Alinco: Final Transistor biasing Alinco DX-SR8T

[kd2goe]

I have 2 bad final output transistors in an Alinco DX-SR8T I ordered 2 new RD100HHF1C
I'm reading up on how to bias this MOSFETS and I'm a bit confused on where to get the current reading on the final's? do I just take it from the overall current the radio is taking from the power supply? so lets say the radio is drawing .9 amps I just bring it up to 1.7amps?

on page 38.
http://dw.hampedia.net:8090/downloads/alinco/hampedia.net.dx-sr8t_Service_manual.pdf

 

[prcguy]

There is usually a jumper you remove so you are only measuring PA transistor current. That's probably the point they say to attach a current meter at CP808 and CP806. That could also be a very low value resistor like 0.1 ohm that you calculate the voltage drop across or actual current divided by 10 or 100 or ?

You might get in the ball park turning the bias to zero, measure total current on transmit then adjust bias up by the amount of the recommended bias, but usually the instructions would point out that method.

 

[kd2goe]

There is usually a jumper you remove so you are only measuring PA transistor current. That's probably the point they say to attach a current meter at CP808 and CP806. That could also be a very low value resistor like 0.1 ohm that you calculate the voltage drop across or actual current divided by 10 or 100 or ?

You might get in the ball park turning the bias to zero, measure total current on transmit then adjust bias up by the amount of the recommended bias, but usually the instructions would point out that method.

Yeah there is no jumper I can find..

I got the new Fets in ill have to wait till my thermal compound gets in all I have right now is "Super Lube Silicone Heat compound" i ordered "Arctic Silver Céramique 2" i use it on my CPU's so it shod be good for this.

 

[kd2goe]