Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Dave Bottom <ars.kd6az@...>

Genuine Nano with Quartz Crystals.  Replacing the Nano to remedy high frequency audio tone.

The official Arduino site says they are out of stock, however I found that the RobotDyn Nano ATmega328 (without headers installed) that has Quartz Crystals 12MHz USB and 16MHz ATmega328.
Without headers installed I can sacrifice the existing Nano without risking damage to the Radunio main PCB.

It is available on Amazon for $6.49.  Free Delivery if you have Amazon Prime.  

I just ordered one so I should be able to try it out replacing the current Nano on Tuesday before I head to Orlando for Hamcation. on Thursday morning.

Dave WI6R

On Sun, Feb 4, 2018 at 3:55 PM, John Backo <jabac@...> wrote:
Jerry is right.

This is a rather rare effect involving only a few nanos.
The use of a ceramic resonator would surely contribute to
the problem. The best solution is to replace the nano (maybe with a real one?).
The new one would most probably not have the problem...Alternatively,
one could build one's own version with a UNO (or other arduino) and check out how that works.

In any event, it comes down really to replacing with a better unit, or shielding
the offending signal away. I suspect many problems would disappear with
good shielding and short shielded leads, (which incidentally is among the
recommendations of Farhan also).

One could spend a lot of time figuring out just where the RFI is coming from.
but to what end? The important thing is to have a rig which communicates.
Finding a proper VFO is easy enough...but to each his own; some are intrigued by
just what is happening and are not satisfied until they know all. Fine enough.


73 Dave WI6R

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