Globe King 500

INTRODUCTION:

The first time I ever heard of the WRL Globe King 500 transmitter was from an ad in an old copy of CQ magazine I picked up at the Gold Country Swap Meet. Prior to ‘seeing the light’, I believed a Yaesu FT-102 or a Kenwood TS-530 was a cool ham rig! After seeing the GK500, I simply had to have one. The tri-level, silver hammertone cabinet with chrome accent strips, the large jewel indicators on the power supply deck, the beautiful, spartan modulator deck and the comparatively cluttered RF deck…just gorgeous and oh, so classy! A true boatanchor!

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ACQUISITION:

I tore off to the internet to see if I could round one up. Some quick research revealed that GK 500s in operable condition tend to fetch a premium among radio squirrels…typically in the $1000 and up neighborhood these days, depending on completeness, condition, and whether or not it’s the “C” model with a built-in VFO. After months of posting want-ads on QRZ.com and other radio squirrel forums, I finally received a response from somebody semi-locally. Ben, W6FDU was located in Campbell, down in the Silicon Valley region of the Bay Area. He described a GK 500 transmitter he was looking to sell as a “free-range turkey” and said it was going to take a lot of work to get it running again, but that it was cheap. So, I coordinated a trip down to Campbell with a visit to the DeAnza College Electronics Swap, as well as a meet-up with an old friend of mine from high school who lived nearby. I met Ben at his house, where he brought me back to a large conex box in his backyard, and showed me the transmitter. I have to admit that my heart sank a bit when I saw the rusty, dilapidated thing sitting there among the other old, unwanted radios that were stacked up like cordwood inside the box. The thing spoke to me though, and I knew I had to rescue it. I paid Ben $100, and loaded the transmitter, plus an extra cabinet that he threw in with the deal, into the back of my truck and drove home.gking1My first sight of the GK 500. As my friend Tom, WA6OPE says, “You never know what’s going to wash up at low tide.”

gking2From the rear, it was obvious that a lot of parts were missing, but it appeared that all of the set’s heavy iron was still in place.

gking3 My heart sank when I opened the top of the Bud cabinet and saw this mess that was once the RF Deck. But hey, it’s a labor of love, and it’s definitely repairable. I asked about the 4-250 final power amplifier tube and the 811 modulator tubes, and was told by the seller that they were in the accompanying box of goodies. Turns out, the tubes were all missing.

 

THE GLOBE KING ARRIVES AT ITS NEW HOME:

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I arrived home, and when I opened the hatch on my SUV, I stared at the big, rusty mess and wondered what I had gotten myself into. I unloaded the transmitter and brought it into the dining room (an advantage of being single at the time). I began by taking about 100 photographs of every piece of the transmitter from every angle possible as a reference and a starting point. The transmitter had evidence of some serious modifications, not to mention some outright butchery. For whatever reason, somebody sawed about half of the stators off of the plate tuning capacitor in the RF deck. Not sure what the purpose of that operation was. I suspected it might be a mod done to enable the transmitter’s use on the CB bands, but it occurred to me, that this transmitter was already capable of transmitting on CB frequencies. Definitely a head-scratcher.

THE STARTING POINT:

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Here’s what it looked like on day 1. It is very evident, that the transmitter was stored for a number of years in a damp place. There was surface rust everywhere, and on the chassis there was severe rust and pitting. All of the iron was rusty as well. I started the actual work of restoration by completely stripping down the power supply, modulator and RF decks. I took hundreds more photos and labeled anything and everything in hopes that it would make reassembly that much easier. Once stripped down, I sandblasted and prepped the chassis pieces for zinc plating. AAA Plating of Sacramento did the plating work for me, and considering all of the deep, deep pitting, I think the plating turned out very nicely. The next order of business was to reassemble the unit’s power supply. The M.O. I established was to start the restoration work at the bottom and work upwards, finishing with the RF deck up top.

IMG_0830This is an overhead view of the power supply deck on day 1. Not pretty, is it?

chassisThe three decks going off to the platers. The middle chassis was partially sandblasted at home, but I realized my little 33 gallon hobby air compressor at home just wasn’t up to the task, so I left this work for the platers to do. 

BAKING THE IRON:

Knowing that the unit spent a good many years in ‘the damp’, I began by checking the transformers and chokes with a megger. It was no surprise, that each and every piece of iron showed very low insulation resistance on the megger. None appeared to have any dead-shorts to their cores or to the outer covers, so that was good. Baking the transformers in order to drive out the moisture that had permeated the windings was going to be necessary. The first couple of transformers I baked, I used a toaster oven I keep out in the garage for doing non-food related cooking, such as curing pieces that have been painted with black-wrinkle paint. The lowest temperature on the oven is 200 degrees, so I started there. I would strip the end-covers off the iron, and place it inside the oven, which was set at its lowest temperature. I inserted the temperature probe from my B&K multimeter deep down into the windings of the transformer, until it was at the closest point I could get to the center of the windings. I then baked the transformer about 4 hours using this method. IMG_0991I love the smell of baking transformers in the morning!

I’d let the iron cool off overnight, and they’d get re-meggered after this overnight rest. I kept a log of pre-bake and post-bake megger readings. Most of the iron started off in the 2 to 8MΩ range, and after baking, were typically between 50 and 100Ω. In discussing my method with a friend, he informed me that “Low and slow” was the way to go with regards to baking iron. He informed me that a lower temperature for much more time was the preferred method for driving out the demons. I shelved the toaster oven, and mounted a ceramic light bulb base into the bottom of a Folgers coffee can. I drilled air intake holes around the very bottom, and installed a grate about an inch down from the top of the can. The transformers would rest on the grate, while the 100 watt incandescent light bulb would slowly ramp up the temperature in the form of gently-rising currents of hot air that would flow around the transformer. I extended the baking time from 4 hours to about 9 hours. During the first hour, I’d wrap the top of the new “oven” in aluminum foil to form a sort of chimney with the top crimped down to about a 1″ opening to speed up the initial heating of the transformer. Core temp using this method seemed to plateau at around 160 degrees. PERFECT!!!

 

More to follow….

 

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