[Heath] IM-2400 External calibration adjustment

[John Klingelhoeffer]

I have an IM-2400 hand-held frequency counter.  One of the design foibles for this product was that although there is a nice, smooth, teflon-insulated rotary capacitor for setting the frequency of the 10 MHz oscillator inside, the case must be removed from the unit to make this adjustment.  Not dangerous, but since the crystal oscillator does not appear to have any significant temperature compensation designed in, this has to be done almost any time an accurate measurement is needed.


Wondering if anyone has attempted drilling a hole through the front panel so that the variable capacitor can be accessed without removing the case.  If so, did you have any problems doing so?  If not, I guess I am going to give that a try.  Is there a good way to make a clean hole without leaving a rough edge?


It is a nice little unit.  I suppose I am on my third or fourth set of nickel-cadmium batteries in the 36 years that I have had it.  Most recent change was 2014.  I would imagine changing to a lithium secondary battery with a new charger would be advantageous now that storage technology is mature.  


Walt Boris did a nice job on the electronics design, but the integration with the mechanical design left a bit to be desired.  


73


John...
WB4LNM
"One of the hams from Heath"


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