On Sat, 30 Oct 2004 09:59:15 -0700, "Joel Kolstad"
wrote:


I'm not quite following this (I don't know what a 'varactor varacitor is'?).
Something like:

signal -- | | -- || -- gnd

Where | | is the 5pF capacitor and || is the varactor with anode facing
'left'? I'm not following how the 'back to back' configuration works.

Something like this (fixed font):

Vt
+-+
| |
| R
| |
+----||------+---||---+
| | |
| R |
| | |
+----||---+------||---+
| |
| |
+--LLLLLLLL+LLLLLLLLL--+
|
---
Gnd

The cent er of the inductance L is grounded to get ground reference
for the tuning voltage Vt. With a small series capacitance and a large
varactor capacitance, most of the RF voltage is over the fixed
capacitor. The anti-parallel structure should reduce the distortion.
You need to bring the tuning voltages Vt to the varactors through
separate resistors R (or through inductor resistor combinations).

Paul OH3LWR