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 collected parts. 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.

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.

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.

Inside your KT-135 you'll likely find an IEC 35W4, an IEC 50C5, both made in Japan, and an IEC 12AT7 made in Great Britain. IEC, or International Electronic Components, rebranded vacuum tubes at a factory in Long Island, NY. You may also find Sylvania or Lafayette brand tubes.

In 1965 Lafayette sold GE, RCA, Mullard and Sylvania brand tubes. In 1966 the Sylvania brand was replaced with Lafayette, so that can help narrow down the date of the radio. The Lafayette 35W4 and 50C5 were rebranded Sylvania tubes, but the 12AT7 was made by Mullard, contrary to their "Made In USA" claim in the catalog.

Sometimes it's obvious the original tubes have been replaced, especially if the radio was sold online. The tubes were scavenged from the radios in the 1960s and '70s to be used in the family table radio, then replaced by a seller 50 years later. For example, Lafayette didn't supply tubes labeled Sears Silvertone or Motorola with the KT-135 kit, so these were pulled from another radio, as were tubes labeled Admiral, Emerson, or Philco. The original 12AT7 will sometimes be in place because they weren't used in superheterodyne radios.

In the 1966 Lafayette catalog, a Lafayette 35W4 was $0.48 and a 50C5 went for $0.90. A 12AT7 was $1.29. They didn't sell the IEC brand tubes, even though you got three with the KT-135.

IEC went bankrupt in 1980, long after the KT-135 kit was out of production.

When this radio was being restored I was unable to acquire IEC brand 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.

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!!!