Inexpensive power tubes...

[AmberB]

I didn't see another place to post about tubes on the forum, so I'm posting this here.  Move the post if you need to.
I was looking at power tubes on ebay, in particular, the 6K6, the type 41, and the 6V6.  I was surprised by how inexpensive these NOS tubes are on ebay.  Less than 10 bucks each for most of them.
I was thinking, a pair of type 41 tubes in a vintage style amp would be interesting...

[PRR]

Type 41?? Isn't that a big Bugatti?

'41 tube is a 6K6 before they changed the base. The 6-pin socket can be harder to find.

[Latole]

I will never buy second hand power tubes or say new tubes from people are not my friend.

Seller may say tubes tester show his power tube are good and they are not because most Tube tester can't do a complete test on power tubes.

[tubenit]

The ECL84 is a triode/pentode tube and it's fairly inexpensive.  However, it only produces maybe 3-4 watts in a push/pull cathode biased format.

Bumble B+/Solow Watt ECL84 (el34world.com)

(8) SoLow Watt ECL84 amp - The Amp Garage

Since it's triode and pentode in one tube, there is some savings in that aspect alone.


with respect, Tubenit

[passaloutre]

I've been sourcing parts from junked radios and have come across a number of Loctal sockets and tubes. The 7C5 seems to be equivalent to a 6V6GT, and a pair can be had for less than a single new 6V6.

[CrocMule]

I will never buy second hand power tubes... from people are not my friend.

+1

[bmccowan]

I was looking at power tubes on ebay, in particular, the 6K6, the type 41, and the 6V6.  I was surprised by how inexpensive these NOS tubes are on ebay.  Less than 10 bucks each for most of them

NOS 6V6s for less than $10? Are you using the Way back Machine? I see $25+
I have successfully bought many NOS 6V6s - ebay and other sources. But I am careful. Good vendor with a good track record? "Tests new" is not good enough. They are getting much harder to find. Most of mine came from military stock.
Right now I refuse to buy Russian tubes. I'm sure Vlad does not care, but I just will not do it. So it's JJs or NOS.

[dwinstonwood]

The 7C5 seems to be equivalent to a 6V6GT, and a pair can be had for less than a single new 6V6.

That is an interesting tube.
If I'm reading the datasheets right the 6V6 needs 460mA of heater current per tube, while the 7C5 needs 450mA per pair.
The 7C5 calls for an 8K OPT while the 6K6 wants a hard-to-source 12K OPT.
14 watts also seems impressive with 285 plate volts.
And the fact that NOS 7C5's are $9.95 at TubeDepot and AES sounds really good.

So, what's the catch? 

[sluckey]

So, what's the catch? 

7C5 requires a loctal socket. Yuck! Got any in your stash?

BTW, it needs 450mA heater current per tube.

[dwinstonwood]

Thanks sluckey.

But, I'm still intrigued by this tube. I found this old thread:
https://el34world.com/Forum/index.php?topic=13954.0

If I do try them it looks like Amphenol or Cinch phenolic sockets off eBay would be the way to go.

[sluckey]

AES has some ceramic loctals...

     https://www.tubesandmore.com/products/socket-8-pin-loctal-ceramic

[mresistor]

The 7C5 seems to be equivalent to a 6V6GT, and a pair can be had for less than a single new 6V6.

The 7C5 calls for an 8K OPT while the 6K6 wants a hard-to-source 12K OPT.
So, what's the catch? 

I think it was HBP that brought up that and 8K OT would be perfectly fine for the 6K6, close enough. 12K OTs from Hammond aren't hard to find.
If considering using a 6K6 for lower power out..,,    the 7C5 does look interesting as a 6V6 equivalent though....

[PRR]

> 7C5 seems to be equivalent to a 6V6GT

7C5 IS 6V6 in different shoes. Sylvania's sheet says it clear.

Don't see 460mA anywhere?

Yes, it IS odd that it says "for two tubes", but repeats the number given for one tube above. People who worked with tubes knew it was 900mA/pair.

6V6 always had the two P-P ratings: for 250V and 10W out, and 285V and 14W output. 7C5 just copied that over.

The "advantage" of 7C5 is that most were well made. OTOH everybody and her daughters made 6V6 in the garage. You could get all the machinery and parts mail-order. That was a sucker bet, but it spread world wide.

[sluckey]

Back in the '60s I broke a few loctals before an old timer showed me how to pull them. Didn't have YouTube back then.   

[dwinstonwood]

Well... I pulled the trigger on two NOS 7C5's and a pair of Loctal sockets. $31.87 shipped. Now, I get to design a 14W push pull project around them. 

[passaloutre]

I’m working on an all loctal 5e3. 7F7, 7C5, 7Z4. Looking forward to it, will report here

The new ceramic loctal sockets are poorly reviewed, but most of the reviews seem to come from people selling the NOS ones…

If you’re lucky you can find an old Philco console with loctal sockets, tubes, and transformers for a few bucks. Mine came with a lovely old Voice of Music three speed record changer

[dwinstonwood]

NOS 6AT6's are like $4 at some online stores. And, I think the Harvard would probably work well with 7C5's. The schematic shows a relatively low 302V on the screens.

https://el34world.com/charts/Schematics/files/Fender/Fender_harvard_5f10.pdf

Budget Cropper?

[tdvt]

Been watching this thread, along with the 6K6 thread, as I am finding some of these more odd-ball tubes interesting & I guess I am inherently cheap (but don't want junk either)


Came across some NOS JAN 6005/6AQ5 at Tubedepot on sale for $5ea. They also have them listed at $15ea (regular price) but the $5 listing is right next to it; same pic, description, etc. so I thought I would try a few.

They also have NOS 7-pin Bakelite sockets.

https://www.tubedepot.com/products/6005-6aq5w


Update 4/7/24- Guess the sale is over....