I would start with adding a common-mode choke on the output of the AH-4 instead of at the feed point. A coiled coax (solenoid) choke provides minimal CM attenutation across the bands due to

David, it is copper pipe. No doubt at all. thanks 73 Colin

Hi Steve, the test of the headset/microphone was done at my friends place. It worked fine with the IC7000. I doubt my radio has any problems. Going to relocate the AH4 outside the shack and connect

As someone else mentioned, the AH-4 is NOT designed to be in the shack or connected to a resonant antenna. It was designed for a singe wire or mobile whip, and not one that is a half or full wave. In

Charles, The base of the 40m Delta loop is directly over the top of my shack. The AH 4 is in the shack so my next experiment is to relocate it outside the window of the house. I tried a coax

Noted chuck. Thank you 73 Colin

Perry, the head is not remote. Operated As a base station. 73 Colin

How bout dat? Both ATT and MN! Thanks Robie. Now those East Coast stations are rattling my malleus, incus and stapes once again. It hurts so good. 73 Ron W9XS

Could you have accidentally turned on the ATT (attenuators)? Robie - AJ4F

Started searching for new countries during CQWW and found that my receive audio was very low. Cranked the AF gain all the way up and could barely make out the East coast stations on 20 meters from 9

No thats not the case. 73 Colin Sent from Yahoo7 Mail on Android

If you have the head remoted be sure you have the small screw that attaches the control cable to the main unit in place! Loss of that ground point will cause lots of RFI issues. Perry

Just to clarify, the common-mode choke needs to be on both the coax and the control cable to the tuner. The situation with respect to common-mode currents is the same for both cables and

The AH-4 has a control cable to the radio, so mounting at the feed point of distant antenna is not recommended. Wherever it is mounted the common-mode choke should be place on the coax to the radio

FWIW -- My memory could be wrong, but I think the AH-4 is a "long-wire" tuner, designed to be mounted at the antenna feedpoint. I think the AH-4 ATU should be mounted at the feedpoint of the Delta

Graham: That's certainly the primary way those currents end up on the transmission line and into your shack, and for some antennas a "common-mode" choke or balun is a requirement or

Colin, When you tested with your friend's radio, was it at your location using your antenna? If so and you didn't see the problem, then the problem would seem to be in your radio. If not then the

Hi - put your coax choke at the antenna as this is how to remove common mode currents traveling on the outside of the coax and back into your shack. 73 de Graham ZL3TV

Hi again Colin Is your water pipe metal too your house from the main, as here in the UK a lot have been changed to plastic, Dave 2E0DMB Sent from: Lenovo S856

Hi Colin Try a RF Choke at the antenna Dave 2E0DMB Sent from: Lenovo S856