Re: Raduino oscilators. 33mhz and 57mhz " . Documentation says one thing, but this is what I measured.
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Yes, I'll need to hook a scope to hear the 3 or 4 hz flutter when your spot on. Thanks Jerry. Hopefully doing more today, as its raining here finally.
On Thu, Mar 8, 2018 at 8:32 PM, Jerry Gaffke via Groups.Io <jgaffke@...>
That's an excellent method to measure the frequency of the 25mhz oscillator.
If the receiver has sufficient low frequency audio response, you could monitor the speaker wires with a scope
and get sub hz accuracy when zero-beating.
I'll check my uBitx (tomorrow?), see how much warmup drift I can detect.
The 2.3khz drift (at 25mhz) you reported seems too large by a couple orders of magnitude.
On Thu, Mar 8, 2018 at 07:55 pm, Michael Shreeve wrote:
I don't know if I responded to this. I thought I explained but then maybe not. What I have always done when there is no buffered output is 1 use a receiver and an "antenna" if you will, one that is near the raduino but not touching anything. 2 turn on a somewhat stable generator and, in my case right now, measure the generator frequency directly with a counter. I can hear that generator in the same receiver.. Zero beat the generator , which is being measured, with the 25 MHz signal emanating from the raduino. Turns out it did change as I indicated, merely from heating up. No direct coupling at all for this measurement. At least to the raduino. If I had a communications monitor I wouldn't need to measure the freq of the generator. Or some other stable generator source. Also, I need to try to determine just how accurate my counter is.
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