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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 446

post #6676 of 10556

Here is a short history of the Melz factory. Seems tubes were produced from 1942 until the 80's(?):


MELZ, Moscow, Russia

Moscow Electric Plant "MELZ" is the oldest in Russia for production of electronic devices. History of the plant began with a workshop for making light bulbs in 1906. Soon workshop has grown to the size of the factory. She launched by 300,000 bulbs per year.

In 1921 was founded the Moscow Association factories tubes . In 1926, automobile designs have been developed and powerful gas-filled tubes . Vacuum tubes produce steel from domestic flint glass. Factories moved with plant production system for streaming. Import radio tubes to Russia stopped. Moscow Electric Plant became the first and largest in the country now - plant. In 1929, all electron tubes factories were placed under the leadership of " the Moscow Electric Plant".

In 1938 the plant was divided into several independent companies . By this time, the emergence of the name of the plant MELZ.

During the Second World War, the factory worked around the clock and releasing the necessary radio tubes . In 1942, the plant began production of tubes . In the same year from besieged Leningrad factory "Svetlana", arrived in Moscow large group of specialists . They, along with specialists MELZ begun to establish pilot production of special generator tubes designed for radar transmitters. In the 60s to establish production of color picture tubes.

In the mid-70s at the plant was organized by central laboratory (CPL), which dealt with the optimization of manufacturing processes electronic devices. In the 80s there was a decline of the plant. Many of its territory emptied. It was only in the mid-90s production began to recover.


In the past few years, special attention is paid to MELZ creation and development of the production of energy-saving light sources: high pressure sodium lamps and compact fluorescent lamps. Just the company started production of glass products for the food industry. But the main activity is the production of electron-optical converters (EOP) 2 and 2 + generations, as well as night vision binoculars with image making false color.


The architecture of the Melz building in Moscow was obviously inspired by tubes:



File:Moscow, Elektrozavodskaya Street MELZ.jpg


MELZ is an acronym for Moscow Electric Tube Plant  (Moskovsky Elektrolampovy Zavod).

post #6677 of 10556
Originally Posted by gibosi View Post

On the eBay listing for these, the pictures show the date with the same format as is commonly seen on the 6N23P, that is "VIII - 80". Maybe into the 1990's the format changed to YYMM? But if so, the two different dates is a bit of a conundrom...




Even those have two dates!


The format did change at some point. When exactly, and whether this is true for all manufacturers, I don't know.

post #6678 of 10556

I think the 9103 date relates to march 91 as year of manufacture. The 73 number is just tied up with a person inspecting in this case at the Melz factory.

post #6679 of 10556
A lot of the sub miniatures only have a maximum plate voltage of 100V unlike the 7963 which has a 165V plate maximum.

Maybe gibosi you can take some readings of the plate voltages on the various sub miniatures before everyone gets too carried away with them. I'd hate to see the tubes arc over in someone's amplifier.
post #6680 of 10556
I just measured the 6832 in my MK IV and I am getting 105V &108V on the plates. I am not sure as to how far overvoltage these will run, but from what I have read, a lot of tubes will tolerate higher plate voltage as long as the current is lower.
post #6681 of 10556

The absolute maximum plate voltage for the 6021 is 165 volts, and for the Russian 6N16B, 200 volts, so no worries. :)

post #6682 of 10556

Hi Mordy, you had uploaded a picture of a 1945 raytheon 6AK5 some time ago. Would it be possible to upload this picture again since the link appears to be broken now? Thanks for your help.

post #6683 of 10556
post #6684 of 10556

Hi lithium 1085,


Here is a picture of this tube:



I have one tube left - please PM me if you are interested.

post #6685 of 10556

Mounted the 6N16B-VR into an octal base last night. I tried to install it into 9-pin socket saver with 18-gauge pins, but gave up. The 18-gauge pins simply wouldn't hold the leads securely enough and I couldn't get all 9 inserted, without some pulling out. Perhaps a higher quality socket-saver would work better.  And perhaps 9 leads instead of 8 plus too much twisting and crossing to get everything lined up correctly. Whatever, after fiddling with it for over an hour, I went back to my "easy and ugly" octal mount. In the event others decide to mount a 6N16B-VR into an octal base, I should point out that it is necessary to tie leads 5 (shield) and 6 (cathode) together.


post #6686 of 10556

Hi Gibosi,


It seems to me that the octal socket pins are thicker than the 9 socket pins. The push pins work very well with a 9pin socket extender providing a good tight fit.



Here is a link to the 9pin socket extenders:




Following the diagram you provided, it was no too difficult to insert each lead in it's place with a small needle nose pliers. It is a good idea to insulate each lead with shrink wrap to avoid contact, but if you are careful, it can be assembled without the shrink wrap.




By buying several 9pin extenders you can switch the sub miniature tubes just like you switch in and out regular tubes, and you do not have to disassemble the tube set up.


post #6687 of 10556



I did try to use a 9-pin socket-saver with 18 gauge pins. And again, the connections were not tight enough.


That you have had good success suggests to me that not all 9-pin socket-savers are the same. I bought these thinking that gold was better. :)




But even though secured with 18-gauge pins, the leads slide in and out too easily.


I did manage to mount a 7963 into one of these gold 9-pin socket-savers. Again, the leads were not as tight as I would like and I used electrical tape to keep everything in place. I planned to do the same thing with the 6N16B-VR, but never was able to get all the leads inserted without others sliding out.


So people should buy the 9-pin socket-savers that Mordy bought. Not the ones I bought. lol :)


post #6688 of 10556

  You can used a sewing needle to tighten the socket pin hole.Gently push in the needle on the side of the socket pin hole to reduced the gap of the socket hole(mine is gold plated 9 pin saver the socket hole is slotted/split) I've done this before just watch your finger while doing this.

Edited by i luvmusic 2 - 6/30/14 at 1:35pm
post #6689 of 10556

Hi Gibosi,


And I thought that all 9pin socket extenders were the same....The ones I bought were the least expensive (4 for $6.59 incl shipping) but don't look to be high quality and are only rated for 200 uses (whatever that means).


Anyhow, how does the 6N16B-VR sound compared to the Sylvania 7963 and the Raytheon 6832?


Hi I luvmusic2,


I have an extender adapter for octal tubes to 9pin that is too tight, and I have to push very hard to get the octal tube in all the way, and use even more force to pull it out. Do you have any advice how to make the adapter less tight fitting?

post #6690 of 10556

Y'all need to build up one of these... :D


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