parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (01/01/85)
x Images on Regency MX5000 Scanner Ed Sirovy (IL-004) Chicago Chapter Moderator Radio Communications Monitoring Association The Regency MX5000 with its 750 MHz IF has images after all. Subtract the second harmonic of the transmit fre- quency from 750 and there is the image! The second har- monic itself will be heard only for some high-power FM-TV stations and then weakly if at all .... but take any sta- tion between 100 and 275 MHz double it (200 - 550), sub- tract it from 750 and you get an image at 550 down to 200 MHz. Take a UHF-TV station at 550, double it to 1100 and sub- tract 750. You get 350 but will find no image as the front end does not pass anything above 550. If this were the MX7000 version, passing everything up to 1200 MHz, images would show up all over the place. Maybe this is why we haven't seen the MX7000. The MX5000 schematic one of our members got a hold of showed the extra circuitry for the extened range [rumor is that Regency has given up on the MX7000 due to this very prob- lem, and is going to offer the MX4000 instead, which won't cover beyond 950 MHz - Bob Parnass]. Please note we are not getting a harmonic of the injec- tion frequency, but of the frequency transmitted and received! -- =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414