On 05/05/2019 07:34, Rod Speed wrote:


"Mike Clarke" wrote in message ...

[snip]

The spec sheet for the ballast https://www.tridonic.com/com/en/download/data_sheets/PC_T8_PRO_36-70W_xitec_en.pdf stated that the leads for the tube ends should have a capacitance of less than 100pF for one pair and 200pF for the other (corresponding to max lengths of 1 metre and 2 metres). This is no problem, they were well within the limits but I'm curious why an electronic ballast should have these different requirements - it's not as though there's any difference between the filaments at each end of the tube. Do any electronics experts here know why this is?

Because a higher capacitance will see not enough of the high
frequency getting to the tube to work as well as it should.

Yes, I appreciate that but I was curious why there should be different
limits for the two ends of a (symmetrical) tube.

https://drive.google.com/file/d/1oyd...ew?usp=sharing
or
https://preview.tinyurl.com/yyx7fuj9