Time to check the Factory High Power settings on AM, advertised to be a 10W carrier:

The Meter Agrees

And the High Power Carrier:

Next we shove 1kHz @ 100mV of Sine wave down its Microphone Jack and see how it likes it:

Not Bad at all, but it can use a bit of help, so here we go:
Under the lid of the Apollo II there are a total of 7, yes, 7 adjustments you or your local “Golden Screwdriver” Award winning Radio Technician can use to make your new radio sound like total ass on the air.

Please make sure he has a sharp crayon to write these down:
W1 – AM/FM High Power Carrier Set
W2 – AM/FM Low Power Carrier Set
W4 – AM High Power Modulation Set
W5 – FM Deviation Set
W6 – AM Low Power Modulation Set
(The Jury is still out on what W3 and W7 do, but I’f I figure that out, I’ll update this list)
First Up, Low Power Adjustment:
I plan on adjusting the Low power setting low enough to cleanly drive the KL-203 Amplifier, and the general rule for these is 1-2 Watts input.
So I Keyed up the radio and adjust W2 until the Meter shows 1.75W

The O’scope was adjusted for the standard Carrier in 2 divisions on the screen:

Next input the 1kHz@100mV at the mic jack and adjust W6 until you are showing 100% modulation (for the mouth breathers, Crayon eating, Whack Pack Installing “Radio Technicians”, that means the signal is 4 divisions on the O’Scope and there is NO FLAT LINE IN THE CENTER OF THE SCREEN)

See This? Proper modulation… Round Positive Peak on the tops, Round Negative peaks in the center… Sounds Good, Lasts long time…
Now for the High Power AM Modulation Adjustment, that is W4
Same 1kHz@100mV into the Mic Jack

Nice, Round Peaks…
Can you See the Roundness and no Flatness, no Squares….?
THAT IS WHAT YOU ARE LOOKING FOR ON AM
Say it with me:
FLAT LINES ARE BAD
SQUARES ARE BAD
JUST SAY NO TO BOXCARS
Therapy Time is over, get off my couch and back to the task at hand…
Say Hello to my little friend… RM Italy KL-203P

The RM-Italy amplifier line get a lot of bad press, mainly by people that don’t take the time to set up their radio to drive the amplifier in its “Happy Space”.
The Power Specs are listed as:
Input Power (AM/FM Carrier): 0.5 – 10 W
Input Power SSB (PEP Watts for the AM Meter Junkies): 2 – 20W
Output Power (AM/FM Carrier): 100W Max
Output Power SSB (or Modulated AM/PEP): 200W Max
If you are the type of guy that thinks you can shove the Max Carrier and PEP limits into this little amp and expect it to survive, You probably should be reading my BLOG..
The General Thoughts on this amp is that the are happy with a 1.5 – 2W Carrier input from the radio, and if you setup your radio correctly with 100% Positive/Negative Peak Modulation, you will be well within the Output PEP limitations of the amplifier and run clean.
First thing I did was to check the Input SWR of the KL-203P using the SWR Meter on the Apollo II (It agrees with my SWR Meter, so it is close enough)

Looks like just an RCH over 1.1.. Nice.
That being said, I set the Apollo II up for a 1.75W Carrier on the AM LOW power Setting, turned the KL-203P on and checked the Carrier Power Output (Aiming for a 20W carrier out of the amplifier)

Just like that.
Then I checked the Carrier on the O’Scope and set it up to show 1 division above and below the 0 Voltage line:

Then I threw the modulation to it to check the Modulation Envelope:

Looking pretty Healthy. Round on the Positive Peak, Round on the Negative Peak.
Can I get more out of it? Probably, and I may experiment a bit more, as long as the amplifier runs clean and doesn’t got into saturation.
Before I do that, I need to attach a cooling fan to the heat sink, as this sucker gets warm quick.
I picked up an 80mm 12VDC cooling fan, and wired the power leads into the amplifier on the power switch. That way when the amp turns on, so does the fan.

The next thing to do is to figure out how to attach the fan to the heatsink…
More to come
BTW.. The FM on this radio has really nice, full audio. I used my Stryker SR-655HP as a receiver with an External Stereo speaker hooked up… Man that FM sounds killer!
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