[Elecraft] VW PTO

[Bill Coleman]

On 3/17/02 8:00 PM, Ron D' Eau Claire at rondec@easystreet.com wrote:

>Usually, the permeability of the inductor is changed by moving a
>powdered-iron core into and out of the inductor using some sort of screw
>mechanism that allows for very precise positioning of the core.

The key feature of a PTO is that, over a certain range, the change in 
frequency very linearly follows the change in core position. This is more 
difficult to achieve with a capacitively-tuned design (usually calls for 
specially shaped capacitor plates).

Before the introduction of very stable (but not necessarily quiet) PLL 
synthesizers, PTOs were very common. 

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901