[Lowfer] JFET (J310) Biasing

[Clive S Carver]

I am curious of the pro's and con's of three different ways of biasing a
J310 for use as an e-Probe front end stage.

1. For example, the PA0RDT mini-whip uses two 1Mohm resistors in a potential
divider across the +12ve to ground supply, with a third 1Mohm resistor
between the potential divider mid-point and the J310 gate.

2. Some designs omit the third 1Mohm resistor referred to above, and connect
the potential divider mid-point directly to the J310 gate.

3. I have also come across a design where there is a single 1Mohm resistor
between the +12ve rail and the J310 gate.

So, what are the advantages/disadvantages in the three methods (besides
using less 1Mohm resistors!).

73's

Clive
GW4EYO