Lafayette KT-135 EXPLOR-AIR radio kit

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Since the radio is working, let's perform an experiment!
 
The schematic in the manual shows the regen control wired this way.
The pictorial instructions say to wire it like this.
 
Which way works better? We need to cut the lead to the resistor at the regen control, then compare how the radio operates with it connected to the right hand lug vs. the center lug. When I touched the resistor it broke at the arrow! That made things easier. Now we have the black alligator clip on the resistor, the green clip on the center lug of the regen control and the white clip on the right hand lug.
 
I had fantasies of flipping the switch and observing a fantastic increase in performance. In reality, all that happened was that the regeneration control needed a tiny adjustment as you switched back and forth.
 
 
 
Experiment over. Let's take this thing apart!
 
Right from the start there were problems. I couldn't get the frickin' knobs off! Two of them had broken set screws. One of them (the one pictured still attached) didn't seem to have a set screw with a head on it, so I started to drill it out. Andrea came to take a look. There was NO set screw. The knob was GLUED on. What a mean trick! I had been drilling into the shaft of the volume control. That dirty bum! (As Ralph Kramden would say.)
 
Harvesting parts.
 
The greenish coating on the chassis is oxidized cadmium. I was advised not to sand it or breathe the dust, so I used Duro "TUB N' SINK JELLY" which is normally used to remove calcium and rust. I then polished it five times with Brasso. I wanted it to remain dull, but it kept getting shinier and shinier. The more I polished it, the shinier it got. There must be a connection, but it escapes me entirely.
 
 
 
The parts collected. The fixed capacitors will be replaced with silver-mica types for improved stability, except for the .01 bypass caps which are "Orange Drops." The "Chatter Teeth" (top left) are not part of the project.
 
This is what you got when you opened the box 50 years ago. I stole this picture from  virhistory.com.
 
The red replacement "firecracker" capacitor wasn't going to look right. It's too big and too bright. The original capacitor was restuffed and sealed with beeswax at each end. The wax will allow easy restuffing by some future owner, such as the Smithsonian Institute.
 
The set was also going to get a polarized plug since there was a 50/50 chance the chassis would be "hot" every time you plugged it in.
 
The main parts are mounted. The antenna connector, which was black, was replaced with a red one. Someone pointed out that neither color should be used for an antenna and convinced me to get a yellow one. This style is getting hard to find.
 
How it looks in the manual vs. how it looks in real life. Pictorial No. 2 makes you think it will be easy to wire the set. Then you get to Pictorial No. 5 and things aren't so easy anymore. (A copy of the manual is on the bottom of page five.)
 
Components were heat sunk with small alligator clips to prevent damage from the soldering iron.
 
The vacuum tubes.
 
Three New Old Stock vacuum tubes were purchased, and one of them was a Lafayette just by accident. I got them at
vivatubes.com. If you want a real NOS tube, this is the place to go. The tubes will arrive in a BOX, not a padded envelope.
 
 
 
Lafayette sometimes sent their own brand tubes along with the KT-135 kit, but for most of the kits they did not. Using the photo on the left I've identified the tubes as "IEC" by the boxes. The tube boxes were magically restored in the picture on the right.
 
    The IEC logo can be plainly seen here. This tube was made in Japan, but many IECs were made by Mullard in England.

    Investigating IEC and Mullard will leave your head spinning. In addition to the histories of IEC and Mullard, you’ll find some amazing facts about vacuum tube filaments, cathodes, plates, grids, pins, getters, tube numbers and ink, and some interesting youtube videos, along with articles on tube counterfeiting.

    In brief, the Mullard company, whose main factory was in Blackburn England (opened in 1938), became the largest manufacturer of “thermionic valves” in Europe. In the 1950s, International Electronic Components, a buyer and seller of surplus electronic parts, was chosen by Mullard to be their exclusive US distributor. Mullard became “IEC Mullard” in the USA, ergo the name stamped on the tubes.
Two 12AT7s. Both labeled "GT. BRITAIN" and "EIC" but only one is labeled Mullard. The ink on the "EIC" label is
different from "GT. BRITAIN," a dead giveaway of a rebranded tube. These were both pulled from KT-135s.
 
   We can assume that any IEC Mullard tube bought in the 1950s and 1960s was made at the Blackburn plant. But IEC was also licensed to use the Mullard name. Consequently, in later years they rebranded tubes as “Mullard” that were NOT made in England. They also rebranded Russian made 6L6 tubes as RCA, Raytheon, and Westinghouse.

    IEC manufactured some of their own tubes in a factory on Long Island, NY. They could possibly be marked "IEC Mullard" because they were allowed to. You could end up with a tube made in Japan and branded "IEC" or a Canadian made tube labeled "IEC Mullard." You might wonder if most people, other than audiophiles, cared where their tubes were made as long as they worked.

    IEC went bankrupt in 1980. Phillips, who owned Mullard, continued to use the Mullard brand name till 1988. Mullard tubes are made today in Saratov, Russia by New Sensor, which is an American company. As of 2016, a brand new Russian made Mullard 12AT7 is $22.95, THE EXACT PRICE OF THE KT-135 KIT IN 1970.

    So where were the IECs in your Explor-Air made? If it’s an early model they are probably Mullards made in Blackburn, England. If you want to replace them with real Mullards, there are legitimate tube sellers on the internet who are experts at identifying tubes and spotting a counterfeit. An IEC 12AT7 made in England in the 1960s easily goes for $50 today.
 

In the 1970 Lafayette catalog, a Lafayette 12AT7 and a Mullard IEC 12AT7 are the same price, $1.44. The catalog states the Mullards are hi-fidelity tubes imported from England. The 10M Series Mullard 12AT7 with gold pins, individually tested and guaranteed for 10,000 hours, sold for $2.55.

A Lafayette 35W4 was $0.75 and a 50C5 went for $1.15. They didn't sell the IEC 35W4 or 50C5, even though you got all three with the KT-135.

Above is one of the tubes after I removed it from its socket. Part of the socket is still attached to the tube. Obviously the radio wasn't going to work again when I put the tube back. The Lafayette tubes had a 2-year guarantee (the IEC had none) but they supplied very low quality plastic tube bases with the KT-135, which sold in the catalog for 18 cents.

It's doubtful anybody ever did this, but you could go into the store and upgrade to a bakelite socket for 31 cents. Whaaaat??! 31 cents?! That's almost double the price, those thieves!!!

 
 
 
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