On Feb 13, 2015, at 11:58 AM, "'Joe Subich, W4TV' [email protected] [Elecraft_K3]" <[email protected]> wrote:
> > Wayne, > > >> A: With preamp OFF, we measured about -125 dBm at 475 kHz and -90 > >> dBm at 250 kHz. We have not measured MDS below 250 kHz, but the > >> receiver will gradually become less sensitive as you go lower in > >> frequency due to band-pass filter rolloff (in the KBPF3, which is > >> required for operation below 160 meters). > > Would it make sense to update the KBPF3 to replace (or convert) the > 0.5 - 2 MHz BPF to a 2 MHz LPF? Perhaps by removing L1/L2, changing > L4/L5 to 2.0 uH, removing C6 and connecting a new inductor (~10 uH) > between pins 2/7 of K2? This is certainly not necessary for use of the 600-meter band, or even for listening to beacons in the 300-kHz range, which I've been doing lately. If you were really determined to improve MDS below 250 kHz, you could do this. I would start thinking about the lower-frequency limitations of the PIN diodes with large signals. 73, Wayne N6KR ______________________________________________________________ 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 Message delivered to [email protected]
