| Author |
Message |
    
Radioreddz
Junior Member
Username: Radioreddz
Post Number: 40
Registered: 9-2006
| | Posted on Tuesday, February 13, 2007 - 8:10 pm: | 
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been using a HR 2510 dead key set at 3.50 watts radio swings a little over 40 watts will this damage the tubes in my amp its an older Scout amp with the HR 2510 amp swings to 800 watts from 250 watt key up. with a cobra 2000 3 watt dead key 15 watt swing i get little over 600 watts from amp. will 40 watt swing hurt the amp |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2383
Registered: 9-2004
| | Posted on Tuesday, February 13, 2007 - 11:26 pm: |
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would need to know more about the amp, but generally tubes are more forgiving than transistors, but only to a point.
if this amp is a sweep tube amp and is 2 driving 4, then you are probably ok.
if it has 1 drivning 2 driving 4, then you might be stressing it.
do you hear the tubes ringing when you talk?
i also think that your wattmeter may be a bit loose.
40 watts is not that easy to get out of a 2510 unless its been heavily modified.
like changing the final out.
just so you know, no one on the receiving end can tell the difference between 600 and 800 watts anyway.
if your 600 watts gave them an S5, then to get to S6 you would have to put out 2,400 watts.
hope this helps,
matt |
Mrclean
Member
Username: Mrclean
Post Number: 62
Registered: 12-2003
| | Posted on Saturday, March 10, 2007 - 1:35 pm: |
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I had a scout and I would think this drive to be very high. about 3 watts DK 12 or 14 swing is all I would drive mine with. It was a 4 driving 4 |
Pogo12
Intermediate Member
Username: Pogo12
Post Number: 115
Registered: 3-2005
| | Posted on Wednesday, March 14, 2007 - 11:22 pm: |
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It most likely will cause the tubes to have a very short life if your modulation peaks very often.My opinion of course. |
Buddyjuice
New member
Username: Buddyjuice
Post Number: 1
Registered: 6-2011
| | Posted on Thursday, June 23, 2011 - 4:28 am: |
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I have a magnum s980 and it swing at 75 watts I want to know if I purchase the Texas Star DX 1000V Mobile this radio needs to turn down the swing and do I have to do any conversion to this amp? |
Sitm
Intermediate Member
Username: Sitm
Post Number: 447
Registered: 1-2004
| | Posted on Monday, June 27, 2011 - 9:51 am: |
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source
(link removed by moderator)
You’ll often hear on the CB radio one operator asking another “how is my modulation?”. The question is actually something that everyone who uses the CB radio should be asking themselves.
WHAT IS MODULATION?
Well the actual definition of modulation as it refers to CB radios involves a fairly technical explanation, but we’ll try to keep it simple. Basically an audio-frequency wave must be combined with a carrier wave in order to be transmitted over the radio. Either the frequency or the amplitude of the radio wave may be modified. Amplitude Modulation or AM is the mode used by CB radios.
When you use your CB radio and your voice enters the microphone it then goes into the modulating circuit of the radio which creates the modulation that is added to your carrier.
A modulating radio wave looks very similar to a wave you’d see in the ocean, except that unlike an ocean wave there is a maximum peak for a AM radio wave. This maximum peak could be explained as maximum modulation or 100% modulation.
As your voice hits its loudest point the modulation peaks as well. If you are talking softly your modulation peaks will be smaller and your modulation may be less than 100%. High modulation nearing 100% in very simple terms means that you are getting the maximum out of your radio and the guy on the other end receiving you will hear your voice without any difficulty.
A majority of the CB radios produced have a special adjustment potentiometer mounted internally that is used specifically to adjust the level of modulation of the radio. The factories install this so that during the testing stage of production the radio’s modulation level can be set to a factory specification very easily.
Modulation affects the output power of a CB radio. As modulation increases the peak output increases. The FCC has strict rules regarding the output of CB radios and therefore most CB manufacturers set their radio modulation levels around 80% or lower to make sure that they are well within the FCC regulations.
One of the most common modifications that a CB operator will make to their equipment is to internally turn up the modulation adjustment so that the CB radio is producing 100% modulation. Not all radios have this modulation potentiometer though, some merely have a set resistor in place and the only way to increase the modulation internally is to change the value of the resistor or to remove it completely.
Most people don’t talk at their loudest all the time and certain vowels or words often are spoken in lower tones which normally would result in less than 100% modulation. To counteract this problem many radio operators use power microphones with high gain or high end radios which have special circuits that help make sure all the highs and lows of your voice are turned into a 100% level of modulation.
If you have a CB radio that has a 4 watt carrier when you apply modulation the output will increase upwards. With 50% modulation your output might increase to a peak output of 7 watts. With 100% modulation your peak output might increase to 12 watts. Since output power also affects the distance and strength of your transmission it’s easy to see the connection and importance of having a CB that is maintaining near 100% modulation.
OVERMODULATION – THE DANGER ZONE
While everyone using a CB should be trying to achieve 100% modulation to make sure they are getting the maximum audio and output out of their radio, there is such a thing as too much modulation.
Since 100% modulation represents a maximum height of the amplitude modulation wave, if someone tries to create modulation greater than 100% a number of bad effects can occur, such as spurious emissions and distortion.
So exactly what causes overmodulation to occur in a CB radio?
Often people will adjust the internal modulation potentiometer in their radio to its absolute maximum. Then, in addition to that modification they will add a very high gain microphone that amplifies their voice to very high levels creating overly strong input into the modulation circuit of their radio. These two things together will produce more modulation than necessary to reach 100%.
Overmodulation will make the CB operator sounds scratchy or may add static type sounds to their transmission. In addition the operators signal may begin “clipping”, this is when the modulation wave becomes distorted due to the overmodulation and creates what are called “harmonics”.
When using the CB these “harmonics” mean that the operators signal has emissions that are not on the same frequency as their transmission. Also referred to as “bleedover”.
I’m sure everyone has heard a station that is overmodulated, or has experienced the “harmonics” of overmodulation when you are on one channel but can hear someone from another channel bleeding onto your channel.
While everyone wants to sound loud and clear when talking on the CB radio, there is a clear maximum level for modulation. Going over this level will result in overmodulation and will have multiple negative and unwanted effects on your transmission. |
