Stereo depth finder noise

So for a few years I've been getting a popping sound in my tower speakers and sub (the components powered by amps). It is def the depth sounder and that was confirmed as when I unplugged the depth gauge the noise went away.

I found that the noise was actually radiating into the RCA cables running from my HSE volume control unit to the amps. I thought that the stereo or HSE unit was causing the noise, but NO, the noise is actually directly going into the RCA cables from the depth finder. This was determined because I put a fresh set of RCA cables into the input on the amps and there was no noise UNTIL I got the cables close to the depth finder gauge. As I slowly moved the unconnected end of the RCA cables toward the depth finder gauge the popping noise got louder and louder.

So it appears if I have the RCA cables within a couple foot radius of the depth finder gauge the pulses from it will radiate directly into the RCA cable that is supplying the amp. I'd prefer not to have to move my HSE unit and probably can't move my head unit. Any suggestions to shield my RCA cables from this depth finder noise, or something else I am not thinking of. I realize the head unit and HSE are not powered and grounded from the same spot as the amps, but that is not the problem here.

TIA for any advice!