Can you identify this?

[jrobert890]

Hi Folks, First time my mast is down since I bought my boat. I’m not sure what the cylinder is for. Any insight?

[jrobert890]

Btw, this is the top of the mast

[team karst]

if its old, maybe sat-nav; as in the 400MHz transit system. If new, then perhaps iridium sat com. Is there a coax feeding?

[scargo]

4G/LTE Antenna ?

[team karst]

oh, sailboat. Neither of my thoughts would be suitable. no good reason to put sat stuff at the masthead. coax losses. Yeah, maybe cellular. But losses there are quite high too for a 70' coax run.

[Tupaia]

Could be an Active Radar Reflector. Echomax or Sea Me

[SaltyMetals]

Or maybe an antenna which pairs with personal MOB units which will set off an alarm if one of the MOB units travels more than a set distance from the boat.
Andrew

[Clivevon]

Maybe an old Navtex antenna?

[rhirwin]

Analog cellular antenna- time to ditch it.

[Doughdish]

Looks like an active antenna for a SSB receiver.

[Moontide]

Guessing a cell phone extender antenna.

[hpeer]

Originally Posted by jrobert890

Hi Folks, First time my mast is down since I bought my boat. I’m not sure what the cylinder is for. Any insight?

Attachment 250818

When did you get the boat?

Do you have any idea of how ling before you the mast was last down?

Might help rule out some more recent devices.

Also how tall a mast?

[sailormed]

Is there a cable going into it? If not it is a passive radar reflector.

[AlanR]

An active HF antenna for Navtex. I have one on my boat. It could also be used for any kind of HF reception. You need to supply it with 12 volts up the co-ax, vis a 'T bias' adapter to use it with another receiver; this would have been built into the Navtex receiver.

[team karst]

a .5MHz antenna; cool. well below the HF range, even. I wonder if its a cylindrical coil wrapped around ferrite with a FET amp.