[HQRP] VFO Caps etc

[K5BDZ@aol.com]

A couple of days ago I read a QRP-L reply (Great reply...sorry I can't 
remember the call of the writer to give credit) concerning taping down the 
VFO oscillator coil to connect a variable tuning capacitor to get the desired 
bandwidth of the VFO from a capacitor with too much capacitance (hence too 
wide a tuning range).

This idea is GREAT and works so very well, it's a shame we don't see more 
designs utilizing this method.  These are just a few good reasons:
1.  If the builder does not have the exact required variable cap (and who 
does these days) this properly placed coil tap will allow any "over 
capacitance" cap to tune the desired narrower frequency range the builder 
desires.
2.  LINEAR tuning across the frequency range (vs a series circuit with fixed 
cap and variable capand non-linear tuning).
3.  Less drift
4.  Tap any turn until you find your desired bandwidth tuning
5.  Easy "wind your own" toroids for VFO coil - mistake?  wind a new coil in 
less than 3 minutes.

I've used this method for years and it works extremely well.  In fact it's my 
favorite design to utilize my available variable caps with any given VFO 
circuit! 

 Thanks again to the QRP-L contributor who "quietly" noted this wonderful 
method so oft overlooked or forgotten.
Bill K5BDZ
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