K0DEW has been collecting and restoring Collins equipment for over twenty-five years, but this old broadcast transmitter turned out to be one of the most challenging and interesting. I had restored a KW-1 and several large military transmitters, so I was ready for this project.
My goal was to make each and every part like it looked and worked when it moved out the front door of the Collins factory in Dallas TX almost fifty years ago. I was informed on a Tuesday that the transmitter was going to the land fill on Saturday, so on a Wednesday I loaded my pick-up with a few hand tools and a friend, KC0VOB.
This is the way I found the old transmitter at the station in southern Missouri. The front door was missing and the transmitter was located against a wall. Because it was so heavy, and we could not slide it out from the wall, we removed the entire front panel to get at the heavy iron on the bottom. All of the hardware was saved in one container and separated later.
When we got some of the big iron out we could move it from the wall and get to the back doors. This move let us remove the other big parts on the bottom shelf. Shown here are two of the High Voltage Filter Caps and the shelf for the Modulation Transformer. The Caps were found to be bad and were replaced.
Here is the High Voltage Transformer on the right and one of the Filter Chokes on the left. All of the wiring and small parts had to be removed in order for two fellows to get it out of the station. Even with everything removed the cabinet weighted at least three hundred pounds. I think the station was built around the transmitter.
All of the wiring was removed and put in a box for transportation back to the home QTH. Photos of everything were taken by KC0VOB, but were of little use putting the old beast back together. After we got the 20V-3 loaded in the pick-up truck we made one last search of the transmitter room and found the front door under a pile of trash.
Alter a lot of work and straining of our two backs, we got it home and on the porch of the work building. This is about as close as my wife would let me get the dirt to our house. The RF box on the left and the modulation box on the right was removed before I gave it a bath with soap and water . The large box at the top contains the Pi-L tuning network, it was removed and cleaned separately.
The RF Deck is on the left and the Modulation Deck on the right. These fans were not the correct ones for this transmitter. Correct ones were added later in the restoration process. These decks were removed and cleaned individually. The rig uses a pair of 4-400s in the Final and a pair in the Modulator.
After each part was cleaned and dried in the sun for several days, each and every part was reinstalled in the cabinet. The wiring was the hardest to get in its correct place. When I got the dirt off the wiring the colors changed and with out the help of Dave, W3CRA, and his wiring photos, rewiring would have been almost impossible. It took about nine months to get to this point in the reconstruction. The large front door had to be repainted along with the two dark grey doors on each side. Minor mechanical items needed to be fabricated, painted and installed. A few modifications to the electronics had been made by the engineers over the course of fifty years, these were either cleaned up or removed.
N0GW, Gary and K0DEW hard at work.
Some times it takes four hands, and two brains, to figure out what is needed to make it work.
I need help finding the RF meter. This is the only missing part.
This project is a labor of love and is a tribute to the many engineers, technicians and workers at Collins Radio that make it possible.
My personal thanks to KC0VOB for taking photos all during the project, to N0GW for helping find where the parts of the puzzle went,to W3CRA for supplying shots of his 20V-3 and encouraging me all the way, and to N7OTQ for his articles on the 20V-3 in the CCA Signal.