Attention: This is an export Price List, valid for companies in the European Community with a VAT Identification number, and for companies or private persons outside the European Community. Inside Europe, please ask for a quote, including 19% VAT tax.

Please also check in the price list under NOS! Not all tubes in the price list are pictured or mentioned here.

5687 Triodes

 

Sometimes, as a tube dealer you can be lucky. Though 5687 is definitely running out off stock everywhere, and new production is out of the question, we were able to buy a resaonable Stock of those, nicely assorted over several USA brands. All tested twice at the AVO CTM163. One time by my supplier, and one time by me. Clean, colored printig and all in their own boxes. This is NOS as best as can be :)

 
Condition 
Qty. 
EURO 

5687-tube-Raytheon5687
Order Number
114-231-39


6587 RCA.
Sorry, we have only 10pcs. (of which 4pcs are reserved)
NOS 
6pcs Left
See 
normal 
price list 

5687-tube-Raytheon5687WA

Order Number
114-216-56

6587 Sylvania

NOS 
60pcs
See 
normal 
price list 

5687-tube-Raytheon
5687WA

Order Number
114-215-63

6587 Raytheon. Date codes on the tubes are from 1960's. These have spiral heaters.

NOS 
40pcs
See 
normal 
price list 

5687-tube-Raytheon
5687WA

Order Number
114-213-39

6587 Westinghouse. These are have data codes from 1962.1966.

NOS 
40pcs
See 
normal 
price list 

 

5687 tube - and how to read it's data sheet.

This is a highly unusual tube, worth a few lines here. To learn about particular tubes, there is a "forgotten" source, called "manufacturer data sheet". People register under fake names on anonymous forums, to ask unknown people. And they appear so well informed about how they sound, even break that down to the shape of the getters, and the color of the mica. Well... I have to pass with that magic. Yet, as an engineer, I sometimes ask those people for the bits and the bytes, let's call it the micro Farads and the micro Mhos, and then I often see, When I ask for numbers, I get answered with letters.

So I have this information from the 5687 data sheet, and in case you find it interesting... I would recommend to read the data sheet yourself.

What does it say there? 5687 is a high reliability tube. It says so on the top right.

I suppose we all expected that anyway. Just Raytheon put in not only in words, but in many numbers too.

In begins with the introduction text, saying this tube can be used in cut-off applications. And indeed not any random tube is good for that. For a clear and nice cut off, as unlogical as it sounds, a very high emission is beneficial. This ensures the function of the grid stays intact, even at rare condition as total cut off. That is why real professionals are always interested to check if an unknown used tube, cuts off nicely and sharp. That means quality. So if not sharp, like it does cut off 95%, but the last bit of cut off needs more, and more negative grid voltage. Whereas a sharp cut off means, when you are close to cut off, you just give a little bit more negative grid voltage and then the tube cuts off sharply. This high emission, which makes the cut-off so sharp, at the same time means, the tube saturates nicely when you switch something with it, so the tube doesn't get hot, and you don't waste power supply energy on that. A tube like this, is not just ideal for switching, (like in a computer) or switch a high voltage or high current load, like a lamp or a relay, but can be used for many other applications as well. If this is so, and what are the possibilities, you can browse the forums for some babble. But it is a lot more intereszing to data sheet first. .

What does it say on the data sheet? There is a signal application too, called Cathode follower. Not everybody may know what this means, but it is just a circuit which has a very low output impedance. What else does it say? This tube characterizes by long life, stabile performance, service under severe conditions of mechanical shock, and vibrations. So we learn here, it is a very probably a low microphonics tube.

5687 can be used where High perveance is needed. Raytheon sais. I had to research a little but what that means. With that, they tell us, the tube can be used at high current and low voltage at the same time. Or in other words, some tubes need higher voltage in order to pull a lot of current, but 5687 can do so at at low voltage already. That again means, emission must be very high.

Then, in the next paragraph, there are a few lines for engineers. It says "TO ELECTRONIC EQUIPMENT DESIGN ENGINEERS". Well, I hope people read that. Though my hope is small, we should never to give up hope in life.

So what does Raytheon say to engineers?

  1. Lifetime will be reduced very much, if used at maximum ratings.
  2. Reliability and performance are jeopardized, if you exceed filament ratings. (which is +/- 5%)
  3. The closer you are to the heater center value, the longer the tube life will be.

That is clear language they use there. You have to realize they write this for a such tough, high reliability, military tube. So guess what happens if you disrespect those three points for lower quality, commercial tubes....???

Positive Grid Voltage. Another thing which catches may attention is this:

  1. Maximum Plate current 36mA (RMS)
  2. Maximum cathode current 65mA (RMS)

This means the positive grid current can be 29mA. This becomes clear from the graph at Page 7, where you can see a positive grid voltage of +50 Volts. This is incredible high, and in that condition the tube can deliver a stunning 1 Ampere plate current, and 750mA grid current. I have to admit, that I have difficulties to imagine the intended use for such high numbers, because definitely the tube will not be happy about it. Yet it shows the intended use of the tube.

All on all, this shows what an amazing tube this is.

Gold Grid. The tubes I checked, all had a gold grid. Though the data sheets do not specify a gold grid specifically,such a grid makes sense, because otherwise with such huge cathodes. some small portions of Barium would land on the grid, and cause all kind of stability problems.

AUDIO USE

Such a great tube can be used for audio also. It is found in many amplifiers, such as: Audio Note M3, Manley Jumbo Shrimp,Ayon CD player, Audio Note DAC 5 Signature and Audio Note amp kits, M5 preamp, M9, KR Enterprise 32BSI integrated SET amp, Modwright 9.0 and Modwright Sony and Denon modded CD players, Modwright Sony NS999ES CD player, Opera Audio Consonance Cyber 800, Zanden, Manley amps, LUX 300B amp,Kondo M1000, Artemis Labs linestage, Emotive Audio Sira, Ray Samuels B52 and Raptor, Audio Tekne TFM-9412, Sonic Frontiers Power 2 Amps, Audio Experience BALANCED A2 preamp (YS-AUDIO, HONG KONG), Ongaku, Audio Note, New Audio Frontiers Legend II preamp, Loth X JI300,Audio Thrills, Mastersound, Sophia Electric KT88 Tube Amplifier, Icon Audio PS3 phono power supply, Almarro.

The unlinear zone is very large too, but this part is intended for the switching applications. For Audio use, you need to operate into the linear zone of the tube curves.

Those load lines are sure not ideal, because I just pencilled them in quickly. I only try do explain why the unlinear zone should be avoided, and then this tube can work nicely distortion free. At the same operating point, where they cross, you can see the red load dives into the unlinear zone, whereas the green load line stays away from there. An even much more ideal behavior is achieved with a grid choke, which is the blue load line.