This may be dumb..... (?? why do CB ops use LSB most of the time ??)

[guitar_199]

I've pondered it a few times but never really put much into it.

I know that most hams, above 10 Mhz, use USB and I've never really thought about it.

But something hit me just yesterday.... and it makes me wonder if it doesn't have something to do with it!!!!????!!!!!
Before 1977 (in the 23 channel days) it seems channel 16 was adopted as the SSB channel.

Ch 15: 27.135 MHz
Ch 16: 27.155 MHz
Ch 17: 27.165 MHz

So,from Ch 16 to Ch 17 there is only a 10 KHz gap.

But downward... to Ch 15 there is an RC channel... but if you look at it a little myopically... it is a 20 KHz gap.

So if you crank up the ALC in sideband.... you have (effectively) 20 KHz to the next channel... leaving a little more room before you run into the next channel.

When 40 channel radios came along...... everybody just whirled that old channel selector up to 37, 38 and so on.... leaving it in LSB...

Like I said..... the may not be the reason.... it may even be goofy...... but it makes me wonder!!!!!!!!

Any comments or thoughts ????

Bob

 

[FlyBoy50]

I've wondered that myself sometimes. Maybe old habits die hard ! Seems as if LSB would be a good place to meet and then jump up to the USB to not be disturbed as much. There I go trying to think again! LOL

 

[brandon7861]

Just my understanding, could be wrong.

Before PLL's, to add the other sideband, it was required to use more crystals (expensive), so SSB gear for a given band typically used just one sideband. A convention was chosen to keep everyone compatible, and I think the split at 10MHz had to do with keeping certain mixer products out. It was my understanding that much of the CB gear was designed around the lower frequency ham gear, not the higher frequency multi-band stuff, and naturally LSB became the sideband of choice because of already-established designs that nobody could justify changing. Unlike the multi-band radios that had to worry about mixer products showing up in bad places, CB is a single band and they didn't need to worry about the mixer products landing where they shouldn't. This allowed them to stick with the simple single-band designs. Once PLLs came out, having both LSB and USB was cheap, but the common usage remained.