It's nearly time to stick the tube in and fire the camera up, just one more thing to do and that's to make some cushioning for the tube to sit on, so I cut some pieces of hobby foam and stacked/glued them where the tube will sit.
Alrighty it's time to stick the tube into the yoke and fire the camera up and hope it works! So I fitted the tube inside the yoke and I first flicked the heater switch to warm up the tube for about five minutes. Now comes the moment where I flick the main power switch to officially fire the camera up!
So flick goes the main power switch and the result was a mix of excitement and some disappointment. The disappointment was there was no picture, the good news is I am getting something out of the tube such as some funky picture noise and also when I run a bright light up and down the lens I am getting a reaction from the tube, so that is a fantastic start!!! :D
Now it's time to start troubleshooting the camera and find out why I'm not getting some form of picture. I thought of a few ideas as to why I'm not getting a picture but am getting a reaction from the tube when shining light on it. My first thought was the deflection yoke must be in the wrong position down the tube neck causing bad deflection of the beam as I can only push the tube so far down the yoke, so I figured I need to get another yoke of some sort or make one. Also there could be an issue with the video amplifying stages as well and one of my tech friends suggested there might be too much gain. So those are things to look into. In the mean time I had a bit of a fiddle around with the camera's adjustments and see if I could get something more tangible on the screen, still nothing but still getting reaction from the tube when shining bright light onto it.
Video output waveform on scope looking very noisy
I posted my progress in the NBTV forums and one of the people there stated that I should completely enclose the tube so only light from the lens hits the tube. Whilst I intended to completely enclose the tube off at a later date when I put the cover on, I decided to make a makeshift covering of the tube area with cardboard and gaffer tape for testing. Also while I was at it I decided to lable all the control pots and sockets and switches at the back so I know which is which.
Testing the camera out once again, the results were still the same.
So I sat strongly on my theory that the problem lies within the deflection yoke positioning. Now as changing the yoke isn't feasible at present I thought I'd look into the video amp stages as my tech friend suggested I might be getting too much gain. So I thought I'd make another target lead and bypass the plumbicon preamp and connect straight to the preamp input of the vidicion video circuit. So I did that then stuck my light box with a test picture in front of the lens and fired up the camera and EUREKA!!!!! :D I SEE A PICTURE WOOHOO!!!! :D
Light box with test picture of an Asian lady holding a rose
A very faint faded crude picture of the Asian lady test picture appears on the bottom of the screen diagonally
The picture isn't wonderful like Yoshio Ozaki's Iconoscope camera, far from it as there's plenty of problems such as the picture being very dim, video noise due to lengthy lead from target to preamp, flyback lines as I haven't connected the blanking circuit, deflection issues etc. but getting a picture alone is a HUUUGE achievement and proving the RCA 1846 Iconoscope tube still works 70+ years later and considering camera is a rough together setup using deflection/video board from my vidicon camera, RCA deflection yoke from a telecine and a magnifying glass as the taking lens it is amazing it actually works!!! :D Here below is another video presenting my camera in operation pointing outside the garage into the street where my car is in view and a car across the road and passing vehicles, plus I adjust the controls showing the effect they have on the picture too.
And I seized the opportunity to do a video recording of the Iconoscope camera's video output, so having a DVD recorder handy in the garage I rigged the camera up to it and did a video recording and here it is below!
What can I say but I am totally over the moon the camera is outputting a picture and I get first hand experience in seeing how a 1930s/1940s era television picture looks (even though it's in a very crude form), it's simply amazing!!! :D
Anyhow the project is far from over, now that I have pictures, it's now time to refine the camera and get it to make good pictures comparable to Yoshio Ozaki's Iconoscope camera so the project continues and so stay tuned for updates and videos from this camera in the near future!!! :)
Since I got my first pictures from my 1846 Iconoscope tube I have made over a dozen videos and have done further mods and tests with the camera and was kindly donated an original yoke for my tube, lots to talk about!!!
Firstly here's some of videos I have made on my Iconoscope camera along with a couple of video stills:
The rest of the videos can be seen via these links:
Now during my construction logs I have neglected a couple of things. Firstly I forgot to talk about the sync pulse generator I use for my camera. The SPG I use is my UTEL Sync Pulse Generator & Colour Bar Generator 2004 which I use for my other cameras requiring external horiztonal/vertical sync pulses. I made up a pair of leads to connect to the SPG socket and to the camera with pins on the SPG end and RCA sockets on the camera end to plug into camera. The SPG does quite a good job at syncing the Iconoscope tube when it's tuned properly though when the tuning is off there is a bit of mismatch resulting in some jerkiness of motion and light pulsing in the video. Anyhow here below is the SPG and the lead I made:
Secondly I forgot to include the schematic diagram of the plumbicon preamp I made earlier on during construction which the pramp can be seen on (page 2). Here is the schematic below:
Which now brings me to the next part of my project. The video from the Iconoscope is very weak and lacking in contrast so I thought I'd try connecting this plumbicon preamp between the target and the video circuit's preamp input to see if it could boost the signal and give a contrastier output. So I did that and the results were a very noisy embossed looking picture, the edges were sharper but the picture was less recognizable so it was a disappointing result but a good video effect. Here below is a video recording showing the result along with a couple of video logs:
So adding an extra preamp between target and video board was not a good idea so I removed the preamp and just connected the target back to the video board's preamp again.
Now recently I have been corresponding with Maurice Schecter who specializes in WWII bomber TV camera blocks and has a site featuring his collection and history documentation http://www.qsl.net/w2vtm/mil_television_history.html . I talked to him about about my camera and it making pictures and he kindly donated to me a spare yoke he had specially made for the RCA 1846 Iconoscope tube and tube socket and here it is the yoke below:
The resistances of this yoke are 6.4 ohms for each horizontal coils and 36.8 ohms for each vertical coil. The yoke had remnants of it's original wires so I desoldered them and attached new wires with sockets to connect to the horizontal and vertical leads. I connected the horizontal coils in parallel to the horizontal output leads and the vertical coils in series with the vertical output leads.