John, VE5EI Two Tube Regen

Hay Dave long time no see! Well here is my 0-v-1. Based on the plans in the 1937 Hammarlund Shortwave Manual. It has a type 30 triode as a regenerative detector and uses a type 33 pentode as the audio stage. It works really well, great sounding audio. I have built up a 32 rf stage for it that hangs outboard, works very well with the rf amp, makes it a new radio. Well if you wish to post to your site please feel free to do so! Take care and we'll be talking to you soon eh! take care John Perry VE5EI

David Trott's Untuned Crystal Set

Thanks for the web site, information, pictures and schematics. I am attaching two photos of a crystal set that I have built. It is my fourth set. I built it in a Lane brand cedar jewelery box. I use a 75ft Radio Shack shortwave antenna and for a ground a hollow iron pipe hammered into the ground. The coil is not tapped, there are no variable capacitors. There is a 47K resistor over the phones and a 1N34A diode and Radio Shack jacks and magnet wire. The coil is a wooden dowel and it is glued to the inside of the lid. I used electrical tape over the magnet wire to insulate it from the coil as it passes over from the diode to the antenna hook up . With no tuning I hear a faint signal from one or two stations during the day. At night , thanks to propagation I pick up the world! Loud and clear too ! As you can imagine the signals are random and often overlap. Thats okay for someone who channel surfs anyway.

I am in Seabrook New Hampshire; right on the coast above Massachusetts. From this location I have at night picked up WSHP South Bend Indiana, WCBQ Monticello Maine I also hear a lot of German, Arabic, French, Chinese and British language bouncing in and out. With no controls ( an open circuit ) you are able to unintentionally scan the low end of the broadcast range.

Thanks for keeping passive radio alive. Your not the only one building these little curiosities out of left overs.

Hello Dave,
I have finished 6 radios now. Like most builders I continue to redo them. I am sending along photos of radio number five. This one uses a nice Chinese made box used to display samples of 5 small perfume bottles. Until I got a hold of it.

This set is my first attempt at using a spider web form. I reused magnet wire from radio number three; now fully disassembled. Nice features are the brass thumb nuts. the upper left is the antenna the one below it is the ground. The two in the upper right are the phones. the works are hidden under a velvet covered plate under the lid. the brass looking trim is really plastic. there are two taps on the coil and I have made my first tap switch using brass nuts and bolts. The tap connects to a 1N34A diode. there is a 47K resistor over the phones. I haven't had much time to test this out but picked up a good signal from a station playing that crazy rock 'n roll. I like swing and jazz.

M2's Dutch Windmill

Dave:

This is a photo of my infamous 12-inch miniature square loop antenna. The total boom length is 12 inches (translates into a side dimension of 8.5 inches !). There are 24 windings of 26 gauge enamel wire (occupying 1.5 inches depth) for the primary, and 2 windings for the secondary (placed 0.25 inches from the primary). The primary is connected to a 365 pF variable capacitor. I used stained and polyurethaned pine for this project (but used walnut for my larger versions). The number and spacing of the windings was based "loosely" on the formulas found in J. Carr's book on loop antennas, but I had to initially experiment with a "cardboard" version of this antenna to get the dimensions correct...

The antenna works pretty well but has very sharp tuning characteristics (almost too sharp - hard to fine tune without a vernier), and covers a frequency range of approximately 450 to 1500 kHz (basically the AM broadcast band). It exhibits a little hand capacitance problem when you bring your hand close to the tuning knob, but it is minor and only noticeable at higher frequencies (above 1300 kHz). Directionality is decent, and sensitivity is comparable to a Marconi antenna of short length (40 feet).

I have this antenna connected to a American Bosch Magneto 48 TRF radio (vintage 1930). If I turn the volume (really the RF sensitivity control, in those days) up too high on this radio with the 12-inch loop connected, I get a slight squeal (probably from regen osc). This squeal is not present with a long wire antenna.

I have found no literature on these small (less than 24 inch) type of loop antennas, but this one seems to work pretty well. Its design came out of an aesthetic need to be placed in a living room (and satisfy my wife). My daughter calls it the "Dutch Windmill"

M2

Neil Madonick's Wireless Broadcaster

This is a repro, but it sure looks real! Congratulations Neil.