Lafayette KT-135

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 instruction sheet says 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 actually made things easier.

Now we have the black alligator clip on the resistor, the green clip on the center terminal of the regen control and the white clip on the right hand terminal. 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.

NOTE: The schematic in the manual is incorrect. There is no connection on one side of the regen control.

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 original capacitor was restuffed and sealed with beeswax at each end (I didn't have any red wire). 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.

Main parts are mounted. Notice the red antenna connector.

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.)

Small alligator clips were used as heat sinks 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 chance. I got them at vivatubes.com.

Using the photo on the left I've identified the tubes in this particular kit as "IEC" by the boxes. The tube boxes were magically restored in the picture on the right.

Lafayette brand vacuum tubes did not appear in the catalog till 1966. In 1965 they sold GE, RCA and Sylvania brands, but in 1966 the Sylvania brand was replaced with Lafayette brand. Lafayette tubes were "Made In USA," so it's possible they were actually made by Sylvania.

At any rate, I think most KT-135s came with IEC brand tubes.

The IEC logo can be plainly seen here. This tube was made in Japan, but many IECs were made by Mullard in England. Tubes labeled IEC Mullard were branded at a factory in Long Island, NY.

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.

This example looks like it was done by hand using "Liquid Paper" correction fluid.
Did the ink get thick at the IEC factory one day, or is this a rebranded fake?

We can assume that any IEC Mullard tube bought in the 1950s and 1960s was made at the Blackburn plant. However, IEC was licensed to use the Mullard name. They rebranded tubes as "Mullard" that were not made by Mullard, or even in Great Britain. They also rebranded Russian made 6L6 tubes as RCA, Raytheon, and Westinghouse.

You could end up with a tube made in Japan and branded "IEC" or a Canadian or Italian made tube labeled "IEC Mullard." You may have an IEC Mullard tube that was actually made by Brimar at a factory in Kent, or in later years, Yugoslavia. Some were made in India. You might wonder if most people cared where their tubes were made as long as they worked. Now that they are no longer made in England it seems to have become important. Today a NOS Mullard 12AT7 is very expensive.

An IEC Mullard 12AT7 made in Italy. It seems the name "Mullard" when paired with "IEC" doesn't mean anything.

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. In 2016, a brand new Russian made Mullard 12AT7 was $22.95, THE EXACT PRICE OF THE ENTIRE KT-135 KIT IN 1970.

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 in the catalog, even though you got all three with the KT-135.

On the left, Mullard 12AT7s from the 1950s. Center, a Russian made Mullard 12AT7 manufactured in 2020. Right, a 12AT7 "made in England."

MADE IN ENGLAND? Mullard didn't use the word "ENGLAND" on their tubes. A mistake at IEC? A counterfeit? A fake? Nope, apparently IEC could stamp the word "Mullard" on any tube they wanted. Whoever made it wanted people to know it's a 12AT7 with the large numbers on the top.

Above is one of the tubes after it was removed from its socket. Part of the socket is still attached to the tube. Obviously the radio isn't going to work again when the tube is put back. The Lafayette tubes had a 2-year guarantee (the IEC had none) but they supplied low quality phenolic 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 Lafayette store and upgrade to a Bakelite socket for 31 cents. Whaaaat??! 31 cents?! That's almost double the price, those thieves!!!