Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help
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I know I'm late to this party but you cannot swap crystals on nano board without first using a atmel programmer to burn the fuse bits that tell what freq it will be using or you will brick your nano.... also if the ftdi or whatever usb chip is using 12mhz, you could get the sparkfunPro 16mhz/8mhz board that does not use usb but instead uses usb to serial cable to upload. Be warned 16mhz board is 5 volt and 8 mhz is 3.3 volt.
I only use the Sparkfun Pro 16 for my projects. Another note if you go with the ATMega32U4 boards they have built in usb....
Maybe this will help someone or maybe not....
Sent from my Galaxy Tab A
-------- Original message --------
From: Arv Evans <arvid.evans@...>
Date: 2/3/18 09:38 (GMT-06:00)
Subject: Re: [BITX20] #ubitx-help Strong Audio Tones in and outside audio receive passband
Interesting observation that the 12 MHz USB clock oscillator is on nearly the same frequency
as the uBITX IF and BFO. If the BFO is offset to the high side of the IF passband it could well
be within audio range of the USB clock frequency. If this is the problem then it might be possible
to pull the USB clock crystal down with a small parallel capacitor. That should not make a
significant change in USB clock timing but could take it out of range of the receiver IF and BFO
frequencies. Some experimenting is probably necessary to tell how far to pull the crystal. It
would not be good to accidentally put it within the IF filter passband.
On Sat, Feb 3, 2018 at 1:47 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I assume you mean changing the Arduino crystal, not cap.