Re: RFI on 2 meters from uBitx


Dale Parfitt
 

Regarding the 2M issue, you might also try disconnecting your HF antenna and see if the issue goes away. If it does, then some #43 snap on ferrites right where the antenna coax exits the BitX should help- same for the key, mic and power leads. Of course, if the rig is not in a metal cabinet then all bets are off.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Evan Hand
Sent: Thursday, June 18, 2020 8:17 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RFI on 2 meters from uBitx

 

Jay,
Ensuring that it is installed in a metal case that is grounded is the only thing that I could see helping.  Are there any modifications installed?

What you are seeing is the 3rd harmonic of the Clock2 out of the SI5351 that is used in the first mixer to convert the incoming RF to the 45 MHz IF frequency.  That is not a mixing product.  It is the local oscillator for the conversion to 45 MHz IF.  Those signal traces are fairly short, so not much of an antenna.  Also, since it is on both transmit and receive, I doubt that the first mixer is damaged. 

I will see if one of my ubitx has the same issue.

73
Evan
AC9TU

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