Electron Engine ™
Printed Circuit Boards by Emissionlabs
EE15. Primary Board, for LL1620, LL1623, LL1627,LL9202
1. 
Primary Boards (You are now here)
We have copyright on this design.
On the primary side, the configuration is chosen. In this example the board is connected for: LL1623, Single Ended. On the secondary side, input and output impedance is chosen. For this, we have also a board. (The Link is above here).
Introduction
The transformer pins by Lundahl sometimes break off, by soldering too thick wires on it. This is not uncommon, because the pins are thin, and wire are of course thick. This is difficult or impossible to repair. With the EE15 PCB, such damage can not happen. In addition this board ensures correct wiring, and it has a better appearance.
Features
- GOLD PLATED
- Works on all PP, SE, and PPZ transformers. (PPZ=Parafeed)
- Ultra Linear tap possible.
Connections
- LL1620/1627 and LL1623/9202 are connected different. For this, apply the solder bridge, at the right side, to use LL1623/LL9202 or at the left side, to use LL1620/LL1627.
- Single Ended (SE) , or Push Pull (PP) or Parafeed (PPZ) is automatically configured when the wires are soldered in at the right places.
- PP Ultra Linear Tap. Though this was not intended originally by Lundahl, the boards provide UL taps. When used PP, there are two taps, at 50%.
- SE Ultra Linear Tap. This is a rare, but beautiful way to connect big pentodes like EL34 or KT88, or KT150 in Single Ended mode. The plate and V+ connection is taken from the SE box, just normally. The UL taps however are taken from the PP box. One UL tap in that case ist at 25%, the other at 75%, and a tap at 50% is taken from the V+ connection at the PP box. WIth a switch you can even connect the screen grid to this 25%, 50% or 75% UL. Switching should only be done with power off.