kl 203 linear amplifier

[jim tylee]

Hi,
Wonder if anyone else is using the 203 amplifier ???? mod done with 500 pf
cap in place of C14 works fine on 60 meters/40 meters/20 meters......
not tried on 18 megs yet.....need bandpass filters......puts out 130 to 150 watts ssb with only a few watts of drive.
Jim G4REK

 

[RatsoW8]

Hi,
Wonder if anyone else is using the 203 amplifier ???? mod done with 500 pf
cap in place of C14 works fine on 60 meters/40 meters/20 meters......
not tried on 18 megs yet.....need bandpass filters......puts out 130 to 150 watts ssb with only a few watts of drive.
Jim G4REK

Jim,

That amp was not designed for use on the amateur radio bands. It's not going to transmit a clean signal without a lot of added filtering. Your better off saving a few dollars for any flavor Ameritron 811 or other well made amp. Someone on eHam had a post about running the kl-203 at between 70 and 85 watts pep out on 10 meters saying the signal was probably clean enough to be used there. You definitely don't want to drive it t full output on 10.

I even stopped using my 203 on 10 meters altogether. The stock output on my HTX-100 is plenty for 10 and I don't worry about polluting the band with harmonics.

Ron
WD8T

 

[jim tylee]

203 AMP

Hi,
I have a Yaesu 2100b linear that i sometimes use......
the 203 amp is okay with bandpass filters on each band and some bias for ssb use its a nice project to work on and cheap.....of course there are many alternatives to play with........
Jim G4REK

 

[Captain Kilowatt]

Jim,

That amp was not designed for use on the amateur radio bands. It's not going to transmit a clean signal without a lot of added filtering. Your better off saving a few dollars for any flavor Ameritron 811 or other well made amp. Someone on eHam had a post about running the kl-203 at between 70 and 85 watts pep out on 10 meters saying the signal was probably clean enough to be used there. You definitely don't want to drive it t full output on 10.

I even stopped using my 203 on 10 meters altogether. The stock output on my HTX-100 is plenty for 10 and I don't worry about polluting the band with harmonics.

Ron
WD8T

That was Tom (Charles) Rauch, W8JI. Tom designed almost all of the amplifiers for Ameritron so he should know his stuff.

 

[MudDuck442]

Ron, I have to ask... how does one "pollute the band with harmonics". A harmonic would be a multiple of the fundamental frequency, so therefore it wouldn't be polluting "the band" with harmonics. Ok, I'll admit I was being a bit picky, but you get the idea.

Ok, now, you can do through all of the trouble of bandpass filters, but the real problem with this amp is going to be IMD, not really harmonics or out of band junk, really. Just keep things reasonable.

Change C14 to about 580pf, 500 is a little low, sometimes I need to use as much as 680pf silver mica. Also doing a little fine tuning on the input section as well yields pretty good results. As long as you don't expect it to put out a whole lot, they work great modified for use on small QRP rigs.

 

[9C1Driver]

RM makes many different HF amplifiers, why not buy the model better equipped to cover your needs?