This article is a reprint from:
Uppers and Lower vs Side Band (USB & LSB)
I will try very hard not to nerd out here, and if I do, I’m sorry and maybe we can meet somewhere in the middle? I have to throw some numbers at you and hopefully it will make sense in the end. I will use a 29 as the example. It has 40 channels, AM (amplitude modulation) that goes from 26.965 (channel 1) to 27.405 (channel 40). That’s a spread or bandwidth of 440 kilohertz (kHz) with a space of 10 kHz between each channel, EXCEPT channels 3, 7, 11, 15, and 19 (more about these later). Now you old schoolers are saying, “yeah, those are the “ALPHA” channels” and 23, 24, and 25 don’t follow the order your would expect. I had to throw that shit in there because somebody will bitch that I left out that info! That’s a regular radio, nothing extra, turn the channel knob and have at it.
UPPERS are a bank of 40 channels ABOVE channel 40.
LOWERS are a bank of 40 channels below channel 1.
So if you have a Galaxy DX 66 V2 or a Galaxy DX 86V, or any radio that has 3 banks of channels, A-B-C, that equals 120 channels. Their bandwidth is 1370 kilohertz (440 X 3 plus 2 skips). If you have a Connex 3300, Galaxy 33 or any radio that has BANKS A to F, you have 240 channels, 6 banks of 40 channels. Now here’s the bad news. You tuned your antenna to channel 19 and you are fairly flat on the regular 40. Go to bank A on a 6 bank radio and you’re transmitting into a minimum of a 10:1 SWR in a truck! I’ve measured 20:1 depending on the antenna. The shorter the antenna, the smaller its bandwidth! This is a fact written by the physics gods and cannot be changed. Hell, a 1 foot antenna does not like to tune through the regular 40s on a truck. Going to the uppers or lowers, you might as well just set the radio on fire!. Bank F, stay the hell away! You will be in the amateur radio band and they take their hobby pretty seriously. And besides, you’ll be talking into such high SWRs, it ain’t worth it. SWRs and antenna length are frequency dependent. Change the freque or change the length, you will change the SWRs. Also, please pay attention to this, and some will get pissed off, but, beware the bullshit on advertised CB antenna bandwidth, it’s freakin criminal what some advertise.
10k switch (if you have one).
I mentioned the skips called the “Alpha channels” above. Let’s say you are on channel 19 (27.185), flip up the 10K switch and you are now on 27.195. Channel 20 is 27.205 so you’re yappin in between two channels. Makes some drivers nutz but there are far more other things to be pissed about. But anyway, 3, 7, 11, 15 and 19 with the 10k on and you are talking on your secret channels until someone else flips up their 10k switch.
SIDE BAND aka SSB (Single Side Band).
Don’t get mad, there’s no math and no theory here, just straight up radio shit. That is a sine wave. If you transmit on channel 19 that wave will occur 27.185 million times a second. If you were transmitting AM, like on a basic CB, your audio will ride on both the upper peak AND the lower peak. (If the peaks get higher and lower, that makes you louder, hence Amplitude Modulation, AM.). Upper Side band (USB) will transmit the upper peak, with just the audio portion of your transmission. The lower peak on SSB (LSB) will transmit just the lower peak with just the audio. It’s such an efficient a method of communications that what you can do with 100 watts on AM you can do with about 12.5 watts on SSB. No bullshit, it’s that efficient!
Drawback in a Truck- I know you know this guy. Vaping, coffee container in hand, cell phone on a holder with a call going on, grabs the mic, and catches 3 gears. I still can’t figure how they do it. Now add the Clarifier control on a SSB radio. It’s just a knob that you have to turn, but first you have to find it and then tune in the station that is transmitting, or they sound like Donald Duck with throat cancer. The audio, is kinda shitty and us Americans just plain old like loud AM ,and to hell with efficiency! No judgment here, I use AM on the road, base station AM and SSB and occasionally I’ll throw in a little FM. I’m such a nerd that I’ll even throw in a little Morse Code but I really suck at it. Sorry I digressed. If you don’t want echo or talkback, there are a couple of SSB radios that sound sweet, with clean audio. Email me if you would like a recommendation and price point analysis, aka bang for the buck.
Mark
No BullShit Radio
The only dumb question is the one that isn’t asked. Feel free to email any and I’ll do my best to answer them at: Mark@nbsr.online
"To those who fight for it, life has a flavor the protected never know."