View Single Post
  #2  
Old 02-12-2018, 09:00 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,184
I'll let someone with direct experience comment on the picture quality of TK-42 vs. TK-41.

The improvement of Plumbicon cameras over image orthicons was particularly in the signal-to-noise ratio. While the Plumbicons had inherently lower detail contrast, their high SNR meant that much stronger image enhancement levels could be applied to compensate. The image orthicon noise spectrum was flat white noise from the beam current shot noise. Plumbicons had target capacitance that was compensated by a feedback arrangement in the pre-amp stage, which meant that the 6 dB per octave roll-off of the target capacitance was compensated by a 6 dB per octave rise in the amplifier frequency response. As a result, the noise spectrum also was triangular, with a 6 dB per octave rise; that is, the low frequency noise (which is most visible to the eye) was much lower than the noise of an image orthicon camera.

By the way, solid state sensors have a flat noise spectrum, but it is much smaller than the image orthicon (since there is no constant beam current, plus the quantum efficiency of solid state sensors is up to ten times better than that of photo-emissive sensors), and generally smaller than an equivalent Plumbicon (since there is no 6dB per octave compensation required).
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany

Last edited by old_tv_nut; 02-12-2018 at 09:06 PM.
Reply With Quote