Tube of the Month : The 45 (revisited)

Hi!

The 45 has already been covered in a Tube of the Month post. Two sets of mono blocks with the 45 got finished recently and it is one of my all time favourite tubes. So it deserves a revisit. This post will mostly be about the different variants. For all technical aspects about the 45 see the original Tube of the Month post. Now get ready for some 45 porn.

The 45 was introduced in 1929  as UX245. It was very popular as output tube in radio sets and has been manufactured in an abundance of varieties by many manufacturers. Probably the most famous is the RCA:

This is the more modern ST shape, with printed base:

Earlier tubes had engraved bases:

RCA Victor 45 with the Nipper box:

Cunningham made by RCA:

Beautifully engraved base:

Different version:

This heap of RCA Cunningham 45s look the same at first sight:

But some are slightly different in their internal construction:

Many tubes have labels from the stores which sold them:

The earlier Cunningham CX345:

RCA globe shape 45:

The top:

Slightly different version with a little glass piece for adjustment of the electrodes:

The base:

Tung-Sol 45:

Westinghouse:

Different Sylvania 45s:

Sylvania globe UX-245:

Philco, made by Sylvania:

Zentih, probably also made by Sylvania:

General Electric:

Delco:

Fivre 45 made in Italy:

Two australian 45 radio tubes made by Amalgamated Wireless Valve Co:

Arcturus 45 in the beautiful boxes with the observatory motif:

Ken-Rad:

Raytheon:

Majestic G-45:

Two different ST shape Silvertone tubes:

Earlier Silvertone UX-245:

In this tube the getters starts to flake off a little. This can be an indication that somebody tried to reactivate the getter by applying heat through a flame from the outside. It can also came off all by itself. The tube tests fine:

National Union ST shape 45s:

NU produced the 45 over a long time, which is apparent from the changes in styles:

Engraved bases on the older types:

Printed on the later tube:

Also differences in internal construction:

Globe shaped National Union NX-245:

Now let's have a look at the internals of a 45 tube. Don't worry, I wouldn't salvage a good tube for this. This unfortunate Philco 45 got dropped on the floor:

Removing the remaining glass:

Close ups of the top showing the suspension of the filament:

Bottom of the electrodes:

The holder of the getter material:

Removing the plate:

Since the top suspensions got cut off the filament lost it's shape:

Close ups:

Next some odd brand tubes.

The first one is quite peculiar and I only ever came across one of these. A ST shape 45 with  ceramic base:

Not sure if this is genuine and was manufactured like this or if somebody rebased a 45. It bears no brand markings. Could be RCA, here a photo of the top:

Gold Seal 45:

Wards Super Airline:

Globe shaped 45 with Super Airline branding (without the Wards):

This one is shorter then the typical globe 45, here a comparison:

Commander 45:

De Forest 445:

CeCo:

Sonatron 45:

Lafayette:

Hy Ray:

Speed:

Perryman:

Champion:

And finally the most peculiar brand name which I came across: 'OK':

I'd like to finish this post with some 45s in operation:

Here a 45 in a new amp which will be shown in an upcoming post:

Stay tuned!

Best regards

Thomas