how to bias a Ge transistor in a rangemaster

[mordechai]

I have just built a rangemaster circuit with a 2n1309 transistor (low leakage, Hfe 115) and got a GREAT sound out of it, really almost indistinguishable to the OC44 I had in the socket.  I have one 10KN bias pot and one 100KB bias pot, and I've dialed in just the right sound.  So I'm guessing the transistor is now properly biased -- now, how do I use my DMM to measure the voltages on the CBE of the transistor, and what value should I expect to find if it's biased right? 

Also...in measuring the pots to determine what value they're actually at, which probe from the DMM (red and black) do I place on lug 2 and lug 3 (both of which are wired to the breadboard points)?  This is a PNP circuit if that helps...

[joegagan]

rg's article on the rangemaster refers to -6.9 to -7.1 v measured between collector to ground as ideal if i recall. if you already like the way it sounds, you are doing great.

i found rg's biasing method to be a good way to sort out which ge trans i liked, as the different sounds and gains would become apparent on the even playing field of the 6.9 bias.

are you using a 100k trim in place of the 68k base to ground R in  the rangemaster?

[mordechai]

Yes...I have a 100KB pot standing in for the 68K fixed, and a 10KB pot standing in for the 3.9K.  I'm finding that I have a wider range of usable signal with the 100K pot than with the 10K pot...the latter produces a usable tone pretty early as I turn the shaft and then remains pretty stable in terms of tone.  The 100K pot has, but not much more, of a spread where different degrees of aggressive tone can be dialed in before the sound fizzles out altogether.