Carl Blare

Following our discussion about “bad language” on certain programs, KDX activated a low low power transmitter on 1550kHz to allow shutting down our full-low-power transmitter at 1680 during periods of bad language. But the 1550 transmitter puts whistles at 1530 and 1570kHz.

Awhile back this situation was discussed here on this site, and the problem was found to be from our FM studio-to-transmitter link. Evidently a 19kHz stereo-pilot tone is appearing on the audio lines from the Technics FM tuner to the ssTran3000 transmitter. Removing jumper S6, treble boost, in the transmitter, does not prevent the whistle.

This whistle was first observed using a C.Crane FM transmitter to send our signal to the AM equipment location, and of course the stereo generator cannot be switched off in the Crane. So we installed a Wholehouse 2.0 which does allow turning off the stereo, but it would appear that it does not cancel the pilot-tone signal at 19kHz.

We’ll probably need to build a low-pass filter that chops the 19kHz by perhaps 20dB, but I bring the problem to the table for any ideas you might have for stopping the whistle.