[Alinco] DX-70 low power adjust and ALC

[Albert Woodhull]

I'd like to adjust my DX-70 low power output to 5 watts or less to operate in QRP class in various events. I understand the VR8 pot is supposed to control the low power output, but it seems to have no effect. I thought I would try another approach by using an external circuit with a couple of AA batteries and a pot to apply  0 to -3VDC  to the ALC jack on the back of the rig, but that doesn't seem to affect the power output either. 


This makes me wonder if there might be something wrong with the radio, which otherwise seems to work well -- it is my main rig at home and I've also used it mobile and for Field Day on numerous occasions. 

It looks from the circuit diagram that the external ALC (EALC) line and the output of IC8A (which should be affected by adjusting VR8) should both affect the ALC line. I have downloaded a service manual as a PDF file, but the component labels on the PC board layout pictures are very hard to read, and I haven't been able to get very far with trying to measure voltages.

Does anyone on the list have any experience with this or suggestions on how to trouble shoot the ALC?

73, 
Al, N1AW

Albert S. Woodhull
Amherst, Massachusetts