Why  a  wire-wound  volume
control in the antenna circuit?

Most radio receivers made in the 1920's controlled the volume by attenuating the signal to the grid of the first RF amplifier by means of a variable resistor in the antenna input. This resistor (usually 2 - 3K) was a heavy duty wire-wound rheostat!

I'm sure some of you may wonder why a 4 watt wire wound pot is needed for a volume control. If any of you have attempted to replace this control with a conventional pot of the same value, then you know a typical carbon pot works poorly. Why is that? Well here are my thoughts on this issue:

• Carbon pots were not common in the early days and those that were available did go low enough in resistance to attenuate the signal adequately when dealing with a strong signal.

• The wire-wound pot with it's loop arrangement served also as a variable inductor that was more efficient at attenuating the signals as it tracked well at the low resistances needed on a strong signal.

• Considering that lightening was always an issue when the typical antenna of the day was high in the air and about 100' long. So even a mild static discharge into the antenna would destroy a low power, carbon rheostat.

I've not read anything about this issue, these are my thoughts and I stand to be corrected. If any of you have something to add or wish to disagree, please do so, I will appreciate any input.

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