Re: RFI on 2 meters from uBitx

Dale Parfitt

Hi Evan,

While there can be a good deal of math involved to optimize ferrite common mode choking impedance, it  so easy to do trial and error that for most cases we can forgo the math.

I had  a serious distortion issue when I was connecting my Drake TR-7 to my solid state SPE Expert HF amplifier. My K3 had always played beautifully with the SPE as had  a number of other boatanchor rigs- both vacuum tube and solid state. I tried ALC, no ALC, all sorts of fixes. The issue turned out to be common mode on the PTT line from the rig to the amplifier. Who would have thunk it.


Dale W4OP


From: [] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:45 AM
Subject: Re: [BITX20] RFI on 2 meters from uBitx


Dale's message prompted me to think of other cables that run near the Raduino.  By chance are you using CAT from the rig?   Snap a ferrite on it and any digital mode cables. 

A good suggestion for the ferrites.  I already have them on my rigs because of RF feedback.


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