Antenna Feed Line Question

[DRBComm]

I have recently relocated my Discone scanner antenna to a higher location and my feed line does not reach my shack any more. What are the downsides to connecting another length of feed line via PL-259/SO-239 vs. running a new single line that is the proper length?

Thanks

 

[TexTAC]

How long of a run is it from the radio to the existing feed line and from the radio to the antenna?

 

[popnokick]

Two things come to mind: 1) Loss associated with the inline connectors. The loss will be greater at higher frequencies and is documented for a given connector (PL259, Type N, etc.) 2) The inline connection is one more "point of entry" for moisture ingress to the feed line. It needs to be carefully waterproofed.

 

[trentbob]

You can see from the questions there just isn't enough information you're giving here. Are you using low-loss coax? If not you should replace the whole thing with low loss coax, you get what you pay for but lmr400, it's okay. How long is the total run? How long would the extension be? Is this for receive only or are you transmitting?

You can use an adapter to hook up pl-259 to another pl259 of the same coax if you want as long as it's all low loss, preferably using the same coax.

As has been mentioned, when you extend a run with adapters you are making more chance for contamination with water , I like to use a product called coax- seal, not real popular anymore but I find it very effective but only if you wrap the connection first with electrical tape then apply the sealant and mold it. That way if you want to remove it you unwrap the electrical tape and it doesn't turn into a gooey mess.

 

[DRBComm]

Thanks for the replies. The general consensus seems to be to replace the entire feed line so that is what I will do. What is the best type to get? And where is the best place to get it from?

 

[krokus]

Thanks for the replies. The general consensus seems to be to replace the entire feed line so that is what I will do. What is the best type to get? And where is the best place to get it from?

Best depends on the freqs involved, and the diameter hole you have for the cable to pass through. Which frequency ranges are you utilizing?

 

[DRBComm]

Best depends on the freqs involved, and the diameter hole you have for the cable to pass through. Which frequency ranges are you utilizing?

Well I have 3 antennas and want to properly configure each.
1. Is my Discone antenna for receive only on my scanner.
2. Is my dual band (2M & 70cm) J-Pole antenna
3. Is my Hy-Gain AV-680 9-band HF antenna.

My original question was specifically geared toward my receive only scanner antenna, but since the questions were brought up, let's get it all figured out here.

The diameter of the hole for the cables to pass through has not been made yet, so that can be whatever I need. I plan to run all cables to an exterior box mounted to my house where I will run them through lightning arrestors before entering the house.

 

[krokus]

Well I have 3 antennas and want to properly configure each.
1. Is my Discone antenna for receive only on my scanner.
2. Is my dual band (2M & 70cm) J-Pole antenna
3. Is my Hy-Gain AV-680 9-band HF antenna.

My original question was specifically geared toward my receive only scanner antenna, but since the questions were brought up, let's get it all figured out here.

The diameter of the hole for the cables to pass through has not been made yet, so that can be whatever I need. I plan to run all cables to an exterior box mounted to my house where I will run them through lightning arrestors before entering the house.

Keeping the J-pole separated from the discone is a good start. The further the better, but a few feet at an absolute minimum. If they are going on the same mast, put the discone at the top and use a stand off mount for the J-pole.

How & where is the AV-680 mounted?

 

[DRBComm]

Keeping the J-pole separated from the discone is a good start. The further the better, but a few feet at an absolute minimum. If they are going on the same mast, put the discone at the top and use a stand off mount for the J-pole.

How & where is the AV-680 mounted?

The center vertical line represents the peak of the roof of the garage and my shack in in the back of the garage. This is the planned placement of the antennas. The J-Pole and Discone will be mounted at the peak and the AV-680 will be mounted on a 20 ft. pole and supported on the eave. The base of the AV-680 will be 17 ft. above ground and 5 ft. above the eave.

 

[prcguy]

Looks good to me. What side of the house is the AC breaker box? For grounding you want a short run from a lightning arrestor or ground block direct to the ground rod under the AC breaker box. It would be nice if that was near the AV-680 or J-Pole.

View attachment 110961
The center vertical line represents the peak of the roof of the garage and my shack in in the back of the garage. This is the planned placement of the antennas. The J-Pole and Discone will be mounted at the peak and the AV-680 will be mounted on a 20 ft. pole and supported on the eave. The base of the AV-680 will be 17 ft. above ground and 5 ft. above the eave.

 

[DRBComm]

Looks good to me. What side of the house is the AC breaker box? For grounding you want a short run from a lightning arrestor or ground block direct to the ground rod under the AC breaker box. It would be nice if that was near the AV-680 or J-Pole.

Unfortunately it is not close by. The house is to the right of the garage and another 40ish feet away from the J-pole installation

 

[krokus]

Unfortunately it is not close by. The house is to the right of the garage and another 40ish feet away from the J-pole installation

View attachment 110968

You can drive another ground stake near the cable exit from the shack, grounding the shack to that. That ground will need to be bonded to the existing ground. (Please read up on how to do that, as doing it incorrectly can damage things in your house.)