[MFJ-Ameritron] MFJ-624D Phone Patch problem

[Ray Brann]

Greetings All,
Really hope someone here can help with this problem I've encountered.

I just purchased this 624D new, have it all connected to phone and rig
with
appropriate cables etc.
Oh, rig is Icom 746.

Gave this setup a trial run this evening on 75m with the help of a
couple of
friends.
Guy on the phone couldn't hear the other gent on his rig very well, yet
his signal
was 10+ over 9.

Seems any adjustment I made to rig or patch didn't improve the
situation. The
gent on his rig could hear the guy on the phone just fine. He did
mention that
he(gent on rig) could hear a phone line hum.
Don't know if that's important or not, but since hooking up the 624D I
can
also hear a hum on all phones in house even with the patch turned off.
This may not be connected to the very low audio output to the phone guy.

I need to provide some communications assistance to some missionaries
for a period of time and really need to get this setup working properly.

Hope you folks can help.
Thanks
Ray / W1RWB