CB Gods hate me .... Ebay LMR 400 is no good?

[niceguy71]

HELP....
hi Guys I bought 40 feet of
TIMES ® LMR400UF Antenna Patch Coax Cable PL-259 UHF Male CB HAM RF LOT from E-bay for $109.00 to go from my antenna to my lightning arrestor.... I had a few big guys over today to put up the big mast ( my Coax Seal came in, easy peasy to put on) so I said hold on led me check the SWR on the meter before we spend a couple hours wrestling that thing up... NEVER EXPECTING anything to be wrong..... but the Shakespeare Big Stick is 33 years old ( it was always in its cardboard tube safely in the hay loft of my barn).... but I Better test it.... so we put the antenna on the fence pole ( see picture) and I was getting 9 SWR on a non adjustable antenna??? so I said let me try my 100 feet of RG8 .... I of course was cursing myself for doing such a good job of putting the Coax Seal on the antenna!!!!.... so we took the antenna down and put RG8 on and put it back up... now the SWR was 1.44 ( see picture)... I put my ohm meter on the LMR 400 no shorts.... so I guess I'll contact the e-bay seller I bought it from on July 07 2023 and see if they will replace it... am I missing anything????
Thanks
Steve

 

[RFI-EMI-GUY]

Open connector on one end? Antenna poorly grounded? Needs tuning? Put a 50 ohm dummy load on far end of the cable and test. Your old RG8 cable may have been masking a poorly tuned antenna.

 

[niceguy71]

Open connector on one end? Antenna poorly grounded? Needs tuning? Put a 50 ohm dummy load on far end of the cable and test. Your old RG8 cable may have been masking a poorly tuned antenna.

open connector??? both ends are attached??? one to the antenna SWR and one to the antenna???..I didn't know I had to ground the Antenna???? so the antenna has to be grounded???? it was working on the RG8???? it was 1.8 to 1.4 but the LMR 400 doesn't seem to be working. so if I put my 50 ohm dummy load on the end of the lmr 400 and put my swr meter on the other end.... what will that do??? is that what I should do??? never thought of the dummy load

 

[RFI-EMI-GUY]

If your LM400 is good, you should see 1:1.0 VSWR on it with a 50 ohm load on the far end. It is always good to properly ground the antenna tight there or as it is it will have RF radiating into the fence and the coax which is unpredictable. Drive a rod right there and perhaps some qty 8 buried radials out 1/4 wave in each direction.

 

[niceguy71]

If your LM400 is good, you should see 1:1.0 VSWR on it with a 50 ohm load on the far end. It is always good to properly ground the antenna tight there or as it is it will have RF radiating into the fence and the coax which is unpredictable. Drive a rod right there and perhaps some qty 8 buried radials out 1/4 wave in each direction.

I put on a 10 watt dummy load ( I also have a 100 watt dummy load but used the 10 watt one) and the SWR is perfect... so does that mean the cable is ok??? funny it worked with the RG8 SWR of 1.1 to 1.4... so does this mean maybe the antenna was grounding to the fence the 2nd time I put it up with the RG 8.. and maybe the first time it wasn't???? I'll go put the antenna back up on the pole and try to connect the LM 400 again then see if I can scratch the base of the antenna to the metal fence pole..... so the antenna has to be grounded... I mean I am going to ground my mast and the antenna will be mounted to the mast.... but I didn't know it got it's SWR from the ground.

 

[prcguy]

If you have a perfect match with a load on the end of the coax then the coax and connectors are good. 100ft of RG-8 has about 1dB loss at 27MHz or 2dB loss round trip when considering the effects on VSWR. 40ft of LMR400 is about .25dB loss or about .5dB round trip. The longer run/higher loss of RG-8 will mask VSWR some compared to the shorter lower loss run of LMR400, but not to the extent you are seeing.

A Shakespeare Big Stick can be influenced by what its mounted to and your pictures show part of the antenna mounted well below the fence. Try the test again with the antenna on a pole well above the fence. The Big Stick is a coaxial half wave dipole and both the top whip and lower skirt are hot with equal amounts of RF. The antenna is decoupled from its aluminum mounting pipe or threaded marine mount, depending on what version you have so having it properly mounted to a metal mast does not interfere with the skirt like sticking it up against a chain link fence.

 

[niceguy71]

If you have a perfect match with a load on the end of the coax then the coax and connectors are good. 100ft of RG-8 has about 1dB loss at 27MHz or 2dB loss round trip when considering the effects on VSWR. 40ft of LMR400 is about .25dB loss or about .5dB round trip. The longer run/higher loss of RG-8 will mask VSWR some compared to the shorter lower loss run of LMR400, but not to the extent you are seeing.

A Shakespeare Big Stick can be influenced by what its mounted to and your pictures show part of the antenna mounted well below the fence. Try the test again with the antenna on a pole well above the fence. The Big Stick is a coaxial half wave dipole and both the top whip and lower skirt are hot with equal amounts of RF. The antenna is decoupled from its aluminum mounting pipe or threaded marine mount, depending on what version you have so having it properly mounted to a metal mast does not interfere with the skirt like sticking it up against a chain link fence.

I'll give it a shot this week... thank you PRCGUY ..
I just went out and tried another spot of the fence and I grounded it.... I got a SWR of 12 on the LMR 400... then I put on the GR8 ...I kept getting an SWR of 4????? I played with bumping the antenna around and got it to an SWR of 2.... then tightened the antenna some more so it wouldn't move unscrewed the RG8 and put the LMR 400 on again... it went right back to an SWR of 12 so I filed the bottom of the antenna to make a good contact and jammed the ground rod up against it... didn't help a bit.

 

[AJAT]

If you have a very short coax jumper check the swr with the jumper. That will eliminate the cable and you will know if your antenna alone is good or not. Once you determine that the antenna is good then work your way back to troubleshooting the coax. If you determine the antenna is an issue you can focus on the antenna, fix that then the coax.

 

[prcguy]

I'll give it a shot this week... thank you PRCGUY ..
I just went out and tried another spot of the fence and I grounded it.... I got a SWR of 12 on the LMR 400... then I put on the GR8 ...I kept getting an SWR of 4????? I played with bumping the antenna around and got it to an SWR of 2.... then tightened the antenna some more so it wouldn't move unscrewed the RG8 and put the LMR 400 on again... it went right back to an SWR of 12 so I filed the bottom of the antenna to make a good contact and jammed the ground rod up against it... didn't help a bit.

A Big Stick is a ground independent antenna, don't ground it directly but do ground a lightning arrestor in the feedline somewhere.

 

[niceguy71]

A Big Stick is a ground independent antenna, don't ground it directly but do ground a lightning arrestor in the feedline somewhere.

I didn't think I needed a ground... but someone had said I needed to ground it and I'm desperate now! ... I have a 5 foot piece of pipe left over from building my 32 foot mast so I'll attach the antenna to the 5 foot pipe and then attach the 5 foot pipe to the fence so it's 5 feet above the fence and see if that works this week.... I was SOOOOOO close to getting that antenna on top of my 32 foot mast...but I'm not doing it until I know that antenna and wire are working correctly.

 

[niceguy71]

If you have a very short coax jumper check the swr with the jumper. That will eliminate the cable and you will know if your antenna alone is good or not. Once you determine that the antenna is good then work your way back to troubleshooting the coax. If you determine the antenna is an issue you can focus on the antenna, fix that then the coax.

great idea I have several 3 foot jumpers... I'll give that a shot thank you....... I'm sure the RG8 is working fine... only bad SWR is the LMR 400

 

[prcguy]

I didn't think I needed a ground... but someone had said I needed to ground it and I'm desperate now! ... I have a 5 foot piece of pipe left over from building my 32 foot mast so I'll attach the antenna to the 5 foot pipe and then attach the 5 foot pipe to the fence so it's 5 feet above the fence and see if that works this week.... I was SOOOOOO close to getting that antenna on top of my 32 foot mast...but I'm not doing it until I know that antenna and wire are working correctly.

Big Stick doesn't need an earth ground, doesn't need a ground plane, doesn't need a metal mast. Just ground coax per NEC on your final install for safety. And hurry up with that test, we (I) want to know how it works away from the fence.

 

[niceguy71]

HELP....
hi Guys I bought 40 feet of
TIMES ® LMR400UF Antenna Patch Coax Cable PL-259 UHF Male CB HAM RF LOT from E-bay for $109.00 to go from my antenna to my lightning arrestor.... I had a few big guys over today to put up the big mast ( my Coax Seal came in, easy peasy to put on) so I said hold on led me check the SWR on the meter before we spend a couple hours wrestling that thing up... NEVER EXPECTING anything to be wrong..... but the Shakespeare Big Stick is 33 years old ( it was always in its cardboard tube safely in the hay loft of my barn).... but I Better test it.... so we put the antenna on the fence pole ( see picture) and I was getting 9 SWR on a non adjustable antenna??? so I said let me try my 100 feet of RG8 .... I of course was cursing myself for doing such a good job of putting the Coax Seal on the antenna!!!!.... so we took the antenna down and put RG8 on and put it back up... now the SWR was 1.44 ( see picture)... I put my ohm meter on the LMR 400 no shorts.... so I guess I'll contact the e-bay seller I bought it from on July 07 2023 and see if they will replace it... am I missing anything????
Thanks
Steve

wow looking at the picture of the antenna... I didn't even think about the antenna mounted too low on the fence pole it is too low!!! I was just doing a little test before putting it up... and if the SWR was a little high it would be better when I get it up on the 32 foot mast.... but now looking at it no wonder it wasn't working.

 

[niceguy71]

well I had work to do today and got home at 7:30PM, dark already!!! but I put the 5 foot pole up with my antenna and the LMR400 what a pain by yourself!!! ..... I was fighting 50 mosquitoes the whole time! .. as you can see with the SWR it is 12 or 13...... I could not stand the mosquitoes another minute and ran for the house... I'll put the GR8 on it tomorrow... but the GR8 seems to work???? so what's the real deal?... well lets wait until tomorrow and I'll put a 2 foot jumper on it and then my GR8 and you guys can tell me what I need to replace.

 

[AJAT]

Did your LMR cable come with the connectors installed? You can do a quick ohm test on it. Take an ohm meter and go from center pin to center pin. You should have a very low resistance close to zero. Then go from one connectors outer shell to the other connectors outer shell. Should have zero ohms. Then center pin to outer shell, should read OL on a digital meter, or no continuity.

 

[niceguy71]

Did your LMR cable come with the connectors installed? You can do a quick ohm test on it. Take an ohm meter and go from center pin to center pin. You should have a very low resistance close to zero. Then go from one connectors outer shell to the other connectors outer shell. Should have zero ohms. Then center pin to outer shell, should read OL on a digital meter, or no continuity.

yes I did... first thing I did... pin to pin has continuity threads to threads have continuity and no continuity from threads to pin...... cable looks good.... I'll look more into it tomorrow.

 

[RFI-EMI-GUY]

Is that a 10 meter or 11 meter Big Stick? Has it ever been tuned before?

 

[niceguy71]

Is that a 10 meter or 11 meter Big Stick? Has it ever been tuned before?

my antenna is a Super Big Stick Gold Band series Model 176-GBS omnidirectional base station CB antenna ..... so I would say a CB band or 11 meters. according to the directions you just put it together no tuning possible ... that was the big thing 30 years ago they were just perfect without having to mess with them.

 

[prcguy]

my antenna is a Super Big Stick Gold Band series Model 176-GBS omnidirectional base station CB antenna ..... so I would say a CB band or 11 meters. according to the directions you just put it together no tuning possible ... that was the big thing 30 years ago they were just perfect without having to mess with them.

I have an identical one but it looks like yours is painted blue. Mine is stock with some weathering and I'll be painting it cammo to blend into a surrounding forest. I'll post pics in a few weeks when I get all the antennas mounted on the mountain cabin.

 

[RFI-EMI-GUY]

my antenna is a Super Big Stick Gold Band series Model 176-GBS omnidirectional base station CB antenna ..... so I would say a CB band or 11 meters. according to the directions you just put it together no tuning possible ... that was the big thing 30 years ago they were just perfect without having to mess with them.

I would dissassemble and inspect for corrosion or breakage and reassemble and make sure it is water tight. No reason to try THE RG8 cable as the LMR sounds like it is OK.