Lee, I am probably not going to be much help on this, but I have had a similar problem with RFI and my rig is very similar (ICOM 756 Pro 2) and has the same rear connection. With one antenna, I would get enough RF in the shack to cause phone distortion. When I got an amplifier, it was much worse and prompted me to abandon my sort of homebrew interface using Radio Shack isolation transformers embedded in one of their products.
When you say the Signalink is powered down, how does this happen? I went to the Tigertronics web site and it says that the power "is always powered by the computer's USB jack." Is there also a power switch that powers down the unit or is it powered up whenever plugged into the computer? Are you unplugging it from the computer and leave the USB cable hanging loose? If you did that, then is it possible that there is some RFI getting into the cable? If you have a dummy load, you could see if the problem still exists when transmitting into it. Otherwise, do you notice increasing distortion with increasing RF output power? Do different antennas vary the problem? Different bands vary the problem? 73, Rick, KV9U KB1NAL wrote: > > _SUBJECT_: Having problems on 75m LSB PHONE with this new > Interface set up. > > *Hello Members:* > ** > * *Can you make some sense out of this? > > _*Audio on 75m LSB Phone Mode is A + when:*_ > > *1. SignaLink USB Interface is powered down and PC is powered down.* > * -- OR --* > *2. SignaLink USB Interface is powered on and PC is powered on.* > > _*Audio on 75m LSB Phone Mode is TERRIBLE when:*_ > > *SignaLink USB Interface is powered down and PC is powered on.* > > *Might you have any suggestions why this is possible?? * > ** > * *My THEORY is : > *since, the RADIO , SIGNALINK , and PC are all interfaced and linked, > **they are all dependent on each other. If the PC is ON and the > SIGNALINK **is DOWN , the audio on 75m phone is terrible. Turning the > SIGNALINK back ON **generates perfect audio on 75m phone. Please > remember, this is a new experience **for me.. * > > MY STATION SET UP: > > PC: COMPAQ desktop running Windows XP > CPU: AMD Athlon XP 2600+ > RADIO: IC-746 PRO > INTERFACE: SignaLink USB (installed JP4) > CABLE: 8 pin din ACCY PORT CONNECTOR > > Comments appreciated !! PLEASE help !! Thanks!! > > 73, > > Lee / KB1NAL > > _ >
