Check this massive rectifier I just got

thehoj

Member
Messages
63
http://i.imgur.com/0sEbN0P.jpg?1

Can't believe the size of this military-grade 5R4 rectifier.. Just had to post a picture of it. works great in place of a 5Y3, similar specs.

It's beside a few other common tubes for comparison.
From left to right: 12ax7, 5y3gt, 5v4g, 5r4wga
 
Messages
14,366
I have some of those, just never seem to think of anything to use them in.

Be careful, the max capacitor value recommended for those is 4uf.

I have seen diy HiFi schematics that use bigger values, though still not as high as you might like without then following it with a massive(expensive) choke.

They probably work fine in small guitar amps that aren't otherwise going near the other design maximums.
 

Blue Strat

Member
Messages
30,686
I have some of those, just never seem to think of anything to use them in.

Be careful, the max capacitor value recommended for those is 4uf.

I thought the spec said 8uf, which is STILL wrong.

100s of these sold (5R4s in general) and used in amps with 20-40uf. Either they didn't think anyone would ever care, someone dropped a zero, or it was just a bad day. If you've ever worked for a company, with people, you know what I mean. ;)
 

pdf64

Member
Messages
8,926
I've seen it explained that these were intended for military / aerospace applications in which the ac power frequency to be rectified would be several hundred Hz, rather than 60.
In which case a few uF would be more than adequate as reservoir and minimise stress on the tube.
Also seen people advising that later info had much higher reservoir cap max values, though no scans to prove it.
Pete
 

thehoj

Member
Messages
63
I have some of those, just never seem to think of anything to use them in.

Be careful, the max capacitor value recommended for those is 4uf.

I have seen diy HiFi schematics that use bigger values, though still not as high as you might like without then following it with a massive(expensive) choke.

They probably work fine in small guitar amps that aren't otherwise going near the other design maximums.

As others have mentioned I think the datasheets list 4uF as a typical capacitor rating, not necessarily max.

I read through a number of threads talking about people running 40uF with no problems. I've got a 22uf cap, and I'm not overly worried about it. I've got two of these and they were cheap. I'll see how it goes.

Here's a pic in the amp.. The thing barely fits in there.
http://i.imgur.com/QZLX8QV.jpg
 

drbob1

Gold Supporting Member
Messages
30,114
I've been using one as an alternative in an Emery Superbaby for a while, off and on, with no trouble. I'm sure I've got more than 8uF in there...
 

Baxtercat

Silver Supporting Member
Messages
12,751
Wonder why they designed such a big base on those.
0sEbN0P.jpg
 
Messages
14,366
I thought the spec said 8uf, which is STILL wrong.

100s of these sold (5R4s in general) and used in amps with 20-40uf. Either they didn't think anyone would ever care, someone dropped a zero, or it was just a bad day. If you've ever worked for a company, with people, you know what I mean. ;)


Good to know.

I have been apprehensive about using them, because of what the data sheet says.

The few I have are pretty much the only nos old rectifiers I have. I should probably build something to take advantage of them.
 
Messages
14,366
I've seen it explained that these were intended for military / aerospace applications in which the ac power frequency to be rectified would be several hundred Hz, rather than 60.
In which case a few uF would be more than adequate as reservoir and minimise stress on the tube.
Also seen people advising that later info had much higher reservoir cap max values, though no scans to prove it.
Pete

Aha, makes sense.

I know I have seen diy hi fi schematics using these with 20-40uf. I wasn't sure if it was sensible or people being daredevils.
 

trobbins

Member
Messages
382
The point to note I think is that the valve has such a high voltage rating. As such, for the stated effective source impedance (125 ohm) the peak hot-switching transient current stays within a certain limit. And so with that stated effective source impedance, there is a relatively low capacitance of 4uF for which the maximum repetitive peak current level is reached for the stated load resistance or current.

The RCA datasheet shows a graph representing the max loading with heater and plate voltages applied at same time, or delayed. That indicates the influence of supply voltage on the peak current stress. I'd be thinking that most applications nowadays would use a relatively low supply voltage, and hence a larger filter capacitance may not end up causing short term problems depending on the effective source resistance.
 

bluesky636

Member
Messages
3,283
I've seen it explained that these were intended for military / aerospace applications in which the ac power frequency to be rectified would be several hundred Hz, rather than 60.

Aircraft AC is typically 400 Hz. If you've never heard a 400 Hz cooling fan, you haven't lived. :omg
 

'58Bassman

Member
Messages
4,935
I thought the spec said 8uf, which is STILL wrong.

100s of these sold (5R4s in general) and used in amps with 20-40uf. Either they didn't think anyone would ever care, someone dropped a zero, or it was just a bad day. If you've ever worked for a company, with people, you know what I mean. ;)

How can you say that? People don't make mistakes, it's all computer errors, right? People are perfect- just ask them.
 




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