On Sat, 2004-10-09 at 13:09 -0700, Kurt Cramer wrote: > This sounds like an image. The IF is 4.915 MHz and I think the VCO will > be 1.9 above the IF, or 6.815 MHz to receive 1.9. The image would be > 11.73 MHz. Am I right? If I am then, I don't know why the bandpass > filters are not putting them way down. But if the signal injection is > not coming from the antenna.....?
Yes the image reception is of the 11.7 Mhz broadcast band (25m band) and it's only those 'monster' signals that manage to get in. In the Early evening I see signals as big as -10dBm here on the 25 M band so it probably takes the combined efforts of the bandpass filters and the TX low pass filters to tame signals that large.. if it was just getting in via the RX antenna socket I would put a Low pass filter in line with my RX antenna but merely activating the RX antenna seems to allow the ingress to occur even when no rx antenna is connected. The RX antenna circuit bypasses the output low pass filters when activated so I guess that's the route in. Modding the K2 to connect the RX antenna after the LP filters looks like it isn't a practical option but I wonder if a trap for the 25mb broadcast band can be engineered (hacked!) into the K2 before the band pass filters to give some more rejection? 73 Brendan EI6IZ -- Brendan EI6IZ <[EMAIL PROTECTED]> _______________________________________________ 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
