Thank you very much for your comments.
Wayne recognized interesting results when we reported yhe MDS, DR and IP3 comparison figures. We have to appreciate his comment “A few K3 users in extremely high-signal environments might benefit from a few extra dB of dynamic range, at the cost of a mixer add-on module like you described”, this may reply to your question. The K3 is a *high performance radio *and for this is very interesting. We are *amateur radio *and we like to “squize” equipment to see if we can get dome extra functionalities. With a radio like the K3 we cannot expect to have improuvements of tens of dB/dBm, like it is possible with other commercial equipment, following similar mods. As you can see we can still squize out something. We are not doing business, only enjoying radio and we like to share our findings with others Hams. We went into the K3 1st mixer mod because it is really the easiest we can apply to a radio…real swap with no soldering iron. http://elecraft.365791.n2.nabble.com/file/n6891521/hmodemixerelecraft.jpg We tried to measure spuries as suggested by Wayne but we were not sure about differences. We decided to do other tests that may help to understand if the improuvements are beneficial or not. Please see the second table figures. The improuvements are not only instrumental but also detectable by ears. The nearly 6dB in noise drop at the loudspeaker is something valuable and can be felt. K3 ORIGINAL MIXER AND 2T H-MODE MIXER COMPARISON TABLE 1 Measurements RF in 14.220 MHz Original K3 Mixer originale 2T H-Mode Mixer FSA3157 MDS (Sensibilita’) -126dBm -128dBm * Dynamic Range 2T 98dB 101dB 3rd Order Intercept IP3 +21.0dBm +23.5dBm (*Audio Noise at output dropped <6dB) TABLE 2 Frequency RF in 14.220MHz Original K3 Mixer originale 2T H-Mode Mixer FSA3157 RF in -40dBm -40dBm IF out 8.215 MHz -44.5dBm -44dBm 30MHz noise level line -80dBm -83dBm RF feedthrough/leakage -72.0dBm Into the noise level LO feedthrough/leakage 22.415MHz -49.0dBm -62.8dBm RF+LO 36.615MHz -57.0dBm -69.0dBm 2xLO 44.830MHz feedthrough/leakage -54.0dBm -63.6dBm 53.045MHz feedthrough/leakage -62.0dBm Into the noise level (The 2T H-Mode Mixer has a diplexer termination) What else?....This is the spirit of amateur radio and nothing more Saluti (73) Sergio, IK8TNG -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-H-Mode-Mixer-tp6889343p6891521.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
