Posted: 5/1/2015 8:18:45 AM EDT
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I am putting a copper J-Pole on the roof of the house and will have a 50 to 60 foot run of LMR 400 from the antenna to house entry point where the coax will be cut and grounded. At the present time all I have for a radio is a 4 watt handheld. My original plan was to run a 6 to 8 foot piece of LMR 400 from the ground into the house and attach it to my 12" antenna saver which is RG -58 coax. Well once I got the LMR coax I see its not all that flexible I am wondering if it would be better to make the 6 foot run into the house with RG 58 set up to attach directly into my radio instead of fighting with the LMR attached to my handheld? Once I get a mobile radio set up as a base in the house I would then run the LMR to this radio. My concern is the effect the 6 to 8 feet of RG 58 will have on my signal strength. So is this a good idea or am I spending money on good coax only to hurt myself with the 8 feet of RG 58?
Thanks for the help, Jim S. |
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It's easy to determine your cable loss - I use this one ----> TlDetails
It's does way more than you need it to for just a short run of well matched (hopefully!) coax, and is pretty easy to use. It has the common types of cable already built in to it's data base. Give it a try, and you will confirm what others have said above! (and congrats BigDaddy, that's a very professional looking installation...) |
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Quoted:
For that short run, you'll never notice it. But why not just make a 4' pigtail inside? That will give you plenty of slack on the HT. Quoted:
My concern is the effect the 6 to 8 feet of RG 58 will have on my signal strength. For that short run, you'll never notice it. But why not just make a 4' pigtail inside? That will give you plenty of slack on the HT. I thought about this but I need to break the cable run outside to hook into the ground and didn't want to use a couple feet of LMR plus connectors to run it into the house then use more connectors to hook in the RG 58. Figured if I can get away with 6 to 8 feet of RG 58 then I only have the connection at the ground block. I'm thinking the run of RG 58 will be 6 foot or less but until I get a hole punched through the side of the house its only a guess as I need to trace some power lines in the wall and make sure of my drill point. I want to do a quality coax run on the house but I also hope to have enough LMR left over to do a run on the camp trailer. Good coax cost me more then the antenna and radio. Thanks for the feed back guys. |
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That's exactly how I do it in my shack. It'll be fine. 
Small lines on the radio side of the arrestors are RG58 BNCs. Larger lines on the antenna side are Davis RF BuryFlex 9914F coax. http://home.comcast.net/~gregbell/ICE%20Upgrade%20Project%204.jpg Nice setup for the arrestor box. What kind of loss do these add? |
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Using a poor performance antenna and you're worried about the loss in 8 feet of RG58? Priorities severely misplaced. Ya know I searched the web for antenna info and every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works. If you must know I purchased the J-Pole to use out of my trailer while camping but since I can't seem to get into a couple repeaters at home anymore I am mounting the J-pole on my roof to see how it does and see if I really care about Ham before I go much further. I messed around with Ham stuff a couple years ago but while I think I want to be interested in Ham I just can't find the interest in guys talking about the weather, there health issues or the truck drivers complaining about everybody on the road but themselves. So my plan is to mess around with IRLP and Echolink for a while and if I decide to go further I will replace the J-pole and probably upgrade to a duel band mobile radio, if not I have the J-pole to set up in hunting camp and the HT for field communications. |
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Ya know I searched the web for antenna info and every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works..... Quoted:
Quoted:
Using a poor performance antenna and you're worried about the loss in 8 feet of RG58? Priorities severely misplaced. Ya know I searched the web for antenna info and every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works..... Well, I don't know if it actually qualifies as a "poor" performer - but it is certainly not up to the hype that some of those 10 favorable post would have you believe! It rarely has the gain claimed, and is usually less than a simple ground plane, but it's main problem is it's inconsistency due to feedline radiation. This causes usually minor, but sometimes major, issues with SWR, radiation pattern, and noise ingress. Having said that, it sounds like you have a good plan - use it to see if you like 2 Meters, and upgrade later if you do, keeping in mind that almost anything (including homebrew goodies like the simple ground plane) will give you a little better, to a lot better, performance depending upon the route you decide to take. If you are a tech-head geek, here is a good write up on the issues with the ubiquitous J-Pole ----> J-Pole Tech-Geek Info Page |
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KnowFear and BroncoGlenn:
Thanks for the kind words and comments on the Station Ground / Lightning Protection Box. More info at link so as to not derail Muddydog's thread. Muddydogs: Check out the ARFCOM IRLP / Echolink Net tonight and every Friday night, if you get a chance. It's a great place to get your feet wet in the hobby, with the friendliest bunch of alcoholics guys on the air. 
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every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works. There are lots of people in amateur radio who will rave about (insert antenna here). Simple reality is that almost any antenna can get you on the air and make contacts. Virtually anything you put 15 or 20 feet up in the air will radically outperform a rubber duck inside your house. Once you start worrying about 1 or 2 dB of feedline loss, it's certainly valid to take into account the probably 5~10dB loss you're throwing away in antenna performance though. It's essentially impossible for a J pole to exceed the performance of a simple 1/4 wave ground plane, and in application is often much worse as the previously linked article discusses. It's trivial to get 2.5~3dB gain in an antenna that's smaller than a J pole. For most applications 1 to 2dB difference is impossible to distinguish on VHF FM. There's that much loss in poor quality connectors, especially the ubiquitous solder PL259 as commonly installed in amateur service. |
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Quoted:
There are lots of people in amateur radio who will rave about (insert antenna here). Simple reality is that almost any antenna can get you on the air and make contacts. Virtually anything you put 15 or 20 feet up in the air will radically outperform a rubber duck inside your house. Once you start worrying about 1 or 2 dB of feedline loss, it's certainly valid to take into account the probably 5~10dB loss you're throwing away in antenna performance though. It's essentially impossible for a J pole to exceed the performance of a simple 1/4 wave ground plane, and in application is often much worse as the previously linked article discusses. It's trivial to get 2.5~3dB gain in an antenna that's smaller than a J pole. For most applications 1 to 2dB difference is impossible to distinguish on VHF FM. There's that much loss in poor quality connectors, especially the ubiquitous solder PL259 as commonly installed in amateur service. Quoted:
Quoted:
every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works. There are lots of people in amateur radio who will rave about (insert antenna here). Simple reality is that almost any antenna can get you on the air and make contacts. Virtually anything you put 15 or 20 feet up in the air will radically outperform a rubber duck inside your house. Once you start worrying about 1 or 2 dB of feedline loss, it's certainly valid to take into account the probably 5~10dB loss you're throwing away in antenna performance though. It's essentially impossible for a J pole to exceed the performance of a simple 1/4 wave ground plane, and in application is often much worse as the previously linked article discusses. It's trivial to get 2.5~3dB gain in an antenna that's smaller than a J pole. For most applications 1 to 2dB difference is impossible to distinguish on VHF FM. There's that much loss in poor quality connectors, especially the ubiquitous solder PL259 as commonly installed in amateur service. What's a better choice for omni-directional 2-meter? |
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What's a better choice for omni-directional 2-meter? Quoted:
Quoted:
Quoted:
every once in a while a guy like you throws out what you said about the J-pole with nothing much to back it but for every post like yours there are 10 posts about how well the J-Pole works. There are lots of people in amateur radio who will rave about (insert antenna here). Simple reality is that almost any antenna can get you on the air and make contacts. Virtually anything you put 15 or 20 feet up in the air will radically outperform a rubber duck inside your house. Once you start worrying about 1 or 2 dB of feedline loss, it's certainly valid to take into account the probably 5~10dB loss you're throwing away in antenna performance though. It's essentially impossible for a J pole to exceed the performance of a simple 1/4 wave ground plane, and in application is often much worse as the previously linked article discusses. It's trivial to get 2.5~3dB gain in an antenna that's smaller than a J pole. For most applications 1 to 2dB difference is impossible to distinguish on VHF FM. There's that much loss in poor quality connectors, especially the ubiquitous solder PL259 as commonly installed in amateur service. What's a better choice for omni-directional 2-meter? IMHO, Cushcraft Ringo ARX-2B is one of the best antennas for the money. Comet GP-9 is even better but costs more. I agree with Gamma. J-Poles work but don't expect any significant performance. They are cheap to build but won't compete with the antennas I mentioned above. Same goes for the "Ed-Fong" J-pole antenna. I carry one in my "Go Bag" because it's small and easy to hang up in the trees. I've compared it to my Comet GP-9. It's like "day and night". The Comet gets 5 more bars on the RX and it's significantly better on TX. Both antennas were at the same elevation and had close to 1:1 SWR. To answer OPs question, 6 ft of RG-58 will work fine. You won't notice any difference. Make sure your lightning arrester unit is rated for the frequency. Also make sure you connect the correct end to the antenna. Based on my experience, Polyphaser lightning/static protectors work best. I use them on both HF and VHF coax cables. |
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What's a better choice for omni-directional 2-meter? Simple 1/4 wave ground plane which can be homebrewed for probably less than $5. A 1/2 wave or 5/8 wave mobile antenna installed on a base mounting kit with ground plane. Any of the commercially made single or dual band fiberglass antennas. More options with increasing cost and complexity. |
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Quoted: My concern is the effect the 6 to 8 feet of RG 58 will have on my signal strength. So is this a good idea or am I spending money on good coax only to hurt myself with the 8 feet of RG 58?
Thanks for the help, Jim S. |
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Quoted: My concern is the effect the 6 to 8 feet of RG 58 will have on my signal strength. So is this a good idea or am I spending money on good coax only to hurt myself with the 8 feet of RG 58? You're losing 0.5 dB on transmit and receive with 8' of RG-58. Nothing to worry about. http://www.timesmicrowave.com/calculator/?productId=122&frequency=146&runLength=8&mode=calculate#form |
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Simple 1/4 wave ground plane which can be homebrewed for probably less than $5. A 1/2 wave or 5/8 wave mobile antenna installed on a base mounting kit with ground plane. Any of the commercially made single or dual band fiberglass antennas. More options with increasing cost and complexity. Quoted:
Quoted:
What's a better choice for omni-directional 2-meter? Simple 1/4 wave ground plane which can be homebrewed for probably less than $5. A 1/2 wave or 5/8 wave mobile antenna installed on a base mounting kit with ground plane. Any of the commercially made single or dual band fiberglass antennas. More options with increasing cost and complexity. I really need something I can pull waaay up in a tree, as I am behind a hill to most of the local repeaters. Something like a GP-X might work OK if I rig up a hanging solution between 2 trees, assuming they are self contained with their own little counterpoises/'radials' (it looks like they are) If so I may add one to the wishlist. I do sort of want dual band...which I did not say earlier. So if I just make a 1/4 wave vertical section what size 'radials' (in wavelength) and how many do I need at the base? |
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Quoted:
You're losing 0.5 dB on transmit and receive with 8' of RG-58. Nothing to worry about. http://www.timesmicrowave.com/calculator/?productId=122&frequency=146&runLength=8&mode=calculate#form Quoted:
Quoted: My concern is the effect the 6 to 8 feet of RG 58 will have on my signal strength. So is this a good idea or am I spending money on good coax only to hurt myself with the 8 feet of RG 58? You're losing 0.5 dB on transmit and receive with 8' of RG-58. Nothing to worry about. http://www.timesmicrowave.com/calculator/?productId=122&frequency=146&runLength=8&mode=calculate#form Less than that. Compare the loss of RG58 versus an equivalent length of LMR400, and the difference is only 0.3dB. |
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Quoted: I really need something I can pull waaay up in a tree, as I am behind a hill to most of the local repeaters. Something like a GP-X might work OK if I rig up a hanging solution between 2 trees, assuming they are self contained with their own little counterpoises/'radials' (it looks like they are) If so I may add one to the wishlist. I do sort of want dual band...which I did not say earlier. So if I just make a 1/4 wave vertical section what size 'radials' (in wavelength) and how many do I need at the base? Quoted: Quoted: Quoted: What's a better choice for omni-directional 2-meter? Simple 1/4 wave ground plane which can be homebrewed for probably less than $5. A 1/2 wave or 5/8 wave mobile antenna installed on a base mounting kit with ground plane. Any of the commercially made single or dual band fiberglass antennas. More options with increasing cost and complexity. I really need something I can pull waaay up in a tree, as I am behind a hill to most of the local repeaters. Something like a GP-X might work OK if I rig up a hanging solution between 2 trees, assuming they are self contained with their own little counterpoises/'radials' (it looks like they are) If so I may add one to the wishlist. I do sort of want dual band...which I did not say earlier. So if I just make a 1/4 wave vertical section what size 'radials' (in wavelength) and how many do I need at the base? The ideal way to mount a Comet GP-x or similar antenna is on a mast attached to something. E.g., my GP-3 that's been up since ~2005, attached to my ugly chimney:  The Comet GP-3 is a great antenna. |
| Where I come from there are mountains and repeaters at different elevations. The J-pole used to be popular because it was sturdy and easy to build (a good thing, back when people used to build stuff). It does not have a terribly narrow vertical beamwidth like a super high gain omnidirectional antenna would have, and that can be beneficial in mountainous terrain. A J-pole is just a zepp turned up on end, essentially an end fed half wave, vertically polarized. In my opinion not a bad antenna at all. It's VHF FM, so mostly you need a path. |
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So if I just make a 1/4 wave vertical section what size 'radials' (in wavelength) and how many do I need at the base? Radials also 1/4 wave, 3 or 4. Some will say to make the radials longer than the driven element by +5% or something, other than it changing the tuning a little you can do it either way. Best impedance match and pattern usually from drooping the radials down to 45 degrees or so. If you do a google images search for "so239 1/4 wave" there are all kinds of photos of different ways people have built them. If you have the idea of putting one inside plastic pipe, remember to account for the change in electrical length due to the dielectric effect of the plastic - elements will act longer, so need to be physically shortened if inside a plastic radome. |
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Radials also 1/4 wave, 3 or 4. Some will say to make the radials longer than the driven element by +5% or something, other than it changing the tuning a little you can do it either way. Best impedance match and pattern usually from drooping the radials down to 45 degrees or so. If you do a google images search for "so239 1/4 wave" there are all kinds of photos of different ways people have built them. If you have the idea of putting one inside plastic pipe, remember to account for the change in electrical length due to the dielectric effect of the plastic - elements will act longer, so need to be physically shortened if inside a plastic radome. Quoted:
Quoted:
So if I just make a 1/4 wave vertical section what size 'radials' (in wavelength) and how many do I need at the base? Radials also 1/4 wave, 3 or 4. Some will say to make the radials longer than the driven element by +5% or something, other than it changing the tuning a little you can do it either way. Best impedance match and pattern usually from drooping the radials down to 45 degrees or so. If you do a google images search for "so239 1/4 wave" there are all kinds of photos of different ways people have built them. If you have the idea of putting one inside plastic pipe, remember to account for the change in electrical length due to the dielectric effect of the plastic - elements will act longer, so need to be physically shortened if inside a plastic radome. Yep, found plenty of images. So this will be better than my J-pole? I'll have to use my piano wire to get the necessary spring for getting it past lower limbs. Thanks for the information. |