have this old altai gdo with all the coils,the dial frequency markings are too course for acurate measurements,can a frequency counter be added to show the exact frequency of the dip?.
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because: no response - so help yourself
Assuming you are a HAM and having a transceiver with CW you can zero-beat the GDO with your transceiver.
It is also possible to use a counter but you must be carefull to not overload the oscillator because it might go out of oscillation.