sx-100, fm broadcast interference on 10 meters

[w7fox]

Hopefully someone has solved this problem before.  On 10 meters, the sx-100 HFO is around 31 Mc and the third harmonic is mixing with strong local FM boadcast stations causing tunable noise that appears up and down the ten meter band.  The noise is "raunchy" but can be identified as a local fm station.  This problem popped up while hooking up push to talk with a Viking 1.  The FM signal was coming in the mute wire because pulling the accessory plug stopped the noise.  With the receiver out of the case, the noise is there all the time, so the case must be shielding it out.  Thanks for reading this.

73,
Chris

[KA0HCP]

how about putting a choke on the line?

[ke7trp]

An FM broadcast band filter on the antenna lead will likely cure the problem

C

[w7fox]

Thank for the tips.  The antenna was the first place I looked, but the fm isn't coming in the antenna, it doesn't matter if is on, off or shorted.  The tuned circuits in the first rf amp are doing their job.  Its getting into the mixer some other way, maybe from other wiring, like the sensitivity control that goes to the accessory socket.