There are SS replacements for the 3B28, they were made by International Rectifier, I think the number is IN 2637? The mercury vapor rectifiers posed the biggest X ray threat. But, as William said, you are only running 450volts. The 3B28s would draw 10 amps of filament current. I use 5U4s and 5R4s in Apaches and DX-100s only because they can stand a huge inrush of power. Another application, a Globe King 500B, I did SS the modulator power supply. The stock 816s were priced out of site. I used 3B28s in the RF power supply. 866s look nice, but they are a problem for warming up. They have X-ray radiation, but to what degree of a concern? I guess you will need to get a Geiger counter-hi. Don't put your eyes next to them for any length of time, you might get cataracts. [hell to get old] 73s Russ. ---- William <[email protected]> wrote: > Hello All, > > Ok, it appears there is no x-ray risk as the voltage is too low to create > any... or too low to create any strong enough to actually exit the tube. > > As to why not use solid state or 5U4GB: The only reason I have is my project > uses 807 and 7193 tubes and a non-top cap 5U4GB would look too bald. I > figured what the heck - I found some rectifiers having a top plate cap so why > not use them? Besides, the tube is filled with xenon. Such a noble tube. > > True, I now need to get a separate transformer for their filaments and have > to see if I even have sockets and look around for larger plate connectors and > my electric bill will go up and and and...and the whole shebang might not > even work. But it will still be fun to try. > > If there are any other alternative non-mercury rectifier tubes having top > caps, please let me know. > > Thanks again for all the responses. > > Best Regards, > > William > > > From: [email protected] > To: [email protected] > Subject: Question: X-Rays from 3B28? > Date: Sat, 14 Feb 2015 03:42:24 +0000 > > > > > Hello All, > > Been thinking of using a pair of 3B28 tubes to rectify an output voltage to > around 450VDC. That value is above the critical anode voltage value of 50V, > so that should not be a problem. Current is less than the 500mA max listed > in the table. With the output voltage far lower than the ~1000V values > listed in the table, I think these things would not even break a sweat. > > Two questions for the experts: > 1. Any issue seen operating arund 450VDC? > 2. The tubes have a sticker on the base with a warning regarding x-rays. > Why is there a warning on the tube base but nothing shown on the data sheet? > > I had no idea these would present an x-ray risk based on what I saw (and did > not see) on the data sheet, so I picked up a pair. Perhaps this my learning > experience for the week. > > Have a great weekend! > > Best Regards, > > William > > > _______________________________________________ > Boatanchors mailing list > [email protected] > https://puck.nether.net/mailman/listinfo/boatanchors
_______________________________________________ Boatanchors mailing list [email protected] https://puck.nether.net/mailman/listinfo/boatanchors
