ICOM IC-746 Low Power Output

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WD4HMA:
 I have a new IC-746 with low power output.  It consistently produces between 65 and 75 watts out on all bands.  ICOM checkup says everything is ok.  Anyone know how to improve/correct this?

Nelson Derks:
Two possibilities come to mind:

You may have a sneaky SWR problem (like water in the coax or an oxidized connector) that's causing the SWR power foldback circuit to kick in at full power...

Or

Your power supply may not be up to the task. Even if the power supply is rated well above the needs of the radio, sometimes manufacturers fudge the numbers a bit by rating intermittent current peak rather than steady duty draw. Modes like FM, AM and RTTY all draw a steady current.

Even if the power supply is supposed to be adequate, a weak electrolytic can cause the supply voltage to drop at full load. Your supply may be capable of holding 13.8 volts at reduced power, but drop down to 12 volts or less on peaks.

And, a few years ago I was putting up an antenna and noticed a hole in the sheath of my brand new, name brand coax coming straight off the reel. Looked like a tiny football and was likely caused by an air bubble. It caught my eye when I saw a flash of copper in the sunlight.

Since that time I've gotten in the habit of eyeballing coax very carefully. It's the small stuff that gets ya'! (Hi)

LA1SJA:
The most likely cause is that your power supply drops it's output voltage when you try run 100 watts out.
The best indicator is that you have the same problem on all bands.
I have a 746, and from memory, when you get 50 watts out you are down to around 11 volts.

WD4HMA:
  The problem is not in the power supply or the load.  With a 30 amp load on the PS, the voltage is 13.7 volts.  The rig performs this way into different dummy loads (plural!), as well as an antenna.  Will not drive amplifiers to full power either.  Tried the same rig at a different ham's qth, same results.  I think the power output setting is low, but cannot find out where it is set, either in hardware or software.  

David Henn:
Hello,,

You might want to check out

http://www.vartel.com/icom746/icom746index.html

There are lots of threads on low output.

Rgds
David
ex G8LIY, DD5CK

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