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CB Band and CB Radios
All things CB. Discuss what you do with your CB as well as review and ask questions about AM & SSB CB radios.

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  #11 (permalink)  
Old 09-24-2008, 08:10 AM
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Quote:
Originally Posted by Bow View Post
EXACTLY!

I have never quite figured that out.. I love the "Break 19 for a Radio Check!"

"Well, your over modulating, very tinny, sounds pretty rough... roll your mic gain down..."

The reply is usually... "What?"
I just tell em, "You are getting out, I hear ya on at least 10 channels"
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Old 09-24-2008, 09:19 AM
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hahahhahaha

But down here around Houston, those guys usually speak Spanish.... on 5-6 channel either side of the channel they are on...
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Old 09-24-2008, 09:38 AM
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In that case:

I just tell em, "Usted está saliendo, yo oye ya en por lo menos 10 canales"
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Old 09-24-2008, 10:58 AM
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Quote:
Originally Posted by Bow View Post
If you have the same radio modified for say... a 2 Watt "Dead Key" and 37 Watts of "Swing"?

Wouldn't you have a lot of over modulation,splatter, and the ability to to get a "Worked all Toasters" award from your neighbors?
the 4:1 ratio for 100% modulation applies to symmetrical AM.
Where symmetry means the peak reduction in power (due to modulation) is the same as the peak increase in power.
Because with AM, modulation is alternating reduction and increase in total power.

Where you get into trouble is when the reduction in power attempts to go past zero power. This hits like a hammer on a nail, meaning its abrupt and wide in bandwidth. This is splatter.
On the opposite end of the cycle, the increase in power, the modulation can exceed 100% with a only tiny increase in distortion. To be loud, you dont want more on the negative side, only more on the positive.

Over negative modulation is a problem with radios and swing kits.
Positive side modulation becomes an issue with power amplifier transistors only able to put out limited power.
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Old 09-24-2008, 11:32 AM
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dudmuck,
You're right, as far as you are going with it. But, the fact remains that that dip into the 'zero power' portion of the 'negative side' is still a result of over modulation. It might be more noticeable than a slight excursion on the 'positive' side. But so what, it only indicates that the whole thing is being over modulated, driven too hard, and you still lose quality or fidelity of the signal. No real benefit to a 'single sideband with carrier' signal. Might as well go that extra step and make it 'single sideband with no carrier'. Imagine that!
- 'Doc
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Old 09-24-2008, 11:41 AM
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Might as well go that extra step and make it 'single sideband with no carrier'. Imagine that!
- 'Doc
DSB mode...
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Old 09-25-2008, 08:12 AM
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Or ISB.
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Old 11-17-2008, 05:54 PM
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i have a cobra 29 that dead keys at 8 watts and swings to 32. i've had it scoped and i've been on the recieve end of my radio and it sounds great!! I am thinking about adding a 1 pill so i will be bringing the dead key down to 1 or 1.5 watts.
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Old 11-17-2008, 06:11 PM
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Quote:
Originally Posted by dodgeman View Post
i have a cobra 29 that dead keys at 8 watts and swings to 32. i've had it scoped and i've been on the recieve end of my radio and it sounds great!! I am thinking about adding a 1 pill so i will be bringing the dead key down to 1 or 1.5 watts.
Then it sounds as if your 29 is right on the money as far as carrier to peak ration is concerned but what will the radio do from 1 to 1.5 watts carrier to peak after you have it detuned so to speak?

If it continues to peak at 32 watts then you've gotten away from your 4 to 1 ratio and it should sound awful with or with out the 1 pill section turned on or at least show to be awful on the same scoped you mentioned earlier.

A more realistic way of measuring is to measure carrier to peak average power so at a carrier of 1 watt the radio should peak at 2.5 watts average power which is 1 and 1/2 to 1 of the resting carrier which would insure a modulation level of 100% which would not endanger the final output stage of being over driven and assure a nice sounding signal.
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Old 11-17-2008, 06:21 PM
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i was kinda worried about haveing 32 watt peaking radio hooked up to an amp! how do i bring that peak down? go back to the stock final?
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