![](https://coimages.sciencemuseumgroup.org.uk/50/651/large_thumbnail_1927_1074__0001_.jpg)
McVitie Weston valve collection
- Made:
- 1933
- maker:
- Mullard Limited
![Mullard double diode triode valve, type TDD4, B7 base](https://coimages.sciencemuseumgroup.org.uk/455/687/medium_smg00257817.jpg)
Mullard double diode triode valve, type TDD4, B7 base, marked 'DUMMY', lacking top cap., glass envelope loose, (RMW/Y185A - McVitie Weston number), made by Mullard Limited, 1933.
Mullard double diode triode valve, type TDD4, B7 base, marked 'DUMMY', lacking top cap., glass envelope loose, (RMW/Y185A - McVitie Weston number), made by Mullard Limited, 1933.