Why always LSb and not USB?

[Scipio Kid]

Also, if you aim your beam directly North (if you have a beam), you'd be aiming right at Mtn Lynx in Alaska and just a few degrees west you'd be aimed at me, on the other side of the world. Give it a shot.

[Bobcat]

I'm going to give my guess and the reason for it.
My guess.... to help stay out of each other's way a little bit.
The way modulation works (and I know that SSB doesn't send the carrier but my story starts with AM anyway!) if there is ideal ZERO modulation your radio is shipping out the carrier with no sidebands. When you modulate (in AM) you get the carrier and the sideband products out both side... the upper AND the lower. In CB the channels are 10 KHz apart so, if you think of it this way... each channel has 5 Khz that it can spread out above AND below the carrier before it starts creeping into the space of the next channel.

We also know that when one starts hitting overmodulation, the resulting distortion causes increased harmonic content greater than the usual which can cause your sideband products to go beyond 5KHz into the next channel.

So if you have one operator on 36 USB and another on 37 LSB, in a perfect world, each would have 5 KHz worth of modulation bandwidth before crossing into the sideband space of the adjacent channel.

HOwever, if everyone agree to the practice of ONLY using LSB.... then you can STILL be modulating down into the USB space of the lower channel....but, since no one would be using USB, it would not cause a problem and each op would essentially have 10 Khz of space.

Don't know if it makes sense, but just wanted to throw it out there.

[MDYoungblood]

Good answer Bobcat. Another thing was the original 23 channel radios had skipped frequencies used for radio control devices, they were the "A" channels, SSB'ers adopted channel 16LSB as their frequency giving them over 15kc's of space near a interfering AM frequency, channel 15.

3's

Greg

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[295 antenna]

very interesting fellas so putting all the answers together im getting over all .its better for everyone to use LSB? i never hear anyone on USB anyway unless your free banding .besides i dont like to keep flipping my radio over..

[Bobcat]

You certainly added some value with yours. I had not even thought of the effect of the gaps between some channels....

Good answer Bobcat. Another thing was the original 23 channel radios had skipped frequencies used for radio control devices, they were the "A" channels, SSB'ers adopted channel 16LSB as their frequency giving them over 15kc's of space near a interfering AM frequency, channel 15.

3's

Greg

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[295 antenna]

So using that philosophy now 38LSB is close to 37 am but further away from 39 am . interesting it seems to me that the reason was like you said ,(back when there were 23 channels) so since then LSB has been the go to ssb for a majority of CB operators. Kind of like a (grandfather)clause