Do I need 18' coax cable for my radio?

Continuity in your output cable is a bad thing. Yes, you could have done real damage or not. Did you straighten out the conductor?
 
Using new cable, still high readings. I'll do more checking when I get home from work.

Also using new 90* mount to the bar the antenna is on. I'll post a shot of it soon.
 
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Something else you might try regarding the extra cable is not store it in a straight continuous loop. My understanding is that the continuous loop can cause issues as it creates a field. Instead us a figure 8 pattern with it. You want to loop back over itself which is supposed to disrupt the ability to create a field and cause issues.
 
Byron said:
Something else you might try regarding the extra cable is not store it in a straight continuous loop. My understanding is that the continuous loop can cause issues as it creates a field. Instead us a figure 8 pattern with it. You want to loop back over itself which is supposed to disrupt the ability to create a field and cause issues.
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I'll try this tonight and see what happens, thanks.
 
I didn't see your post 19 before my post 20. I would still check the mounting bolt etc. I have read that a short in the antenna cable or mount will damage the radio. It mainly causes damage when trying to transmit. I don't think it happens immediately though at least not with the J&M depends on how long it has been that way.
 
Ridingfl said:
I didn't see your post 19 before my post 20. I would still check the mounting bolt etc. I have read that a short in the antenna cable or mount will damage the radio. It mainly causes damage when trying to transmit. I don't think it happens immediately though at least not with the J&M depends on how long it has been that way.
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Very possible it has been like that since I got the bike. It has never had any distance sending or receiving.
 
Seems to me that shorting out the RF output is a make or break kind of deal. You've got some form of semi-conductors handling the RF stage and if the output was shorted they would be like fuses or not. That you still had output would bode well I would think. Have you had a chance to recheck your SWR or did I miss that?
 
Rechecked the SWR after the new cable install. Then pulled the adjustment screw tip out and checked again. All with no change in the readings. I will take the coil out of the cable and check again. I may pick up another shorter cable and try that.
 
Here is another way that I learned from here on the forum and worked on my bike. Use the standard 9 ft cable from the radio to the antenna. Make sure you have the orientation of the banjo bolt at antenna end correct and nylon spacers are installed correctly, this can be reversed if not careful and short out your antenna. Then add a 9 ft number 12 stranded coated wire from the ground post on the antenna and loop around under the seat. Do not ground the other end. Then check your swr. Before this I could not get a good swr, now I am good on all channels.

Here is a little more topic. https://www.st-owners.com/forums/showthread.php?85216-J-and-m-2003-and-grounding-antenna
 
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If the coax was still attached on one end to the antenna when you measured the short, it may still be ok. Some antennas provide a DC ground. (I don't know about yours, but I'm guessing the center conductor isn't grounded - in which case something is shorted.)

If the coax was completely disconnected on both ends and you measured a short, it's definitely bad. Either someone did a bad job of mounting the connectors, or the coax was damaged badly (and this amount of damage should be pretty obvious).
 
v8-7 said:
Any local hams around that can help out ?

Bring it over here and I'll fix it !
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My Mother had a place in Sun City real close to you. My Mother-in-law lives in Sebring FL and we still go down to visit her when we can. Wife and I plan on riding the 1100 down there for a weeks visit next spring. If I don't have it lined out by then I will definitely get with you. Will send you a PM anyway when we are going to be there, & hopefully have lunch while we are there.

Gary.
 
roadriderg said:
Here is another way that I learned from here on the forum and worked on my bike. Use the standard 9 ft cable from the radio to the antenna. Make sure you have the orientation of the banjo bolt at antenna end correct and nylon spacers are installed correctly, this can be reversed if not careful and short out your antenna. Then add a 9 ft number 12 stranded coated wire from the ground post on the antenna and loop around under the seat. Do not ground the other end. Then check your swr. Before this I could not get a good swr, now I am good on all channels.

Here is a little more topic. https://www.st-owners.com/forums/showthread.php?85216-J-and-m-2003-and-grounding-antenna
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This will be my next thing I check.

Here is a picture of the 90* and the way it is mounted. I have a heavy ground wire from the bar to the frame.


100_5213.jpg

Thanks, Gary.
 
ST_Jim said:
If the coax was still attached on one end to the antenna when you measured the short, it may still be ok. Some antennas provide a DC ground. (I don't know about yours, but I'm guessing the center conductor isn't grounded - in which case something is shorted.)

If the coax was completely disconnected on both ends and you measured a short, it's definitely bad. Either someone did a bad job of mounting the connectors, or the coax was damaged badly (and this amount of damage should be pretty obvious).
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Coax was disconnected and looked like it had been smashed pretty flat in more than one place. It looks like it had a braided metal coax cable, but with a outer clear coated plastic.

I put the new longer coax on it with the same SWR results, and it was not grounded from the connection to the center pin.
 
I had occasion to talk with a tech type at Firestick, and his advice was that the coax on NGP antennae is made to a tuned length, and should be replaced complete in case of any damage. For mine, the lug broke off at the antenna bolt, so I cut it back and re-terminated it. No success at all. I bought a new one, it worked fine. Less than $20, as I remember.
 
GreenZR said:
Coax was disconnected and looked like it had been smashed pretty flat in more than one place. It looks like it had a braided metal coax cable, but with a outer clear coated plastic.

I put the new longer coax on it with the same SWR results, and it was not grounded from the connection to the center pin.
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Are you sure you do not have a ngp antenna? This type requires a ngp antenna cable setup not the standard wire. The two will not work together.
 
On my set up I have a 2' firestik ground plane antenna which is grounded to the top case mounting plate thereby grounded to the bikes frame. Between the radio and the antenna I have a 9' firering cable. Since both my radio and antenna are in the tail, I had quite a bit of extra antenna cable. I made the excess wire into a loose figure 8 (never coil it) and that I put on top of the rear fender under the seat. Iirc my swr was 1.3 across all 40 with 1:1 at 20.
 
Think I have it close enough for it to work well. I put an extra 9' 12 gauge wire onto the bracket mount and ran it along the frame. I did not ground it, just wire tied it to secure it. Got SWR of 1.5 at ch. 20. & closer to 1.1 on ch. 1 then got 1.9 on ch. 40. Going to let it go at that for now. Thanks for all the info. Gary.
 
GreenZR said:
Think I have it close enough for it to work well. I put an extra 9' 12 gauge wire onto the bracket mount and ran it along the frame. I did not ground it, just wire tied it to secure it. Got SWR of 1.5 at ch. 20. & closer to 1.1 on ch. 1 then got 1.9 on ch. 40. Going to let it go at that for now. Thanks for all the info. Gary.
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With those numbers and if most of your transmissions are between channel 1 and 20 you are in great shape. If you want to go further your antenna is just a little bit too long.

Also when checking your swr you should be away from structures, cars, ect that will affect the swr readings. I do mine at least 10 ft away from anything.
 
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