RM ITALY KL-203 BOARD

[TonyV225]

Anyone ever used one or added one top a radio? What is the actual output on AM and SSB? They say they have 1 X RM-3 transistor. The add claimed up to 200 watts SSB but I know thats not realistic. Will these atleat do 100 watts?

 

[bob85]

tony,
a kl203 has 4x rm3, 10w in gives 100-120w out, anything over 5w in is pushing them into compression

 

[RatsoW8]

I posted this KL-203 relay repair a while ago if you want to see the innards of this cheap little amp. Link below. At best with a max of 1-2 watts you'll see 70 -100watts out. I think the input power is probably in the neighborhood of 200 watts. But, what do ya expect...they can be had new for $54.00. I was going to use it with 10meter radio but need to add some filtering first.

http://www.worldwidedx.com/amplifiers/91765-rm-kl-203-repair.html

 

[bob85]

ratsow8 are you talking about 1-2w AM deadkey swinging up?
we use them on FM & SSB,
the best i have seen is 122w out with 10w input from an icom 703 on either mode @ at 14v,
some people abuse them with 20w ssb and claim 160w out but imho 10w is overdriving them.

 

[TonyV225]

Bob I was thinking about doing a project or 2 with these boards in 10 meter radios thats why I was curious as to if they will atleast do 100 watts or it wouldnt even be worth doing in my opinion.

I guess I would just adjust the radios output until I seen 100 watts out on SSB. Aslong as they sound okay on SSB it would be a nice addition into one or 2 of my radios here.

The next concern would be sheilding to contain stray RF from leaking and bouncing around getting into the audio section.

 

[RatsoW8]

ratsow8 are you talking about 1-2w AM deadkey swinging up?
we use them on FM & SSB,
the best i have seen is 122w out with 10w input from an icom 703 on either mode @ at 14v,
some people abuse them with 20w ssb and claim 160w out but imho 10w is overdriving them.

I was just talking dead key in AM. When I get home I'll experiment with it and post what it will actuall do without frying it. I can drive it with an HTX-100 for SSB. Not sure how clean it sounds on SSB and I'd bet without some additional filtering the output isn't very clean.

And Tony..these things are small enough to mount on top of or under a 10m rig. The entire case on the KL-203 is actually the heatsink so even if you mount one inside a radio you'll have to have a heatsink somewhere to attach the three transistors.

 

[bob85]

unlike the single transistor class C rm amps the kl203 sounds surprisingly ok on ssb, european mosfet amps of old sounded crap on ssb,
the kl203 is not linear and not filtered but it does not sound distorted either

 

[RatsoW8]

This kind of surprised me.

AM
1.5 watt carrier = 40 watts out
1.5 watt carrier modulated to 5.5 watts = 125 watts out

SSB
15 watts in = 150 watts out.

 

[TonyV225]

Thanks for the power info I may buy 1 or 2 of these to play with. 100 watts would be fine but Ill take the 125 - 150 SSB
Now to find heatsinks that fit these boards for the projects.

 

[bob85]

surprised me too the first time i tested one,

good luck tony

 

[TonyV225]

Bob my main concern was if indeed they do 100 watts hows the sound of the audio on SSB I mean 100 watts is useless to me if I cant use it on SSB last thing I need is to get on the radio go to 10 meters keyup and sound like im talking through a peice of cellophane paper LMA:laugh:!!

 

[bob85]

don't expect smoothe warm triode audio tony, the kl203's i have heared/tested sound acceptable at 100w on ssb.

 

[TonyV225]

LMAO!! I understand what your saying Bob and I think you pretty much understand what I was getting at. Acceptable sounding is better than horrible sounding. There no way to get triode sound otherthan to run triode

 

[dd18]

KL203

Don't worry about these little amps. They perform surprisingly well for their size.
Don't be fooled. You can see well over 100w with them on SSB and they still sound OK. On a scope I don't know but they sound OK. They also can go down to 14mhz!!
If you want more power the KL503 is two of these boards in parallel but driven with a single mosfet which effectively limits the input to 5watts or so. What a waste...if they had done away with the driver we would have had a US$125 250-350 w pep amp with a 35 w or so drive. Perfect for a twin final export radio. Heatsinks on the kl203 are very small so additional cooling is required. No need to feed with more than 13.8v.
Just adds to the heat. I don't know how they look to the pros on paper but they work very very well. You won't be disappointed. Best bang for the buck out there for a quick 150w.

 

[9C1Driver]

I think they are talking about the KL-203 Stinger type boards you have to install in/on a radio. I have the red heat sink version of the KL-203 external amplifier and love it. They now have an up-dated version thats blue.