They also make 1000v 3 amp diodes, I got a bunch on line once, quite cheap. That is a lot of current....
Brett ----- Original Message ----- From: <[email protected]> To: <[email protected]> Sent: Sunday, October 04, 2009 4:22 PM Subject: Re: [AMRadio] Solid State 575 mercury vapor RectifierReplacementsneeded > >My understanding is that they no longer require the equalizing >>resisters and caps across them as the reverse current is similar to >>avalanche diodes, they are so cheap now that you >>can just stack 20 of those rascals. > > Yep, that's been my experience too. I prefer to use diodes that are > all from the same "run", at least bought at the same time, so that the > diodes are similar to one another. But that precaution may not be > necessary. > >>If one ... needs more than one amp, it is very easy, >>just build two stacks and add a little resistance in series with >>each stack before connecting them in parallel. the resistance nearly >>balances the load between each stack as the drop across the resistor > is much >>more than the drop across the diodes. ten Ohms should work fine. > > Excellent point about putting strings of solid state diodes in parallel > for higher current capacity. > > Steve WD8DAS > > [email protected] > http://www.wd8das.net/ > --------------------------------------------------------- > Radio is your best entertainment value. > --------------------------------------------------------- > > > -----Original Message----- > From: Bernie Doran <[email protected]> > To: Discussion of AM Radio in the Amateur Service > <[email protected]> > Sent: Sun, Oct 4, 2009 9:31 am > Subject: Re: [AMRadio] Solid State 575 mercury vapor > RectifierReplacementsneeded > > > > > > > > > > > Hi Steve: I have used the 4007s many times. My understanding is that > they no > longer require the equalizing resisters and caps across them as the > reverse > current is similar to avalanche diodes, they are so cheap now that > you > can just stack 20 of those rascals. some one needs to check that. also > if > one is concerned about forward current and needs more than one amp, it > is > very easy, just build two stacks and add a little resistance in series > with > each stack before connecting them in parallel. the resistance nearly > balances the load between each stack as the drop across the resistor is > much > more than the drop across the diodes. ten Ohms should work fine. > Bernie > W8RPW---- Original Message ----- > From: <[email protected]> > To: <[email protected]> > Sent: Sunday, October 04, 2009 10:04 AM > Subject: Re: [AMRadio] Solid State 575 mercury vapor > RectifierReplacementsneeded > > >> I've made my own solid-state plug-in replacement rectifiers for a >> variety of tube types. I look up the tube specs and select > solid-state >> diodes that stack up appropriately for current and forward and reverse >> voltages. I usually end up using either 1N4007s or 1N5408s. From >> on-lline sources like Digikey or Mouser or All Electronics the diodes >> are very inexpensive, ten cents to maybe 30 cents each. >> >> I put the diodes on a rectangular piece of perfboard sized to fit >> upright with its bottom end tucked within the sides of the base of the >> defunct tube it is replacing. A small L bracket holds it in place. >> >> If you use diodes from the same "run" (which is easy if they are sold >> on the paper tapes used by manufacturers today) then I find no >> equalizing components are needed. I add a few more diodes than the >> calculated voltage required for an extra measure of safety and have >> never had a failure, even in broadcast rigs on the air 24/7 with lots >> of lightning and power bumps to deal with. >> >> You can expect somewhat higher voltage from the new stack than the >> original tube rectifier - if that is a problem for the rig, then add a >> series power resistor to simulate the internal voltage drop of the >> earlier tube. So far I've only needed to do that once when the new >> higher B+ exceeded the rating of the by-pass caps in the other > sections >> of the rig. Otherwise the rigs seemed to thrive on the higher > voltage. >> >> Steve WD8DAS >> >> [email protected] >> http://www.wd8das.net/ >> --------------------------------------------------------- >> Radio is your best entertainment value. >> --------------------------------------------------------- >> >> >> >> ______________________________________________________________ >> Our Main Website: http://www.amfone.net >> AMRadio mailing list >> Searchable Archives: > http://www.mail-archive.com/[email protected]/ >> List Rules (must read!): http://w5ami.net/amradiofaq.html >> List Home: http://mailman.qth.net/mailman/listinfo/amradio >> Post: [email protected] >> To unsubscribe, send an email to [email protected] with >> the word unsubscribe in the message body. >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: > http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > > > > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. 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