Morrow is one of the companies that use "active" antennas to
overcome the fatal signal losses resulting from enormously
high impedance (~ 1 Megohm, albeit mostly reactive) of
extremely short antennas fed into 50-ohm receiver inputs.

Your circuit board probably contains an FET follower to
convert the high impedance of the antenna to a low impedance
of 50 ohms. To do this with a coil would probably render the
system so lossy as to not work at all.

You should be able to vary the antenna length modest amounts
(I'm thinking +/- 20%)with no noticeable difference. Just
how far you can go will be a question you can answer easily
by trying different lengths of substitute antenna.

On the other hand, if it was working fine with no antenna at
all, (was the coax connected to the circuit board?) do you
really need to go to this trouble?

Good luck, and let us know how you make out!

Chuck

RB wrote:
Does the length of a LORAN metal whip matter much? I recall a time when I
found I didn't even have an antenna on my LORAN (years ago); just a coil of
coax under the console, and it worked fine. So, can I stick just about any
whip on the coupler and get good results? Or, is there some reasonant
length that is needed?

I'm putting a LORAN in my 18' cc, and want to use a short metal whip on the
coupler, if that'll work OK.