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CB Radio Myths



1.    Buying a new stock rig and putting on a power mic will give me a lot of good audio.



All rigs have ALC/AMC (Automatic Level Control/Automatic Modulation Control) limiters in them. This is to prevent distortion and/or over modulation. The ALC circuits are cheap using only a few components. These limiters should have been designed to be used when needed – on voice peaks (if needed) and at the point of over modulation only. Instead, the circuit is on all the time regardless of your audio level. Buying a power mic and expecting it to sound powerful is not going to happen. The ALC limiters in the rig wouldn’t allow the power to come through. You will sound the same as a cheap cordless phone. Asking for a radio check is useless because those who don’t have an inkling of what good audio is, will tell anyone that you sound good, even if it’s 5% modulation, using headphones as a mic, or 2 tin cans attached to a string. As long as this person “hears” anything in English or Martian and can somewhat understand it, will tell you that you sound good. Totally useless! What’s even more stupid, is buying a power mic that HAS built in ALC limiters! What a joke!! Nothing like negating the purpose of buying a power mic!

Why did you buy this? Because you didn’t know. You’re under the impression that if you buy a power mic, it will sound loud w/out all this red tape. I know it’s another can of worms, but it’s eye opening being a tech for 40 years. I (and others) have removed a TONS of ALC’s from rigs & mics to allow your audio to fly instead of the cheap cordless “phoney” audio that you may have bought as a cordless phone, not knowing that some of these cordless phones have the same ALC’s in them. You don’t know this until after you buy it and use it. The CB radio & mic industries have to adhere to the FCC’s rules & regulations regarding over modulation. Therefore, these industries have to install these cheap circuits which make you sound like this. Have you ever noticed that if you use the rig in PA, the ALC’s are disconnected? In PA the ALC is defeated. If you can read a schematic you’ll see it. Back in the 60’s when everything was tubes, certain rigs had ALC’s in them but weren’t all that effective. It didn’t effect your audio as it does today.

 From time to time, to show people, I’ve had to put a temp switch in the ALC circuit to show a few people, on the air, the before and after difference. They agreed. Unfortunately, there are a few people that don’t care, as long as they ‘hear’ some kind of intelligible noise. So why did they buy a power mic?


Putting on a new rig right out of the box using a stock mic or a power mic you will probably notice only about ½ watt of upward due to the limiters (using an RMS wattmeter – not Peak). Your power supply wouldn’t notice much extra current being drawn as you modulate. There isn’t much audio due to the limiters. After the rig has had the ALC’s removed, your audio goes up to the normal level (as it does in PA), the power supply supply’s more current to the rig, and your upward modulation increases a lot. You’ll notice this on the audio LED or on the S meter.

Don’t get misunderstood. Removing the ALC’s from any rig is not super charging the rig. You’re only bringing it back to normal, as if the rig didn’t have ALC’s in it to begin with. You can simulate this in any stereo system. Put a # 47 (or equivalent) bulb in series w/one of your speaker wires on both channels. Start out w/low volume. Turn the volume up slowly. Watch the bulb light up where there is bass in the song. At this point, the bass suffers due to the bulb absorbing the power. The higher you turn up the volume, the brighter the bulb will become, and the more of a simulated ALC will be heard in the bass. Don’t turn up the volume past the point where the bulb will burn out.

After putting on a power mic on a stock rig w/the ALC’s still in the rig, the usual thing to do is to ask for a radio check. The usual replies end up to be: "I'll turn down the power mic, how's that?" or “I don’t sound good? No one ever told me that before”, Ah and the famous one – "It must be the battery".

Let’s break this down.


"I'll turn down the power mic, how's that?".

Why did you do that? Why did you buy a power only to have to turn it down to a stock mic level or lower? Turning down a power mic defeats the purpose of buying one. What you're actually turning down is the ALC and your audio. You were never loud to begin with.

"No one ever told me that before.".

Either they did but you didn't want to hear it or you believe that a new rig & power mic should sound good regardless without any further knowledge. It's new so it HAS to sound good otherwise they wouldn’t have made it.



Most people have no idea what they or anyone sounds like or should sound like especially with a new rig right out of the box. They hear their friends sound tinny, low, compressed and noisy voice and figure that’s the way it is. Over time they get used to it regardless of how they hear their friends. They claim "It sounds good". They really don't know or they don't want to insult the other party. Sometimes they just don’t want to know. In actuality it sounds like your talking to them on a cheap cordless phone. "Phony audio". When they change the mic and ask the same person how it sounds, 50% of the time you will hear that they like the first mic better with all the ALC effect, etc. That’s because they’re used to hearing that person using the first mic. regardless of the ALC effect. People don’t know and side with what they are used to listening to.

"It must be the battery".

This is the most commonly one used. It’s never the battery unless the battery is dead. At that point there’s no audio. I always told everyone to throw the battery away in my can. After a while I had a stack of batteries and they were all good. For years, I never bought a battery and always used the ones that people claimed “It must be the battery”. You hear that persons ALC effect. You know it's not the battery and you know this is not a natural sound. There’s no reason why you should sound like that on the air. You don't sound like that in person do you?. The person transmitting has no idea unless he trades bases with the other person to hear it for himself. Some of the times, being that they don’t know what to listen for, will say that there’s nothing wrong with the way their base sounds. They replace the battery and of course the audio and the ALC effect are the same. They don't know what to say next except that they will have the radio checked out. After it's checked out and was told that it's working fine, they still believe they sound good. The person who checked out the radio only checks its operation as stock. It's real simple. The audio limiters, AMC's/ALC's are still in the rig and should be removed. Some are set too high preventing you from modulating over 85% and as for the Panasonic rigs, nothing over 65%. It's in the manual folks! The more ALC you have, the lower the punch and audio level. When the ALC level is extremely high, your audio will "Pop" on voice peaks. Remember "Poppy" from Clifton? He had a Panasonic. The people who had no idea what audio should sound like gave him the handle "Poppy" and didn’t know any better and accepted it! The higher you turn up the mic, or the louder you talk, the more ALC effect you will have. If you’re going to run a stock rig then buying a power mic is a total waste of time & money. You will never have the punch or loudness that your trying to achieve so "Get it Modified". “Stock is a Block" ...... "Modified is World Wide”.

You’re looking to sound good and not like a cheap compressed cordless phone. The best way is to hear your own audio is with headphones from a wattmeter or a local receiver. This way you can hear the before and after difference when the limiters have been removed. Your stereo doesn’t have ALC's nor do PA systems. Remember nothing is being super charged as removing the limiters only brings your audio back to normal. From there you can use a power mic to sound louder and at the same time you will notice your upward modulation increase to where it should be.

Also beware of the power mics with built in ALC’s. Check the schematic as they are easy to spot.

"How's my upward with this new radio and power mic?".

There will hardly be any upward as the limiters have de-gained your audio which prevents upward. When the ALC's are removed, you will notice an upward swing and "normal" audio will be heard as this is what you should sound like.




2.    Noise canceling power mics.


This is one of those stupid gimmicks like those motorized bikes you used to use in your room to lose weight. You turn on the switch, and the motor pedals for you. This mic is a power mic and will amplify any noise made. Noise canceling? How? Where? I've done a few tests with these. They operate just like a normal power mic. There are no special circuits in them electronically or mechanically. The theory sounds good but it is only an advertising ploy. These mics have a piece of rubber on the top where you talk which is only 1/4" high supposedly to shroud out external noise. A megaphone would work better.



3.    Peak Reading Watt meters.


If your stock rig says you’re putting out 4 watts on AM with upward to 10, 20 or 30 watts, either you have a peak reading meter, the meter is not properly calibrated, or it’s not tuned for 27Mhz and is detecting the audio envelope only. You are really not doing that kind of wattage. Let’s say your meter displays upward to 16 watts, then we should see about 3db of upward on all of our S meters and we don’t see that. We never see that w/stock rigs. If you think you have upward to 16 watts then you MUST be drawing an extra 1.5amps when you talk, let alone the approximate 2-3 amps required just for the carrier. It also means that you must have at least an 20 watt modulator (minus losses) to produce 16 watts of upward. They have never put high power modulators like that in any CB radio. If you have 5 watts input, the audio power required is ½ the carrier power which means you only have a 2.5 watt modulator. So to hear someone say that they are putting out 16 watts RMS of upward, just isn’t true.

If someone says that they are putting out 30 watts of upward, they must be drawing an extra 4 amps from the supply. In turn, we would see about 8.9db of upward on our S meters and we don’t and the final certainly wouldn’t do it. The average 2SC1307 final is rated at 25 watts input. Your input power must be developed first in order to produce ½ the output. This can be seen on your power supply current meter. At 30 watts of upward on a little Radio Shack 3 amp power supply. It’s just not going to happen. The average transmit current draw on a stock rig is approx 2.5 amps and only up to approx 2.85 amps during audio due to the ALC’s. If the ALC’s are taken out, your audio draw current will increase to as much as 1.5 - 2 amps extra.

For true measurements, use a Palomar 500 watt meter where you can switch back & forth from Peak to RMS (Forward/Reverse) switch, or use a Bird RMS meter.  These radio shops that tell people that their rigs are doing 8 watts, swinging to 16W is not true. These are PEAK reading meters. Per the current that is demanded from the supply, for what these PEAK reading meters tell you, doesn’t add up to the power input that is required.

Power supply’s aren’t taken into consideration. First of all, you’re not going to have 16 watts RMS of true upward w/the limiters still in the rig. Secondly, even if the rig had the ALC’s removed, the power demand from the supply will increase, therefore you’ll need a bigger supply. People think that you can get something for nothing. The power supply isn’t thought of. “I’m putting out 8 watts swinging to 16” on my Radio Shack 3A power supply. Is it RMS or is it PEAK? Do you know the difference? The human ear doesn’t hear PEAK. Is the supply regulated or is the rig causing the supply voltage to drop as a trade off for more current? The rig, on Xmit, will draw X amount of current. All rigs are different and will draw a little more or less than another rig. Also depending if the rig is mod’d.

Depending on the rig, depending on the supply, depending if the ALC’s are removed, determines what current the rig will draw, (of course the rig will draw more if mod’d), if the supply is regulated and to what % of regulation. Some of these ‘regulated’ supply’s still drop the voltage as much as 10% and say they’re regulated. When the voltage drops during Xmit, your wattage output drops. When the voltage drops even more during modulation, therefore, the carrier drops even more w/the superimposed audio on the carrier. You can not fool anyone by saying “My rig puts out 8 watts swinging to 16”. It doesn’t work that way. If you had an upward swing of 16 watts, that means you have a full S unit of upward. We don’t see that on anyone’s S meter. You’re only fooling yourself using a PEAK reading meter. Again, the audio power isn’t variable in the rig. It stays the same power it was designed for (2.5 – 3.5 watts). Only the carrier is variable in the Pi network/tank circuit. Also, with an increase of carrier, the audio drops as the ratio between carrier and audio has changed one way only. It’s best to leave the carrier alone or tune for max upward during a whistle or using a signal generator. Audio (RMS) is what you hear not carrier.





4.    I can run a beam that has hollow elements but if I use a linear, the elements must be of solid aluminum.



Due to the “skin affect”, most of the current will radiate on the outside of the element. This cuts down on manufacturing and shipping costs as solid elements will only make the beams heavier. The only thing I could think of why solid elements should be used is for high power applications where you’re at the end of the power rating of the beam and solid elements would prevent the elements to heat up as solid elements would act as a heat sink.




5.    I can hook up my rig using correct or incorrect polarity to my battery or power supply.



If you’ve blown the fuse, replaced it w/the proper one or slightly higher. Don’t put a 20 or a 30 amp fuse. How I can remember that famous line “That’s all I had”. Using a higher rated fuse could cause a melt down. The rig will blow but the fuse wouldn’t. I’ve also seen the blown fuse wrapped in aluminum foil too!

If the someone doesn’t know that red is + and black is – and has a problem where they keep hooking the rig up wrong and constantly blows the fuse, there’s a couple of things you can do to rectify that. You can install a full wave bridge in the rig. Then polarity doesn’t mean anything. You’d have to use hefty diodes though like 1N5401’s. The only set back about that is your rig isn’t operating on 13.8V anymore. Due to the 2 diodes in forward bias, the operating voltage is now only 12.6V. This cuts down on your power output on the carrier and audio a little.

The better way to go is to install one big diode in series with the positive line. The drop is lower and if you reverse polarity and the rig wouldn’t turn on at all indicating that you did it backwards.



6.    Miscellaneous:

Cobra may have made a good 148GTL but couldn’t spell to save their life! Who is “Dynamike”? Who is “Mike Gain”?


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