6-Jul-2004
Completed drive circuit:
Note that the drive circuit shown here is the "alternate" circuit as shown on page 22 of the QEX article and not the drive circuit shown on the full schematic. That drive circuit requires an input signal at 4F which my DDS exciter cannot do.
4-Jul-2004
Drive circuit under test -- and no, this is not my only scope :)
21-Jun-2004
The completed power supply:
1-Jun-2004
Work on new amp begun last week. With little to post at this point, and wanting to show you something, here is a picture of what I have so far. This board will be the power supply -- power for this project consists of rectified and filtered 240V mains providing about 340 VDC to power the amp:
Yet to populate this board are 4 x 1000 uF 200 V electrolytics, a 20 VA PCB-mount transformer to drive the smaller bridge, a 7815 and its heat sink, a relay and some resistors. Since I didn't have the big filter caps on hand, and was going to have to buy them anyway, I ordered Cornell Dubilier 380LQ series caps; these are high ripple and average 27% smaller than their 380L series. These are only 25mm in diameter which will just fit on this tiny board I chose. The larger bridge in this picture is much larger than it needs to be -- this is a 25A 400 PIV model, and the amp will only draw about 4A typical -- this is just what I had on hand. Most of the parts you see here were lifted from switch-mode power supplies from old Sun and DEC servers.