I know legal CBs have no FM option, only AM/SSB, but I also know that there are many people with imported radios around, and many of those have FM. Maybe even most of them. However, I never heard anyone using FM on the air. Not sure how well it would perform on the skip, but I thought people would use it for local communications because of better sound quality. Am I wrong?
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Why people are not using FM on CB in States?
- Thread starter vlad_k
- Start date
Legal radios don't have it and it's not as powerful, so most won't use it.
A lot of operators won't run it because there is no swing.
Is what it is.
A lot of operators won't run it because there is no swing.
Is what it is.
FM was mandatory here when legal Cb was allowed here, propagation is the same whatever modulation you use.
Just because SSB uses a smaller bandwidth and smaller bandwidth recievers that tends to bring more distance.
Now SSB/Am/FM is also allowed here, the problem was most people had their own antenna's for TV when Cb as allowed and our version of the FCC didn't want Cb to interfere with TV's so hence the FM modulation only.
Now everyone here is on cable and fast internet, so no more tv interruptions.
I made some nice DX in FM, no swinging meters, but P.A's easy to build, simple clas C amplifiers were easier to make as class A/B amplifiers as for SSB.
If you keep the FM bandwidt narrow some good DX is possible, no nice swinging meter though....
Bandwidth on AM or FM is about the same 2.5 KHz modulation index, and when the signals are good, modulation in FM can be clear as a bell .
It is just what was used and you got used to, FM or am/SSB.
Most here overdrive FM audio, so you got splatter in the next channel, most used modification here was adding a monolithic X filter of 10.695 Mhz in the first I.F. of 8 KHz wide, preventing splatter and making the radio narrower iin reception better selectivity as well.
Must still have a few of them around somewhere, Cb is almost dead here, i can turn over 11 meter and just get some DX from Italy or so, no peep from here.
One reason i got so many spare Imax 2000 antenna's for free
Just because SSB uses a smaller bandwidth and smaller bandwidth recievers that tends to bring more distance.
Now SSB/Am/FM is also allowed here, the problem was most people had their own antenna's for TV when Cb as allowed and our version of the FCC didn't want Cb to interfere with TV's so hence the FM modulation only.
Now everyone here is on cable and fast internet, so no more tv interruptions.
I made some nice DX in FM, no swinging meters, but P.A's easy to build, simple clas C amplifiers were easier to make as class A/B amplifiers as for SSB.
If you keep the FM bandwidt narrow some good DX is possible, no nice swinging meter though....
Bandwidth on AM or FM is about the same 2.5 KHz modulation index, and when the signals are good, modulation in FM can be clear as a bell .
It is just what was used and you got used to, FM or am/SSB.
Most here overdrive FM audio, so you got splatter in the next channel, most used modification here was adding a monolithic X filter of 10.695 Mhz in the first I.F. of 8 KHz wide, preventing splatter and making the radio narrower iin reception better selectivity as well.
Must still have a few of them around somewhere, Cb is almost dead here, i can turn over 11 meter and just get some DX from Italy or so, no peep from here.
One reason i got so many spare Imax 2000 antenna's for free
To get decent distance on FM you would need a min of 100w FM is really not worth with on CB. A tuned up radio with a good microphone will sound nice on AM and AM to dx with as little a 8w to 12w FM to dx 400w+.
With 0.5 watts on FM i worked distances up to 50 miles on 11 meter.
As said RF is not behaving different if you use FM/AM/SSB mode of voice transmission.
I worked in FM the repeater of New York on 10 meter with 1 watt output on the iMax 2000 from the Netherlands where i live, propagation does not care what mode of voice transmission you use.
you might like the sound of Am orSSB better as the noise from FM, but that is a different story.
FM is full quieting when the signal is just above the noise level.
AM SSB is more prone to QRM/QRN.
As said RF is not behaving different if you use FM/AM/SSB mode of voice transmission.
I worked in FM the repeater of New York on 10 meter with 1 watt output on the iMax 2000 from the Netherlands where i live, propagation does not care what mode of voice transmission you use.
you might like the sound of Am orSSB better as the noise from FM, but that is a different story.
FM is full quieting when the signal is just above the noise level.
AM SSB is more prone to QRM/QRN.
Not as powerful? My Yaesu puts out 100 watts CW, SSB, and FM. No issue with power. Most FM capable radios run the same on FM as on SSB excepr CB export rigs which may run the FM carrier at the same level as the AM carrier. Again.......same power output.
People need to get over this "swing" thing. The ONLY radio service concerned about how much the needle bounces around is CB.
Is what it is.[/QUOTE]
I left Europe when I was still a kid, so I don’t know things first hand, but I was told CB is not that popular over there either. People who I talked with were surprised to hear that only AM/SSB are used in US, thus the question.
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It was a rage here when it was allowed, but the usual crap happened and people got turned off , serious people got their license and never looked back, I had a good time repairing the stuff, and PSU's etc, helped to fill the kitty for the hobby.
Mostly i repaired 10 to 15 cb transceivers a week, next to my work.
Saw a lot of golden screwdriver stuff that time, and repaired the lot, shaking my head.
If you doný have the measuring equipment and knowledge don't tinker with it.
Mostly i repaired 10 to 15 cb transceivers a week, next to my work.
Saw a lot of golden screwdriver stuff that time, and repaired the lot, shaking my head.
If you doný have the measuring equipment and knowledge don't tinker with it.
I was referring to the common export radio where the FM power is tied to the AM carrier level. It would only be as much output as the highest dead key setting on the radio.
Also with the lack of swing, most CB guys shy away from it.
FM on Ham bands is mostly but not limited to repeaters on 10 meters and up on VHF and beyond. SSB is the preferred voice mode although there is some AM mode being used on the upper portion of 40 meters.
FM on CB is of course not legal to use here in the states as far that I remember so CB's are AM and SSB for the pricier ones. That may have something to do with it because it wasn't available on CB's just only on exports that I recall so back in the 70's CB craze, AM was the most common mode used.
What others have said about the AM modulation power swing and needle watchers is why AM is the choice for the big radio crowd.
I like the FM sound especially with a strong signal. There is minimal noise and the voice is clear.
FM on CB is of course not legal to use here in the states as far that I remember so CB's are AM and SSB for the pricier ones. That may have something to do with it because it wasn't available on CB's just only on exports that I recall so back in the 70's CB craze, AM was the most common mode used.
What others have said about the AM modulation power swing and needle watchers is why AM is the choice for the big radio crowd.
I like the FM sound especially with a strong signal. There is minimal noise and the voice is clear.
I suppose if the switch for FM was on the radio, people would be tempted to use it. I have GMRS radios that work great on FM.
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