Jim, the websites that you gave cannot be downloaded. Thank you.
Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com ----- Original Message ----- From: "Jim candela" <[EMAIL PROTECTED]> To: <amradio@mailman.qth.net> Sent: Wednesday, November 19, 2003 12:26 AM Subject: [AMRadio] Screen Regulator Circuits, 20a, etc. > > > Hi Guys, > > I have been working on two HV regulator circuits in the past year where I > needed +375 volts at up to 100 ma. In the first case I had 600 volts to > start with, so I used a tube circuit. In the second case, all I had was > about +430 which dips to about 390 at maximum output, and reduced AC line > voltage, so I went solid state. > > My two circuits are here: > > Tube version: > > http://pages.prodigy.net/jcandela/CentralElectronics20AModifications/CE_20A_ > QRO_Power_Supply.jpg > > Solid State version: > > http://pages.prodigy.net/jcandela/Sherwood_S8000/HV_REG/SS_HV_VOLTAGE_REGULA > TOR.jpg > > The first circuit shows my complete power supply in my Central Electronics > 20A QRO #2 rig. I used a pair of 7591's in the RF final to make up to 12.5 > watts AM output, or about 55 watts PEP SSB output. I ended up with a 6W6 in > the series regulator as it had more emission than a 5V6, even though the 6W6 > only had 5 1/2 volts on the filament. This regulator is always at +374, hot, > cold, month after month. The ripple from it is unmeasurable (with my > equipment), and dynamic load response is excellent, although I cannot > remember exactly what the results were, as that was last winter. The rest of > my 20a info on the web is at: > > http://pages.prodigy.net/jcandela/CentralElectronics20AModifications/ > > > The second regulator circuit is much simpler, and cheaper to build, and the > performance is similar with one big exception. The regulator only needs a 15 > volt delta input to output, whereas a 6W6 at zero bias triode connected > needs closer to 100 volts (and that is saturated, i.e. no regulation)to pass > 100 ma. The main drawback is that the solid state circuit is not adjustable. > You have to get a string of zeners to add up to the desired output voltage. > This is no big deal though. You can buy from Mouser (www.mouser.com) the 1 > watt zeners series (1n47xx) for about 15 cents each in packs of 10, and they > carry them up to 200 volts, although I prefer to go no more than 100 volts > per zener for power dissipation reasons. For folk with higher input > voltages, there are higher voltage fets that can pass 900 volts or more, so > that isn't a big problem. The one I use is rated at 500 volts, and can be > had for about one dollar. To keep the power dissipation down, add as much > series "R" into the regulator input so that you have slightly greater than > 15 volts across the regulator circuit shown at maximum load current, and > minimum ac (brownout) voltage. The opto coupler in this circuit has a > Darlington transistor, and the CTR (current transfer ratio) is very high, > hence the excellent closed loop regulation. Reduction of power line ripple > is > 40 db. With only 1 ma through the zeners, the zener warm-up drift is > about 1-2 volts rise. Keep in mind that this solid state regulator is still > a work in progress, and still populates a proto-board on top of my Sherwood > 30+30watt stereo amplifier with 4 X 7868 output tubes. I designed the > circuit to be short circuit proof with the intention that if the output were > shorted, the Sherwood fuse would pop before anything fried too bad. I have > been way "too-chicken" to try this feature out. Maybe one of you brave souls > can perform this test using components bought from your very own checking > account! > > These circuits can find there way into all sorts of AM equipment...I hope > that somebody tries one of these circuits and then asks me "why didn't you > do this _____ instead" > > Regards, > Jim Candela > WD5JKO > _______________________________________________ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio > > _______________________________________________ > AMRadio mailing list > AMRadio@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/amradio
