[hpsdr] Added Line-In Gain Selection of Janus/Ozy With SDR 1000

[joetorrey at cablelynx.com]

I added the ability for selection of the Line-In gain by the selection of
different pairs of resistors that make up voltage divider circuits at the
Janus line-in unbalanced inputs behind the 39 kohm resistors before the
Janus op amps. I read an article by John Eckert that he posted on HPSDR -
6/7/07. I used 1 kohm and 2.2 kohm resistor pairs. The selector switch
used has two selections with center off which selects Janus mounted dpdt
relays. This gives me the ability to select low (1 kohm), medium (2.2
kohm) and high (off - single 39 kohm  @ normal unbalanced input) depending
on the band and noise level. I tested other values and these seemed the
best. John mentioned the use of the 1 kohm resistors in his article.
Instead of just installing the single resistors I wanted the ability to
choose basically the IF gain depending on the band conditions.

Joe
WD5Y