Quote:
Originally Posted by peter_scott
I've cropped your screen shot (right hand side) and compared it with what I think is a full scan. If you are using a long exposure then perhaps the set is not interlacing correctly. I guess you'll need to magnify the image below to see the detail. Principally in the background.
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Yes, you are quite right. I magnified the image. The height of those small boxes represent about 7% of the active vertical scan time. So it is either a photo of just one field, or the interlace was poor.
Quote:
Originally Posted by Panrock
The other thing I found about the 5FP4 was that full frame scan (to cover the complete circular shape) was not possible at standard drive levels.
Is there a replacement-type 7-inch tube that could go into a 905?
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Yes, that is right, the vertical drive needs increasing a little for a 5FP4, which is also why it needs the added resistor in series with the sawtooth integration capacitor, to give a trapezoidal wave at the output valve's g1, to assist rapid flyback, otherwise , with the increased drive, the linearity suffers a little at the top.
I'm not sure about a possible tube for the 905, possibly a 7QP4, which off hand is magnetically focused and deflected, but I'd have to check if its non-aluminized. The 7DP4 used in the 621TS could work, but the circuit would have to be modified for electrostatic focus. There is a Russian TV CRT that would work, but I cannot recall the number off hand.