG-8 and RG-58, you'll need "reducers" as the coax is thinner than the connector inner diameter. RG-213/214 are thicker and fit just right.

LM400 which is highly recommended everywhere might not fit well your PL-259 connectors (it's a hit and miss depending on coax and connector manufacturers). I would use it with N-connectors for long spans of cable only.

 

[Raptor05121]

I'm not scared at all with building anything. but I have a few sections of LMR-400 lying around here. I wouldn't want 2-3 pieces running up to an antenna, I'd rather buy a new, single piece and get it all done right. Thanks guys.

 

[ermin]

I'd build. If your handy with PVC pipe and copper tubing you could make a great antenna.

73

Ermin

 

[prcguy]

RG-214 is up to $10/ft due to the cost of silver and I hear they found RG-213 buried with some Dinosaur fossils, so it's a bit outdated, especially for the cost.

RG-213 and 214 are basically the same performance within the range we use for VHF/UHF monitoring, which is good but not great for long runs.

LMR400 is under a buck per foot and really hard to improve on without taking a huge leap in price.
prcguy

These charts will help you select a cable:

Coaxial Cable Attenuation Chart

The most popular ones are RG-8, RG-58 and RG-213/214.

If you want to do 440MHz then RG-213/214 is highly recommended.

Also note that for installing PL-259 connectors on RG-8 and RG-58, you'll need "reducers" as the coax is thinner than the connector inner diameter. RG-213/214 are thicker and fit just right.

LM400 which is highly recommended everywhere might not fit well your PL-259 connectors (it's a hit and miss depending on coax and connector manufacturers). I would use it with N-connectors for long spans of cable only.

 

[LtDoc]

"RG-214 is up to $10/ft..."
I would be tickled to death to sell you RG-214 for $5.00/foot. You'd save over $5.00/foot!!
Anyone quotes you that price, hang up and call someone else!
- 'Doc

(At $5.00/foot, I'd be making a 100% profit.)

 

[sparks40]

I've had very good performance using LMR400 on a homemade 2 meter J-pole made of 3/4" copper pipe. In the original install, i used RG58, as seen in the photos. It is at 20', and currently fed with 50' of LMR400 minus the wound coax choke.

 

[Rt169Radio]

I've had very good performance using LMR400 on a homemade 2 meter J-pole made of 3/4" copper pipe. In the original install, i used RG58, as seen in the photos. It is at 20', and currently fed with 50' of LMR400 minus the wound coax choke.

Is there a reason why you put the pipe inside the pvc? To make it look better? Or keep it out of the elements?

 

[sparks40]

Is there a reason why you put the pipe inside the pvc? To make it look better? Or keep it out of the elements?

The pipe has a male adapter soldered to it, which is screwed to a 3/4" reducer mounted to the top of 2" pvc. The antenna is not inside the pipe, it's painted white.

 

[mass-man]

Copper J poles...twinlead J pole in PVC...coat hanger ground plane. Lots of easy to build, good peforming antennas out there for 2 meters. And when you are done, you can always brag that you built it...and probably learned something at the same time.

 

[KJ4ODU]

for my 2m Base Radio, I built a J-pole, and used RG6 Coax with PL259 Connectors, its been 2+ years 20ft off the Ground.

I can still hit Repeaters 75+ miles away.

Radio puts out 50 watts on High.


when I get a tower up 60ft high, 10m beam and a 2/440 Jpole on top of that, I will be using RG6 for the 2/440 antenna.

 

[KJ4ODU]

Here a good J-pole Build Info.

The SIMPLE 2m Copper 'J' Antenna
or
Building A 2-meter J-Pole Antenna I think I used this.


and where I made the connecting I did not Solder the pl259 to the j-pole, what I did was took this.

http://file.seekpart.com/productsimage/2010/12/30/2010123014424629s.jpg

and split it down the middle and clapped it to the J-pole.

 

[LtDoc]

If you're satisfied with the performance of your present antenna (if it were in good shape) then I would look for another like it. There are a number of very nice commercially made antennas, just depends on your wallet and particular purposes. Another solution is to make your own version of your present antenna, or one you think would be better. It's certainly not impossible, but sometimes it isn't as simple as it could be. Just depends on how 'handy' you are and what you have available.
I'm seeing a lot of 'hype' about RG-6 coax lately, about it being so good for general use with antennas. It isn't the 'best' by any means, but it is cheap. Most commercial antennas are made for use with 50 ohm feed line. RG-6 isn't 50 ohms, so you will have some impedance matching to do to use it. Also not impossible, but it usually negates that 'cheap' thingy that makes RG-6 so appealing. For instances where the characteristic impedance isn't important, receiving only, then RG-6 is certainly an option. For instances where it's impedance doesn't 'fit' the requirements, it's more trouble than it's worth so not a 'bargain' anymore. Coax such as (TM) LMR-400 is more expensive, but it works very well at VHF, and is worth the expense. Suit yourself...
- 'Doc

 

[Raptor05121]

Noob question time: Whats the difference between a J-pole and a regular 19" copper antenna with three ground planes?

 

[LtDoc]

A 'J'-pole is a 1/2 wave antenna with a 1/4 wave matching stub. That 19 inch antenna with a few radials is a 1/4 wave antenna. there's a difference in their radiation patterns, which is a biggy.
- 'Doc

 

[Raptor05121]

Okay, guess I have some learning to do. 1/2 wave is better than 1/4 wave then?

I'll give a look at those J-poles how-tos