Hi,

I recently purchased an ICS NAV-5 Navtex that came without an antenna.

Reading user guide and docs on the web I can purchase and fit a NAV 4
passive antenna or an active VTRONICS ..
Being inquisitive I wondered what is in these?

Can't find a CCT of them but found some very interesting articles on use of
short whips ( as used in the active antenna) at LF, in particular the high
impedance antenna being couple to the gate of an FET.. a few comments on
making sure the whip is insulated, and likely life of the FET if any static
or lightning about. Makes me wonder if a passive ant would be more reliable
than an active ant?

Does anyone have any experience of active antenna use and reliability?

PS NAVTEX reception around the Clyde/West Scotland is reported as poor so an
active ant might be attractive

Regards

Bob


GM4CAQ

Simply Blue Too
Clyde

On Dec 13 2008, 1:27*pm, "Robert Miles" wrote:
Hi,

I recently purchased an ICS NAV-5 Navtex that came without an antenna.

Reading user guide and docs on the web I can purchase and fit a NAV 4
passive antenna or an active VTRONICS ..
Being inquisitive I wondered what is in these?

Can't find a CCT of them but found some very interesting articles on use of
short whips ( as used in the active antenna) at LF, in particular the high
impedance antenna being couple to the gate of an FET.. a few comments on
making sure the whip is insulated, and *likely life of the FET if any static
or lightning about. *Makes me wonder if a passive ant would be more reliable
than an active ant?

Does anyone have any experience of active antenna use and reliability?

PS NAVTEX reception around the Clyde/West Scotland is reported as poor so an
active ant might be attractive

Regards

Bob

GM4CAQ

Simply Blue Too
Clyde


I use the NAV-5 with an Active antenna (about a 3' whip). I can pick
up NAVTEX broadcasts from Nova Scotia in New Hampshire, which is
pretty far away. The active antenna has an amplifier built in.
I've used it for many years with no problems.

dan