#106
Posted: Wed Jun 18, 2014 12:52 pm
Thank you, it's a very interesting information, and a text I have not read before.
If the color is 2000K, it must be quite yellow - and it is, but how yellow is yellow? The glow of the filament is indeed yellow, not at all white. But the reflected light looks more similar to "warm white" CFL, which is why I thought it is 2700K.
Even more interesting is the influence of heater voltage on temperature, where almost 10% increases just 100K - this difference is something the human eye cannot distinguish, but the intensity of reflected light is what we base our estimate on.
Further, at 2000K expected life is much longer than 1000 hours, as for instance declared for GM70, but it does increase further with 1900K - at the expense of a little emitting power.
That said, I have fine tuned my current electronic transformer (the one where I have wound myself two secondary windings of 4 turns each). Based on my calculation, output was between 9.5 and 9.8 (worst-best case scenario). After removing 2 turns from the primary (easy!!!), from 67 to 65, I should have 9.8 to 10.1, which I consider as perfection when working with so many unknown variables and few secondary turns.
No problem in operation, reading on DMM is not logical (increased from 15.8 to 17V), but the light is slightly less subdued and it seems just right. I can still look at the filament and it is bright yellow. It seems that both tubes have increased emission, since the cathode voltage is slightly higher (but that is something I should measure within the shortest period of time, not "tomorrow". Anyway, the sound seems to get that extra edge of precision and speed.
Edit: strange how I started wrongly using taught instead of thought as past form of to think?! I saw it in a couple of forums used by native English speakers and started using it without too much of a thought. Still, something did not seem right, and I had to check... thus here we are, editing.
If the color is 2000K, it must be quite yellow - and it is, but how yellow is yellow? The glow of the filament is indeed yellow, not at all white. But the reflected light looks more similar to "warm white" CFL, which is why I thought it is 2700K.
Even more interesting is the influence of heater voltage on temperature, where almost 10% increases just 100K - this difference is something the human eye cannot distinguish, but the intensity of reflected light is what we base our estimate on.
Further, at 2000K expected life is much longer than 1000 hours, as for instance declared for GM70, but it does increase further with 1900K - at the expense of a little emitting power.
That said, I have fine tuned my current electronic transformer (the one where I have wound myself two secondary windings of 4 turns each). Based on my calculation, output was between 9.5 and 9.8 (worst-best case scenario). After removing 2 turns from the primary (easy!!!), from 67 to 65, I should have 9.8 to 10.1, which I consider as perfection when working with so many unknown variables and few secondary turns.
No problem in operation, reading on DMM is not logical (increased from 15.8 to 17V), but the light is slightly less subdued and it seems just right. I can still look at the filament and it is bright yellow. It seems that both tubes have increased emission, since the cathode voltage is slightly higher (but that is something I should measure within the shortest period of time, not "tomorrow". Anyway, the sound seems to get that extra edge of precision and speed.
Edit: strange how I started wrongly using taught instead of thought as past form of to think?! I saw it in a couple of forums used by native English speakers and started using it without too much of a thought. Still, something did not seem right, and I had to check... thus here we are, editing.