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Author Topic: HF Station Coax Run  (Read 2188 times)
TMTYLER357
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« on: June 19, 2008, 06:43:20 PM »

I need to know if it would be acceptable to run RG-58 coax (the type you can get at Radioshack that has the solid inner conductor), for a new HF station. I have just recently upgraded to General and am working on the Extra. I want to set up an antenna, but I'm on a very low budget. I wanted to know if RG-58 coax has high or low loss on HF. I can't seem to find the RG-58 coax with a solid conductor online. When I type in RG-58 coax it comes up but it all has stranded center conductors.

I hope someone can answer this question.

Thank you very much + 73,
Tyler
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TMTYLER357
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« Reply #1 on: June 19, 2008, 06:44:26 PM »

Sorry, I forgot to mention that it would be between 100 and 150 feet from the antenna to the station.

Thanks again
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W3LK
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« Reply #2 on: June 19, 2008, 07:29:38 PM »

(1) I would not run RS coax anywhere. It's about the poorest quality coax made.

(2) I would not use RG-58 (of any brand) for a 100-150 foot run. The loss  is simply too great.

The accepted practice is to use RG-213, LMR-400, Bury-Flex 9914 or other reasonably low-loss coax for HF use for anything over about 50 feet.

The question is, how much of your signal are you willing to lose in the coax before it gets to the antenna?

73,

Lon - W3LK
Naugatuck, Connecticut
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W3LK
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« Reply #3 on: June 19, 2008, 07:30:53 PM »

<< but I'm on a very low budget >>

The very LAST place you want to pinch pennies is on your feed line.

73,

Lon - W3LK
Naugatuck, Connecticut
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K9KJM
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« Reply #4 on: June 19, 2008, 11:43:24 PM »

On a really low budget, Your best bet is going to be to find a friendly local cable TV installer, And ask for a "spool end" of coax.   Ask nice, Offer some donuts, And try for both RG-6 AND some RG-11.

RG-11 is similar size to RG-8 series coax, And actually has lower loss, But all cable tv coax is 75 ohm, Not the 50 ohm "standard" of ham radio.  
With most HF type antennas, That will NOT make any difference anyhow. Just go ahead and use it.
Standard PL-259 connectors will work, But be aware you cannot easily solder to the outer shield of the television coax (Aluminum with stainless drain wires)
Just fold the drain wires back to make a tight screw fit so you have a good shield connection.

I agree, Radio Shack is about the last place to go for coax.
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WB2WIK
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« Reply #5 on: June 20, 2008, 08:53:22 AM »

I also would not use "Radio Shack" coax.  Mil-spec RG58A/U or RG58C/U isn't bad stuff, if purchased from an actual manufacturer of high quality cables (or better still, purchased "surplus" as new old stock, with government inspection tags and all -- surplus coax is usually a great deal and far better quality than Radio Shack).

However, for 100-150 feet, I'd want to know exactly what kind of antenna was at the other end before I decided to use such small cable.  I'd also want to know exactly how the coax would be routed from the station to the antenna, because RG58-sized cable is small and a bit frail and you can't really walk on it, kink it, drive over it, wrap it around sharp chimney (or similar) corners, etc.  It just isn't designed for that kind of abuse.

The reason it's important to know "what kind of antenna" and also what bands it will be used on is because RG58 has moderate loss per 100 feet when it's perfectly matched; but some antennas create a very large mismatch for the cable and under those conditions, the loss can increase quite a lot and also the power handling ability (about 500W on HF when it's matched) can be seriously degraded (to less than 100W on HF under mismatch conditions).  So, the coax is part of the "antenna system," and the more you know about the entire system, the better off you are.

Rather than buy "new" RG58 cable, I'd buy surplus RG213/U for about the same cost, and end up with far better cable: Lower loss, higher power handling, more mechanically robust, longer life.

WB2WIK/6
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N8EKT
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« Reply #6 on: June 20, 2008, 11:02:01 AM »

Belden 8214 has 1.2 Db loss per 100 ft at 50 mhz and is a VERY flexible RG8 with a foam dielectric and stranded center conductor that is well suited for HF.
Belden 9914 has 1.1 Db loss per 100 ft at 50 mhz and is a semi-flexible RG8 with a stranded center conductor.
Since cable loss is no issue below 30 mhz, your prime concern is power handling and ease of use.
8214 will handle full legal limit and is by far the most flexible and easy to terminate.
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K0EKL
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« Reply #7 on: June 29, 2008, 06:37:36 AM »

RG-58 coax has significantly more loss per foot than RG-8 does. I would never use RG-58 for anything but short runs and jumper or patch cables. RG-8 can also handle much more power than RG-58 can.

Signal loss per foot increases as frequency increases. A 150 foot run of RG-58 might by OK if you're on 80 meters but on 10 meters the loss per foot is much higher and a great deal of your signal will be lost in the coax. On 6m it will be worse and in 2m it will be worse still. Keep in mind that loss in the coax will weaken a signal you are trying to receive just same as it will the signal you are transmitting.

The difference in loss between stranded and solid center conductor is insignificant. The primary difference between coax with stranded vs. solid center conductor is flexibility. Stranded will bend more easily and can withstand more repeated flexing than can solid.

Radio Shack coax is generally regarded as being of poor quality.

As to burying the coax, there are special types of coax which are intended for direct burial. I recommend you seek out one of these for your project. Non-burial rated coax will be destroyed by the slightest nick or cut in the jacket. If a rock cuts the outer jacket of your buried coax or a rodent chews through the jacket moisture will seep in. When that happens the signal losses in the coax skyrocket and the coax is ruined. Bury-rated coax has a tougher jacket it is often "flooded" with a sealant which prevents moisture ingress even if the jack it nicked.

 




I need to know if it would be acceptable to run RG-58 coax (the type you can get at Radioshack that has the solid inner conductor), for a new HF station. I have just recently upgraded to General and am working on the Extra. I want to set up an antenna, but I'm on a very low budget. I wanted to know if RG-58 coax has high or low loss on HF. I can't seem to find the RG-58 coax with a solid conductor online. When I type in RG-58 coax it comes up but it all has stranded center conductors
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NV2A
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« Reply #8 on: July 10, 2008, 05:54:52 AM »

(gee, I said Radio Shack cable was cheap cable on another thread and got my head handed to me on a plastic platter!  Where are all those guys now?  LOL)

If per chance you are a young man who finds it difficult to cough up $1.30Plus per foot of better cable (for 150 run) then just run what you can afford now and know that it is your weak link till you can replace it with hamfest found cable or get a better job.

You will likely still make contacts and have fun.  When you finally replace that cheap stuff you might still find uses for it later for bazooka antennas or other fooling around.

Just get on the air, plenty of time to tweak your station into perfection!  If you start out with 100 watts at the xmtr and end up with 5 watts at the antenna then consider yourself a qrp station for the time being and have fun with that.
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W7ZRC
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« Reply #9 on: July 11, 2008, 02:32:15 PM »

Tyler,

What type of antenna are you going to use? It might make more sense (cost wise too) to use twin lead or open wire feeders. Lowest loss and inexpensive. Then a balun at the shack end or at the tuner.

This solution is actually better for a balanced antenna than coax.

Have fun and 73, Rod
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K4BTC
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« Reply #10 on: January 15, 2009, 01:28:00 PM »

well I have found that the good old "ladder line" works pretty good. If you can't buy it, you can make it. You can even go to Radio Shack and use their foam filled tv 300 ohm ladder line. Not the best of what is available, but it is cheap and it will work pretty good with a tuner, until you can afford the more costly stuff. just remember, experimentation is half the fun of Ham Radio, give different ideas a shot and then pass your experiences onto the next ham looking for ideas.
Have Fun! and 73's
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