*Hi Wayne, Thanks very much for the prompt comments, very much appreciated. I have discussed your points with Gian, I7SWX.* Hi Sergio,
Thanks for reporting these interesting results. 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 is one of the reasons why we tried the mod and also to see how much a good K3 could be improved, we are homebrewers… hi* However, I'd be concerned about the possibility of additional mixer spurs. Switching mixers put out a large number of VHF/UHF spurs that can mix with harmonics of other signal sources (primarily the VFO) to produce HF-6 meter spurs. This is an inherent issue with high-level superhet receiver designs. Our first mixer design trades about 1 dB of dynamic range and conversion loss for excellent rejection of mixer products above 60 MHz by integrating a balanced low-pass filter into the commutating path. Without this, there would be a "picket fence" of additional VHF/UHF products and thus many more spurs. *This is a very interesting note. We have not thought about VHF-UHF additional products and spurs. The H-Mode Mixer has the mixing function done by the transformers and the FST/FSA Switches are not involved in the signal path. The 2T H-MM has an RF-LO isolation of >50dB, average 60/70dB, while the RF-IF isolation is >60dB. We believe that the Band Pass Filters in the K3 are good enough to attenuate strong signals outside their bandwidth. * Please let me know if you do a comparison test of the two mixers in this regard. The best way to do it is to slowly sweep through each ham band in CW mode using a narrow crystal filter. *We will see to manage some comparison with the two mixers. we have to see about the filter. For some infos on the 2T H-Mode Mixer you may visit http://martein.home.xs4all.nl/pa3ake/hmode/2t-hmode.html but probably you do know the site. Thanks again for the comments. Best 73 Sergio, IK8TNG* 73, Wayne N6KR -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-test-w-o-w-I7SWX-2T-FSA3157-H-Mode-Mixer-tp6812860p6815176.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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
