I have been experimenting just this week with the 1LA6 and adapter on two different chassis. 6A40 and 6L40. Models A600L and L600 respectively.
Here is my shot at making an adapter. The wire you see is coming from the shell just in case I need to use it some time.
1LA6 Adapter 1.jpg [ 222.33 KiB | Viewed 443 times ]
1LA6 Adapter 2.jpg [ 18.23 KiB | Viewed 443 times ]
I have used a piece of PC board as the base this takes the pressure of insertion quite nicely. With removal though one has to be more carefull and lever the tube up and off. I wonder if any one has experimented with a shield and taking the coonection to the filament? The result is supposed to modify the capacitance?
The 1LA6 seems to be a very willing oscillator and can operate at very low filament voltage. The down side I have found on both the above chassis is significant band shift such that complete alignment was necessary and even with that the the 16m band was impossible to bring in line. A brass slug in the oscillator coil almost makes it but not worth leaving in there as almost is not good enough.
It would be interesting to hear about others failures and sucesses with this mod.
Today I am experimenting with the 50A1 SS circuit. Here are a couple of pics.
SS 50A1 1.jpg [ 22.9 KiB | Viewed 443 times ]
SS 50A1 2.jpg [ 26.43 KiB | Viewed 443 times ]
I have made it an adjustable supply and am currently moving components around to minimise heat transfer from one component to another, rightway up and also upsidedown operation. So far this regulator looks very tight and operates over a wide range of input voltages. After this I will simulate a short circuit in the chip and see what voltages and currents appear. I am using the Transoceanic B+ and filament supply but instead of the tube filaments I am using an adjustable resistor to simulate various load conditions.