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Deadkey vs swing
- Thread starter Simbalage22
- Start date
Yes, yes I am aware that garbage in equals garbage out hence if the radio is Deadkeying at 4W but swings 40W pep which in turn with AMP ON shows 100w deadkey on amp swinging to 400W pep then is this good or still over modulation? I am thinking still over modulation since the source being the radio is over modulated, but the amp output modulation appears to be outputting the correct ratio?
Im researching, hence the relic post brought back from the dead lol
That 4 and 40 watts was over modulated to start with and is still over modulated, it's just stronger.
Im finding it hard to put my words across, American English is my second language.
I think that just proves the point of the amp not being linear at all to me./
In fact, if that amplifier is really putting out a 40 and 400 watts from the 4/40watts input, the amplifier is remarkably linear.
The amplifier should not change the percentage of modulation but cb linear aren't always so linear.
4:1 pep to carrier equals 100%. Always has and always will. A tone generator, scope and watt meter will prove it. My cheap meters are close. My bird 43 with pep kit is spot on.
"4:1 pep to carrier equals 100%." Oh boy, now we get to deal with measuring units (Avg/Pep). That's always fun, especially if someone isn't familiar with those measuring units. Get the basic idea understood then worry/discuss how things are measured and the changes in ratios etc.
And that's not a personal 'dig' at you 543_Dallas.
And that's not a personal 'dig' at you 543_Dallas.
No offense taken. I'm trying to figure out where the 2:1 ratio comes from. You aren't the first person I've heard say this.
How power is measured is about as basic as it gets. It's also important to determine that from the beginning so someone doesn't fill in the blanks with their own theory about the ratios.
If we were using an average meter on AM and inject a tone to achieve 100% modulation the power should not increase with modulation. If it does the waveform is flat topping, hitting baseline or maybe just asymmetrical if the transmitter is capable of that. It is something other than a sine wave.
There will be some fluctuation in average power when it is modulated with a voice but it should be no where near 2:1. If you're making 2:1 on an average meter you're well over 100% and/or have a distorted waveform. Normal everyday stuff on 11 meters.
100% modulation of an AM carrier is indeed four times the carrier. This is easy to see if you are using a proper pep power meter. If you are looking an an oscilloscope or an older VTVM or RF voltmeter you will see a value twice that of the carrier. Since twice the applied voltage results in twice the current flow it results in four times the power. I'm wondering if this is where some people get confused about meters and values.
Good point.
A ssb guy was giving AM pointers on 75m recently. He said it was a 4:1 ratio only if you were using a tube rig. "Plastic radios" are 2:1 and you have to run a 750 watt carrier out of the amplifier to make legal limit AM with a modern radio.
This guy missed a few minor details and made up the rest. He's always on some kind of technical subject spreading misinformation.
So in another nutshell, if the amp is showing a 4.1 ratio, and I understand it just goes why what it is being fed from the radio. How does the amp come about modulating with a 4.1 ratio when the radio itself appears to be over modulating. ( 4-30/40w pep )? I would have thought the radio should be 4-16W pep for correct modulation ballpark wise?
Obviously that SSB guy is someone to avoid for info. Tube or solidstate makes no difference when it comes to power output. I have even heard some claim that 100 watts from a tube radio is better than 100 watts from a solid state rig and will carry further. Some folks are just too stupid for their own good but unfortunately there are many who will follow their preachings.