I recently had a similar problem with one of my TS570's.

The problem turned out to be an apparently dirty connection between 
the power cable and my Astron 35, which caused a voltage drop at the 
radio end of the cable.

Cleaning both the power supply terminal bolts, and the ring lugs on 
the power cable solved the problem.

The output went from 70 watts to 98 as measured by the TW1.

Someone with a multi meter can confirm the voltage as it appears on 
the terminal bolts. The voltage can also be checked on the radio end 
of the cable, where it is normal to see a slight drop, but not the 3/4 
of a volt drop that I was seeing before cleaning and tightening all 
the connections.

Of course, shortly after going through all those gyrations, that newly 
cleaned power supply was the one that took the lightning hit about 2 
months ago.


Mike Duke, K5XU
American Council of Blind Radio Amateurs