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I found here and here that Voyager transmits its main radio signal at 23 watts. In other words, the strength of the signal coming from its radio dish is 23 watts.

However, what I want to know is how much electrical power does that dish draw?

No system is 100% efficient, so it has to draw more than 23 watts. Maybe it's 24, 25, 50, 100, or 23.001. I don't know what the typical efficiency of a dish is when measured by electric power in versus signal power out.

Also, if I'm not mistaken, this will be the same for Voyager 1 and 2.

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The "radio frequency" system draws up to 111.7 W (PDF on Voyager design, table 2 on page 10). This is purely the power amplifier, modulation/demodulation is listed separately at another 11 W.

Note that this has nothing to do with the dish. Those 23 W is what comes out of the antenna as radio waves. The dish reflects pretty much 100% of this.

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  • $\begingroup$ I'm not sure I understand you. If this has "nothing to do with the dish" then what system is that 111.7 Watts going to, if not the dish? Are you distinguishing between the transmitter in the center of the dish and the circular part of the dish itself? $\endgroup$
    – DrZ214
    Commented Jul 18, 2015 at 19:16
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    $\begingroup$ Yes, I'm distinguishing between the transmitter and the antenna. The dish is just a convex piece of metal that's part of the antenna. It doesn't draw power. The power is drawn by the transmitter electronics (tuning circuits, power amplifier). These electronics are located in the spacecraft body. The radio signal is sent through a cable from the electronics to the small cone at the center of the dish. The cone contains the antenna. $\endgroup$
    – Hobbes
    Commented Jul 18, 2015 at 19:45

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