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CB FM Mode

Rwb

tell the devil im gettin there as fast as i can,r
Jun 30, 2018
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Well been tracking my Little Thomas radio and says it will be here by Friday. Brings thoughts about using a mobile antenna with it. I know I'm a greenhorn compared to most of you but I wonder about tuning a regular AM CB antenna for use with FM. Is there anything you can do to enhance the antenna for FM use. Or just adjust the SWR on AM and Let Er Rip ?
let er rip n report results to us here
 

whiteastro

Sr. Member
Feb 22, 2019
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let er rip n report results to us here
That sounds simple enough to handle ! Even I could do that. LOL I did do something different I haven't done before. This morning I turned my cobra 2000 on 38 LSB just to check for DX and it wasn't rolling but I did here a guy shouting CQ CQ from about 30 miles away in the Lackawanna valley. ( Tough area to get something out of because I'm in a valley also ) I though just for the heck of it I'd turn on my little KL-300 P and reach out and see if I could touch him and to my surprise he shouted back from his mobile in his truck. Of coarse if DX had been going it would have never happened. But always nice to get a surprise.
 
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Enterprise312ok

Active Member
Jun 12, 2022
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That sounds simple enough to handle ! Even I could do that. LOL I did do something different I haven't done before. This morning I turned my cobra 2000 on 38 LSB just to check for DX and it wasn't rolling but I did here a guy shouting CQ CQ from about 30 miles away in the Lackawanna valley. ( Tough area to get something out of because I'm in a valley also ) I though just for the heck of it I'd turn on my little KL-300 P and reach out and see if I could touch him and to my surprise he shouted back from his mobile in his truck. Of coarse if DX had been going it would have never happened. But always nice to get a surprise.
My kl-203p supprised me today, the texas star is down rite now so I had the 203 in my car behind a 138xlr going to a 102 ss whip and decided to shoot a little skip on the way home from work on am 28 and to my supprise my wife answerd back from the base station 25 miles away in a valley.
Back on topic I am looking forward to trying out fm mode when I get my lincoln II.
Btw any of you run fm on sweep tubes? Can it be done or is it bad idea?
 

M0GVZ

Sr. Member
Oct 18, 2011
1,771
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I know I'm a greenhorn compared to most of you but I wonder about tuning a regular AM CB antenna for use with FM. Is there anything you can do to enhance the antenna for FM use. Or just adjust the SWR on AM and Let Er Rip ?
Makes no difference what mode you're using the antenna on when it comes to tuning it, it's the frequency. So you tune it just the same as you ever have done. When you tune the antenna in AM and get a specific SWR when you change to FM mode it'll be the same SWR.
 

Woody-202

Sr. Member
Sep 5, 2018
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www.cbdaze.blogspot.com
My kl-203p supprised me today, the texas star is down rite now so I had the 203 in my car behind a 138xlr going to a 102 ss whip and decided to shoot a little skip
A timeless classic, the Cobra 138xlr... I've used one now for about 25 years, and it's had a rough'n tumble life in various vehicles, but I don't know what I'd do without it. Took a chance on a parts-only-we-can't-test-it eBay buy-it-now the other week for $35 and... it works like a champ!
 

whiteastro

Sr. Member
Feb 22, 2019
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Well I received the little Thomas AM FM Cb radio today and put it on the bench in the radio room for testing. My Dosy meter is saying it is putting out a full 4 watts right out of the box. Right away I tried it in the FM mode and heard No one on any of the channels but did notice it seem to have more Air noise while in the FM mode than in the AM mode which I expected to be the other way around. In AM mode it seemed to have good sounding receive but could never be sure if I was getting a radio check because of the way people seem to answer on the radio anymore. ( Don't want to talk to strangers ) I'll play with it on the bench a couple days to try to learn the ins & outs of it before I put it in the car and take it out in the Wild World checking out the FM. If anyone has found the adjustment points for dead key and modulation that info would be appreciated. Thanks Mike
 

whiteastro

Sr. Member
Feb 22, 2019
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That "air noise" you are talking about being higher on FM than AM is typical. That is just the way an FM receiver is. Most of the time the squelch control is hardly needed on AM but without it on FM you would go crazy listening to all the noise.
So can you cancel out the air noise with the squelch without cutting the receive. So far I am impressed with the AM receive but it is too early to really tell.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
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Nova Scotia,Canada
So can you cancel out the air noise with the squelch without cutting the receive. So far I am impressed with the AM receive but it is too early to really tell.

Yeah just advance the squelch until the RX is quiet. Commercial VHF radios, 2m ham gear etc are FM and when the squelch is properly set even noisy barely readable signals will still break thru and be heard.
 

Alabama Buckeye

Dogma Heretic
Jul 29, 2022
242
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Magic City Alabama
My Cobra 2000GTL has 70 extra channels non-repeats. My radio has the Switch Mod using the ANL or NB and ANL/NB combinations. Not to my liking.

ANL only Chnls 15-27; 26.815 to 26.955, chnls 31 and 36; 26.995 and 27.045 respectively.
NB only Chnls 1-40; 27.605-28.045.
ANL/NB Chnls 15-27; 27.455-27.595, chnls 31 and 36; 27.635 and 27.685 respectively.

ANL and ANL/NB groups of 15 each are not entirely sequential
NB chnls 23-25 sequence jumble as well.

I've no idea of the correlation between your Switch Mod channels and mine or anyone else. The channel designation and the lack a sequence frequency variance is befunddling. It not as though there is a name sake for any of the groups; such as in the case where you might say, "go to channel 20 on PA group for more rag chewing on the matter". And I'd respond with, "Sorry, can't do. I don't have PA group, I got SHTF, LSMFT, and OMG". :)
 
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