From: "Terry Fritz"
Date: Sun, 04 Feb 2001 00:04:44 -0700
Subject: Re: [TSSP] 50 ohm Generator hookup
Hi, >What I really >need to do is pull off the winding and insert a copper foil ground shield >between the two windings (being careful not to make a shorted turn). Just >wanted to point this out to others that may make one of these. > I added the foil shield to the transformer and it decreased the current leakage 1000X!! The primary to secondary current is now far down in the noise. I am surprised how well it worked! I also ground the near winding. I took some quick measurements of a 498.32 ohm resistor with the new box: F (kHz) V I R Error % 10 0.500008 1.00143 497.35 -0.19 20 0.500013 1.00140 497.37 -0.19 40 0.500068 1.00121 497.52 -0.16 100 0.500083 0.99956 498.35 0.01 200 0.500010 0.99352 501.31 0.60 400 0.500050 0.97354 511.64 2.67 1000 0.500081 0.85668 581.47 16.69 I could probably get even closer with a few correction tables, but the box works great without any correction other than for the 9.961 ohm current sense resistor. I corrected Vin for each reading and disconnected the V cable for the current measurements. I will play more with correction factors tomorrow and look into what that long cable may do to things but the box is now working great after rebuilding the transformer 4 times :-)) Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.