The "Sky King" Solid State Regen Radio

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Sky King
Sky King with his niece Penny King and nephew Clipper King.
Can you imagine how Hollywood, with its sleaze and perversion, would portray the Sky King show today? Perky little Penny all alone out on the ranch with Uncle Sky. Look at Sky with his firm jaw and his "no nonsense" gaze. He's wearing a holster. He's got a gun to shoot bad people with! Quick, change the channel. It's not politically correct, it's "offensive," and the gun is "triggering!"

I'm glad I grew up in the day when a kid could watch good guys shoot bad guys on TV, and you'd feel really good about them getting shot.

You have to wonder as you look at this, where are Sky and Clipper's other hands?

Back to the radio...
The short wave band (Band 4) didn't work very well.
radio coils
The shortwave band is at the top of the green coil, composed of six turns of wire. The coil works well for broadcasts but I had to turn the volume all the way up to hear any "hams." A coil of ten turns of 24 gauge wire, space wound on a 1ΒΌ inch coil form, covers the same band. When placed inside the main coil, the difference in the radio's volume was dramatic.
Radio Coil
Coil Switch
The little coil now lives inside the big coil and is the new "Band 4."  I hooked it up backwards the first time so I used red and black wire to prevent me from getting the wires mixed up.
RF control
After using the radio, it was found that the control above, which coupled the RF amp to the tuning coil, did very little. In series with the 365 pF variable capacitor was a 47pF fixed capacitor, which gave a total of 42pF with the plates fully meshed. It was replaced with a 33pF fixed capacitor, which costs about 20 cents versus the variable cap which costs about 20 dollars!
The control was replaced with a "fine" regen control, which works very nicely, but I had to peel the paper faceplate off the front and make another one with the new designation.

LM386 amplifier
LM386 amplifier
They say that one definition of stupidity is doing the same thing twice and expecting different results. The little LM386 amplifier module I made in the left-hand photo gave me nothing but trouble. The "stupid" part was that I had used this in the "Ferrite Ferret" and it gave me nothing but trouble. If you turned the volume up too high it would break into an ear-splitting howl. I thought I had "fixed" it, but it wasn't fixed.

I replaced it with a $1.98 module that came as a kit from China. It works great, has plenty of volume, and the LED can be mounted on the front panel as a "power on" indicator.

Sky King Radio Rear View
Rear View. The "binding posts" for the antenna and ground have been replaced with 1" Fahnestock clips.

How well does it work? Here's an example above. It just shows it working, I didn't put much effort into the video.
I give it a score of "pretty good." I think that putting the small coil inside the larger coil was probably detrimental to its performance. Also, with the wires going all over the place, this is the poster child for how NOT to wire a regen radio.

The original idea to use the circuit Greg sent me to build a solid state Peebles "Two Tuber" with onboard Peebles antenna tuner evolved into this. Mike Peebles himself liked the circuit. As a matter of fact, he created the schematic below for this webpage.

regen radio schematic

LM386 kit
LM386 kit
The audio section is a standard LM386 kit, but the jacks and pins on the circuit board weren't needed for the radio. The price range is all over the place, depending on where you buy them. In 2015 they were $1. In 2022 they were $1.98, but some people sell them for as much as $10, so be careful where you order from.

Sky King and radio
Sky King, Penny, and Clipper admire the radio while listening to "Coast To Coast AM" with George Noory.
They are discussing time travel in this episode of the program. That's amazing, as George would say.


Gary's radio
Remember Garry, the guy who told me to change the value of the source resistor? He built a similar radio that only has one knob.
He used a stick to control the regeneration. I would like to strangle him. Coincidentally, the month and day  on the battery is my birthday.

By the way, the Sky King airplane shown on the previous page, which I used to designate the "model number" of the radio, crashed in 1962, killing its pilot.