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2 pill amplifiers...
- Thread starter Oatmeal
- Start date
Carrier is the dead key out of the amp with no modulation on AM mode.
There is no carrier on SSB mode.
73
Jeff
There is no carrier on SSB mode.
73
Jeff
Low pass filters will help clean a dirty station up. They are not a bad idea to use. Having a clean radio that isn't peaked and tweaked for every last watt and an amp that is clean and isn't being over driven will keep things clean most of the time. This is coordination with a good antenna and coax and having all equipment and antenna grounded properly. It takes a bit to get it right. If you have neighbors that are really close you may want to get a low pass filter it won't hurt. Good RF chokes will help, use as many as needed. I did have some RFI issue getting into the neighbors stereo and computer speakers, I placed some ferrite snap on chokes on all the wires and issue was solved. Haven't had this issue since changing radios either. But remember clean in equals clean out vise versa. Hope this helps. God bless.
If amp is right and linear, usually best to put low pass filter between radio and amp to clean up before it gets amplified. Voltages are much lower and easier to take care of at source.
In answer to the Mike Gain Question.
Yes, by turning the Mike Gain ( dynamike ) control all the way down and keying the radio, that will show the carrier alone.
I will use Exit 13`s pictures.
The above picture shows a AM carrier with no Modulation, or no audio, this is what you would see on a dead key with the mike gain turned off.
The power output remains constant across the screen.
Note the scope is set so that there is one division( or square ) above the center line, and one division below the center line.
On a watt meter you would see the needle rise to a level, lets say 3 watts and remain there, speaking into the mike will not change the reading on the meter because the potentiometer or knob that controls the mike level is turned off.
Here is what you will see when the mike gain is turned up to allow the radio to be modulated, notice in this example that the waveform now shows the envelope going several divisions ( squares) above what was the single division shown on the carrier or dead key picture, and below the single division of the carrier shown in the first picture.
The peaks above carrier are positive modulation, the "dips" below the carrier are negative modulation.
This picture is an example of a radio that has been modified to allow the positive to go above 100% while still holding the negative to stay below 85/90%.
In a standard radio, I would expect to see the waveform to show about equal positive and negative peaks near 100%
What you would see on a wattmeter is that the needle would rise to the carrier level , again 3 watts, and then move forward when you speak into the mike.
How much the needle moves forward depends on a lot of factors.
If it is a AVG reading meter do not expect the needle to move forward a lot.
A peak reading meter, depending on how it is designed and built will show more forward swing than a AVG reading meter.
This applies to AM mode only, SSB and FM are different.
73
Jeff
Yes, by turning the Mike Gain ( dynamike ) control all the way down and keying the radio, that will show the carrier alone.
I will use Exit 13`s pictures.
The above picture shows a AM carrier with no Modulation, or no audio, this is what you would see on a dead key with the mike gain turned off.
The power output remains constant across the screen.
Note the scope is set so that there is one division( or square ) above the center line, and one division below the center line.
On a watt meter you would see the needle rise to a level, lets say 3 watts and remain there, speaking into the mike will not change the reading on the meter because the potentiometer or knob that controls the mike level is turned off.
Here is what you will see when the mike gain is turned up to allow the radio to be modulated, notice in this example that the waveform now shows the envelope going several divisions ( squares) above what was the single division shown on the carrier or dead key picture, and below the single division of the carrier shown in the first picture.
The peaks above carrier are positive modulation, the "dips" below the carrier are negative modulation.
This picture is an example of a radio that has been modified to allow the positive to go above 100% while still holding the negative to stay below 85/90%.
In a standard radio, I would expect to see the waveform to show about equal positive and negative peaks near 100%
What you would see on a wattmeter is that the needle would rise to the carrier level , again 3 watts, and then move forward when you speak into the mike.
How much the needle moves forward depends on a lot of factors.
If it is a AVG reading meter do not expect the needle to move forward a lot.
A peak reading meter, depending on how it is designed and built will show more forward swing than a AVG reading meter.
This applies to AM mode only, SSB and FM are different.
73
Jeff
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