Mike Peebles' Two Tube Regen Kit mashup

   Analog Dial       Page 1       Page2       Schematic       
 
A Mike Peebles "PO-425" kit with added audio amplifier and speaker.
 
The set employs a 1T4 vacuum tube as an RF amplifier and another 1T4 regenerative detector.
The audio output is fed to an LM386 audio amplifier IC mounted on a board beneath the speaker.
 

CONSTRUCTION

 
The first thing made was the coil. Sort of.
Read more about the coil on the next page.
All of my previous coils were on cardboard tubes.
This one is made of black PVC pipe.
 
Polyurethane station on the kitchen counter (at two in the morning).
 
Andrea made the base. The front panel came from the arts and crafts store. I didn't want to use the Luan subfloor stuff I used on the Ferrite Ferret because it's a little too thick. This panel is a thin sheet of plywood. The entire piece was used, so I didn't have to cut it. The size of the front panel determined the size of the base.
 
A test fit of the dial plate. Compare to the top picture. The dial plate was edited to accommodate the rotary switches.
 
Next a copper plate was attached to the front panel and the base from the kit was used to transfer the drilling spots.
 
All of the parts from the kit are mounted. Once the front panel is attached and the coil is wired to the rotary
switch there would be no way to remove the front panel. It had to be wired correctly the first time.
 
Because I'm easily confused (except when I vote) I drew
a diagram of how the rotary switches should be wired.
I also drew a diagram of how to wire the components,
since I had done away with two terminals in the kit.
 
Next the audio amplifier was built. By the time all the batteries were in place there was almost no room for it!
 
At this stage the radio is working. The "kit" is complete; all that is needed are the amplifier and speaker.
 
The radio can be tested by connecting high impedance headphones to the two wires coming out of the speaker hole.
 
Completed on March 2, 2014. It looks kind of "Steampunked".
 
Andrea at the controls. We brought the radio into the dining room because there would be less crap in the
background for the picture. With six feet of antenna wire and no ground we picked up several locals. Regeneration
on the BCB is very smooth. It's much tighter on the Shortwave settings.
 
Over a dozen Shortwave stations were easily heard the first time the set was tested, as well as several "hams".
The set tunes to about 6200 kHz. I should have put another tap on that coil! In addition, the "Shortwave 1"
setting spreads out the top of the broadcast band nicely.
 
One word of caution - with the added amplifier turned up the set picks up EVERYTHING that emits interference. A strong signal, however, easily drowns out the interference. Some of the shortwave stations were very loud and clear. (This was about an hour after sunset).

Televisions, computers and light dimmers will cause a buzzing in the radio.

We just turn off the protected outlet strips that everything is plugged into and the airwaves become quiet.
 

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