Wire Noise

There has been a lot of noise made by some regarding "wire noise" because of strand jumping, surface contaminents, plating, etc.

Well, lets look to another engineering discipline for an answer.

We're going to look at rf(radio frequency), specifically, commercial rf repeaters. These are units that receive and transmit at the same time, on a common antenna, in order to increase 2-way communication range of land-mobile radios. These are licensed for transmitter power outputs up to 350 watts. At the same time the receiver must be able to hear signals as low as 0.5uV(microvolts), or less in some models.

Converting to a common format makes the transmitter power output +55dBm and the receiver sensitivity -113dBm, which equates to a differential of 168dB. So if wire creates noise, it's further down than 168dB from the generated signal(i.e. - the transmitter at 350watts), otherwise the noise created would mask the receive signal in the repeater. Remember, noise is a broadband signal. I would say that qualifies as inaudible.

This holds true for solid, stranded, tin plated, and silver plated type wire construction in coaxial feedline.

Calculations

To convert from microvolts(uV) to dBm at 50 ohms:

20*log(0.0005/223.6)= -113dBm, where 0.0005 is 0.5uV

At 50 ohms, there is 223.6mV of signal for 1mW. (P=V^2/R)

To convert from watts to dBm:

10*log(350/0.001) = +55.44dBm, where 0.001 is one milliwatt.