On Dec 25 2009, 8:26*am, Jeffrey D Angus
wrote:
David wrote:
So here’s my question: Building the pre-amp was a fun and useful
project, but is my scope’s performance without the pre-amp typical?

I have one of those...And yeah, sounds like your gain is down a
bit from normal.

Jeff

Yes, I think this is the problem.

I put my oscilloscope on an isolation transformer and placed its probe
across the tank circuit (filter) at the output of the vertical
amplifier that drives the SB-601's cathode ray tube. With the SB-301
receiver tuned to it's internal 100kHz crystal oscillator, I measured
an 80 Volt peak-to-peak swing for a 1/2-inch thick trace, indicating
that the deflection constant for the CRT is about half of what it's
supposed to be. I suppose I could re-engineer the SB-610 to account
for the weak CRT, but it isn't worth it.

-Dave Drumheller, K3WQ