"rickman" wrote in message
...
On 10/19/2015 3:34 AM, Brian Howie wrote:
How does the coil affect the tuning range of the cap? A cap is limited by
the ratio of the minimum to maximum capacitance. The ratio of frequency
is limited to the same ratio.
In a multiturn loop you get huge capacitance between turns.
For a given variable capacitor it appears in parallel.
The Q of that big coil might be higher but as you need to add
fixed capacitors to the variable one to get useful tuning range
you loose almost what you gain.
I saw descriptions using a 128 pairs telephone cable and spending
several days to wire it as a 256 turns loop.
A bad idea IMHO.