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RG-6 AS TRANSMISSION LINE




 
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W2PFY
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« on: March 03, 2021, 02:18:57 PM »

Have you ever used RG-6 as a transmission cable and if so, what power level, frequency and length did you use and your results?It looks like it could handle descent power but I wonder how it would work at 500 feet on 160-40 meters

Thanks Terry

Attached is a power chart comparing RG-6 with other cables.


https://owenduffy.net/transmissionline/RG6/index.htm


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kc9pcp
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« Reply #1 on: March 04, 2021, 11:00:18 AM »

I use 50ft of RG-6 regular ATV cable for my FT-450 for connecting to my 20m to 6m  fan dipole and it works good. Of course this is only max 100 watts.
Also it has to be RG-6 or 72 ohm cable all the way. Using a 50 ohm cable to the the ground block and then 72 ohm RG-6 would not work with the autotuner.

Linas KC9PCP
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Tom WA3KLR
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« Reply #2 on: March 04, 2021, 12:09:32 PM »

Hi Terry,

RG-6 was engineered for TV service 50 - 500 MHz. Amazingly low loss for its size. The copper-clad steel center conductor serves as the center pin in the F connector.

I don't have any practical experience with RG-6 on HF transmission. BUT, for 160 meters I would go with the solid copper center conductor. This is mentioned in the link of yours, a good reference.  The loss curves at the top of the article are computed based on one loss reference point and does not show the actual loss with the copper-clad steel conductor at 2 MHz. The actual loss will be higher since the current now is forced below the skin depth of the copper clad and steel has more resistance plus it is a high permeability material with high skin effect.
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« Reply #3 on: March 14, 2021, 06:50:38 PM »

I run about 40-50 feet of RG-6 to my OCF Windom antenna (with a 4:1 balun at the feedpoint). I'm primarily interested in 80 and 40 meters and it seems to work quite well there.
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« Reply #4 on: March 16, 2021, 04:35:52 PM »

Thanks Guys! What type of connectors do you use on the RG-6? I have heard that there are adapters to go from the RG-6 connector to BNC? I haven't done any research on connectors as yet so anything suggested would be helpful!

There doesn't seem to be a lot of use for this cable with hams but for the price and with moderate power levels, how can you go wrong?

tnx

Terry
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« Reply #5 on: March 16, 2021, 05:07:46 PM »

75 ohm BNC crimp on connectors are readily available for RG6. Lowes has them as standard items.
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ka1bwo
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« Reply #6 on: March 21, 2021, 04:38:43 AM »

Have you ever used RG-6 as a transmission cable and if so, what power level, frequency and length did you use and your results?It looks like it could handle descent power but I wonder how it would work at 500 feet on 160-40 meters

Thanks Terry

Attached is a power chart comparing RG-6 with other cables.


https://owenduffy.net/transmissionline/RG6/index.htm




Hi Terry,
I miss your witt talking to you on the air. What impedance is transmission line terminated into, 70 ohm at resonance or Z vs frequency across the band. What worse case length of RG6 are you going use? I don't assume anything. I can post a (S21) insertion loss plot vs frequency.
Joe
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ka1bwo
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« Reply #7 on: March 21, 2021, 11:28:43 PM »

Have you ever used RG-6 as a transmission cable and if so, what power level, frequency and length did you use and your results?It looks like it could handle descent power but I wonder how it would work at 500 feet on 160-40 meters

Thanks Terry

Attached is a power chart comparing RG-6 with other cables.


https://owenduffy.net/transmissionline/RG6/index.htm




100 feet of RG6U belden 7915A, first plot: insertion loss vs frequency  terminated into 50 ohms, 2nd plot:  terminated into 75 ohms. Source impedance in both cases is 50 ohms.   


* image39.png (10.65 KB, 661x661 - viewed 67 times.)

* image38.png (9.74 KB, 661x661 - viewed 72 times.)
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« Reply #8 on: March 22, 2021, 08:50:32 PM »

Hello Joe & all, thanks for your response. The xly on this end is suffering from dementia so that and the fact that I ain't getting any younger adds to my slow response in getting back to a thread. Yes, I miss talking with everyone on the radio but in a few weeks I should be on at least a few times each month till cold weather shows up again:(

Well Joe, I have been thinking about buying a new SSB rig maybe a 7300 and I'm leaning toward 17 meters and above perhaps with a fan dipole. I also found out that BNC connectors are expensive along with a quality crimping tool to go along with the setup. I wonder if you Joe have any suggestions about an antenna for 17 and up? I also wonder  how much strain the weight of the cable might impose on a crimp style connector? The antenna would be up about 80 feet between two pine trees or whatever tall tree fits the bill at my camp. I wonder if RG-6 would work as a Bazooka antenna? I used to work the world on 100 watts on 17 meters so that is about what I expect that I will do. Any thoughts?

tnx Terry     
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ka1bwo
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« Reply #9 on: March 23, 2021, 05:10:21 PM »

Hello Joe & all, thanks for your response. The xly on this end is suffering from dementia so that and the fact that I ain't getting any younger adds to my slow response in getting back to a thread. Yes, I miss talking with everyone on the radio but in a few weeks I should be on at least a few times each month till cold weather shows up again:(

Well Joe, I have been thinking about buying a new SSB rig maybe a 7300 and I'm leaning toward 17 meters and above perhaps with a fan dipole. I also found out that BNC connectors are expensive along with a quality crimping tool to go along with the setup. I wonder if you Joe have any suggestions about an antenna for 17 and up? I also wonder  how much strain the weight of the cable might impose on a crimp style connector? The antenna would be up about 80 feet between two pine trees or whatever tall tree fits the bill at my camp. I wonder if RG-6 would work as a Bazooka antenna? I used to work the world on 100 watts on 17 meters so that is about what I expect that I will do. Any thoughts?

tnx Terry     

Terry,
I'm very sorry to hear about your wife's situation.  When I worked at Raytheon we had a amatuer club station at the plant. The antenna that we used was a fanned dipole it worked really well. The only problem mechanically construction is a bit challenging. The other antenna I would recommend is a doublet it pretty simple, effective and efficient. For matching I use a linked coupled network, Johnson flashbox.  What type coax are you going to use with a crimped bnc connector?  Never built a bazooka antenna hope others have and comment. Here is one more scenario using 100 feet of RG-6 feeding a 40 meter dipole, 65.5 feet long, #12 wire, height of 30 feet . Plot: showing coax loss 
Joe


* image41.png (9.54 KB, 661x661 - viewed 44 times.)
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« Reply #10 on: March 23, 2021, 06:35:52 PM »

Joe, the crimped connectors BNC would be for the RG-6 since you cannot solder to the foil. I haven't looked at all RG-6 cables but maybe one of them has a woven copper cable bedded in the jack/foil area? If that type of cable is mfg. then it could be soldered. The whole thought with RG-6 is that cable is really cheap and light weight. Four connectors are about ten dollars and a real good crimp-er is about 85 bucks. So for me to spend that kind of money for a chimp-er I think I'd better talk to a couple of nearby hamboners and see if they want to experiment with some RG-6? I think it may be a hard sell and I'll end up buying what ever is needed to try out this cable.

I am not an engineer and the one thing that stood out to me was a statement the gentlemen said about RG-6 and that was from memory Make no assumptions about its velocity factor, measure it for length critical applications. I don't know what he meant because he did not explain that? Is cable with the lowest number the best? Is it when you choose a certain length that things would go wrong?

Thanks for the 40 meter data Joe.

Terry
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« Reply #11 on: March 23, 2021, 07:04:16 PM »

There is an IDEAL brand crimper that crimps both F and BNC.  I can't recall the model and uts buried in packed boxes but I got it at depot or Lowes for a lot less than 80 bucks, that's for sure.

Couldn't tell you how many crimps I did with it, but works great.


--Shane
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« Reply #12 on: March 24, 2021, 02:13:31 AM »

Joe, the crimped connectors BNC would be for the RG-6 since you cannot solder to the foil. I haven't looked at all RG-6 cables but maybe one of them has a woven copper cable bedded in the jack/foil area? If that type of cable is mfg. then it could be soldered. The whole thought with RG-6 is that cable is really cheap and light weight. Four connectors are about ten dollars and a real good crimp-er is about 85 bucks. So for me to spend that kind of money for a chimp-er I think I'd better talk to a couple of nearby hamboners and see if they want to experiment with some RG-6? I think it may be a hard sell and I'll end up buying what ever is needed to try out this cable.

I am not an engineer and the one thing that stood out to me was a statement the gentlemen said about RG-6 and that was from memory Make no assumptions about its velocity factor, measure it for length critical applications. I don't know what he meant because he did not explain that? Is cable with the lowest number the best? Is it when you choose a certain length that things would go wrong?

Thanks for the 40 meter data Joe.

Terry

Terry,
I didn't realize that RG-6 OD is only .015" smaller than RG-58. I bought a crimping tool for bnc connector on line for $35 to make up cables using RG-58 it works great. That crimper should work for RG-6 too. It must be the same one that Shane has.  I'll check the brand and model #and post . Don't sweat the cable VF.  If the VF=1 the wave will propagate along the line at the speed of light (V), if the VF=.5 the wave will propagate along the line at .5 the speed of light. 
 Wavelength =(V)(VF)/frequency.   Physical length of a wavelength of line with VF=1 is twice as long compared to a cable with a VF=.5 at a given frequency.    https://catalog.belden.com/techdata/EN/7915A_techdata.pdf   
Forgot to post 40 meter dipole feed point impedance presented to 100 feet of RG-6.
Joe   




* 40M feedZ - Copy.txt (1.08 KB - downloaded 19 times.)
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WD8BIL
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« Reply #13 on: March 24, 2021, 08:06:24 AM »

Hi Terry......... he means if you're gonna use it for stuff like phasing lines you'll need to determine the VF or cut for a VF of 1 then trim as needed.
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« Reply #14 on: March 24, 2021, 10:39:44 AM »

Was thinking wow I have a few spools of that! But no, upon re-inspection it's RG-59.

Not going off topic but in case anyone else was thinking about a spool RG-59 in their garage for transmission line, it's worth adding that RG-59 doesn't stack up well against RG-6. Don't do it.


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« Reply #15 on: March 24, 2021, 09:13:15 PM »

Quote
I bought a crimping tool for bnc connector on line for $35 to make up cables using RG-58 it works great

Hello Joe, the crimper that I saw at Loews would crimp on RG-6, RG-59 and two others but I forgot what they were?

Thanks Budly about the V factor. I remember when Tina W1IA was crunching numbers for his phased array that I think was TV hard line. He got it to work but I don't know if it is still up in the air as it came down once before if memory serves me correctly?

I am going to go out 500 feet with the RG-6 just to see how it works. I also have some RF ammeters and some big ass non inductive resistors, that I could put on at the other end and get an idea how much RF is making the trip, to the other end?
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« Reply #16 on: March 24, 2021, 10:23:20 PM »

Hi Terry,

You can measure the loss from one end of the coax with the MFJ-259x or similar gadgegators in 'coax loss' mode, far end of coax is open.  Just move the test frequency around some to make sure you are not parked on a resonant frequency; look for the indicated loss number to be consistent in a range of frequency in your region of interest.
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« Reply #17 on: March 25, 2021, 02:00:33 AM »

Quote
I bought a crimping tool for bnc connector on line for $35 to make up cables using RG-58 it works great

Hello Joe, the crimper that I saw at Loews would crimp on RG-6, RG-59 and two others but I forgot what they were?

Thanks Budly about the V factor. I remember when Tina W1IA was crunching numbers for his phased array that I think was TV hard line. He got it to work but I don't know if it is still up in the air as it came down once before if memory serves me correctly?

I am going to go out 500 feet with the RG-6 just to see how it works. I also have some RF ammeters and some big ass non inductive resistors, that I could put on at the other end and get an idea how much RF is making the trip, to the other end?

Hi Terry,
What  terminating resistor value or values are you going to use at end of the line? Here are few plots. Plot 1: 500 feet of RG-6 terminated into 50 ohms, transmitter output=100 watts , Power delivered to the load vs frequency. 2nd plot: Total power loss, db vs frequency. The line losses is a combination of transmission line insertion loss and standing wave.   


* image44.png (10.76 KB, 661x661 - viewed 48 times.)

* image45.png (11.41 KB, 661x661 - viewed 47 times.)
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« Reply #18 on: March 25, 2021, 02:04:17 PM »

Well Joe the resistors in series and parallel would come out to about 83 ohms so it would be high at about 8 ohms.

Ok Tom, on the gadget, I have one of those things and I'll give it a try. I guess I could put a 500 watt flood lamp on it and look out into the woods for a glow Cheesy Cheesy Would it make a difference if it was still coiled up on the roll rather than payed out to test it?



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« Reply #19 on: March 25, 2021, 03:22:50 PM »

Well Joe the resistors in series and parallel would come out to about 83 ohms so it would be high at about 8 ohms.

Ok Tom, on the gadget, I have one of those things and I'll give it a try. I guess I could put a 500 watt flood lamp on it and look out into the woods for a glow Cheesy Cheesy Would it make a difference if it was still coiled up on the roll rather than payed out to test it?




Terry,
If you can get to the end leave it on the roll.  Plots for 83 ohm load, 500 feet of RG-6. Plot1: Power delivered to load vs freq for 100 watt transmitter output. Plot 2: Loss db vs freq.


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