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FERNSEH · 2nd Feb 2023, 1:48 pm

The Baird T5 focus coil has a resistance of 19Kohms, whereas the focus coil in the T23 is 1000 ohms. Is it possible there focus coil in the T5 has the correct ohmic value? After all, the focus control does have a limited effect on spot size on the 9" Ferranti CRT. The Cathodevisor 15MW4 CRT has a much thicker neck compared with the Cossor tube in the T23.
The fact the T23 seems to have a appetite for focus controls could be due the much lower focus coil resistance compared with the 19Kohms coil in the T5.
The T5 coil needed more ampere turns compared with the T23 coil.
The vision receiver is on the work bench again, the local oscillator has stopped working again.

DFWB.

2nd Feb 2023, 1:48 pm	#478
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Baird T5 restoration project. The Baird T5 focus coil has a resistance of 19Kohms, whereas the focus coil in the T23 is 1000 ohms. Is it possible there focus coil in the T5 has the correct ohmic value? After all, the focus control does have a limited effect on spot size on the 9" Ferranti CRT. The Cathodevisor 15MW4 CRT has a much thicker neck compared with the Cossor tube in the T23. The fact the T23 seems to have a appetite for focus controls could be due the much lower focus coil resistance compared with the 19Kohms coil in the T5. The T5 coil needed more ampere turns compared with the T23 coil. The vision receiver is on the work bench again, the local oscillator has stopped working again. DFWB.