Peak the grid, dip the plate

In Amateur Radio, long before transistors were put in radios, there was a phenomenon called “dipping the plate current”, and then “peaking the grid current”. This was done for the vacuum tubes in the final amplifier section of the radio. The reason for this procedure was to make sure that the most power went into the antenna. If the plate current was not “dipped”, then an unsafe condition would happen, where the vacuum tube would start to conduct more and more, and a condition known as thermal runaway would happen. This would cause the circuit breaker to pop, and then the radio would have to be reset. Also, doing this too much could cause permanent damage to the tubes. In fact, I was so ignorant of this concept when I first got my Heathkit, that I had to have the guy that sold it to me come over and give me another lesson on how to use it.

Electrically, the most power is transferred when the source and load impedances are matched. Here is an example which proves this mathematically (although it only deals with DC — radio waves are AC).

With a radio, the output circuit is called the “tank circuit”. It is usually a PI network of an inductor and a couple of capacitors, or possibly two inductors. Maximum power is transferred when this circuit is resonant, mathematically, ( XL = XC ).

So it gets me to thinking — many times, our lives are unbalanced. For example, we may emphasize “truth” over “grace”, or vice versa.

But God is a God of grace and truth.

John 1:12-14 (ESV)

12 But to all who did receive him, who believed in his name, he gave the right to become children of God, 13 who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. 14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.

Christ, the Word (logos), came to dwell among us, and showed us His glory. He showed us grace and truth.

How does this apply? Sometimes, we emphasize God’s rules, and beat ourselves up at our inability to be perfect. We forget God’s grace. (law keeping)

Sometimes, we emphasize God’s grace, and forget that there are rules, and that cause and effect does apply. (antinomianism)

We need to have a balance of these in our lives. When we do, just a like a resonant circuit, matching the final amplifier of a radio to an antenna, we can be most effective in our daily walk with the Lord.