[TowerTalk] SB-220 affecting SWR curves

[Chuck Dietz]

Pete Smith wrote:

> I have an SB-220.  This morning, I measured the SWR curves of my Force 12
> C-3 through the SB-220 (with the amp off) and then with a barrel connector
> replacing the amp.  To my surprise, there was a huge difference! 

If you have some SWR on your feedline from a mismatch between the
antenna and line, it will change when you vary the line length.  Try
adding a couple of feet of line in place of the amp to verify this.

If you have some resistance in the amp internal line, probably due to
dirty or pitted relay contacts, there would be DC resistance from the
input center conductor to the output center conductor.

The problem is probably due to the first circumstance.

Chuck, KE5FI

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