I have measured the 6m sensitivity of my K3 #1198 using a sig gen and two methods of measuring the output signal level of the K3. I measure the noise floor of the K3 (50.015, preamp on, usb, 2.3kHz bandwidth, agc off) at -127.1dBm. Using the calculation provided by Ian GM3SEK (RadCom Oct 1999) I get from this a noise figure of 13.5dB, agreeing with Ian's measurement.
This is disappointing and a lot worse than my current rig, a 19 year old IC575 which measures 5.6dB. I've found that an external preamp with the IC575 to bring the overall NF down to 4dB helps with weak dx. I have also measured the antenna noise here (a rural location) and in some directions it is only 1.8dB above thermal. So there is quite a lot to be gained by reducing the noise figure, and I wonder if Elecraft have any response to this. I'm interested in using the subreceiver on 6m and this would currently require two preamps if I want to use two antennas. Regarding preamps, my measurements suggest that to get an overall system noise figure of 4dB, you need a preamp with NF 3dB and gain 16dB, or NF 2dB and gain 13.7dB. Graham _______________________________________________ Elecraft mailing list Post to: [email protected] 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
