A Philips PF 603E/51. This lamp is different from an ordinary G.L.S. in two ways...

1. A thick coating of Titanium Dioxide diffuses the light very evenly so there are not bright spots which would be projected onto the photographic paper, developing it more rapidly at that location. This is also the reason why the etch is on the neck, because the crown of the bulb is projected onto the paper.

2. Although 75w at 240v, this lamp is actually overburned, so its more like a 50w, 180v lamp. This makes it brighter and increases the colour temperature and produces more blue output to develop the paper more rapidly. The lifespan of this lamp is consequently reduced to 100 hours as opposed to the normal 1000 hours for a similar G.L.S.

Actually this is a rather rare 120v version, although I have HEAPS of the 240v version, I have never seen the 120v version! So this is more like 50w, 90v to get 2700K. Or is this 220v, never seen that rating either.

My Philips Catalogue says...

PF603E/51 120v 75w E27 1300lm 2950K 100h
PF603E/51 240v 75w E27 1150lm 2950K 100h

Plant code "*" = Weert, Netherlands
Date Code "66" or "6B" = June or February 1976

Thanks for the detailed info to this lamp. Yesterday I made my first prints in darkroom and I used a Philips LED 11 Watts bulb as light sources. Its brighter then the original bulb which I want to safe and has also no delay at switch on. The prints came out fine. As red darkroom light I used my color changer led bulb in pure red mode at lowest setting. I didn't harm the paper...

It's great you are still doing wet developing at home. My father used to do our monochrome family photos using an enlarger with this exact type lamp in it (a 240v model but it looked identical). He turned the old bathroom into a darkroom. I loved watching the images come up in the developing tray! The safelight was either a PF710 or PF712 I recall. with a B22 base/cap.
When I was young, about 6 years old, I called this lamp, "the letterbox globe" because on the older blue and yellow format box of these PF603's, white bordered prints were depicted on a "conveyor belt" emerging from under this lamp's light beam. I thought they depicted post box slots!
So these PF603's and PF605's hold special childhood memories for me!

I am in photography since I was 6 years old and I also dreamed about a way to take pictures without any cost. This way is called digital as we all know now but it is a very interesting thing to go back to the roots of photography now and I enjoy it very much. It also helped me to take better pictures using a camera with film where you have to think about every picture you take. Even with this topic there are collectable lighting bulbs involved...

I have several of these lamps, which I saved from when my father had a darkroom when I was growing up. I spent many happy hours in there as a child

Actually this is a rather rare 120v version, although I have HEAPS of the 240v version, I have never seen the 120v version! So this is more like 50w, 90v to get 2700K. Or is this 220v, never seen that rating either.

My Philips Catalogue says...

PF603E/51 120v 75w E27 1300lm 2950K 100h
PF603E/51 240v 75w E27 1150lm 2950K 100h

Plant code "*" = Weert, Netherlands
Date Code "66" or "6B" = June or February 1976

I think you've made a couple of errors here, Andrew

The date code is 6G which comes back as July 1976, also it's 220V not 120V.

I have a couple of the Philips 240V ones, also an Atlas one, which I'm still trying to date.

I have one of these aswell..it is 240V (I still have not a clue how a european bulb got to my local junkyard).

I have one of these aswell..it is 240V (I still have not a clue how a european bulb got to my local junkyard).

Hey, I have no idea how a GE 120V 1000W bulb from 1950 made it to a surplus shop in London..!