Now it was time to wrap gaffer tape around the lens hood/carriage so it can fit between the two rails with little gap, so a few layers of gaffer tape around the bottom of it did the trick. Then for the main lens carriage area I needed to block out as much light as possible, so I used most of the craft foam for that purpose cutting it out into shape to fit snug into the carrage and I secured it with model glue and hot glue. Between the lens carrage and the foam I placed a cardboard paper arch so the carriage can slide back and forth easily. So there you have it, a roughly made rackable lens system.
Lastly I decided to tie the target volts of both the plumbicon preamp and the vidicon preamp circuits to ground as I was told the Iconoscope target works at 0V bias, should I need to add DC bias later on I will make an adjustable DC power supply to add the desired voltage bias.
So that's the latest updates on my construction of my Iconoscope camera project. I am very glad I have made it this far with it and I reckon I will have the camera completed within the next couple of months provided I keep motivated and keep at it!
UPDATE 4/2/15!!! I've been working hardcore on my Iconoscope camera since last update, am very close to actually whacking the tube in and firing it up so have been eager to get put all together and getting it to testing stage! So here are my updates:
Firstly I felt it was about time I started testing out my video and deflection circuits I ripped from my vidicon camera project to see if they still work or not, so I connected the power up to them and applied the signals. Firstly testing the deflection board, I decided to apply the horizontal and vertical sync signals externally from my sync pulse generator instead of internally (reasons explained in video below) so I made some connection leads to plug into the SPG and to the deflection board, RCA input sockets were choice for the deflection board end. After connecting everything I fired up the camera and I got the horizontal and vertical deflection signals at the outputs so the deflection board still works fine! :) Then I tested the video board and I got on power up the video signal without video but with just the black level tips and then I touched the input pin and got noise on the video signal which was excellent so the video board still works fine as well! :)
Connections to the sync pulse generator and the inputs of the deflection board
Test leads connected to the horizontal/vertical outputs of deflection board
Top screen: horizontal output. Bottom screen: vertical output
Video board connected to scope for testing
Top screen: video output without video signal. Bottom screen: video output with noise applied to input by touching input pin
Now it's time to hook up the preamp to the video board and see if it will work well with it, so connected the preamp output to the input of the video board and fired them up and on the scope I got overdriven noise and even just putting my finger near the preamp input had effect on the output, so way way too much gain as the video board also had a preamp so I was double preamping hehe. I then thought perhaps I will bypass the first couple of amplification stages on the video board and connect the preamp just before the amplification stage that has the black level inserted, so I did that and I got a much more stable amplified output when touching the preamp input. The signal still badly distorts when I full on touch the preamp input pin but when I lightly touch it the signal is still stable with video noise. So for now I am sticking to this configuration for amplifying the target signal from the Iconoscope tube.
Now that I have the circuitry down pat, next thing I decided to was to incorporate a power switches for the mains power. I thought to myself, I would want to warm the Iconoscope tube up first before applying the rest of the power so I decided to use two power switches, the primary switch to power just the 6.3VAC tube heater transformer and the secondary switch to power the rest of the circuitry once the tube has warmed up a bit. After that I decided to make a rear plastic panel to mount all the switches, inputs and controls onto for convenience so I took a bit of scrap plastic and cut it into shape and cut out the holes and fitted everything to it, did some screwing and gluing and they are now all nicely secured to the panel.
Next was to fit the Iconoscope tube in the yoke once again to work out where the target cap will be positioned and also how much padding will be needed for the tube to sit on. So have carefully placed the tube in and marked the position where the target cap is and the rough height the cap is off the platform is about 1cm. I also orded some anode caps off Ebay as I needed one to connect the preamp to the target cap, turns out those anode caps were slightly too small so I pulled the metal bits out of two of them soldered them criss cross and bent them so they fit nice and snug over the target cap and that worked fine, just now need to work out the arrangement of it on the preamp.
Now comes the part where the tube needs to be rejuvenated. I was only recently been told by a valve expert that old valves that haven't been used in over 40 years need to be rejuvenated by gradual power up of the valve's heaters for a lengthy period of time which he applies 3VAC to his valves for 2 hours then steps the voltage up to 5VAC for an hour and then the valve is good to go. So I did just that with my Iconoscope tube, I was a bit worried it might spring a leak and go white at the neck but thankfully it didn't, the base end got pretty hot so I let it cool off for 30 min before putting the tube back into storage. Anyways the tube is as far as I know ready for testing once I have got the camera completed to testing stage which is not far off! :)
So that's it for my updates, I have made great progress and I am literally almost ready to test this camera and hope to do so within the next few days! :D Stay tuned for the results in my next update!