[time-nuts] Frequency counter questions
bruce.griffiths at xtra.co.nz
Wed Apr 26 17:19:20 EDT 2017
Use a USB or LSB mixer, it only requires a few more parts and a little ingenuity.
> On 27 April 2017 at 06:52 al wolfe <alw.k9si at gmail.com> wrote:
> I am surprised that no one has mentioned the idea of heterodyning a
> known frequency with the unknown to measure the unknown. I use a
> Minicircuits doubly balanced mixer fed on one port from a PTS160
> synthesizer that is locked to 10 mhz. from a TrueTime xl-ak GPS locked
> receiver. The second port is fed by the unknown though an attenuator.
> The third port of the mixer gives me the sum and difference. If the
> difference is an audio note then a cheep but frequency locked counter
> will read out the difference or measure the period of the beat note
> which can be added to the frequency of the synthesizer. A program such
> as Lady Heather can also be used to determine the audio frequency to
> much less then sub-cycle accuracy. The only fly in the ointment is
> figuring out which side of the unknown the synthesizer is set to.
> Alternatively, the PTS160 with 0.1 cycle control can be set to nearly
> zero beat with the unknown. Then watching either lissajous or dual
> trace scope patterns and timing the beat notes one can get the unknown
> frequency very close.
> Al, retired, mostly
> AKA k9si
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts