RECTIFIERs replaced with DIODEs - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: RECTIFIERs replaced with DIODEs (/showthread.php?tid=9582)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: RECTIFIERs replaced with DIODEs (/showthread.php?tid=9582)
RECTIFIERs replaced with DIODEs - Bradley Rush - 05-19-2014
Is there any info (book or link) that shows you what diodes(Solid State) can replace the various Tube Rectifiers? I have seen the links on the 5Z3 and the 80.
RE: RECTIFIERs replaced with DIODEs - morzh - 05-19-2014
There is plenty of info on forums.
Basically you do not want just to replace (the diodes like 1N4007 can be used) - you also need a resistor to emulate the tube rectification.
Another thing is, it takes time for the tube to warm up and diodes are instant, so if there is some reliance upon tubes being hot at the same time as the rectifier, this is not the case anymore and the high voltage will be present before the load is applied to lower it.
RE: RECTIFIERs replaced with DIODEs - tab10672 - 05-19-2014
There are youtube videos where it is done
RE: RECTIFIERs replaced with DIODEs - Bradley Rush - 05-19-2014
I watched the youtube on the 5y3 very interesting. He did take into account the secondary windings and what is needed on the B+. I just thought there was a book for RADIO repair to show how each rectifier tube would be replaced. I looked at the 83, 5y3 material available. Most of this talks about tube testers. Not interested in re-inventing wheel design. This would allow me to know if a RADIO had a bad rectifier tube in a radio I can get the radio going.
Morzh which forums? I just got into the RADIO museum.org they are mailing me my password.
tab10672 are there any different tubes on youtube other thn the 5y3 one?
RE: RECTIFIERs replaced with DIODEs - tab10672 - 05-19-2014
I think the 5y3 is the one I watched where he had to add extra resistance, I dont think others would be any harder you would just need to know the drop of the radio in question to figure what resistance to use.
RE: RECTIFIERs replaced with DIODEs - morzh - 05-19-2014
I do not remember which exactly, but I remember reading it when searching for something else: people discussed how to substitute diodes for tubes. Try to do context search on the web, I am sure it will give you something.
RE: RECTIFIERs replaced with DIODEs - Arran - 05-19-2014
Other then a few books I have on selenium rectifiers, I haven't seen anything specific about how to replace a given type of tube rectifier, like a 117Z6, 35Z5, with a solid state one. In the case of a 5Y3 I wouldn't even bother, it's a common enough tube that there really isn't any advantage in using a solid state substitute, unless you want higher B+ voltage. Generally speaking when someone is talking about substitute rectifiers it usually involves replacing a worn out selenium rectifier with a silicon rectifier, selenium rectifiers have a higher forward drop then silicon but they are still instant on.
To mimic the operation of a tube one would have to use a current limiter or a thermistor, although with a directly heated tube rectifier they are still almost instant on. The last time I substituted a tube with a silicon rectifier was to replace a 117Z3 in a weird post war radio/phono combo unit, since it was 117 volts (120 volts) it ran directly off the power line.
The other time I substituted a tube with a silicon rectifier was in a brand Z three way portable because I did not have a 117Z6. I needed to add a dropper since the battery tube filaments are run in series with the B+ supply, but the instant on aspect did not matter since battery tubes are pretty well instant on as well.
Regards
Arran
RE: RECTIFIERs replaced with DIODEs - codefox1 - 05-20-2014
Aye, when tubes are cheap, why buy a cow?
Note well very helpful comment about portables. Replacement rectifier or not, higher mains voltages today invariably raise the filament string voltage a bit more than I am comfortable with, although the rest of the voltage divider somewhat less of a problem.
RE: RECTIFIERs replaced with DIODEs - K7Sparky - 05-21-2014
Depends on whether you are replacing a regular or mercury vapor rectifier.
The MV rectifier has a relative constant forward voltage drop like a SS device. Around 12V as I remember. A resistor will not be your friend. If you want to be weird put a batch of diodes in series for forward drop or add a couple of 5W zeners you will need to check output current to spec. to size the wattage. I ignored the extra 12V of B+ the few times I used silicon.
I feel much the same about regular rectifier tubes as well if there is not a design reason for voltage roll off with current. Which I don't ever recall seeing. Not much of a chance of roll off needed in a radio.
Hickok TT and the like are a special cases as they use a rheostat in series with the transformer primary and every amp down stream has an effect. Might be worth looking into a TRIAC frontend regulator for the TT rheostat. Anyone thought about or tried it? If there is much interest or discussion a new thread?
You can always pull all the other tubes and see a max B+. B+ will be lower with the tubes plugged in. About the only thing I might look at is the screen voltage of the audio output and not be too picky.
You can calculate the max B+ current (forget adding screen current - it is lost in the decimal point) and install a temporary bleeder if it makes your antenna rotate or just for the education factor before plugging the tubes back in.
I like the glow of the tubes, especially the MV purple / blue so I stick with tubes most of the time.
Any tube that runs in a series filament chain like the 35Z5 is another beast. The filament pins need to be bridged with the HOT resistance of the filament. A decade resistance box with a current rating as high as your filament current is your friend. Start with too much R and turn down to get 35V and add a resistor close in standard resistance with plenty high W rating. Resistor should be same / close to Hot resistance from a data book.
As Codefox says mains are higher today If you replace a 35Z consider using a resistor for about 45V or higher hot filament drop. That will do the rest of your series tube filaments a BIG favor.
High filament voltage is a top tube killer and REALLY BAD for outputs.
OK, shorted caps can kill your rectifier if you don't add a AC line fuse.
The flip side is weak tubes will get "new life" with high filament voltage. OH DRAT! nothing is absolute
There were LOTS of 35Z & 50C tubes at Dayton last week. Many in the $1 to $2 range. Not rare why bother? Must be a hamfest in your neighborhood to look for fleas at.
Selenium rectifiers are easy to restack to repair. Get a hand full of different plate dimensions as you can find them cheap. Count the plates on your original and stack one with the same number of plates. It is often possible to do a bit of scraping and air dry varnish to repair a bad plate or 2 or center tube on your original. May need to wiggle the plate to plate contacts during assembly. Plate area is current rating. I guess these days you need to be aware that Selenium is not good for you so take whatever precautions deemed prudent.
Line voltage today is held close to 120V. Vintage radios worked with a wide voltage variations as that standard. I remember 110 as normal and 100 regular low. Don't loose the trees for the forest. You're trying to make a vintage radio work and LAST not build a top fueller.
RE: RECTIFIERs replaced with DIODEs - TV MAN - 05-24-2014
I kinda like the idea of tubes in a tube radio. With Ebay, you can get about any obsolete tube you need and oft for a good price. I tried a diode replacement for a selenium rect before I knew I needed a dropping resistor - promptly blew out the aged filter cap. There IS something about the glow of those tubes inside instead of the darkness of about everything modern.
My 2 cents..
RE: RECTIFIERs replaced with DIODEs - David - 05-25-2014
Compare a Hallicrafters S-38E to a S-120 to see how it was done in a factory built set. I like tubes got rid of my S-120 years ago. David
RE: RECTIFIERs replaced with DIODEs - K7Sparky - 05-26-2014
David
Thanks for the lead. Was interesting to see how Bill Halligan or more likely Bob Samuelson or Bill jr solved it.
RE: RECTIFIERs replaced with DIODEs - David - 05-27-2014
You are welcome. Two more to look over a Philco Model B956 (Riders 23) and Zenith Model T825F, G, andR Chassie 8T01 (Beitman 1955). I have both sets enjoyed fixing them both the Zenith was my first am/fm the Philco my 3rd am/fm set. Replaced the selenium with a in4007 in both and added app 50-100 ohm resistor sorry for not knowing the exact value I used. Reduce my line voltage to 105-110, mains run 119-124.8 from FPL. David