45 tube types

I'm looking at getting a 2A3/45-based amp and so, for the heck of it, I hit a couple of the online tube stores and didn't see a single one. Are there variations on the 45 tube, numbered in some other way, that I'm simply not seeing?
Are there variations on the 45 tube, numbered in some other way, that I'm simply not seeing?
I'm pretty certain the answer is "no."

You might want to take out a subscription to Antique Radio Classified, which would allow you to place a free want ad each month. 45's were used in a number of high-end antique radios ca. 1932.

Also, some of these places might be worth contacting.

-- Al
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They are on Ebay fairly often... typically you can get a pair of National's or Philco's new for around $90 a pair. I can't recommend any seller in particular.

Of course you can always go to Emision Labs.
Following my earlier post, I received an informative communication from member Audiofeil, who indicated the possibility that variants of the 45 might have been produced under the designations 245 and/or 345, with identical specs and differing only in the shape of the glass (these being what is referred to as globe shaped). I then looked in the book "Tube Lore," written by Ludwell Sibley, who is a renowned expert on early tubes. It lists the 45 as AKA (also known as) the following types:


The book also indicates that 300-series counterparts of many 2-digit tube types were issued under the Cunningham label, so a CX-345 is also a possibility.

There was also a 45A, which the book indicates was similar to the 45 except uprated from 250 volts to 325 volts, and from 1.6 watts to 3 watts.

Hope that helps, and my thanks to Bill Feil.

-- Al

This is what I was getting after with the numbering variations. I have an old radio that has a couple of these CX-345's in it and was wondering in the back of my head if I could utilize such a tube (and other such tubes) in a current configuration.

Thank all you guys for the responses so far.
Sounds to me like you are in luck!

Here is a datasheet on the CX-345, which as you'll see speaks of it as if it were a 45.

I compared the spec numbers with those of a 45 that appear in a reprint of an early tube manual I have. There are a few differences, but they are EXTREMELY minor (examples: mutual conductance 2100 vs. 2050; plate resistance 1670 vs. 1700; g-p capacitance 8pf vs. 7pf).

As an antique radio collector, I have never encountered any incompatibilities between 2-digit tubes and their 200 and 300 series counterparts.

Finally, the Sibley book states that the "only important exception" to the Cunningham numbers paralleling standard industry and RCA practice was the type 373.

Good luck!
-- Al
This place may have some.I don't know anything about this seller.[http://www.audiotubes.com/audtube.htm#aud%20list]
I cannot believe nobody has posted this yet, but the best 45s are actually NEW PRODUCTION anyway - TJ (Full Music) and EML.

They are not cheap but last a long time.
A friend uses the EML meshplate 45s. He really likes that tube a lot (he has many NOS variants, including old globe 45s).

I use both meshplate and solid plate EML 2a3s. Both are very good, particularly the meshplate tubes.

My only caveat is that the website lists some very specific operating conditions. The recommendations should be strictly followed. EML tubes cannot be pushed excessively hard--that dramatically shortens life (it shortens the life of all tubes, but, the EMLs seem to be a bit more delicate in that respect).

If you have any questions about the use of EML tubes in your particular gear, contact George Lenz at Tubes USA (US seller of these tubes). He is VERY helpful, forthright and conscientious.
Larryi, my Wavelength Cardinal Signature XS pair is new to me as are 45's in general. I appreciate your quick response and suggestion. BTW, I also use the Naim CD555.
VERY excellent system you have.. WOW!
Oops, the Cardinals are my 300B pair. My 45s are an early Wavelength Silver pair commissioned by Larry Kay. My embarrassment.:)
Don't waste your time with all that old crap. Just get EML 45 tubes. The mesh Plate is sublime.
I am using 4x Eml 45 mesh tubes in parallel on a triode labs integrated amp. 

After over 20 years of being an audiophile , I would say that these tubes are the most pure sounding tubes being made. 

Surpassed my 300b,s and all other tube systems I’ve had over the years. 

The 45 mesh is the top.