Trying to make a vision IF and Detector - fun!

[AdrianPH]

Here is a list of what I have got the markings off,  Better look tomorrow after I burn all the cardboard boxes and packaging they are in.

1 x 3BP1
1 x 4EP1
2 x 5BKP1  Think one is to air, I may have 3 as I wrote another CRT down as 5BKP31   ???
1 x 5CP1
2 x 5FP7
3 x 5NP1
1 x CR87
1 x CV1397
1 x CV1526
1 x CV960
1 x DG13-2
1 x Cossor 89J
1 x MW6/2
1 x RCA unknown 50mm CRT

Adrian

So basically a mix, mostly I would suggest radar tubes, the odd scope tube, one projection TV tube, with screen damage.

Adrian

[peter scott]

A wealth of projects ahead!

[AdrianPH]

Think I have identified the RCA unknown as a 2AP1, also missed another CRT 1 x VCR517B which I believe is another log persistence tube.
Although what afterglow YYM36 is I do not know?


That CRT may be used on the TV first as a try, it has unfortunately a loose base and has wires soldered to the pins, but I am sure something can be sorted.
Adrian

[peter scott]

I have a VCR517 that I removed from an H2S radar display when I was a teenager. I started building a transparency scanner with it but never completed it.

Peter

[AdrianPH]

OK a bit of an update, progress is slow as I work things through in my head, but within the recent CRT's I got was what I believed to be a 2AP1 tube, a loose base that fell off whilst handling.  So after spending some time with it I thought I would try and see if I could use it.

I am using grid modulation and varying the cathode for brightness, there is quite a low allowed voltage difference between Cathode and Heater on this tube so I had to use a separate 6 volt transformer for the heaters and allow it to float, or connect one side of the Heater to Cathode.

This is the death trap for the unwary at the moment.
   
   

It is displaying the test card from Hedghog, I can not focus it, the focus voltage being done for the DG7-3 not this tube, so either I modify the blue box on the back or fit the other tube.
   

I had major issues with hum bars and trying to find where they came from, in the end, it was a mixture of EHT ripple and heater to cathode ripple both sorted by caps to ground.

I hope to make things a bit better later tonight or tomorrow, My caps between the timebases at plates are at their very limit, so I need to find some 0.1uF at 1 or 1.5 KV.

Adrian

[ppppenguin]

It's probably better not to float the heater. Can't quite justify that but it feels right. If you've got video on the cathode then don't connect directly to the heater. Try a 100K or so resistor. The capacitance from the heater supply to ground will not help HF response. Special transformers were used back in the day to deal with HK shorts.

[AdrianPH]

I am using video on the grid of these CRT's and varying the cathode potential for brightness.  The cathode and heater are presently tied.

The grid is sitting at +120 Volts Cathode at approx 150 Volts.

Adrian

Also DG7-5 not DG7-3 as published.

[peter scott]

That's looking promising! The HKS transformers that Jeffrey is referring to had their primary and secondary windings side by side rather than one on top of the other.

Peter

[AdrianPH]

The transformer I rewound for the heater is like that, primary at the top heater winding on the bottom in separate bobbins, thought it was best to aid isolation breakdown.

Adrian

[Murphyv310]

Nice work Adrian.
That's quick as well. I've had a go using the MW6 - 2 but I've got waylaid by other things. Other problems are it's too cold and expensive to heat the shed and my close vision is slowly deteriorating so projects are getting harder to do and I find I'm making more mistakes. Oh well I've had fun in my time.
Keep up the good work.