[1000mp] Hum on phonepatch input-FT-1000MP

[Ronald Walters]

The soundcard software program that I occasional run needs USB,
it is MT63 by IZ8BLY, unfortunately my old MP does not have the CPU upgrade
that allows for the packet mode USB but only LSB.

For the record I use the packet input for all other soundcard modes and they
work great without any hum, however if I use the phone patch input on the
back of the MP I can hear some hum.  I am using isolation transformers for
all inputs to and from the MP to the computer.

Question?  Does anyone know if there is a load requirement for the phone
patch input.

I am using a Radio Shack 1:1 isolation transformers, any suggestions?
Should I isolate the transformer with a cap?  Any parallel resistor network
required?

Ron W4LDE