3. - Feedback lines between the two ladders and the audio chassis itself must be shielded using two-conductor cable, and example being Belden 8451. The balanced feedback circuit must be reversed in phase - observe the F.B. 1 and F.B. 2 notations on Schematic 1.
4. - The audio chassis, containing the 2E26 tubes, input transformer and associated components, can be any chassis box which simulates the shape and size of the original speech amplifier assembly. It should have a good ground connection to the main deck.
5. - It is preferrable to install a connector on the audio chassis of the same kind used in the original speech amplifier assembly, thus allowing the existing wiring harness to be plugged in without modification.
6. - A source of 6.3 VAC must be provided for the 2E26 tubes (approximately 2 Amp capacity). This filament transformer can be located on the new audio chassis or elsewhere in the transmitter.