SWR problem with Linear on

[Gregmiddo]

Strange one for some guru to give insight..
Antenna is 1:1 SWR without amp inline, between 26.5 and 28 mhz (approximately)
Tested with low and high power from AT-6666 radio (5 watts to 60 watts)
Now, if I connect the amp, a Palomar Eliteline TX-5500, SWR is still good on High and Max settings.... however, on Low and Medium the SWR is off the scale, around 9:1.
Where do I start looking?? The 4 position switch? And what can cause this?
I could understand if the higher settings were giving the problem, but confused how the lower power settings kill the SWR. Any suggestions appreciated.

[MDYoungblood]

Where is the SWR positioned? Between the radio and amp or between the amp and antenna?
I am not positive about your amp some but amps attenuate input power to reduce output where others reduce voltage to the transistors. I would have to dig up a schematic for it to make sure?
3’s

Greg

[Gregmiddo]

SWR meter is between amp and antenna.
I have since taken the cover off the amp... 2 fried resistors on the rotary switch.. looked like a simple fix.. Well, replaced both faulty resistors, and SWR went way high on all amp power settings.
Hmmm... cut those resistors back out of the circuit, and back to having High and Max power setting working OK.
CCT Diagram attached if that helps..
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By the way, it looks like the CCT Diagram for the TX5500 shows LOW and MAX in the opposite position to what they should be

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