Wednesday, February 4, 2015

Battleship Iowa Transmitter Reactivated After Almost 25 Years

Well, we finally got one of the transmitters fired up today after last being powered on in 1990.

Here's a view looking into the Transmitter Room, located "On Broadway", directly across from Engine Room #2. The exciter/power amplifier units are to your right, while the Antenna Couplers are all in the racks to your left:




And this is one of the Exciter/Power Amplifier sets:



The exciter is at the top, the Power Amplifier is in the middle, and the bottom unit is the high voltage power supply for the amp.


One of the "Grey Radio Gang" team members had installed new drive chains in the exciter a couple of weeks ago, and after verifying that the RF output cables did indeed go to where we thought they did, and verifying that when patched to the dummy load it was indeed connected to the load, we had the ships Electrician check the power wiring (440V, 3 phase) for shorts and grounds, made sure all the switches and knobs were set per the start-up guide, and proceeded to power it up.

Nothing.......dead as door nail.

Some checking revealed that one of the interlocks where the exciter slides in to the rack was stuck, and freeing it up, we were able to power up the exciter and power amplifier.

Power amplifier voltages and currents checked as normal, but keying up the unit and speaking in the handset revealed NO RF power output, and NO drive from the exciter. We then inserted a power meter between the exciter and power amp and confirmed we had no RF drive to the amp.

The first thing I checked was the 5 MHz reference oscillator source, which was switched to "External", and since the 5 MHz Reference Oscillators were removed from the ship when she was in mothballs, I switched it to "Internal", and we tried again.

Still no RF drive to the amp.

Since this exciter/amplifier pair had been more or less picked at random to be the first to be powered up, and had the drive chains replaced so that all the frequency set knobs worked, we then looked for an exciter that had at least the tens, ones, and hundreds knobs in working condition so we'd pretty much know what frequency we were tuned to.

We found an exciter that had those digits working, and proceeded to swap the two exciters.

Powering up the set after swapping exciters revealed a missing fuse, and after we replaced that, everything powered up as expected.

And this time we had RF drive to the final power amplifier.

Results?

How's about 950 Watts output @ 14.250 MHz into the dummy load, as measured by the built-in metering!

We still have quite a ways to go before we attempt to put one On-The-Air, but the results were quite encouraging for a transmitter that was last powered up sometime in 1990.

I'll be bringing in my power meter and spectrum analyzer so we can get a calibrated power measurement, and check the signal for spurs and modulation level, but BB-61 should be On-The-Air later this year with a BIG voice!

14 comments:

  1. Woooooh, OH YEAH! I'll have to get some more wattage so I can reach you when it finally comes online. Good Work.

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    1. We're on already using a Kenwood TS-850 connected to the disc/cage on the bow.

      Look for NI6BB most Wednesdays!

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  2. BZ and Out-(insert appropriate Navy-talk term here)-standing :) Looking forward to hearing the Iowa back on the air. 73 de Brad / NP4AI (ex-NSGA Sabana Seca)

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  3. Awesome, look forward to working you on the air.

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  4. WELL.....the original transmitters will only be used for certain special events.

    To actually get them on-the-air, we'll have to reconnect the disc/cage to the antenna couplers, and have one or two people down in the Transmitter Room, along with one or two people at the receiver racks, and another one to watch the "Coke Machine" to make sure it's patched correctly for audio and PTT in/out.

    We currently operate SSB with a Kenwood TS-850 running to the Disc/cage, and CW running a Kenwood TS-940 to the aft Trussed Monopole antenna.

    We're on almost every Wednesday from about 1000 to 1630 local time, so look for NI6BB if you'd like a contact.

    We always get spotted on the clusters and eHam, so you're chances of finding us are pretty good!

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  5. Hope to work you from station NM1JY sometime. 73, WA1NH

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  6. Gah....a URT-23C? Commence flashback in 3, 2, 1... We ran these in the 80's at the US Coast Guard Radioman "A" school in a comm simulator lab. I had the...privilege...of maintaining them. They were temperamental beasts.

    A tip: Inside the amplifier/tuner are some circuit boards which slid into board-edge connectors. They didn't have gas-tight connectors back then so the board-edge and the connectors tend to get corroded. Sometimes you can clear a problem with the amp/tuner just by removing and reinserting the circuit board a few times. A pencil eraser is a good tool to have around too. For the connectors you can try to buff the contacts with a relay contact file but that gets tedious. I got hold of some ultra-fine sandpaper (1000 grit) and glued it to a piece of stiff cardboard slightly thinner than the circuit board. Sliding that homebrew tool into the connector would clean all the contact fingers at once.

    Thanks for the trip down memory lane, and have fun.

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    1. Thanks for the tips!

      I've run into situations like this before, and usually working the cards in and out of the connectors a few times with some "contact cleaner" clears it up.

      So far, I haven't seen any corrosion on any of the connectors, but that doesn't mean it isn't there!

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  7. So you actually use that unsightly back-yard clohesline thing on the bow? I'm sure the antenna's effective, but lordy lordy is it *ugly*! It totally wrecks the smooth lines of the bow. :)

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    1. That "clothesline thing" is a great antenna and we've talked around the world with 100 watts.

      As far as beauty - The IOWA was designed for speed and sheer brutal power, not for her pretty lines.

      You must be jealous. I know you want one of these antennas in your back yard!

      Doug, N6DJI

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  8. Oh wow. Talk about a blast from the past. I never thought I'd see this devils again once I left the Navy. These things were the reason I lost so much sleep on all of my deployments. They worked great, when they worked. I went to a C school specifically for these things. Thanks for the pictures.

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Keep it civil, please....