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I'm having a hard time with high SWR with my mobile setup...
- Thread starter biz
- Start date
no.... in fact i saw someone drive by with a predator on their truck and i was tempted to flag em down...
is cutting 6 inches off a 5 foot whip out of the ordinary?
I really didnt want to trim it at all if i didnt have to but they swr was getting better and better every inch i trimmed so i figured it was what i needed to do...
is cutting 6 inches off a 5 foot whip out of the ordinary?
I really didnt want to trim it at all if i didnt have to but they swr was getting better and better every inch i trimmed so i figured it was what i needed to do...
As I stated before...You might need to raise or get a longer stinger since you cut it. Also, check all your connections. Sounds like something else might be going on as well. Got pics of your setup? Post'um up, maybe we can see something you don't.
i triple checked my numbers before i started trimming....
i started the whip somewhere half-way and my initial numbers told me i was long... so i started lowering... and the swr went down.
thats when i started trimming and it was getting better and better..
my tri-mag mount came with 17 feet of coax.... everyone i see says use 18.... could that be the problem?
i started the whip somewhere half-way and my initial numbers told me i was long... so i started lowering... and the swr went down.
thats when i started trimming and it was getting better and better..
my tri-mag mount came with 17 feet of coax.... everyone i see says use 18.... could that be the problem?
The real simple answer about the coax length making a difference in the SWR is that if it does, then there's a impedance mismatch usually with the antenna, that it hasn't been tuned correctly for whatever reason. If the radio is 50 ohms, the feed line is 50 ohms and the antenna is 50 ohms, there's just no SWR that will amount to much. Finding out where thing s are not 50 ohms is the way to correct things, right?
So, tell me how I'm misunderstanding what's happened, or what I'm missing.
I'm taking for granted that the antenna tuning was done with an external meter (and jumper). That jump in SWR to 2:1 was found with an internal SWR meter, or did you put that external meter back in-line after "going directly to the antenna"? I'm also assuming that there wasn't any huge changes with something else, like moving the antenna to another spot, slamming the coax in the car door, something like that? Very simplified, what changed? For an SWR change like that, something had to have changed.
- 'Doc
So, tell me how I'm misunderstanding what's happened, or what I'm missing.
I'm taking for granted that the antenna tuning was done with an external meter (and jumper). That jump in SWR to 2:1 was found with an internal SWR meter, or did you put that external meter back in-line after "going directly to the antenna"? I'm also assuming that there wasn't any huge changes with something else, like moving the antenna to another spot, slamming the coax in the car door, something like that? Very simplified, what changed? For an SWR change like that, something had to have changed.
- 'Doc
the built in swr meter on the radio showed me 1.5-1.6 across the board, that was while i had the external meter in-line with a 2 foot jumper.
when i removed the external meter and connected the antenna directly to the radio, the built in swr meter jumped up to 2.0 ish all across.
i didnt move or change anything and to be sure i just went outside and checked it again.
how much power should i be pushing when setting up swr?
when i removed the external meter and connected the antenna directly to the radio, the built in swr meter jumped up to 2.0 ish all across.
i didnt move or change anything and to be sure i just went outside and checked it again.
how much power should i be pushing when setting up swr?
How much power when checking SWR? It doesn't really matter, SWR doesn't change with the power level. How accurate that SWR meter is certainly can change with power levels and that's why they should be re-calibrated when power levels change. Since output power does change when the microphone 'hears' something, it's a fairly good practice to disregard any SWR readings gotten when speaking into the mic, they just won't be accurate with a meter that requires calibration. It's also a sort of typical practice to turn the mic gain down as far as possible so that there's no power change from ambient noise in the room (or the dog scratching on the porch?).
- 'Doc
- 'Doc
I never ran the radio past the half way point and never had a problem with the SWR. Sounds to me that you clearly have a problem with the antenna. I would ask a friend to look at what you've got going - to give a fresh perspective. I surely wouldn't run with it until it gets sorted out...
yea i kept the mic gain all the way down....
the power on the other hand.... as i go up the swr goes up...
when the power is all the way down... i have very low swr reading.. 1.0 on the radio and on the external meter...
as i turn it up though.. the swr starts going up.
i have sent an email to the guys i got the predator from...
i friggen hate this.... its like having a Ferrari parked in the garage but you dont know where the keys are.
the power on the other hand.... as i go up the swr goes up...
when the power is all the way down... i have very low swr reading.. 1.0 on the radio and on the external meter...
as i turn it up though.. the swr starts going up.
i have sent an email to the guys i got the predator from...
i friggen hate this.... its like having a Ferrari parked in the garage but you dont know where the keys are.
biz, a couple of things you said have got me thinking you may be doing something wrong in your SWR checking.
just to be sure, are you re-calibrating the SWR meter every time you change the power output level of the radio?
you should be.
what exactly is your calibration procedure?
are you sure you are on the right band? as in, on the regular 40 CB channels?
that radio will show channels 1-40 on all bands and your antenna is probably not broadbanded enough to cover the whole range that radio has to offer.
you should do your antenna tuning on the band where channel 1 is 26.965mhz and channel 40 is 27.405mhz
if you were doing your tuning on another band, that would explain the high SWR.
also, i would take that external meter out of line and just set the SWR with the radio's meter, it is self calibrating and will get you where you need to be.
the bad news is you are probably going to need to buy a new stinger for that antenna as you have most likely chopped way too much off.
a well made CB antenna installed properly should not have to be cut to get a low SWR in the CB band. (26.965-27.405) there should be enough adjustment built into the antenna to get it to work properly.
also, forget all that stuff you heard about using 18 feet or 17 feet or whatever for your coax length. thats a myth, and if cutting your coax makes a difference in your SWR then you MOST DEFINITELY have an antenna problem that should be corrected at the antenna.
think about it, what was the purpose of inventing coaxial cable in the first place?
we needed a feedline to run to antennas that didnt radiate a signal and could be run at any length.
if it didnt do its job well, why would we still use it?
good luck with your install, and dont let the guys in the CB shop take you for a ride. LOL
LC
just to be sure, are you re-calibrating the SWR meter every time you change the power output level of the radio?
you should be.
what exactly is your calibration procedure?
are you sure you are on the right band? as in, on the regular 40 CB channels?
that radio will show channels 1-40 on all bands and your antenna is probably not broadbanded enough to cover the whole range that radio has to offer.
you should do your antenna tuning on the band where channel 1 is 26.965mhz and channel 40 is 27.405mhz
if you were doing your tuning on another band, that would explain the high SWR.
also, i would take that external meter out of line and just set the SWR with the radio's meter, it is self calibrating and will get you where you need to be.
the bad news is you are probably going to need to buy a new stinger for that antenna as you have most likely chopped way too much off.
a well made CB antenna installed properly should not have to be cut to get a low SWR in the CB band. (26.965-27.405) there should be enough adjustment built into the antenna to get it to work properly.
also, forget all that stuff you heard about using 18 feet or 17 feet or whatever for your coax length. thats a myth, and if cutting your coax makes a difference in your SWR then you MOST DEFINITELY have an antenna problem that should be corrected at the antenna.
think about it, what was the purpose of inventing coaxial cable in the first place?
we needed a feedline to run to antennas that didnt radiate a signal and could be run at any length.
if it didnt do its job well, why would we still use it?
good luck with your install, and dont let the guys in the CB shop take you for a ride. LOL
LC
DXman
Yes, that's 3100 degrees F. Nine yrs of hard work.
Loosecannon,
The 10k comes with a long stinger so one can trim it for the 10 or 11 meter band. I know of no one that has make an install with this antenna and not had to do some trimming. I removed about 3" from mine when I installed it.
From what I have read here, it's looking like Biz is not getting a good ground with the Mag Mt. Try moving the mt. around and see if the SWR may change.
Another thing Biz, look real close at the coils on the antenna and make sure they are all spaced evenly, just a slight variation can upset your reading.
You might some day want to look into getting a MFJ 259b meter, it would sure make your antenna work lots simpler.
Good Luck
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