Late production substitutes for 6BW7 and 30F5 pentodes - UK Vintage Radio Repair and Restoration Discussion Forum

FERNSEH · 7th Aug 2022, 4:04 pm

The attachments show late sixties production 6BW7 and 30F5 television RF pentodes. Clearly, these valves don't resemble the original valves made by Brimar and Mazda. It's most likely the valves shown in the pictures are the Mazda 6F23. The second attachment is a real 6BW7.
If that is the case, if one was to fit the substitute valve in a receiver some adjustment would be necessary, for starters there will be slight differences in interelectrode capacities.
At the same time as these valves were being marketed Mazda were supplying PCL83 triode-pentodes as a substitute for the 30PL1.
Later KB VC51 series TV receivers were supplied with Mullard EF80 valves as replacement for the out of production 6BW7.

DFWB.

7th Aug 2022, 4:04 pm	#1
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,379	Late production substitutes for 6BW7 and 30F5 pentodes The attachments show late sixties production 6BW7 and 30F5 television RF pentodes. Clearly, these valves don't resemble the original valves made by Brimar and Mazda. It's most likely the valves shown in the pictures are the Mazda 6F23. The second attachment is a real 6BW7. If that is the case, if one was to fit the substitute valve in a receiver some adjustment would be necessary, for starters there will be slight differences in interelectrode capacities. At the same time as these valves were being marketed Mazda were supplying PCL83 triode-pentodes as a substitute for the 30PL1. Later KB VC51 series TV receivers were supplied with Mullard EF80 valves as replacement for the out of production 6BW7. DFWB. Attached Thumbnails