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HF Rig Amperage Question
- Thread starter Riverman
- Start date
As you change the power output the efficiency changes too. Its hard to say. Some rigs may draw an amp or so in receive mode.
Don't starve the radio and overwork a small power supply. It will bite you eventually.
Don't starve the radio and overwork a small power supply. It will bite you eventually.
It is skewed. As mentioned above the efficiency goes to hell when the power is reduced. Get a power supply that will supply more than what you need and then don't worry.
Well, thats a bass ackwards observation.
It really depends on actual transmitter output power (which may vary with VSWR).
Well, thats a bass ackwards observation.
It really depends on actual transmitter output power (which may vary with VSWR).
If you change the impedance of the load the transmitter can draw more current at the same power output.
What happens when an amplifier is mistuned? Doesn't matter if it's transistor or tube.The efficiency goes down. There are guys building CB amps in their basement that understand this.
I think this can be worked out with Ohm's law (& maybe another equation) to give you data you could then plot on a graph-chart, & instantly know the current demands for your desired output.
But, change one variable (like input voltage) and the whole chart would have to be re-worked.
Someone smarter than me will have to bring the required intellect to explain this further.
A formula exists just for this question; that much I'm sure of.
-LeapFrog
Ohm's Law does not apply here at all. If one wanted to know current draw versus power output then simply insert an ammeter in the power cord and record the current at various power levels. The efficiency of the RF power amp changes with output levels and is most efficient at full output. I have to ask WHY is this even being asked at all? If a power supply of sufficient amperage is used to allow full power operation, and that SHOULD be the case, everything else is moot.
I agree with CK, after thinking about it.
Download/open the user manual for your HF rig, somewhere in the book it will let you know the max amp draw, buy a power supply larger than that #. (Make sure the power ratings are for continuous output not peak)
I see now that V=I/R is not going to help him.
I have a reason for asking this, Captain, but was hoping I wouldn't have to give it because I know what kind of remarks are sure to follow. That said, I'll share it but ask that everyone please exercise some restraint.
The rigs I am looking at are all 100 watts. However, at my present location I will only be using it at low power because my antennas wiil be dipoles and end feds located in my attic and It is my understanding using full power in those situations is dangerous (fire hazard) and very likely to cause tvi or other electrical interference. and so, I am trying to determine what power supply I need for low power operation.
I will be limiting my transmit to 25 watts and wanted to know hat the amperage requirement would be for a radio that draws 23 amos at 100 watts, that's all. I'm guessing about 6.
Was thinking about saving money by getting a smaller power supply (12 amp) since I will be running low power. But since the MegaWatt 30 amp supply is only $50 I might as well get that and be done with it. Wasn't too clear in my thinking. Guess the laughs are on me.
Getting old is no fun. Trust me.
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