Tech-Master NIB TV Kit #5516

[old_coot88]

Originally Posted by dieseljeep

Boost the line voltage another 10 volts or so.

And if that shows promise, consider sticking a few 9V batteries in series in the B+ line feeding the H.out circuit. That would give it even more grunt, B Boost and HV without overstressing the heater string.

This would at least give a yes/no whether raising B+ further on the H.out circuit would help.

The battery string would go in the B+ line feeding the plate (pin 5) of the 12AX4. If it helps, then consider building a small dedicated supply in place of the batteries.

Just a thought FWIW.

[old_coot88]

P.S. If you're interested in trying the 9V battery trick, I have a ton of them which are pulls from smoke detectors in my building. They are Mallory Duracell and all test well into the green on a standard batt. tester. The pulls are always good since they're changed on one-year interval.
Free for postage. PM me if interested. Bill

[Crist Rigott]

Here is a video of the picture quality. The picture is a lot more focused just after turn on but then looses focus after that. Watch the SUN day of the weather to see what I mean.

https://youtu.be/DXsw8_pofTA

[old_coot88]

Originally Posted by Crist Rigott

Here is a video of the picture quality.
https://youtu.be/DXsw8_pofTA

The raster shows some 'hourglassing' from powerline ripple causing the slow bend on the sides that drifts up. What's the value of the two main filter caps (right after the rectifier)? The second one may need to be bigger to get rid of the ripple.

[Crist Rigott]

Originally Posted by old_coot88

The raster shows some 'hourglassing' from powerline ripple causing the slow bend on the sides that drifts up. What's the value of the two main filter caps (right after the rectifier)? The second one may need to be bigger to get rid of the ripple.

Both are 220uf

[Crist Rigott]

Originally Posted by old_coot88

P.S. If you're interested in trying the 9V battery trick, I have a ton of them which are pulls from smoke detectors in my building. They are Mallory Duracell and all test well into the green on a standard batt. tester. The pulls are always good since they're changed on one-year interval.
Free for postage. PM me if interested. Bill

Stand by for preliminary tests.

[Crist Rigott]

Originally Posted by old_coot88

And if that shows promise, consider sticking a few 9V batteries in series in the B+ line feeding the H.out circuit. That would give it even more grunt, B Boost and HV without overstressing the heater string.

This would at least give a yes/no whether raising B+ further on the H.out circuit would help.

The battery string would go in the B+ line feeding the plate (pin 5) of the 12AX4. If it helps, then consider building a small dedicated supply in place of the batteries.

Just a thought FWIW.

OK, it's worth a try. What, like 27 to 36 volts?