My Philco 47-1230 has a 5Y3 rectifier tube which seems to run fairly hot when in operation. Would there be any consequences I might experience if I were to use one of these solid-state rectifier replacements being sold on e-bay? Would it run cooler? I wouldn't want to damage any circuits in my radio since it took a lot of time and effort to restore this chassis, but it seems if I could cut down on some of this excess heat it may last longer. The transformer runs cool, but I've still mounted a small quiet cooling fan from an old desktop behind the chassis and behind the two 6V6 output and one 5Y3 rectifier tubes to maintain air flow.
Your fan is likely not needed. These radios are designed to work with everything the way it was.
As far as a SS replacement 5Y3, it would run cooler, but it would also raise the odds of shorting out the input filter because of the instantaneous, unloaded B+ voltage. Ideally, the original tube allows all the other tubes to warm up so that most or all of the load is present by the time full B+ is available.
The heat, if the regime of the radio is what it's supposed to be, is a normal way for a rectifier to run.
The thing is - you will have to dissipate that heat no matter what.
If you replace it with solid state than your voltage due to lower losses will go up, and yes, your rectifier may be cool but those extra volts will make the res of the tubes run hot.
So, you will need to engage a drop resistor to cut those volts. Guess what that resistor is going to do? Right you are, it will get hot.
So, chose your favorite place to dissipate. But you will have to do it.
Short of, of course, taking apart your transformer and reducing the secondary turns, and then engaging the solid state. That will do it. But do you really want to go through that kind of PITB?
I would not recommend using a solid state replacement for the 5Y3.
The problem is that the SS rectifier will increase the B+ voltage. The 5Y3 has a certain voltage drop which was taken into account when the set was designed to provide the proper voltage output. Since the SS rectifier has a much lower voltage drop, the voltage output will be much higher. So although the 5Y3 will not be generating heat, the rest of the radio's parts and tubes will be getting hotter due to overvoltage thereby reducing their life.
In effect, the 5Y3 acts as both a series resistor and a rectifier, which is why it gets so hot.
Thank you all for your informative feedback. I think I'll leave everything just the way it is. As for the cooling fan, BrendaAnnD, in the long run, if I don't have this fan running, the top of the wood cabinet will become quite warm. When it runs, it doesn't. Maybe just to save the finish. I never gave a thought to the tubes warming up together and the SS running instantly.
Hi,
I thought some of those SS replacements available had other components inside to give a 'soft-start- just as a tube would?
(
http://www.webervst.com/ccap.html)
Yes, replacing the 5Y3 with just a couple of diodes you'd get more B+ and you'd have to adjust that,(again, heat dissapation from a resistor) and you still have the instant B+ which a standard tube does not give right away.
Personally, I'd leave the tube in as designed.
As far as your fan, that's up to you. I would have the fan pulling the warm air out, instead of blowing on the tubes. Pulling the ai out might give a better overall airflow to the whole chassis. Remember though, you have to have a source of incoming air.
Agree, keep the 5Y3. It's a reliable tube, and maybe that's why there are still plenty of 'em around.
If there is plenty of space you could always staple a scrap of attic insulation on the inside top of cabinet to reduce heat. Yup, just the opposite of the normal usage. Anyway a little fan does no harm.
Also remember: there is no such thing as a noiseless fan.
Also fans in continuous operation tend to fail aftr a few years and they become noisy pretty quickly.
I would go for:
1. keeping the tube,
2. Slapping a piece of a heat insulator under the top (there's that nice one, with foil outside and the insulation inside).
And in those big floor radios the back is open so plenty of air inside.
I have the fan set up that it only runs when the radio is switched on, so it really doesn't run continuously. It does seem to keep everything much cooler. That 5Y3 does get as hot as an incandescent light bulb. One of the hottest running tubes that I've come across in any of my old radios. The foil backed insulation is a good idea, and something I didn't think about. I'm going to give it a try.
Hi, the 5Y3 will run hot , just by the nature of it. Same as an incandescent bulb, that's about right. If you have red glowing plates though, you may have other troubles
I have not made any readings, but some of the mini tubes like the 35W4 and 50C5, to me at least, seem to run hotter.
The insulation doesn't have to be too thick, the idea is to dissapate the heat over a wider area, compared to just above the tube.
No, the plates inside the tube are not glowing red and all voltages are within range. I was worried that all that heat might damage something on down the line, like damage to the tube socket or burned wires underneath. I haven't experienced any trouble like that so far, but just trying to be better safe than sorry.
Take a look at the inside of the cabinet. If there's no burned or badly discolored spot above the tube, then heat's not a problem. After all, this set is over 60 years old, and if heat were a problem, it would have shown up long ago.
As a rule the tube filament is well inside the envelope of the 5Y3 above the tube socket, so all of the heat rises. In fact the filament pins do not even get warm. If you want to see a hot running tube check out a 50Y6 rectifier or a 6BG6 horizontal output tube, I'm not counting ballasts as those are not really tubes but resistors.
Regards
Arran
I don't count any tube as "HOT" if I can pull it by holding onto its base immediately after turning the device off.
I have a 47-1230 too.
The 5Y3 DO run burning hot. (BrendaAnnD: you WILL burn yourself if you try to unsocket the 5Y3 without waiting several minutes - we're talking seriously hot here)
The cabinet becomes warm (not hot)
The radio was designed with that in mind: the socket will withstand the heat. Its been doing it good for 70 years already.
Heat won't get inside the radio, by nature. Its plain physics. Heat rises. Goes into the big area, and into your cabinet. As Arran pointed out, the tube's pins won't even get warm.
If you are mainly scared for the chassis.... don't. Those things are heavy duty.
If you are mainly scared for the cabinet... I could understand the concern, but I don't think there's a problem there either. The top of the cabinet is where all the 5Y3 & 6V6s heat goes, you can feel it. It doesn't seem normal - I even asked if it was "ok" on these phorums when I started to work on my 1230...
but, When I refinished my cabinet, the top of the cabinet was the single place with the less damage to its finish. The front of the cabinet had chips, the sides had marks, scuffs, and what I assume was UV damage from 70 years of sun exposure, the round areas had lost lacquer in a not so good looking manner... but the top of the cabinet was pretty much intact.
I don't think that mild heat is a big source of concern over lacquer, compared to scuffing or permanent sun exposure.
Now, keeping heat away can't do much harm either. I didn't think about doing that (being told that this heat was normal...)
I am curious as how you did it.
If I was to do it, I'd get a 80mm 6VAC fan and connect it directly to the chassis trough the phono lamp wire. That might have to do with the fact I have no phono lamp and these wires are loose on my chassis...