13-01-2020, 12:53 PM
(This post was last modified: 13-01-2020, 01:05 PM by Mike Watterson.)
The DK40 (rimlock) was used for SW sets as the DK91 / 1R5 was poor at HF. Later replaced by DK92. I've one Pye with all B7G except for frequency changer, DK40. The 25mA DK96 was also poor at HF, and the 25mA + 25mA DL96 limited in power compared to 50ma + 50mA DL94, hence "better" battery sets after DK96 and DL96 would use DK92 for extended HF or DL94 for x2 volume. I've one Philips set post D*96 series that uses 2 x DL94 and a DK92. A later model added DM70/DM71 magic eye by replacing ONE of the two DAF92 valves. One was detector/preamp and other for phase splitter. It uses EIGHT "D" cells for LT and 2 x 45V HT, but on mains the HT on the DL94 is at the Philips absolute max, for a massive volume. Also usually uses multiple loop aerials disgused as beading in series or parallel for SW (no telescopic) as well as the LW & MW internal loops.
The USA used the 1LC6 (1.4 loctal) for SW battery sets, later replaced by the B7G 1L6, even in many USA MW sets. Very few USA models used 25mA battery valves, except the sub-miniature valve pocket sized battery valve sets on 45V or 67V pack like a long PP3. Those valves only used for hearing aids in UK. Some test gear weirdly used them.
The DK92 is different construction and looks like different pinout to the 1L6. A direct swap will work on MW. Higher frequency bands need re-aligned as the capacitances are all different.
There is a B7G mains 6.3V Triode-Hexode, that manages by using one heater pin also for the cathode.
Some Noval valves are 12.6V only heaters without a centrer tap. Some 6.3V types (with and without centre tapped 12.6V) are also designed for 300mA series mode.
The USA used 150mA rather than 100mA (after both switched from 200mA) for series as they often had more valves and thus a 100mA series chain would exceed the nominal USA supply voltage.
The USA used the 1LC6 (1.4 loctal) for SW battery sets, later replaced by the B7G 1L6, even in many USA MW sets. Very few USA models used 25mA battery valves, except the sub-miniature valve pocket sized battery valve sets on 45V or 67V pack like a long PP3. Those valves only used for hearing aids in UK. Some test gear weirdly used them.
The DK92 is different construction and looks like different pinout to the 1L6. A direct swap will work on MW. Higher frequency bands need re-aligned as the capacitances are all different.
There is a B7G mains 6.3V Triode-Hexode, that manages by using one heater pin also for the cathode.
Some Noval valves are 12.6V only heaters without a centrer tap. Some 6.3V types (with and without centre tapped 12.6V) are also designed for 300mA series mode.
The USA used 150mA rather than 100mA (after both switched from 200mA) for series as they often had more valves and thus a 100mA series chain would exceed the nominal USA supply voltage.
