The first thing I would check is ALL of the coax connectors. If the connectors aren't screwed in and the notches lined up, enough RF can leak onto the outside of the shield to cause RFI in the shack.
Next check your ground rod connection for tightness and no corrosion. I assume you have the AH4 tuner case grounded also, along with lightning suppressors ground at the entry point. Your RF ground rod should be bonded to the electrical panel ground rod,
but that is more for lightning protection than RFI.
The shack ground wire has too much inductance to be a good RFI eliminator. A common-mode choke near the feed point is always the best solution to stop RF on the outside of the shield.
Baluns can fail and result in several problems that aren't always obvious when an auto tuner is in the path. Checking the SWR at full power between the tuner and antenna will usually show if the balun is failing. Visual inspection of the balun coils,
ferrite and connections occasionally is a good idea. Loop antennas require a 4:1 CURRENT balun. Many hams buy a less expensive 4:1 voltage balun, which doesn't provide common-mode isolation.
Have you run any new feed lines into the shack recently. They may be the source of RFI. Also, try moving other cables that connect to the radio (power, rig control, sound card, etc.) to see if the symptoms change. If the antenna is near the shack it
doesn't take much of a change in the location of nearby conductors to create an RFI problem.
I assume the display is attached to the radio chassis, but in case you are using the remote cable, make sure the cable's grounding screw is tight. Also, the screw must have the correct head diameter so it contacts the metal shield, not just the plastic
I had an 80M loop as my first antenna and all of the above are based upon personal experience....
, wrote :
Thanks for viewing.
Running a IC7000 as a base station now for 4 years and have never had an issue with RF getting into the rig.
On transmit the screen shows RF distortion on 14mhz and 7 mhz HF only.
Recently purchased a new HEIL headset/microphone and while using it noticed the problem. I was ready to blame the new headset/microphone until I plugged in the hand microphone and found the same issue . Its the first time I have every had this problem.
Running a AH4 ATU 4:1 balun into a 40m loop. Power output 100watts
Up until now had absolutely no problems running this arrangement. I have the rig grounded outside.
I would be interested to hear from you if you have any theories of what the problem might be and how to address the problem.