The following camera tubes are B&W image orthicon TV camera tubes dating around the early/mid 1950s. The first one with the blue base is a General Electric GL-5820 and the second one with the mustard yellow base is a RCA 5820. These 3 inch IO tubes were mass produced between the late 1940s and say mid 1960s for usage in B&W image orthicon station network TV cameras eg. RCA TK-30. These type of tubes were also used in the first commercially made colour TV cameras, the RCA TK-40/41 series. IO tubes have a distinct characteristic to them which is when the camera is pointed to bright objects or scenery a dark halo forms around the object/scene, an example being a bright light. An explanation on the cause of the halo effect can be read here .
Anyways I've imported these IO tube from USA, won them in an Ebay auction. I didn't realise how huge these tubes were until it arrived on my doorstep, it was massive, the face of the tube is 3 inches (7.6cm) and the length is 15.2 inches (38.6cm), very large tube indeed. It's not the biggest tube made neither, in the 60s the 4.5 inch image orthicon tube was put into use, now those would be colossal over the 3 inch. The General Electric tube is in excellent cosmetic condition, looks like it's only just came off the factory conveyer belt in a tube plant, whether it works good or not is a mystery, the RCA tube looks to have something loose inside so it may not work. I have a dream to one day build myself a home brew IO camera using this tube and modern solid state equivalent electronics, I have schematics of a 1970s home brew IO camera which I found in CQ-TV issues 89-91 1975 which I think will be very helpful in making it possible. In the meantime I am studying up this technology as I have a lot to learn.
I also have the data for these camera tube, the GE tube data can be found here and the RCA tube data can be found here. This tube data is a valuable source of information for understanding the characteristics of this camera tube.
Here below are a number of photos of these great camera tubes, I placed a torch beside the GE tube in one of the shots to show how big this tube really is.
Both GE and RCA IO tubes side by side and a tape measure to show how big they are
RCA 5820 B&W image orthicon tube
My three 3 inch B&W image orthicon tubes, two RCA 5820s and a General Electric GL-5820
2 inch Hitachi HS-124E image orthicon tubes
Wow this is amazing, image orthicon tubes not only came in 3 inch and 4.5 inch sizes, they also came in 2 inch size as well!!!!! I have just acquired two 2 inch Hitachi HS-124E image orthicon tubes from Ebay, I initially thought they were 3 inch in size looking at the auction but when they arrived I was gobsmacked to see they were 1/3 size smaller than my 3 inch IOs!!!!! I trawled Google to find info on 2 inch IO tubes but found very little info apart from the fact they were invented by Japanese broadcasting corporation NHK in 1965 and that they produce better pictures than the 3 inch variety. What applications 2 inch IOs were used for is also a bit of a mystery, probably low light industrial work, medical operations and astronomical photography. If anyone can provide me with more details on these tubes, it would be much appreciated!!! Anyways here's some pictures of these super rare 2 inch IOs:
2 inch IO tube next to one of my 3 inch IO tubes to compare size
This little gadget comes in the newer IO tube packages, it determines whether the tube has been tipped upside down face down during transit in which the ball bearing falls through the funnel into the larger chamber. Image orthicon tubes must not be positioned face down because at the back where the cathode is there are particles which play a role in that area of the tube and they can migrate down to the faceplate of the tube damaging the image elements if the tube is face down causing blemishes in the picture such as black spots.
English Electric Valve Co. 7295/E 4.5 inch image orthicon tube
This here is an English Electric Valve Co. 7295/E 4.5 inch image orthicon tube which came from my Marconi MKIII B&W camera I recently acquired. This tube is the largest of the image orthicon variety and indeed it is HUGE!!!!! These tubes became mainstream in B&W cameras by the late 1950s, the Marconi MKIII cameras I believe were the first to officially incorporate the 4.5 inch around the mid 1950s, then it caught onto the rest of the later manufactured British cameras such as Marconi, PYE, EMI etc. and then in USA with their newly developed RCA TK-60 and other countries manufacturing cameras. The 4.5 inch image orthicon has a big advantage over the 3 inch variety, the pictures are so much sharper and the dark haloing around bright lights is less intense. Anyways below are some photos of this tube and the line up of the 2 inch, 3 inch and 4.5 inch image orthicon tubes side by side for size comparison.
Westinghouse 5820 3 inch image orthicon tube
This is my latest image orthicon tube to enter my collection. Like all the other IO tubes, I have won it off Ebay and got it imported from USA. This tube looks to be in brilliant shape and comes in its original plastic case. This tube is the common 5820 type which were widely used in most B&W IO cameras of the 1950s. So this tube is now the 4th 3" IO tube to enter my collection. I am now back to 3 tubes as I recently have given away my RCA 5820 with the mustard coloured base to a collector/preservationist on indefinite loan on his request. Anyways back to the Westinghouse, here is some photos of this tube below: