internal or external antenna?

[tmg1]

I'm looking at buying the Lowrance 520c or the 522c. have heard of problems with the 522 internal antenna system. Any input on which one is better? Also, wondering if sonar on these units will pick up my downrigger balls, as the Eagle fishfinder I have now will not pick them up. I am also open to any other suggestions.

 

[Boatist]

Re: internal or external antenna?

The external antenna is better, it gets better reception and get blocked less.
However if you are going to use this unit in the car or another boat as well then go with the internal.

Picking up the down rigger ball.
All depthfinder should be able to pick up the down rigger ball if the ball is in the cone angel of the transducer.
Most of the time if useing a 200 khz 20 degree transducer you will not see the downrigger ball.
A 20 degree transducer in 30 feet of water or downrigger 30 feet deep probably will not be seen.
At 30 feet down a 20 degree transducer will cover a 10 foot circle under the boat or 5 feet each side of the transducer.
If the transducer is a shoot thru hull and mounted near the center on a 8 foot beam boat then will only see transducer if within 1 foot ot the boat.
If your downrigger has a 3 foot arm you will not see it.
If you fish deeper then at some point you will see the ball maybe.
If you are fishing deep say 60 feet you should see the ball if the ball is under the tranducer.
What happends when go deeper the ball and cable will have more drag and this will cause the ball to angle farther behind the boat. If this angle gets more than 10 degrees then the ball will be behind cone form the transducer.
So with a 20 degree transducer to see the ball you need to fish deep and use a heavy enough weight to keep the down rigger ball almost straight down.

This is hard to do so the best way to see the downrigger ball is get a dual frequency unit and a 50 khz transducer with a 45 degree cone angle. While this is the standard 50 khz transducer it not easy to find.

Both Lowrance and Eagle dual frequeny unit assume you are fishing deep saltwater, Garmin also. So they come with transducer that help see bottom fish in deep salt water. Their standard dual frequency transducer is 200 khz at 12 degree cone angle and the 50 khz at 37 degree cone angle.

The 37 degree cone angle will make it much more likely you will see the ball than the 20 degree cone angle of the 200 khz single frequency transducer.

Another thing that many people do is not set the sensivitity high enough. Many will set where the screen looks clear with almost no noise. They only see the biggest fish never bait. You should turn it up to a point where you have lots of noise or false returns. This will also widen the cone angle some and make it more likely you will see the ball.

Do not belive Lowrance or Eagles up to 60 degrees cone angle. While it is true what they do not tell you is if you turn sensitivity up that high the entire screen will be black and you will see nothing. The returns in the center of the cone will give so many false returns that the eitire screen will be black.
Might work some where like lake Tahoe where the later is very clear and you can see down 60 feet your self or if you boat in distilled and filtered water.

Hope this helps.

 

[BillP]

Re: internal or external antenna?

Internal or external totally matters on where the unit is mounted. An internal open to the sky is no different than an external open to the sky. Regardless, most current internals will easily see though a bimini, t-top or single hardtop but may drop signals with multi layer hardtops, bridges, towers etc.

I don't know where the downrigger arm length has anything to do with ball reception is coming from. If the ball is in the tranducer cone it will be picked up no matter what length the arm is. Where I come from, most people troll the ball too far back to be seen by the transducer anyway.