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Should I say you bet I can do that?

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...And forget about any wideband audio. Generally speaking...those mods sound like crap above around 160--200% on a typical CB receiver.

Very good point, who can listen to such extreme stations and hear everything clearly?

I like my SDR for bench testing, having an SDR makes it easy to avoid the diode detector in CB's. Having one setup full time just to listen to Hi-Fi stations isn't high on my list of priorities, though, maybe it should be.

The 20$ RTL-SDR dongle and freeware program "SDR#" allow me to listen to stations with extreme modulation, also those that have that wideband audio. I know you know this Mustang 131, but I figure I'd add it to the thread.


OldTech03, what you describe sounds to me like the customer is uninformed or misinformed by "CB Experts" on YouTube who likely make extraordinary claims but don't even show a carrier reference, if someone wants a good or service performed... obviously they should understand the full ramifications of what they are really asking for.. a channel splattering ill-eagle radio, a sick bird that don't fly or sound right!
 
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OldTech03, what you describe sounds to me like the customer is uninformed or misinformed by "CB Experts" on YouTube who likely make extraordinary claims but don't even show a carrier reference, if someone wants a good or service performed... obviously they should understand the full ramifications of what they are really asking for.. a channel splattering ill-eagle radio, a sick bird that doesn't fly or sound right![/QUOTE]
First I the whole thing was resolved before we both hung up the phone with the customer saying WOW no need to do this. Asking the question on WWDX was to invoke discussion. I already knew where he had obtained the information "Video". Now there was a few that injected the standard we are /or why are we "Beating a dead Hoarse" scenario but that was not the agenda it was merely to invoke thought and in that sense mission accomplished. Sorry I have to much time on my hands and thought maybe others on WWDX might need to chew up some bandwidth talking about something in the technical realm. I will try to find a subject next time that is more acceptable and that has never been discussed before. Please forgive me for I have sinned.
 
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No one sinned OldTech03. Forgive me for not getting technical in my post, Kopcicle did a great job in his post.
I welcome these kind of threads, but who am I..

In the beginning all I knew about modulation was "you want forward swing", and all the locals made sure "set it low and let it swing" was ingrained into my head before 3 months into CB, it was a long journey for me to appreciate less distortion on the CB..

Some people enjoy the crunch, the bleeding highs and feedback of too much echo + talkback w/ an overmodulated station, that's not me, but to each his own!

I'm glad it was resolved before you got off the phone.
And I enjoy the thread you posted.
This hobby for me was about fun in the beginning, I'd like to keep it about enjoyment.
Maybe I should just avoid the internet for a while, sorry if I rubbed you the wrong way.
 
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Less power makes it more difficult to make a contact in DX especially when conditions are weak.


That's the whole point. Why would you want to reduce your power to make yourself sound louder at close range but unable to make the trip in DX?

Louder is completely useless in dx. Reducing your carrier only hurts your performance. It might sound impressive in the parking lot to other people but a reduction in power always equates to a reduction in performance. Keep in mind we're not talking about commercial broadcast stations that can afford to waste power because they have paid advertisers. Stretching out the positive Peaks and reducing the carrier does absolutely nothing for long distance communication it only hurts it. You really do need that carrier. If anything, speech compression would be a step in the right direction to increase your mean power. Dropping the carrier simply reduces your mean power.

Reducing carrier?? Who said anything about reducing carrier power? I am not talking that low carrier high peak crap properly called Double sideband reduced carrier AM. We ran full carrier power on AM with the positive peaks modulated to 120% and the negative to 100%. With zero modulation the carrier was full rated power. Broadcast stations are rated by carrier power and a 10 Kw station with 120% modulation will still have a carrier of 10 Kw without modulation peaking to 48Kw pep at 120% modulation.

You said it is useless and I disagree if you want to be LOUDER. You do NOT necessarily have to reduce carrier to do it. Now what I do agree with you about is
the need for carrier on DX. International shortwave stations typically run 85% modulation with a great big mo-fo carrier. The reason is that the RF finals loaf along in class C while the modulator tubes take a beating in class AB service. Running this way it makes monetary sense to get as long a life from the tubes as possible while hitting a target area with as much RF as possible and still maintaining a decent audio level. We used to typically run a pair of tubes in modulator service for almost a year and then swap them out to the RF section for another year and install new tubes in the modulator section but NEVER the other way around. That is how big of a difference the tubes operate in those different applications and you can imagine the co$t of a pair of 250 Kw tubes for a shortwave station.
 
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Dude, you sound more like a radio repairman than a truck driver...

And yet you care to argue with a man that’s been in commercial radio most of his life? Really... you wanna go there?

Sit down on the front row, I believe the man is about to school your ass.
I'm sure being in commercial radio he can teach me lots of things about wasting power for the sake of sounding a certain way. It has no relevance in two way radio where maximizing efficiency is the name of the game.
 
Direct audio injection of a harmonically clean audio signal makes all the above a wasted discussion. Then the only limitation is the dissipation of the PA.
What happens when the harmonically clean audio signal hits a nonlinear rf section? LOL
It distorts, plain and simple. So much for a harmonically clean signal. Always start with a perfectly linear RF section and work your way backwards. Folks are spinning their wheels trying to bypass the audio section when they should focus their attention on the RF section.
 
I'm sure being in commercial radio he can teach me lots of things about wasting power for the sake of sounding a certain way. It has no relevance in two way radio where maximizing efficiency is the name of the game.


I would think it was more important in commercial radio than in schoolyard walkie talkies. We’re talking about China made friggin’ radios, everything that he said applies to these radios and absolutely would help and matter.

I’m not on the mans favorite list and I damn sure bet you’re not but one thing is for certain, he can quickly and easily take your ass to school in the subject of radio and audio quality. If you’d hush ya mouth and listen for a minute, you might just mess around and learn something useful.

67490AE7-6F50-4F44-93F9-B13839037469.gif
 
What happens when the harmonically clean audio signal hits a nonlinear rf section? LOL
It distorts, plain and simple. So much for a harmonically clean signal. Always start with a perfectly linear RF section and work your way backwards. Folks are spinning their wheels trying to bypass the audio section when they should focus their attention on the RF section.


Well sounds like you’re ready to trade that class A license in for a service monitor and an RV of your very own. I’ll be damned, the student has become the teacher. Right on!!
 
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Commercial stations can go as high as 120%. However SW use 100% or less due to selective fading.
I run less carrier and more mod to REDUCE the load to my transmitter. The carrier does nothing but make quiet and run up your electric bill. A little slang ain't a bad thing.
But when push comes to shove....channel 6 mode..MORE carrier and LESS audio gets the job done. Narrow audio and high carrier running just 90-100% positive peaks.
 
What happens when the harmonically clean audio signal hits a nonlinear rf section? LOL
It distorts, plain and simple. So much for a harmonically clean signal. Always start with a perfectly linear RF section and work your way backwards. Folks are spinning their wheels trying to bypass the audio section when they should focus their attention on the RF section.
You can imagine what you want to.
You seem to spin your wheels all over trucking and radio forums, I should bypass you.
Not all radios are designed the same way, remember that.
You must be too busy pretending to know what is going on in someone else's head to acknowledge this simple fact.

I could care less about you, RPC; but not by much.
I've never come across an online stalker like you RabbiPorkChop.
Remember next time you try and showcase other peoples work in your private Fine Tune facebook group, you're hurting the hobby over all, not helping.

You ain't hurting my pockets, but I will be a son of a bitch If I don't try and save people from getting ripped off by your lord & master, Sherman. :notworthy::notworthy::notworthy:

I can create a private group, an echo chamber, but I prefer reality...
BTW thanks for all the views, I have seen a 25% increase in traffic to my YouTube, over the last 30 days.
 
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What happens when the harmonically clean audio signal hits a nonlinear rf section? LOL
I'll let the devices themselves as well as the godfather of BJT RF amplifiers do the talking here.
https://alltransistors.com/pdfdatasheet_mitsubishi/2sc1969.pdf
The MRF475 isn't noticeably different from the 2SC1969 in any significant way.
Helge O Granberg is worth reading in any form.

I can lead you to water but I can't make you think.
Toshiba, Motorola, And Helge have done their job the rest is up to you.
 
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efficiency
damn , do we have to go back to skool yet again?
https://www.worldwidedx.com/threads/pill-factory.230557/#post-628379
Toshiba BJT's ? We're all chumps...
View attachment 23953 View attachment 23954 View attachment 23955

The first is a DC to 54 SDR @ 500mw
Next is it's 300w amplifier. Note the filter section.
Then the big brother 1.8-54 Mhz for 2xBLX188XR .

I'll spell it out in plain english.


Amplifier Class Description Conduction Angle
Class-A Full cycle 360o of Conduction θ = 2π
Class-B Half cycle 180o of Conduction θ = π
Class-AB Slightly more than 180o of conduction π < θ < 2π
Class-C Slightly less than 180o of conduction θ < π
Class-D to T ON-OFF non-linear switching θ = 0

Lets get some fundamental myth out of the way .
View attachment 23956


Solid-state amplifiers cannot be class "AB1" or class "AB2". A bipolar transistor amp cannot be a sub 1 or sub 2 class because they do not have grids to have or not have grid current. Solid-state amplifiers have bases or gates, and a bipolar transistor always has base current.

Class AB does not mean the amplifier is linear. "Linear" in the context of amplifiers indicates a linear transfer function, or a transfer function that has the proper transfer function curve shape to minimize odd-order intermodulation products. A linear transfer function generally means the output power level tracks the input power level in a way that does not cause excessive 3rd, 5th, 7th and other odd-order mixes. Only odd-order mixing or distortion produces annoying splatter.

The bias current can NOT remain steady because the bipolar requires a change in base current to produce a change in collect current.
If the bias current remains steady with varying drive, the amplifier will have gain compression.
If the VOLTAGE supplied to the bias system remains fixed at a level that produces the correct Ic for the device junction temperature, the amplifier will not gain compress when the exciter power rectified in the EB junction tries to add negative voltage back into the bias supply.
If the current is regulated, the bias will go negative as drive is increased.
That's why high power transistors can not be correctly biased without an active bias system that maintains constant voltage with a very low bias dynamic source impedance .
FET's, because they have no gate current (hopefully), require only
a regulated voltage source of almost any impedance.

I'd like to thank Tom Rauch and https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html for the text and graphics
Sławomir Kleczyk for the photos.

I'd rather convert DC/DC to get the necessary voltage and use a modern output device .
Directive 2002/95/EC, originated in the European Union in 2002.
This was the initial death knell for the Toshiba 2SC2879. Production modifications were made within the year.
All applicable products in the EU market since July 1, 2006 must pass RoHS compliance. This killed 2SC2879.
Short version , lead free.
Long version Beryllium free.
Longer version is BJT's had outlived their design expectancy and the only market was HF radio. Toshiba threw in the towel and cut what was becoming a loss leader. This was sixteen years ago!
Then the imitators and outright fakes.

If you read this far I commend you because all this remedial education is putting me to sleep.

Bias is not resistors , diodes or even a fixed source .
Class of operation is determined by bias
BJT's are dead
LDMOS or MosFet
Damn I long for a time when tubes were a simple affair of a few volts here and there and a tank circuit out of the handbook.

As you were
 
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