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. Regards, -- Al |
| Post removed |
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: SE-3921 38045 UX-245 VT-45 FR-304 CV596 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. Regards, -- Al |
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 |
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. |
