It's very unlikely any solid-state amplifier uses an input attenuator: Transistors and FET's just don't have that much gain.
Grid-driven tube amplifiers may indeed have enough gain (without the input pad), but there are a couple potential problems. Without the input pad, the amplifier may not be stable and/or its input impedance may not be anywhere near 50 Ohms. If that isn't a problem, spurious outputs may be. Spurious outputs from a QRP transmitter that cause no trouble barefoot might be way above the FCC limits when amplified by 25 dB. 73, Scott K9MA On Dec 20, 2010, at 4:09 PM, DOUGLAS ZWIEBEL wrote: > Almost 30 years ago now, before I was 99.9999% a QRPer, I had an Alpha > 76CA (3 tubes). It had a giant swamping pad on the input (I still > have it - the swamping pad, that is). Just take it out and like > magic, you could drive the amp with QRP. My intention was never to > exceed legal limit, just to be able to use the amp when driven with a > QRP rig. I don't remember how much out I could get with QRP in, but it > was nowhere near 1500 watts. > > I have no clue what they have on the inside of the KPA500, but if > there is a swamping pad, you can probably take it out. What is > Elecraft's motto? Hands-on radio? :-) > > When I used to use a Ten Tec Titan Amp, it required 36 watts of drive > for 1500 watts out on 20m. That was probably 25 years ago. > > Finally, if you want to fly under the radar, there are certain high > quality amplifier manufacturers overseas (closer to W6 than W2...hint > hint) who will custom make you an amp for low power drive. Check the > FT817 Yahoo group archives. > > de Doug KR2Q > had my fill of QRO ages ago > ______________________________________________________________ > Scott Ellington Madison, Wisconsin USA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
