6C33

[Tony]

these are 6C33 tubes i ordered from Moscow, i am setting them up, burning in so to speak, these high transconductance tubes are prone to run-aways, so this burning-in is one way to mitigate such effects....filaments are wired in series for 12 volts and fed from a UPS transformer just discarded....the transformer has an unloaded voltage of 14volts......

since these tubes have been in storage for about 28 years(date code on the box says 1983), i found the pins are tarnished so that checking the filament continuity yielded an open circuit, scraping the pins by using fine grit sand paper restored contacts and confirmed thru the socket pins...







half an hour into the tests, i took some temperature readings:






these reading increased further after 2 hours, i plan to burn-in the tubes for 24 hours in total before putting them in service.

the next part of the testing program is to monitor power consumption using a power monitor:
wattage in total:

line frequency:

line voltage:

transformer primary current:




filament voltage:

total filament current:


from the test data, of the 184 watts consumed, about 34 watts is lost in the transformer and the rest on the tube filaments.
these are really hot tubes.....

based on these results, design of the power transformer can then be undertaken.....

[Helmuth]

Cool hot tubes

What will it become Tony PP or a PSE.

[Tony]

yup, i am making a push-pull amp....russian all the way....

6P15P driver, 6F12P input, probably like Wavebourn tower...undecided...

i am going to use grid chokes instead og grid leak resistors...

i am trying to get a feel of how hot the sockets are going to be under our 30*ambient temps.....

[rvrazvan]

with 2 tubes per channel you can get 30-ish watts per channel :P in SE. Why botter with PP ?

[rvrazvan]

bdw. i've read that some people burn them for 72 hours before they turn on b+

[Tony]

Originally Posted by rvrazvan

with 2 tubes per channel you can get 30-ish watts per channel :P in SE. Why botter with PP ?

why not push-pull?

[radiostar]

I usually burn them for few hours on lower voltage, and than for next 24 hours full voltage!

[FullRangeMan]

Originally Posted by Tony

these are 6C33 tubes i ordered from Moscow, i am setting them up, burning in so to speak, these high transconductance tubes are prone to run-aways, so this burning-in is one way to mitigate such effects....filaments are wired in series for 12 volts and fed from a UPS transformer just discarded....the transformer has an unloaded voltage of 14volts......

since these tubes have been in storage for about 28 years(date code on the box says 1983), i found the pins are tarnished so that checking the filament continuity yielded an open circuit, scraping the pins by using fine grit sand paper restored contacts and confirmed thru the socket pins...

these reading increased further after 2 hours, i plan to burn-in the tubes for 24 hours in total before putting them in service.

Dear Tony,
Thanks for post this topic, Iam in doubt right now about the 6C33 burning.
I need to burning some Svetlana 1969 and Iam complete newbie about it.

What exactly I have to watch??
In which case I must reject a 6C33??

These your tubes are Ulyanov and have full getter on the photos, I have 4 Svetlana and all 4 tubes have very few getter than this tubes in your photos.

Even one tube labeled X 69 OTK4 B*28n BbInyck XII -1969 r. have very few getter, and the head tube looks near transparent when puting a lamp light near the tube; This is normal??

A third tube labeled X 69 OTK4 B*28Л BbInyck XII -1969 r. have spots on the getter around the inside dual pins tips.

This is usual on the Svetlana tubes??
I thanks in advance for any input,
Gustavo

[Tony]

hi Gustavo,
this is my first venture into these tubes so i am not familiar with those Svetlana tubes you mentioned, my stocks, (i have 8 of them) seem to be dated 1983....

there are a lot of other 6C33 tube threads here, i suggest you go over them hopefully to answer your queries...

hope other members can chime in...

[FullRangeMan]

Thanks Tony for your reply.
I say your tubes are Ulyanov why Svetlana factory stop 6C33 production in begin 70 years, and production go on at Ulyanov factory since then.
Regards, Gustavo