|
|
|
|
|
|
|
SUBJECT: # 13249: Sounder interference with VHF
Submitted by Rich A (169.200.25.140) from NORTH CAROLINA on 12/28/1999 10:44:00 AM
I have a 4 year old humminbird wide vision depth sounder. When the machine is on and a vhf is also on, the vhf will pick up the sounder. Here is the catch. Not only will my fixed mount radio pick up the sounder, but my handheld will also pick it up as well as any other radio within 100 feet. I called humminbird and they said to send it back because there was a problem with the unit, but because it is 4 years old and way out of warranty it may be more cost effective to just bite the bullet and buy a good color scope. Any suggestions on how I can fix this on my own. As always any information is greatly appreciated.
- 12/29/1999 9:26:00 AM
Submitted by
ed (204.151.168.2) from NEW YORK says RFI interference
There are a few things you can try , but it really depends on where the RFI bleed-thru is originating. An old trick is to use an AM radio tuned off the scale. use as a scanner, wave it around and listen for the interference to be picked up by the radio, will probably make a whining or screaching noise. First give it its own power wire , and put a small 1mF filter on it (radio shack).check the ground wire, make sure its healthy. Check the transducer cable.Try and isolate the transducer cable from any other wires, or give it as much clearance from all other wires as possible. check the ends of the transducer cable for exposed wiring. It is possible that the rfi is coming from a circuit board within the display, if thats the case you'll have to send it in or replace it.
- 12/29/1999 9:42:00 AM
Submitted by
Gale (63.78.179.66) from TEXAS says Same problem - unfortunately, no good solution
Rich, I fought this problem for several years. I attribute the main part of the interference to having one of the transducer frequencies the same as the internal IF frequency of the VHF, 455kHz. Through what miracle of engineering foresight Humminbird chose that frequency, I can't imagine. Anyway, I filtered the DC lines at the fuse block where both the VHF and the sounder get their power and ground. I connected 3 ceramic disk capacitors in parallel - 0.01uf, 0.1uf, and 0.47uf, between the 12V bus and the ground bus on the fuse block. You can get these at Radio Shack; don't use anything rated less than 35V, and keep the leads reasonably short without putting stress on them. For me, it lowered the interference down to a medium aggravation, but it's still there. BTW, on my present boat, the very same VHF gets its DC power from the same fuse block as the Lowrance X65, and has no interference at all. Good luck.