Chris wrote:


To reduce the drive power to an amplifier and make the modulation louder.

Chris

I see. But reducing the carrier won't make the modulation louder, only
more distorted.

Well, let me back up a little. What I said is true if the modulation is
100%.

But let's suppose that the transmitter is capable of only 50%
modulation. In that case, you *can* make the modulation louder by
increasing the amount of audio applied to the carrier. If the
transmitter is fundamentally designed to handle 100% modulation, this
would require only more audio gain or a "hotter" microphone. That would
be the best way to make your modulation louder.

But let's say that instead, you reduce the carrier from 4 watts to 1.
Then the 1 watt carrier would be 100% modulated. (100% modulation of a 4
watt carrier takes 2 watts. 50% modulation takes only 1/2 watt, which
will modulate a 1 watt carrier 100%.) Now you have 100% modulation of
the 1 watt carrier. There's the same amount of transmitted audio power
as before -- 1/2 watt --, so you're really not making the audio any
stronger, and no one will be able to copy you any better than before.
(In fact, your weaker signal will have more trouble getting through in
the presence of noise or interference.) But if you're the only signal
being heard, the receiver's AGC (automatic gain control) will react to
your weaker carrier by turning up the receiver's gain, making the audio
sound louder. The person receiving your signal can make your audio just
as loud with a 4 watt carrier by manually turning up the volume.

So I'll relent and say that reducing the carrier might make your audio
sound louder -- but only if your transmitter is undermodulated in the
first place, there's no stronger signal to control the receiver AGC, and
if you don't reduce the carrier so much that it makes the modulation
exceed 100%. But your ability to get through interference and noise will
probably be reduced.

Roy Lewallen, W7EL

So let's use a typical amp rated at 100 watts AM/CW/FM and 200 watts PEP on
SSB. Assuming that the transmitter is modulated at 100%, how many watts
should the carrier be?

Chris
"Roy Lewallen" wrote in message
...
| Chris wrote:
|
|
| To reduce the drive power to an amplifier and make the modulation
louder.
|
| Chris
|
| I see. But reducing the carrier won't make the modulation louder, only
| more distorted.
|
| Well, let me back up a little. What I said is true if the modulation is
| 100%.
|
| But let's suppose that the transmitter is capable of only 50%
| modulation. In that case, you *can* make the modulation louder by
| increasing the amount of audio applied to the carrier. If the
| transmitter is fundamentally designed to handle 100% modulation, this
| would require only more audio gain or a "hotter" microphone. That would
| be the best way to make your modulation louder.
|
| But let's say that instead, you reduce the carrier from 4 watts to 1.
| Then the 1 watt carrier would be 100% modulated. (100% modulation of a 4
| watt carrier takes 2 watts. 50% modulation takes only 1/2 watt, which
| will modulate a 1 watt carrier 100%.) Now you have 100% modulation of
| the 1 watt carrier. There's the same amount of transmitted audio power
| as before -- 1/2 watt --, so you're really not making the audio any
| stronger, and no one will be able to copy you any better than before.
| (In fact, your weaker signal will have more trouble getting through in
| the presence of noise or interference.) But if you're the only signal
| being heard, the receiver's AGC (automatic gain control) will react to
| your weaker carrier by turning up the receiver's gain, making the audio
| sound louder. The person receiving your signal can make your audio just
| as loud with a 4 watt carrier by manually turning up the volume.
|
| So I'll relent and say that reducing the carrier might make your audio
| sound louder -- but only if your transmitter is undermodulated in the
| first place, there's no stronger signal to control the receiver AGC, and
| if you don't reduce the carrier so much that it makes the modulation
| exceed 100%. But your ability to get through interference and noise will
| probably be reduced.
|
| Roy Lewallen, W7EL

Oh, how do you convert from WPEP to WRMS? Does it have to be converted to
voltage and multiplied by .707?

Chris
"Chris" wrote in message
k.net...
| So let's use a typical amp rated at 100 watts AM/CW/FM and 200 watts PEP
on
| SSB. Assuming that the transmitter is modulated at 100%, how many watts
| should the carrier be?
|
| Chris
| "Roy Lewallen" wrote in message
| ...
| | Chris wrote:
| |
| |
| | To reduce the drive power to an amplifier and make the modulation
| louder.
| |
| | Chris
| |
| | I see. But reducing the carrier won't make the modulation louder, only
| | more distorted.
| |
| | Well, let me back up a little. What I said is true if the modulation is
| | 100%.
| |
| | But let's suppose that the transmitter is capable of only 50%
| | modulation. In that case, you *can* make the modulation louder by
| | increasing the amount of audio applied to the carrier. If the
| | transmitter is fundamentally designed to handle 100% modulation, this
| | would require only more audio gain or a "hotter" microphone. That would
| | be the best way to make your modulation louder.
| |
| | But let's say that instead, you reduce the carrier from 4 watts to 1.
| | Then the 1 watt carrier would be 100% modulated. (100% modulation of a 4
| | watt carrier takes 2 watts. 50% modulation takes only 1/2 watt, which
| | will modulate a 1 watt carrier 100%.) Now you have 100% modulation of
| | the 1 watt carrier. There's the same amount of transmitted audio power
| | as before -- 1/2 watt --, so you're really not making the audio any
| | stronger, and no one will be able to copy you any better than before.
| | (In fact, your weaker signal will have more trouble getting through in
| | the presence of noise or interference.) But if you're the only signal
| | being heard, the receiver's AGC (automatic gain control) will react to
| | your weaker carrier by turning up the receiver's gain, making the audio
| | sound louder. The person receiving your signal can make your audio just
| | as loud with a 4 watt carrier by manually turning up the volume.
| |
| | So I'll relent and say that reducing the carrier might make your audio
| | sound louder -- but only if your transmitter is undermodulated in the
| | first place, there's no stronger signal to control the receiver AGC, and
| | if you don't reduce the carrier so much that it makes the modulation
| | exceed 100%. But your ability to get through interference and noise will
| | probably be reduced.
| |
| | Roy Lewallen, W7EL
|
|

Chris wrote:

Oh, how do you convert from WPEP to WRMS? Does it have to be converted to
voltage and multiplied by .707?

Chris

While the conversion from PEP to RMS is simple for a sine wave or other
simple waveform, it's not simple when dealing with a real voice
waveform. It depends heavily on the characteristics of the voice, and
any audio processing (such as compression or RF clipping) that might be
taking place. Typically, the PEP value of an unprocessed voice waveform
is many times the RMS value.

Roy Lewallen, W7EL

Chris wrote:

So let's use a typical amp rated at 100 watts AM/CW/FM and 200 watts PEP on
SSB. Assuming that the transmitter is modulated at 100%, how many watts
should the carrier be?

Chris

Zero. As universally used, SSB means "single sideband suppressed
carrier". There is no transmitted carrier in this mode.

And, modulation percentage has no meaning when talking about SSB, since
it refers to the relationship between the modulation and the carrier.

Roy Lewallen, W7EL