SWR Jumps With Amp In-line Even If Turned Off

[bgosper]

When I put my old tube base amp in line, the SWR jumps way up. This is even with it off. Any ideas what to check? Could it be a bad connection or component in the amp?
Thanks,

 

[W5LZ]

There are two 'paths' through an amplifier, one is a 'by-pass' around the amplifier when it's off, the other is through the amplifier when it's on. These two paths are typically controled by a relay switching between them. That relay is a very common place for changes in SWR to be caused. The usual 'cure' is to clean the contacts of that relay, or just replace the thing.
You do want to check to see that the by-pass line isn't 'boogered up' in some way. From there it can get complicated.
- 'Doc

 

[Moleculo]

There are two 'paths' through an amplifier, one is a 'by-pass' around the amplifier when it's off, the other is through the amplifier when it's on. These two paths are typically controled by a relay switching between them. That relay is a very common place for changes in SWR to be caused. The usual 'cure' is to clean the contacts of that relay, or just replace the thing.
You do want to check to see that the by-pass line isn't 'boogered up' in some way. From there it can get complicated.
- 'Doc

The relay and also the obvious things - the SO-239's. Especially make sure the one going to the antenna isn't torched.

 

[bgosper]

To clarify, the high SWR is at the radio side, not the antenna side.

 

[mackmobile43]

To clarify, the high SWR is at the radio side, not the antenna side.

That is where all SWR is indicated, check the relay and so-239 in the amp as suggest.

 

[bgosper]

Thanks, I will try checking all these contacts and connectors. Appreciate the help!