| Author |
Message |
    
Hollowpoint445
New member
Username: Hollowpoint445
Post Number: 7
Registered: 6-2004
| | Posted on Sunday, June 13, 2004 - 3:49 am: | 
|
Can someone tell me what's the deal with swing mods? AM doesn't swing much. At 100% modulation the output is only 50% higher RMS than the carrier alone. With average modulation levels of less than 30% for normal voice communication it shouldn't swing a meter much at all. So what's the deal with people wanting to see swing? Are these mods attempts to supress the carrier and make it more like Double Side Band? Why even bother when you could just use Single Side Band and then have the advantage of better filtering and selectivity? Especially when radios already do SSB and no modification is necessary? |
Tech548
Moderator
Username: Tech548
Post Number: 111
Registered: 5-2004
| | Posted on Monday, June 14, 2004 - 12:51 am: |
|
Hollowpoint445
Excellent, excellent point.
However, most CBers want to see the needle of their meter move from one end to the other. It's just an ego trip my friend.
But those in the know that use 20 watts of PEP, know very well that using 40 watts of PEP will not be seen on the receiving end S-meter since you have to more than double RF power just to come up 1/2 S-unit. Just going from 20 watts to 40 watts just doesn't cut it.
I agree 100%. SSB is the way to go.
Good post HP445.
Jeff. |
Geekster
Junior Member
Username: Geekster
Post Number: 11
Registered: 6-2004
| | Posted on Wednesday, June 16, 2004 - 7:15 am: |
|
I myself have asked this question for several years. I still don't know? Yep to get that one "S" unit you need to up power by 4 fold so that would be 256 watts from 4 watts to equal one "S" unit on recieve.
I guess it hasn't quite sunk in yet. I guess the movement of the power needle is an ego trip as described above.
Doh |
Brownsmillsch18
New member
Username: Brownsmillsch18
Post Number: 3
Registered: 2-2004
| | Posted on Thursday, June 17, 2004 - 9:44 am: |
|
I guess the only reason for it is to drive an amp harder, and to "seem" louder to a local station.
my $.02 |
Tech808
Moderator
Username: Tech808
Post Number: 2675
Registered: 8-2002
| | Posted on Thursday, June 17, 2004 - 10:23 am: |
|
An AM signal is fully modulated when the swing doubles the carrier.
For a radio to reach 100% modulation a 4 watt key should swing no more than 8 watts.
Anything more than that is distortion to your voice.
The AM carrier is necessary for the receiver to properly demodulate the audio from the signal. If you add excessive swing it will distort your audio.
It will not help you get out better.
As Geekster mentioned to even see a 1 S-unit difference on the receiving end of a signal a person needs to multiply there signal 4 times.
Lon
Tech808
|
