[Mldxcc] Need help from the brain trust--Buzz/hum and broadcast radio

[Rich NU6T]

Help!  I'm trying to get set up for SS SSB and have a buzz/hum on 40m 
and 20m (not checked on other bands but probably there too) when I push 
the PTT.  It is constant across the band and the volume is constant 
regardless of the K3 RF knob position.  I hear it whether the K3 is in 
Test mode (no RF output) or normal mode.  With the buz/hum, I hear a CNN 
radio broadcast.  I don't hear the buz/hum or the broadcast listening to 
RX on the K3.

Antenna is a dipole up 57 feet.  Feed line is coax with 5 big ferrite 
rings and 6 turns of coax (RG-213).  The coax is a complete run to the 
radio.  I've put 2 or more ferrite clamp-ons on every wire running to 
the radio, but not reducing the buz/hum.

My AM/FM/SW radio shows high noise across the AM band in DX mode.  I did 
not find that broadcast listening to the AM radio in local or DX mode.  
(Loral Langmier and then Chris McKay shows).

Any suggestions for resolving this will be appreciated.  If anyone is 
available for a 40m contact, I'd like to see if this is a RX only 
problem or an also a TX problem.

Thanks.

Rich
NU6T