Garmin 430 wierd issues

My partner and I just bought a '79 Mooney M20J with a 2 year old Garmin
430 Comm/Nav as the Comm # 1 adn a Bendix 170B as the Comm/Nav # 2. (yes
we had a pre-buy and everything "seemed" fine") I have some strange
issues with the 430 that I am sure you can help guide me thru. Issues:

1.) On the ground if you set the 430 to our UNICOM freq TYQ 123.05 and
do a radio check they can not hear you. TYQ has an AWOS and you can hear
that fine on the ground (120.725).

2.) On the ground if you set the 170B (nav/com # 2) and do a radio check
they come back as "loud and clear" (and yes they are at the station when
I try the radio check on comm 1) :-)

3.) One time we were on the ground set up on the Comm 1 and trying to
get the UNICOM operator to hear us when a Piper over the airport said we
were "loud and clear".

4.) Our local UNICOM is 123.05. UMP an airport 15 miles away's UNICOM
is 123.00. While airborn we kept picking up their transmissions.


I was going to try swapping antenna connections between Comm 1 and Comm
2 but as I peered under the dash looking for the antenna leads I said
"I'll screw more up then I'll ever fix so I left it alone)

Any suggestions or advise? Is this going to cost a fortune to fix?
Thanks in advance for your help!!

Jon Kraus
PP-ASEL-IA
Student Mooney Owner
4443H @ TYQ