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While I agree with most of FreeCell's comments we are talking about two different conditions. Extreme harmonics can cause the watt meter to exaggerate forward and reflected readings. When the SWR goes from 1.1:1 bafefoot to 2:1 when you turn a solid state amp on, most of the time that's oscillation. In this case turning the drive up often lowers the SWR because the fundamental frequency drowns out the oscillation.

Changing coax lengths can appear to fix SWR problems in the oscillating amplifier for the reasons I described in the above post relating to any slight change effecting the operating characteristics of an unstable amp. The second way coax length effects SWR in the absence of an oscillation is due to a mismatch between the coax and the antenna.

This creates standing waves on the coax. Depending on the length of the coax you can find a spot where the standing waves on the coax will represent a 50 ohm match to the meter. Due to the phase of the current and voltage on the line. This does not compensate for the lost power in the mismatch between antenna and 50 ohm coax.

<blockquote data-quote="Shockwave" data-source="post: 198419" data-attributes="member: 10882">While I agree with most of FreeCell&#039;s comments we are talking about two different conditions. Extreme harmonics can cause the watt meter to exaggerate forward and reflected readings. When the SWR goes from 1.1:1 bafefoot to 2:1 when you turn a solid state amp on, most of the time that&#039;s oscillation. In this case turning the drive up often lowers the SWR because the fundamental frequency drowns out the oscillation.Changing coax lengths can appear to fix SWR problems in the oscillating amplifier for the reasons I described in the above post relating to any slight change effecting the operating characteristics of an unstable amp. The second way coax length effects SWR in the absence of an oscillation is due to a mismatch between the coax and the antenna.This creates standing waves on the coax. Depending on the length of the coax you can find a spot where the standing waves on the coax will represent a 50 ohm match to the meter. Due to the phase of the current and voltage on the line. This does not compensate for the lost power in the mismatch between antenna and 50 ohm coax.</blockquote>

[QUOTE="Shockwave, post: 198419, member: 10882"] While I agree with most of FreeCell's comments we are talking about two different conditions. Extreme harmonics can cause the watt meter to exaggerate forward and reflected readings. When the SWR goes from 1.1:1 bafefoot to 2:1 when you turn a solid state amp on, most of the time that's oscillation. In this case turning the drive up often lowers the SWR because the fundamental frequency drowns out the oscillation. Changing coax lengths can appear to fix SWR problems in the oscillating amplifier for the reasons I described in the above post relating to any slight change effecting the operating characteristics of an unstable amp. The second way coax length effects SWR in the absence of an oscillation is due to a mismatch between the coax and the antenna. This creates standing waves on the coax. Depending on the length of the coax you can find a spot where the standing waves on the coax will represent a 50 ohm match to the meter. Due to the phase of the current and voltage on the line. This does not compensate for the lost power in the mismatch between antenna and 50 ohm coax. [/QUOTE]

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