I haven't been able to find much on-line about the "new" KL-503 from RM Italy so I thought I'd share my first impressions... Just finally got a chance to put it in my truck last night and played with it a bit today... I'm using a Galaxy 949 from Sparky's and a Wilson 2000 antenna.
I checked my "sparked" 949 and with the RF output at the minimum it's putting out 1W deadkey on AM and around 10W PEP on SSB... (Measured with a Radio Shack power meter, so take those readings for what they're worth

Using the same RS power meter, here's what I'm getting for output: (approximate readings of course! - The scale on the meter makes you guess a bit...)
Power Level 1: 10W DK on AM and 100W PEP on SSB
Power Level 2: 20W DK on AM and 200W PEP on SSB
Power Level 3: 25W DK on AM and 225W PEP on SSB
Power Level 4: 50W DK on AM and 250W PEP on SSB
Power Level 5: 60W DK on AM and 300W PEP on SSB
Power Level 6: 120W DK on AM and 350W PEP on SSB
The specs for the amp show up to 650W PEP, but I'm not so sure about that...

I don't have a frequency generator so to get the readings on SSB, I just gave it a whistle... On AM, I got numerous "loud and clear" reports, but couldn't find any SSB action to try to jump into to get some feedback...
It is small enough to have it mounted right on top of my radio, which itself is on a hump mount in my truck with an external speaker... I didn't use it that much yet, so I can't comment on heat levels
So far it seems like a pretty nice amp for less than $130... I'm really curious to see how clean it is on SSB though... I'm in NW PA (Erie)... Anyone else on this board around me to give me a radio check????

-JWR1221