[1000mp] RE: FT1000MP PA Issue

[David Robinson]

> I was asked by a couple of people to post the resolution of this issue, if
> I found it!
> Probing around the PA module with a power meter, I determined  the problem
> to be one of the predriver transistor pair in the PA module was "leaky".
> It was a 2SC3133 (yaesu part # g3090086) at a cost of around $11.
> Replacing the transistor  restored the power to normality, 120W on all
> bands. 
> Dave
> G4FRE, WW2R
> Ft1000MP PA Issue
> Mon, 3 May 2004 18:13:30 -0400 
> Returning from the 3B9C trip I switched on my FT1000MP to find the PA
> behaving strangely. The power rolls off severely with frequency 
> On 160m the PA runs 22A and produces 140W 
> On 40m the PA runs 20A and produces 110W 
> On 20m the PA runs 8A and produces 45W 
> On 15m the PA runs 5A and produces 20W 
> 0n 10m PA runs 7A anp produces 40W 
> The powers were measured at the output of the PA board 
> I have measured the drive to the PA module and it is flat within +-1dB.
> The bias voltages on the transistors seem correct, suggesting its not a
> transistor problem
> Has anyone else encountered and fixed this problem? 
> Dave WW2R, G4FRE 
> WEB: http://users3.ev1.net/~g4fre/ww2r.htm
> <http://users3.ev1.net/~g4fre/ww2r.htm>  
>