• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Data for 6RA3

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#2
6R-A3 was originally designed for the regulator tube for the PSU.
It`s specification is similar to 6R-A2.
6R-A3 was produced by Toshiba and NEC.

Specification:
Heater: 6.3V/1.0A
Maximum plate voltage: 250V
Plate dissipation: 15W
Maximum plate current: 125mA
Amplification factor: 3
Transconductance: 12500
Plate resistance: 240 ohm
Hiro
 
#3
Thank you. Are you sure its rated at 15W though? It's the same bulb size as tubes like the 6BM8, which has a total max dissipation (both anodes + screen) of 8W, or the 6CW5 which has a max dissipation of 10W.

Do you have the heater-cathode voltage rating?
 
#9
Emailing is described in the FAQ, but seems to be disabled on this forum. However, by clicking on the Post Reply button (ie do not use quick reply), you can attach files to a post, up to only 195 KB for bitmaps, but up to 976 KB for jpeg's or pdf's. That seems quite adequate for datasheets.

Can you please use this method? If the datasheet is larger than 976 KB, can you break it into 2 or more segments, and use 2 or 3 posts?

Best Regards,
Keit
 
#11
According to my copy of Philips Technical Data, 7th Edition (1967), the max allowable plate dissipation for 6CW5 is 10W. However, for comparison with other tubes of the same bulb size, I should have added the screen dissipation, which is rated at 1.75W, giving a total of approx 12W. However, the 1968 RCA Receiving Tube Manual gives the max plate disspation, when used in audio power stage service, as 14W.

Since my first posting, someone refrered me by private message to Issue 16 of Vacuum Tube Valley, which states on page 12 that the max allowable plate dissipation of the 6RA3 is 12W.

We all learn something every day, especially me!

I hope SVStube posts the data sheet, as the VTV article gives limitted information without a traceable reference.

Keit
 
#12
Keit said:
Emailing is described in the FAQ, but seems to be disabled on this forum. However, by clicking on the Post Reply button (ie do not use quick reply), you can attach files to a post, up to only 195 KB for bitmaps, but up to 976 KB for jpeg's or pdf's. That seems quite adequate for datasheets.

Can you please use this method? If the datasheet is larger than 976 KB, can you break it into 2 or more segments, and use 2 or 3 posts?

Best Regards,
Keit
Click to expand...

File size 1312 KB. I break it into 2 parts RAR or ZIP. Files are not loaded, the loader writes "Invalid file"
 
#13
You should use one of the file formats listed - zip is listed but not rar. An alternative is to edit it in a graphics editor (Windows Paint will do) to break it into two parts. Alternatively, use an application intended for editing/resizing/restoring photgraphs such as ArcSoft Media Impression to reduce the file size. Usually this will not noticeably affect readability when not resizing too much.

Keit
 
#17
The circuit uses the output transformer to the cathode winding. Transformer can be used without it.
The amplifier has a very good sound. Instead 6R-A3 can be used 6S19P, but the sound will be a little worse.
 

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