In the fall of 2004 we returned to the Battleship North Carolina looking for another project to start. This year our crew consisted of hams, Bill AG4PA, Allen KX2H, Jack WD4OIN and Terry, ship's electrician.
We decided to tackle the TDE Transmitter. This was the last communications transmitter installed on the North Carolina, added to the ships suite during a refitting. The transmitter was placed in service on 9-25-1944. It's rated for 125 watts out on CW and 30 watts on AM.
We had some obvious problems from the start, for example, a roller inductor was missing, two meters and the whole motor-start circuit was simply gone. The motor-generator was in place but the start circuit for it had been scavenged at some point. A rheostat that adjusts the generator output was also inoperable.
We started the project by trying to find parts. We wanted a roller inductor and drive that would match the front of the transmitter if possible. Keep in mind that the ship is a historic museum, so appearance is important. We also needed the motor start circuit and a rheostat. We sent out feelers to other ships and through the Navy but sadly we couldn't find any parts anywhere.
After a month and a half we still had neither parts nor leads on parts. We decided to see what we could improvise. For several weeks, we searched the ship for old parts that we could make into a motor start circuit. Just as the ship was starting to heat up from the summer's heat we found some parts that we thought that we could use to make a motor start circuit. The Battleship North Carolina becomes rather warm in the hot North Carolina summer sun. We decided to suspend our work and return in the fall when conditions are cooler. One can only imagine the determination of those that served and fought on this ship in the steamy south pacific.
In the fall of 2005 we returned to the ship. We had some luck over the summer in locating a roller inductor and the drive indicator, a nearly identical part ! We installed the Inductor and 2 meters .
We looked into the problem with the rheostat and found that the ceramic insulators were broken. Two insulators on the shaft were bad. Now what could we do ?
We tried and rejected several makeshift solutions. We were determined to solve the insulator challenge. We decide to try one of our club members, who is a skilled woodworker among other things, to try to make some wood insulators. Bob, W4LWS, handcrafted nearly identical insulators out of wood. I hope the pictures here show the incredible craftsmanship that went into the making of these insulators.
The insulators were installed on the keyed shafts and we were able to turn the rheostat and see the potentiometer change values!
Next we were ready to tackle a workable motor start circuit. Thanks to Terry's skill and expertise, In just a few weeks, we had our first motor start circuit ready to try.
The big day arrived. We were again ready to fire up a transmitter that has not had power on it in over 50 years. We had removed all the B plus fuses, the idea here was to check the generator and see if the tubes light up.
The power was turned on, the generator hummed, the tubes shine their ghostly light and about the same time, we were dismayed to see smoke coming from our motor start circuit! So it was back to the drawing boards.
Several weeks passed as we worked to rewire the motor start circuit. At last we were ready to try again. Hi ! Terry had done it, the tubes were on, the motor running and, this time no smoke! We used our voltmeter to verify that we saw all of the proper generator voltages. We installed all the fuses and tested the transmitter. No, we didn't have any output yet. We were hoping, but were not that lucky.
In the fall of 2006 when we came back to the ship,we started our trouble shooting, The first problem was that 2 of the meters was giving terrible readings . We worked on this problem for 2 weeks before the old brain started to think ! Hey, that's the same 2 meters we had replaced 6 months ago.
When we changed the meters out we didn't have any power on the transmitter and we used a ohm meter to test the wires, one lead had a solid ground on it. This naturally had to be the negative lead for the meters and that's the way we hooked the meters up.
Yes, we had hooked up the 2 meters in reverse ! These meters were reading negative going values.Took 2 weeks to figure this out.
Now that we had out meters working correctly we could continue with the tune up process. Allen,KX2H, started tuning the transmitter by the book and as the load was applied the high voltage fuse blew,a 1000 volt fuse. Now we have a good problem . That fuse is a special fuse , we have searched the internet and electrical stores for a month with no luck.
Terry suggested that we try some buss fuses that he had in stock. They are slow blow 600 volt fuses with close amphere ratings to the fuse that had blown. The 1000 volt fuse that blew was a fast blow fuse. Terry rewire the circuit to accept the buss fuse.
We had the load off the transmitter and cut the power back on. The fuse was holding . We applied the load and the fuse blew again. Now it's time to isolate some B+ leads and try to fine out were the problem is.
Most of the connecting wire in the transmitter is shielded ,cotton wire. We locate a lead that has a ground on it and remove it from the B+ line. Replace the fuse and cut the transmitter back on. The fuse is holding so we think we have isolated the trouble lead.
We cut off the power and start working on our grounded lead. We take off both ends of the wire and check it for ground again and are dismayed to find that the ground is gone. It has come clear on us. We resolder the leads and cut the power back on. The fuse holds.
We start the tune up procedure and the transmitter works ! About 125 watts out on 20 meters.We retune the transmitter and fine we can tune the transmitter on 40 and 80 meters also ! What a happy day.
We retune the transmitter to 20 meters and set up a schedule with W1SRR, a radio man who was on the North Carolina when it was commissioned and decommissioned. W1SRR,Mac, had no trouble hearing our signal on 20 meters. Mac was the first contact on the TDE Transmitter in 60+ years !
Mac being the radio man that he still is today informed us that we had a good strong signal but we have a hum on our carrier.
As the summer heat of 2007 set in on us we left the ship knowing we still had a problem with the TDE but we are almost home . Almost have a transmitter that we can tune on multiple bands ,quick.