I recently acquired a Symmetricom 8040C Rubidium Standard, hoping to use one of my Thunderbolt GPSDOs to further refine its 10 MHz output. To my surprise, connecting the 1 PPS output to the 8040C did nothing- the "1 PPS SYNC" indicator stayed dark. I hooked up my other Thunderbolt and got the same result.
The power supply I was using to run the Thunderbolt was a Hviele T-30B switching supply made in China, that came with one of the Thunderbolts. It appears to be well-made, similar in quality to those made by Mean Well, and it puts out +5 VDC at 3 A, +12 VDC at 1 A, and -12 VDC at 0.5 A. Either Thunderbolt works perfectly on this power supply, but I only used the 10 MHz outputs. When I looked at the 1 PPS outputs with a 'scope, I could see that the 1 PPS was riding on a 5 or 10 Hz noise. Since two working Thunderbolts had the same noise problem, I suspected that the power supply had a spurious output. I hooked up a linear triple-output bench supply to run the Thunderbolt, and now the 8040C locked up perfectly on the 1 PPS signal. Since I don't want to tie up one of my bench power supplies to run the Thunderbolt, I plan to try adding some filters to the outputs of the T-30B switcher. I'm thinking that some low-ESR tantalum capacitors might do the trick. Rather than re-invent the wheel, I wonder if others found this problem, and what their solution was. I also wonder if this T-30B power supply requires a minimum load on any of its outputs, for it to operate properly. Hmmm. 73, Eric Lemmon WB6FLY _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
