Introduction

There's something delightful about saving these beasts from becoming scrap metal. Parting them out is one thing, while hearing them return to the air doing new service cutting through the QRM with powerful audio again is even better. After they are moved into their new home, our imagination is stimulated from the lingering smell of overheated insulation, solder flux, and the sight of pencil marks, cigarette burns and coffee stains on their tattered schematics. We reminesce about the  thousands of hours of music and talk that eminated from them, probably with some long nights spent trying to keep them on the air, along with occasional lightning strikes trying to knock them off, with curses from station management about the cost of fresh tubes. The spectacle of glowing, pulsating tubes in the front window provided wonderment to young technicians and engineers who came into the business. There are still some big box kW rigs out there, probably keeping long hours providing a voice to many people. Their replacements have no soul, coming in cabinets no taller than a personal computer. Their silicon power devices, while efficient, lack the warmth and excitement of glass tubes. The new transmitters don't impress us with their compactness, lacking the authoritative klunk of a main contactor closing before the meters read upscale. Preserving these big transmitters for another generation is a very satisfying endeavor. The tasks of  planning space for them, hauling them, cleaning and restoring them, converting them to the lower HF bands, adding PTT, setting up audio chains and beefing up antennas and feedlines all add to the excitement of operating AM - beyond what the average desktop ham transmitter of yesteryear does.

The two transmitters that I relocated are representative of state-of-the-art for 1973 and 1980, respectively. Both are capable of modulating up to 125% positive, and out to 10 KHz audio response. The plate modulated model has 6 tubes, and the pulse width modulated has only 3. Power consumption is 3850 watts for the former and 3500 for the latter, at full modulation with 1 kW carrier. Both weigh approximately 770 pounds, considerably lighter (!) than the previous generation. What follows is a description of each move, with some technical details about the transmitters. As work progresses, these pages may be updated.

John, K5PRO