2 Eagle Sonar units on one cable?

[Mark_VTfisherman]

I have an Eagle Fishmark 480 on my boat, as well as a FishElite 640C. I use the 640C for GPS but would like to incorporate sonar data (temp, etc.) for both units. I LOVE the big display on the 480 for sonar. and the grayline feature makes it wicked useful.

My question is this: has anyone tried to run two Eagle/Lowrance products off of one transducer? LEI Extras' website doesn't list an adapter or "splitter"- some older Eagle products DID have an adapter to run two heads (one in front, one in back for example) off the same transducer.

Of course Eagle/Lowrance doesn't "recommend" cutting the transducer cable, but I would like to power both units and also send sonar info to both units- mostly for temp, but I can foresee times when I might have only the 640C aboard if my Niagara has the 480 and the bigger boat has the 640C

Any thoughts? Hints? HAVE YOU done it!!?

Just want some input before I move ahead on my $120 (the cost of two new cables!) experiment

 

[Silvertip]

Re: 2 Eagle Sonar units on one cable?

If that were acceptable the devices would be available. By the way, speed and temp and not SONAR data. That data comes from a totally separate pickup (paddle wheel sensor and thermister in one separate unit). The reason you cannot run two transducers is you essentially place them in parallel. That changes the electrical characteristics of the entire circuit with messes with the head unit. You could fashion a switch that allows you to select either transducer but you MUST run just one at a time -- never both.

 

[Mark_VTfisherman]

Re: 2 Eagle Sonar units on one cable?

I get speed from GPS... I just wanted to be "able" to run both head units as it might be handy to have a second display in the rear reading the same data since I DO have too units.

I think it was the Magna series a few years back that offered a splitter that queued the transducer pings from one unit and returned the info to both units. Since that WAS offered, I imagined that it can't be rocket science to make my own since there is not one offered from Eagle/LEI

Of course if I had deep pockets I know Lowrance and Raymarine offer "networkable" displays but they cost more than replacing both my boats and all my gear combined!

Anyway, was just hoping someone might have done this- I can't be the only nut out there but maybe I am LOL

 

[dingbat]

Re: 2 Eagle Sonar units on one cable?

Splicing a transducer cable isn't rocket science. Transducer schematics are not hard to come by.

Most finder companies make some sort of the switch box. Lowrance makes one but it has diffrent connectors on it. Buy the switch, cut the ends off the existing cables and wire them into the switch box.

Save some money and go down to Radio Shack and find a 2 way switch that has enough contacts. You could at least switch between the units. The dual input would be a bit tricker. You need to come up with a method to take a single analog signal and convert it to two anolog outputs.

 

[Silvertip]

Re: 2 Eagle Sonar units on one cable?

Using two head units on one transducer "is not" rocket science but the fact remains you cannot run both head units at the same time because by paralleling the inputs you upset the input characteristics on both units. They simply were not designed to operate that way. I have a networkable PinPoint unit that can be networked. But locators do not have that feature by default. It is built into the head unit. Most manufacturers did offer a transducer switch that allowed running two head units, but you could only view one at a time. If that's what you want, go to Radio Shack, buy a water tight box, a rotary switch, some grommets, and have a go at it. Cut the transducer cable and wire the three leads (one from one head unit, one from the other head unit, the one from the transducer to the rotary switch. If you get a switch with enough terminals you could even do the !, 2, Both scenario to convince yourself it either does or does not work. My bet is it will not.

 

[Mark_VTfisherman]

Re: 2 Eagle Sonar units on one cable?

Thank you Silvertip and Dingbat- good info and confirms my thoughts.

It sounds like I would need to know the mA of the signal and have an "amplifier" of some sort so that the signal is not 'halved' by the parallel wiring- too much electrical for my skill level. I get the principles but don't know how to make these circuits.

I may try the A/B switching as suggested, but after doing a lot of reading have decided to try this method first:

The Eagle 640c manual suggests that TWO devices with separate transducers can be convinced to work together by adjusting the ping speeds on both units until interference disappears. I don't like the idea of two different transducers hanging off my transom, but this sounds like a reasonable solution to try before I start cutting $60 cables.

Incidentally, the first several outings this spring I have finally figured out how to adjust the Eagle Fishmark 480 so I know what I am seeing and am confident that I am not missing fish. I also ran the new 640c for 4-1/2 hours at Lake Eden yesterday in split-screen mode (GPS/Sonar). Nice unit that 640c - not sure what all the colors mean for real yet, and not used to the menus, but I think I like it.

It takes a long time, however, to pop up a menu or window that asks, "Do you want to see your current position?" after the unit acquires the satellites. I can't find a menu option that defaults to showing the current position on "boot" however. If you scroll before it asks you if you want to see current position it wants to navigate- give directions from the starting point to where you scrolled to. I guess the simplest solution to that is to turn the unit on when I leave the driveway and have it acquire and lock the location on the way to the launch- then it won't use up 5 minutes or so before you can see your track.

After and hour around with the menus and figuring it out, I did boat three rainbows: 12", 12-3/4", and a 13". Not sure if they are fresh "stockies" due do amazingly bright colors- prob natural propagation or holdovers from last year.

Thank you again for the comments and info. I will post again after I try the separate transducers- or cut cables!

 

[bkwapisz]

Re: 2 Eagle Sonar units on one cable?

Is the other graph on the bow near a trolling motor? I ended up buying another transducer and run them that way. I looked up your units and didn't see a splitter, but I did notice that a lot of those products from Lowrance run the same connectors but don't list them as cross-usable. For example, my boat came with an X-125 graph, and I already had an LMS 527 GPS on my other boat. Well the LMS plugs right into the old spot for the 125, cables and all. In fact, they list the power cable for the LMS as a $70 cable, but the power cable for the 125 is only around $20. If you aren't using the networking (which I'm not) then you can use the other cable. I'm not sure what ends your graphs take, but I'd look into it before buying anything.

 

[Silvertip]

Re: 2 Eagle Sonar units on one cable?

You still don't understand this "mismatch" I keep talking about. It is not about signal loss. it is about signal input circuit impedance matching which is an electrical characteristic for nearly any electronic device that has an input and an output. Simply amplifiying a signal does not compensate for that mismatch. An impedance mismatch (or any electrical mismatch for that matter) means the head unit will no longer be able to interpret the signal. Every electrical waveform has a particular shape and strength and the input circuitry is designed to recognize that waveform. By paralleling two transducers or two head units you upset that match and the head unit can no longer recognize it and may actually be damaged. The simplest way to describe this to consider one 500 ohm resistor in a circuit. If you add another 500 resistor in parallel the total circuit resistance is now 250 ohms. If whatever circuit that resistor is in REQUIRES 500 ohms in order to operate properly, dropping to 250 will drop that circuit out of its operational window. It's called circuit design and these values are very critical design considerations. Regardless where you fish in a boat, one person cannot generally see two head units anyway so why not just mount a transducer on the troller and be done with it. The two units will rarely interfer with each other when operated simultaneously.

 

[Mark_VTfisherman]

Re: 2 Eagle Sonar units on one cable?

You still don't understand this "mismatch" I keep talking about..... Regardless where you fish in a boat, one person cannot generally see two head units anyway so why not just mount a transducer on the troller and be done with it. The two units will rarely interfer with each other when operated simultaneously.

Thanks for the detail on the mismatch- I see your point now.

As far as two units are concerned: we often troll and want to see the same info displayed at the stern that is seen at the helm. That way one of us isn't trying to see "through" the other of us to view the sonar display. The higher-end networkable units do this easily of course.

I have the Fishmark 480 which I use for sonar- I finally installed the FishElite 640c GPS and that is right next to the 480. They both run the same model transducer/power cable, which got me thinking....

 

[Mark_VTfisherman]

Re: 2 Eagle Sonar need extra power cable?

Re: 2 Eagle Sonar need extra power cable?

So I have come to a conclusion - color Sonar is OK but I prefer the Fishmark 480 for sonar. I will run the two units simultaneously but only the 480 for sonar. So not trying to blatantly "solicit" but I have a need- or two that does not violate iboats terms of use.

I am going to run both units- but I have two boats. No prob- I can put the transducer that came with the 640 on the other boat. The issue is that the transducer and power cable are one and the same. So to run two units I need two more power cables.

What I am looking for is at least one, better: two, Eagle 320/480/500/600-series power cables. Of course I can buy them new for $80 but since I only need the power- the transducer can be missing or cut off. Anyone have a damaged Eagle/Lowrance transducer/power cable or two you would like to sell cheap? PM me...

Thanks...