How much audio power one typically see in CB and Export Radios

[Onelasttime]

We have over the years seen companies tout 4 watt, 5 watts and 10 watts of audio output power. So what is typical to actually see at 100% modulation?

I ask because the rating of the audio IC does not matter that much if the rest of the circuit tops out long before the IC does. Likewise it does not matter how much final you have once you run out of audio power that is game over from a practical stand point. Same thing with NPC and Asymetric etc.....People always focus on minals and amp's and driver and pre-driver but no one really focuses on the audio ic becaue it is not an easy drop in swap.

So where do we run out of gas? How much power can the radio's chassis take if you direct inject for instance? Is it 3, 5, 10, 15, 20 watt's????

 

[JoeDirt]

The standard TA7222 audio amp is around 6 watts I doubt you will ever max that out. Most of the time your modulating around the milliwatt scale. NPC actually would help you "IF" you were running out of audio drive power. If you understand how a NPC mod works that will make sense. Your RF driver and final transistors will run out of steam well before the audio amp.

So how can Cobra and Galaxys use the same audio amp but the Galaxys have a much higher dual final output? Well Galaxys have a higher gain modulator scheme with more stages of amplification.

The only problem I see with the TA7222 is the %10 THD. So before all your crappy NPC mods and overvolted class C comp boxes your already starting out with %10 total harmonic distortion!

 

[JoeDirt]

I want to say on a cobra 148 direct inject 4 watt carrier to modulate to %100 your looking at a no more than 150 milliwatts (dont quote me on that thats just an educated guess) I doubt any line level rack gear will be over 1 watt. Either way other than the distortion the factory audio amp will drive a lot.

 

[Onelasttime]

Ok so I could build a rather small tube amp not some beast. I was worried I would need to build 8 watt tube amp to match the 5-10 watt's of audio claims made by OEM. I asked because initially I was thinking a 1/4-2.5 watt really warm hifi tube amp would work than I got cold feet when I started looking at audio IC's and such in various radio's. The less power I need the more I can focus on sound quality that I want. It is much easier to get the "sound" you want in a tube design when you do not have to hit some particular wattage target. It also opens up a lot of doors for tube selection when huge power is not a factor.

 

[M0GVZ]

Every single CB ever made is capable of having the mic gain overdrive the radio. On most CBs I've heard the ALC circuit is working flat out because they've upped the mic gain too much. You can overdrive a radio with the stock mic.

The correct amount of audio drive is the one that is the lowest you can use and achieve maximum TX power. That will give the cleanest signal and increasing much over that just means distorted audio. The overdriven distorted crap you hear on Ch38 LSB is not what you want to be doing because you can't understand it half the time yet it appears to be the goal of most people. On my Icom 7000 mic gain was around 18%, on my Kenwood TS480 and TS590 its around 25% and on the Yaesu's I've used its usually around 30%. I've never had mic gain even at half way.

Next you're also shoving all that lovely sound out of a transmitter with 6kHz bandwidth at best most likely to be received by a radio with 3kHz bandwidth on receive so 90% of what you're doing and hear out of your monitor never makes it to the speaker at the other end of the conversation. With the way filtering is set up in the receivers anything you do outside of 200Hz-3kHz probably won't ever get heard. My amateur radios are set up for SSB with the low cut at 300Hz and the high cut at 2.7kHz so anything you do outside of that I'll not hear. CBs and ham radios are there to give communications grade audio, not broadcast so as such they're designed to work over a narrow range typical in speech to get the best out of the power you put out of the antenna.

Direct injection is the latest craze that idiots who should be the last people to ever take the lid off a radio do.

 

[w9cll]

On my Icom 7000 mic gain was around 18%, on my Kenwood TS480 and TS590 its around 25% and on the Yaesu's I've used its usually around 30%. I've never had mic gain even at half way.

I agree, I run my Yaesu mic gain somewhere near 15% and the meter is always set to monitor the ALC settings. I use the drive control to keep the ALC low.

 

[JoeDirt]

Direct injection is the latest craze that idiots who should be the last people to ever take the lid off a radio do.

I disagree, direct injections is for people who want to take their skills to the next level. Direct inject isn't just for idiots but people interested in improving their knowledge of AM radio, CB and Ham included. How dare you suggest its the latest craze for idiots, people for the most part are interested in improving their audio quality and people like you should be ashamed.

Next you're also shoving all that lovely sound out of a transmitter with 6kHz bandwidth at best most likely to be received by a radio with 3kHz bandwidth on receive so 90% of what you're doing and hear out of your monitor never makes it to the speaker at the other end of the conversation. With the way filtering is set up in the receivers anything you do outside of 200Hz-3kHz probably won't ever get heard. My amateur radios are set up for SSB with the low cut at 300Hz and the high cut at 2.7kHz so anything you do outside of that I'll not hear. CBs and ham radios are there to give communications grade audio, not broadcast so as such they're designed to work over a narrow range typical in speech to get the best out of the power you put out of the antenna.

Just as a reminder 300hz to 2.7khz is the minimum for voice communication, most of us talk on the radio for conversation not for the "power you put out of the antenna"

 

[Captain Kilowatt]

Just as a reminder 300hz to 2.7khz is the minimum for voice communication, most of us talk on the radio for conversation not for the "power you put out of the antenna"

Actually it is not the minimum for voice comms but is a compromise between intelligibility and frequency response. I have used 1.8 KHz and even 1.5 KHz filters on SSB with great success during heavy QRM. My standard filter is 2.3 KHz.

 

[M0GVZ]

I disagree, direct injections is for people who want to take their skills to the next level. Direct inject isn't just for idiots but people interested in improving their knowledge of AM radio, CB and Ham included. How dare you suggest its the latest craze for idiots, people for the most part are interested in improving their audio quality and people like you should be ashamed.

Direct injection is done by people who have heard something that sounds cool but they don't actually have the first clue about what they're doing or in many cases even why other than its something someone said is good, you are also included in this group. You don't even know what the hell you're doing or what you should be adjusting for when you set up the EQ and you're telling me I'm wrong.
You do not need to directly inject audio to get good quality audio and if you did the only valid reason to do it would be to bypass the microphone pre-amp because you have a source with a lower distortion factor and the place that is valid to do it is immediately after the microphone pre-amp.

It doesn't improve their audio quality as they think it'll do and very few of them if any bother to listen to their own transmissions through another CB or ham radio but because they can hear it on the mixer monitor they assume that what they transmit sounds the same. It doesn't. All you have to do is look at the receive bandpass for your radio to see why. Unless you modify the receiver circuit, fitting wider filters or removing them altogether, on most radios most of the audio outside of 100Hz-3kHz never even makes it to the AF stage let alone the speaker so you can hear it. You'll see these halfwits making adjustments at 6, 12, 18kHz as well and that definitely doesn't do anything even on ESSB.

They're also not even focussing on altering the right frequencies because they have basically no idea how human hearing works so they whack up the bottom end too much, don't do anything much around 1kHz and end up with something that sounds booming, which basically seems to be the goal of these halfwits, but is actually not that easy to understand. And then when people are saying they can't work out what they're saying they up the mic gain.

And in the meantime they've got a signal splattering 30kHz wide whenever they transmit. I've watched these people on a waterfall on my Flex 6500 and not one of them has had a signal that is narrow enough to fit in a single channels bandwidth.

I shouldn't be the one who is ashamed because I can get good quality audio and stay within the bandwidth limits of the band, the RX bandpass filters of those listening to me and channels I'm using unlike you and 99.9% of these halfwits.

Here's a signal from an Italian amateur who is infamous over here and who has the kind of audio you want. His signal is over 10kHz wide

 

[LeapFrog]

I think some of the people that do these high fidelity modifications do not care that they are exceeding 10kHz and splattering on the adjacent channels, "as long as they get most of that audio on channel." It's a little different than the guys just clipping limiters and splattering on multiple channels for a crunchy distorted sound they consider "LOUD".

I have to say though some of the "great audio guys" like MMM, Machete, & Mustang are not heard on the adjacent channels nearly as much (or at all) as the local "clipped limiter guys" who splatter wide, is this just distance related or do some of these guys actually know how to run a hi-fi station that doesn't bleed?

Not a trick question: If a CB channel is 10 kHz wide and I transmit 10 kHz wide will I be heard on an adjacent channel if my wave-form looks clean (neg peaks in check)?

 

[LeapFrog]

So how can Cobra and Galaxys use the same audio amp but the Galaxys have a much higher dual final output? Well Galaxys have a higher gain modulator scheme with more stages of amplification.

Of course you know this but someone else may not, the AM only Cobra radios use a modulation transformer instead of the balanced modulator I.C. scheme found in the Galaxies and 148's/2000's.

IMO The balanced modulator scheme takes better advantage of the audio produced by the ta7222 and the radio does not necessarily have to be ran in class C mode, like the Cobra 29 does. <== Maybe someone can enlighten me a little here, am I way off base?

Direct Injecting a radio with an AN612 is relatively easy, using audio from a p.c. Soundcard's output (And a Little processing) it's very easy to overdrive the rig with too much audio, skip over the mic amp stages/ ta7222 & just run any audio you want into the AN612. The key is not over-driving or the audio will get "crunchy/distorted" and an oscilloscope w/rf sampler is key for these experiments to get the full picture.

Monitoring your tx on a factory CB will help you understand how much of this hi-fi is lost when the rx station is running a stock rig.

-Leap

 

[unit_399]

~JoeDirt



The balanced modulator scheme takes better advantage of the audio produced by the ta7222 and does not have to run class C. Direct Injecting a radio with an AN612 is child's play, using audio from a p.c. Soundcard's output it's very easy to overdrive the rig with too much audio, skip over the mic amp stages/ ta7222 and run any audio you want into the rig. The key is not over-driving or the audio will get "crunchy"/distorted.

HUH ???????

 

[JoeDirt]

Direct injection is done by people who have heard something that sounds cool but they don't actually have the first clue about what they're doing or in many cases even why other than its something someone said is good, you are also included in this group. You don't even know what the hell you're doing or what you should be adjusting for when you set up the EQ and you're telling me I'm wrong.

I agree with you, yes there are people who should never touch a radio but there are other that are just interested in learning. I dont know what im doing and I will be the first to admit that, I also dont have any problem admitting when im wrong either. Im engaging in conversation with you for my own benefit in learning (and who ever wants to read our banter)

CBs and ham radios are there to give communications grade audio, not broadcast so as such they're designed to work over a narrow range typical in speech to get the best out of the power you put out of the antenna.

For me it has nothing to do with the efficiency of the communication. Its like quantity vs quality, I would rather have less higher quality, higher bandwidth conversation than more narrow bandwidth conversation. Our versions of the best power out is apparently different and im sure its a trend that will keep continuing though. CB and Ham radio absolutely have the ability for broadcast grade audio even your Flex is more than capable but not all of us can have a Flex.

You do not need to directly inject audio to get good quality audio and if you did the only valid reason to do it would be to bypass the microphone pre-amp because you have a source with a lower distortion factor and the place that is valid to do it is immediately after the microphone pre-amp.

You are correct and I do not disagree, you can have great audio either way. Direct inject is easy, cheap and offers line level input for external processing. Those are excellent reasons!

It doesn't improve their audio quality as they think it'll do and very few of them if any bother to listen to their own transmissions through another CB or ham radio but because they can hear it on the mixer monitor they assume that what they transmit sounds the same. It doesn't. All you have to do is look at the receive bandpass for your radio to see why. Unless you modify the receiver circuit, fitting wider filters or removing them altogether, on most radios most of the audio outside of 100Hz-3kHz never even makes it to the AF stage let alone the speaker so you can hear it. You'll see these halfwits making adjustments at 6, 12, 18kHz as well and that definitely doesn't do anything even on ESSB.

I also agree there are plenty of idiots who just dont get it, I dont think its fair to lump everyone in that category just because you think 10khz wide is wasteful when myself and others think its beautiful Most us who can transmit wide can also receive wide, that would be dumb if we couldn't? Just because someone has a receiver with a filter width of 100hz-3khz doesn't mean 10khz wide wont sound bad. If you adjust your eq right it shouldn't matter how wide or narrow anyone is it will still sound great, so operators adjusting at 10khz or more is not concerned about the operator with the narrow receive. Thats juicy goodness for the wide operator who is listing!!!

They're also not even focussing on altering the right frequencies because they have basically no idea how human hearing works so they whack up the bottom end too much, don't do anything much around 1kHz and end up with something that sounds booming, which basically seems to be the goal of these halfwits, but is actually not that easy to understand. And then when people are saying they can't work out what they're saying they up the mic gain.

I try to correct those people or ignore them but since you grouped me in with those people I have a question for you and I want you honest opinion.

And in the meantime they've got a signal splattering 30kHz wide whenever they transmit. I've watched these people on a waterfall on my Flex 6500 and not one of them has had a signal that is narrow enough to fit in a single channels bandwidth.

I shouldn't be the one who is ashamed because I can get good quality audio and stay within the bandwidth limits of the band, the RX bandpass filters of those listening to me and channels I'm using unlike you and 99.9% of these halfwits.

Here's a signal from an Italian amateur who is infamous over here and who has the kind of audio you want. His signal is over 10kHz wide

Most of the idiots you speak of will transmit wide regardless of direct inject or factory radios with clipped mod limiters and NPC mods. Have you tried to transmit 30khz wide? Its not quite as easy as you may think. Thoes who are transmitting that wide have a lot of other problems! BTW.... Whats wrong with 10khz wide? Whats the limit on how wide you can transmit? As long as your not interfering who cares? I see more narrow SSB operators interfering for no reason than to protest wide band audio. I think on the Ham bands the wide operators are really respectful much more than the narrow band curmudgeons that I group you with!

 

[JoeDirt]

Actually it is not the minimum for voice comms but is a compromise between intelligibility and frequency response. I have used 1.8 KHz and even 1.5 KHz filters on SSB with great success during heavy QRM. My standard filter is 2.3 KHz.

You are correct, I was trying to say anything less than 300hz-2.7khz is hard to listen too without fatigue (IMHO).

 

[JoeDirt]

I think some of the people that do these high fidelity modifications do not care that they are exceeding 10kHz and splattering on the adjacent channels, "as long as they get most of that audio on channel." It's a little different than the guys just clipping limiters and splattering on multiple channels for a crunchy distorted sound they consider "LOUD".

I have to say though some of the "great audio guys" like MMM, Machete, & Mustang are not heard on the adjacent channels nearly as much (or at all) as the local "clipped limiter guys" who splatter wide, is this just distance related or do some of these guys actually know how to run a hi-fi station that doesn't bleed?

Not a trick question: If a CB channel is 10 kHz wide and I transmit 10 kHz wide will I be heard on an adjacent channel if my wave-form looks clean (neg peaks in check)?

If everyone was 10khz wide with perfect filtering....... No your good.