[Central-Electronics] 10B Mod

[k7fm]

Hi Jim:

A few years ago, I built a pocket sized transceiver using a voltage tuned 
vfo.  It drifted badly and needed temperature compensation.  Having 
compensated vfos many years ago with few instruments, I wanted to make this 
attempt as painless as possible.

So, I dragged out a drawer of small capacitors (including temperature 
compensating caps), my wife's hair dryer, a digital capacitance meter, a 
frequency meter and a infrared temperature probe.  First, I calibrated the 
drift of each capacitor.  Then, I applied the hair dryer to the vfo 
monitoring the frequency.  You can do the same thing with the crystal 
oscillator in the CE.  It will be easy to see if it is the crystal or the 
circuit.  If it is the circuit, temperature compensation is painless.  By 
the way, silver mica caps can be useful, but they are all different in 
drift.

73,  Colin