At this frequency for a receive application the impedance is not very
critical.

However, if it would help you sleep at night you can put a 3 dB attenuator
at the end of the coax to match the impedance.

For coupling into the receiver, wind a coil of wire big enough to go around
the entire receiver. Perhaps 3 or 4 turns would suffice. Then place the
receiver inside the coil.

If the signal out of the antenna amplifier is strong enough, you might get
away with just setting the receiver next to the coil.

To clarify, the setup would be like this:

Antenna----amplifier----Coax----attenuator----Coil near receiver.

And if it was me, I wouldn't bother with the attenuator.

--
Jim
N8EE

to email directly, send to my call sign at arrl dot net
"amdx" wrote in message
...
I have an AM radio on an aluminum boat. The radio is shielded on
six sides by aluminum. I want to mount an antenna on the boat and
run coax inside and couple the signal to the ferrite rod in the radio.
I'm thinking about an active whip antenna with a 50 ohm output. If I
did this, I would have a coax with 50 source impedance at the radio!
How do I create a 50 ohm load at the radio over the AM band? The radio
has a 2-3/8" x 3/8" ferrite rod.

I would appreciate any other solutions to get a signal to my radio.

Mike