I was trying to tune my new to me cb antenna this weekend and have high swr readings on channel 40 (2.5+) and a good reading on channel 1 (1.2). Channel 20 is around 2.0. So this sounds like my whip needs to be longer, Is there a way to accomplish this without buying a longer whip? It's on the middle of the roof on my saab. I get similar readings when I place it on an explorer and a pilot. The whip is extended as far as it will go so now what. The antenna is a K30. I got it from a yard sale used for a couple bucks. The whip is the correct length and has not been cut.
CB antenna tuning
Started by 79yamdt, Jan 31 2012 12:12 PM
7 replies to this topic
Posted 31 January 2012 - 12:12 PM
I was trying to tune my new to me cb antenna this weekend and have high swr readings on channel 40 (2.5+) and a good reading on channel 1 (1.2). Channel 20 is around 2.0. So this sounds like my whip needs to be longer, Is there a way to accomplish this without buying a longer whip? It's on the middle of the roof on my saab. I get similar readings when I place it on an explorer and a pilot. The whip is extended as far as it will go so now what. The antenna is a K30. I got it from a yard sale used for a couple bucks. The whip is the correct length and has not been cut.
Posted 31 January 2012 - 01:31 PM
get a longer spring to mount it on if it even has a spring. is your antenna the 35" magnet mount model?
just looked it up, you could buy a short spring maybe 1-2" and see if that gives better readings
just looked it up, you could buy a short spring maybe 1-2" and see if that gives better readings
Posted 31 January 2012 - 01:51 PM
79yamdt, on 31 January 2012 - 12:12 PM, said:
I was trying to tune my new to me cb antenna this weekend and have high swr readings on channel 40 (2.5+) and a good reading on channel 1 (1.2). Channel 20 is around 2.0. So this sounds like my whip needs to be longer, Is there a way to accomplish this without buying a longer whip? It's on the middle of the roof on my saab. I get similar readings when I place it on an explorer and a pilot. The whip is extended as far as it will go so now what. The antenna is a K30. I got it from a yard sale used for a couple bucks. The whip is the correct length and has not been cut.
Make sure you dont have metal around it. I mean another vehicle close by, inside a building, near a metal shop,metal door. Park it out away from everything. How does your antenna mount? If its the 3/8"-24 threaded stud, you can either add a spring, some washers etc. Or prune your coax a little and start over. Are you using 50 ohm coax, ie maybe an RG58U/X?
I like to see no more than about 1.7:1 max. But always shoot for the lowest number.
Dont coil up any extra coax either, that makes for an inductor and absorbs your RF.
Tune your radio for the middle of the band, it 27.205Mhz area.
Posted 31 January 2012 - 02:26 PM
toyota_mdt_tech, on 31 January 2012 - 01:51 PM, said:
Make sure you dont have metal around it. I mean another vehicle close by, inside a building, near a metal shop,metal door. Park it out away from everything. How does your antenna mount? If its the 3/8"-24 threaded stud, you can either add a spring, some washers etc. Or prune your coax a little and start over. Are you using 50 ohm coax, ie maybe an RG58U/X?
I like to see no more than about 1.7:1 max. But always shoot for the lowest number.
Dont coil up any extra coax either, that makes for an inductor and absorbs your RF.
Tune your radio for the middle of the band, it 27.205Mhz area.
Thanks for.the response. Now I understand what people say when they say ad a spring. It's a mag mount antenna. The coax is whatever came on it. Would cutting the coax have similar results to adding springs or washers? Here is a link to a pic of it. http://pimages.solid...K-30_medlrg.jpg sorry I am having trouble posting pics with my phone.
Posted 31 January 2012 - 03:08 PM
79yamdt, on 31 January 2012 - 02:26 PM, said:
Thanks for.the response. Now I understand what people say when they say ad a spring. It's a mag mount antenna. The coax is whatever came on it. Would cutting the coax have similar results to adding springs or washers? Here is a link to a pic of it. http://pimages.solid...K-30_medlrg.jpg sorry I am having trouble posting pics with my phone.
I suspect you may have it backwards. I found this:
Quote
Channel 40 SWR is greater than Channel 1 SWR. If the reading on Channel 1 is less than the reading on Channel 40, your antenna is too long and needs to be shortened. Use the appropriate tuning feature, discussed above, to make the adjustment. (In the unlikely - and unfortunate - event that your antenna isn't easily tunable, you'll need to physically shorten the antenna by cutting it.) Make very small adjustments and then re-check readings on both channels. If your antenna has a weather cap that covers the tuning screw, make sure it's in back place before taking your SWR readings.
http://www.roadtripa...dio-Antenna.htm
So grab an allen wrench and try to shorten the antenna.
Posted 31 January 2012 - 03:46 PM
Yes I did. I'm not sure how i got confused. Thanks for the tips anyways. Shortening the antenna is a lot easier than making it longer. That.ks for catching my error. One more question.
The cb is a midland 75-822. When i use the weatherband i get seem to get better reception without the larger antenna hooked up. Is it bad for the radio to be on without an antenna when using the weatherband. I do use this function somewhat often and dont wanna damage anything.
The cb is a midland 75-822. When i use the weatherband i get seem to get better reception without the larger antenna hooked up. Is it bad for the radio to be on without an antenna when using the weatherband. I do use this function somewhat often and dont wanna damage anything.
Posted 31 January 2012 - 05:49 PM
79yamdt, on 31 January 2012 - 03:46 PM, said:
Yes I did. I'm not sure how i got confused. Thanks for the tips anyways. Shortening the antenna is a lot easier than making it longer. That.ks for catching my error. One more question.
The cb is a midland 75-822. When i use the weatherband i get seem to get better reception without the larger antenna hooked up. Is it bad for the radio to be on without an antenna when using the weatherband. I do use this function somewhat often and dont wanna damage anything.
The cb is a midland 75-822. When i use the weatherband i get seem to get better reception without the larger antenna hooked up. Is it bad for the radio to be on without an antenna when using the weatherband. I do use this function somewhat often and dont wanna damage anything.
Posted 31 January 2012 - 07:23 PM
That's what I was hoping to hear. Thanks. I really miss the weather band function, the only thing I miss, that my stock stereo had. Its something nice to have access to. Instead of waiting 60 minutes on the radio for the forecast. You get a detailed forecast instantly.
