VHF interference

[chilli]

A friend recently contacted me to help him trouble shoot some interference problems that he has recently encountered with his VHF. The radio was working fine prior to a combo gps/sonar install. After which the VHF would experience static interuptions every three seconds or so. The combo unit is installed in close proximity to both the radio and antena. I recall hearing about fishfinders interupting an interanal VHF frequency but can not recall any of the specifics. I would appreciate any insight you all may have.

Specifics: Combo Unit: Sitex Profish II
VHF Radio: Uniden Solaris
Antena: Sheakspear Whip, Base Loaded

The combo unit and the antenna currently reside about 18" from each other on the top of a console. The radio is mounted inside the console about 18" below both the antenna and combo unit.

I suspect that the close proximity of the systems is causing the interference.

[Overcurrent]

I have a similar problem with an Icom M59 and Garmin 188 Sounder - particularly on channels 13 and 83A. I'm going to try to reroute the tranducer cable as far away as I can from the VHF coax/antenna and see what happens. Right now the two run in the same cable bundle for about 6'

If I turn off just the sounder portion of the Garmin or disconnect the antenna cable from the Icom, the noise goes away. That leads me to believe it is a radiated noise from the transducer cable being received on the VHF antenna cable.

[HOTSPOT]

Be sure everything is grounded very well. Also be sure the connector on the end of the coax has a good connection.