Texas Star DX-350HDV Why?

[Mudfoot]

I picked up another DX-350. It has DEI's. When I hook up any CB or Export radio, It has high SWR on channels 1-18, like real high. All the other channels, it's flat. I'm driving around a watt or so, into a Gainmaster. My analyzer shows flatness. My other 350 with Toshiba's, behaves normally. Is this a DEI thing? Oscillations?

 

[9C1Driver]

I would say cheap build quality, they didn't spend much time on the 50 ohm match.

 

[Mudfoot]

Shame, all my RM amps work fine, too.

 

[543_Dallas]

If you don't have a scope check for parasitic oscillation with a pep watt meter. Turn the mic gain all the way down and switch between avg and pep. The power readings should be the same. If you get a higher reading in pep mode oscillation is most likely why.

 

[Mudfoot]

Yes, it does.

 

[Shockwave]

How do the two 10uh chokes look? I remember one of them had bias through it and RF across it. Poor design used to get away without having to install a 3 pole relay. To make a long story short, if the amp was ever over driven, this choke will char and lose the ability to isolate RF. That makes them very prone to self oscillation once the choke is over heated.