There were some mods that changed the gain distribution within the K2 RF and audio paths that some suggested could increase the IMD. I suspect that's where the comments about not doing them on a KPA100 came from, although it's hard to see how an S-9 signal running 5 watts is any less sensitive to IMD issues than an S-9 signal running 100 watts <G>.
One change you can make that only increases the input from the mic and doesn't affect the gain distribution within the K2 is to increase the value of R14 on the KSB2 module. The "stock" value is 1K. Raising it to 5K or more has helped a lot of rigs make full output from an existing mic without extra help. Since it's at the microphone input it has the same effect as using a slightly "hotter" microphone. Don mentioned a mic that should work. In general it seems that dynamic mics are more likely to have marginal output for driving the K2 to full output. I originally used a dynamic mic on my K2/100 and switched to an electret element that had considerably more output. The bargraph on the K2 is will show you the peak output. Since the RF output on SSB is a function of audio and RF levels, and the RF gain in the transmitter is lowest on 10 meters, that's a good band to check if you want to be sure you have full output on all bands with a given mic. Be sure to set the compression level to where you want it before checking. Higher compression levels require a little more audio from the mic. On voice peaks the last bar on the bargraph should just flicker at times in RF mode. A better way is to switch to ALC mode on the bargraph. The bargraph reads backwards in ALC mode to remind you that you're not in RF mode. If the right-most bar flickers on voice peaks running 100 watts, you are getting all the output you can use. The flickering bar indicates that the K2 is turning down the gain to hold the RF level to 100 watts. As you reduce the power level below 100 watts, you'll see more bars light up on peaks, indicating that the ALC is turning the gain down more and more to hold the output to the requested power. As long as one bar flickers, more audio gain won't make your signal any louder. About the level changing after the first syllable, you'll see the same thing on CW mode too sending the first dit or dah. That's a function of how the power control works. The POWER knob sets a requested power level. When you transmit the K2 senses the actual output power and the ALC circuit then adjusts the RF gain in the transmitter to provide the requested power. It may take a moment for this to happen, so you'll often see a higher or lower power on the first syllable (or code element in CW) until the ALC circuit has time to react. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
