I completely agree, and said so at the outset. Best,
-John =============== > As I said its slowly seems to be pumping down. > Let it go for 2 weeks. > I have had to do that with travelling wave tubes... > Cost $2 for electricity. > If that doesn't work go for the big guns. > > > On Sun, Jan 17, 2010 at 5:03 PM, J. Forster <[email protected]> wrote: > >> I just looked at eBay and most everything suitable is well over $200. >> >> -John >> >> ============ >> >> >> > The small Bertan modules in particular are extremely stable and >> > well-behaved. You get exactly the voltage that you program, accurate >> to >> > within about a tenth of a percent. No spikes, no drift, and no >> obnoxious >> > AF >> > whine like you get from the HP modules. >> > >> > The smaller ones are good for 500 uA, and the larger modules are good >> for >> > 2-5 mA depending on model. >> > >> > -- john, KE5FX >> > >> >> -----Original Message----- >> >> From: [email protected] >> [mailto:[email protected]]on >> >> Behalf Of J. Forster >> >> Sent: Sunday, January 17, 2010 8:00 AM >> >> To: Discussion of precise time and frequency measurement >> >> Subject: Re: [time-nuts] 4 KV Power Supply Recommendations >> >> >> >> >> >> The small modules are nice, but many PMT supplies do not go to 5 mA. >> 5 >> >> mA >> >> @ 4 KV is 20 Watts output, more at the input. That's a lot for a PMT >> >> supply. >> >> >> >> Also, remember that some supplies designed for gas lasers have a HV >> >> "kick" >> >> at startup that may go to 20-30 KV. >> >> >> >> -John >> >> >> >> ============== >> >> >> >> >> >> > >> >> >> Since it appears to be making some progress, I'd be tempted to >> just >> >> >> continue. The pump rate of an ion pump varies with the current, so >> it >> >> >> seems you are pumping, just somewhat more slowly than w/ the >> external >> >> >> supply, as long as you are not overloading the internal supply. >> >> >> >> >> >> If you don't have a lab supply, get an old transformer from some >> >> vaccum >> >> >> tube gear and use the HV secondary to drive a Cockroft-Walton >> >> multiplier >> >> >> to get to what you want. Pretty trivial to build these days. Put >> the >> >> >> primary on a Variac to adjust the voltage. >> >> >> >> >> >> BTW, a commercial supply at that voltage and current is going to >> cost >> >> >> several hundred dollars. >> >> > >> >> > The nicer Glassman rack-mounted supplies are spendy, but smaller HV >> >> > modules >> >> > for PMT and laser work are common and inexpensive. Go to eBay >> >> and search >> >> > for "<manufacturer> supply", where common manufacturers include >> Emco, >> >> > Bertan, Spellman, Fluke, and Glassman. E.g. item 220539685243 . >> >> These >> >> > smaller modules tend to sell for well under $100, and are handy to >> >> have >> >> > around. >> >> > >> >> > -- john, KE5FX >> >> >> >> >> >> >> >> _______________________________________________ >> >> 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. >> >> >> > >> > >> > _______________________________________________ >> > 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. >> > >> > >> >> >> >> _______________________________________________ >> 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. >> > _______________________________________________ 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.
