Date: Sun, 9 May 2010 14:13:30 -
Author: Bernard Cleyet
Subject: Re: Frequency Generator
That is a variation of the original model that created the HP "brothers'" company. The oscillator is a negative feed back twin T notch filter w/ a tungsten positive feed back amplitude control. GR made a more sophisticated (transistorized) model.
I presume your oscillator has a big dial w/ a small one as a reducing drive (friction not gear).
bc has several plus a non-working GR one
p.s. the output should be a trasnformer. On some models one may vary from the 600 Ohms by changing the taps, IIRC. For one lab exercise I introduced an audi matching transformer to obtain a Z of a few ohms.
On 2010, May 09, , at 11:27, Marc Zeke Kossover wrote:
> One person suggested (and I lost the name in an email crash) the HP 240C Oscillator for $99 used on Ebay. I bought that, and it has worked like a dream. It doesn't have a digital display but has dial which doesn't seem to be right on, but is close, and a cheap frequency counter seems to work fine with it.
> It has a nice control knob that lets you adjust the frequency very slowly and precisely.
> It is has quite a bit of amplitude but only a high impedance output.