On Jan 19, 2024, at 9:22?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
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I will no longer use any wall warts to supply DC to anything that¡¯s sensitive. I learned the hard way with one of my old Trac CMOS keyers. I had to replace all eight chips and a transistor when the wart failed.?
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
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On Thu, Jan 18, 2024 at 21:45, Evan via groups.io <k9sqg@...> wrote:
As to DC ?wall cubes, test first. ?Some of them have high onset voltage until the regulator kicks in, and some of them are prone to RFI altering the output voltage.
On Thursday, January 18, 2024 at 02:17:48 PM EST, Paul Christensen <w9ac@...> wrote:
I¡¯ll soon be installing a K4DPK VFO stabilizer in my TR-4Cw.? The stabilizer works on 10-14 VDC.? Since there¡¯s no low voltage in the TR-4Cw, I¡¯m curious how others have attempted the supply voltage dilemma,.? Here are some options:
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Use the 12.6VAC filament line and use a well filtered half-wave rectifier and Zener diode.? The stabilizer draws relatively low current so ripple shouldn¡¯t be too difficult to manage;
Use a filtered full-wave bridge rectifier on the 12.6VAC line for better ripple suppression. ?Note that one side of the 12.6VAC winding from the AC-4 power supply is grounded/bonded to the chassis.? As such, a standard two-diode full wave rectifier isn¡¯t easily managed here;
Or as Drake engineers loved, consider hot, power-hungry wire wound resistors to drop voltage on one of the B+ lines.? Frankly, it¡¯s not an option to add even more cabinet heat to a problem that is heat generated in the first place;
External DC wall cube.? This throw-in-the-towel solution and #3 above just aren¡¯t viable for me.? ?
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Other options come to mind?? I¡¯m not keen on anything that uses DC-DC switching regulators no matter how well they¡¯re filtered.?
