The P3 should operate normally down to 8V or les.  I have successfully powered it from a 9V battery.

Alan N1AL


On 9/1/2024 2:55 PM, Corky wrote:
I was having trouble with my P3 going into brownout mode when transmitting 50 
Watt digital. This used to be fine, but seems to have been getting worse over 
the past several months. When I monitored the power on the front panel of the 
K3 I found it was dropping about 1.5 V when transmitting digital signals. This 
would occasionally drop below 12 V and cause the P3 to go to brownout and shut 
down.

I immediately assumed this was a problem with my distribution system and/or DC 
power cables, however, on further examination, that does not appear to be the 
case. The voltage at the distribution system shows no change in voltage when 
transmitting. I tried replacing the power cables from the distributions system 
and using alternate terminals with essentially no change in the behavior.

Next I cleaned the terminals on the radio with de-oxit, and moved to AWG 10 
wire for the power connection (I had been using AWG 14). I also shortened the 
power cable to 3 ft and used a separate power supply so that the radio is 
connected directly to the power supply. This improved the situation a bit, but 
the voltage still drops 0.6 to 0.9 V on TX (digital or key down CW).

While I am now in the range that I no longer get P3 brownouts, this still seems 
excessive. At this point, it appears that the problem is somewhere at the K3 
power connector or somewhere inside the radio. Has anyone else experienced this 
and if so are there any suggested resolutions or things to test. I know, 
especially since I am now using a separate supply I can increase the supply 
voltage to address the problem, but there is still a lot of heat/energy being 
wasted somewhere.

Thanks and 73,
-Corky, AF4PM
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