I have an Atwater Kent Model 30 which is powered by my ARBE III. Resetting the ARBE III for different radios is cumbersome for me. Even with 9-pin connectors, I have to change jumpers and reset the A+ voltage.
So, I wanted a dedicated power supply for my favorite radio, the AK 30. As luck has it, a couple of summers ago I bought a Bosch Nobattry for ten bucks.
To get to the point--I gutted the Nobattry and built a K-101A Battery Eliminator Kit (from AES via Amazon) to put inside it.
I thought I’d just duplicate the ABC connections that I used with the ARBE III or follow the Atwater Kent battery diagrams. They differ slightly in the C- connection--maybe it’s not really a difference. Then, the K-101A instructions makes one mention of connections for negative bias, and it seems to be different as well. On top of that, I have a 171 “power tube” in the last stage which requires higher B+ and more-negative bias than the standard tube used in all of the battery wiring directions.
Here is an Atwater Kent Model 30 schematic, and a summary of the diagrams or notes from Atwater Kent, ARBE III, and K-101A.
I have no problem with A and B voltages. I’m unsure of the C connections.
- The K-101A C- is adjustable from zero to -22 volts.
- The diagrams above assume -4.5 V grid bias at 90 volts B+.
- The UX171 data sheet specifies -16.5 V grid bias at 90 volts B+.
I will be most grateful for advice on the C connections.
Link to a highly illuminating 11-pic series on what I’ve done with the Nobattry:
https://flic.kr/s/aHskyeMTdS