Exhibit B

Gary's Second Regenerodyne, the "Eavesdropper"

This receiver is electrically the same as exhibit A, just a bit smaller. Again, the schematic appears in the Regenerodyne construction page. These are just a couple photos that i think show in better detail the receiver itself.

The radio itself was constructed in a small Bud box, again from the 1930s, which i was fortunate enough to find in my favourite Military Surplus store in Orlando (dare i mention who? Skycraft, on Fairbanks right off of I-4, of course! In the past 28 or so years i have made countless pieces of equipment from parts purchased from these folks. Nowadays there is not so much emphasis on tubes and chassis and you won't find five-dollar ARC-5s anymore, but they are still an excellent place for parts. BTW, they have no idea that i am plugging them. And the first time i get gaff from 'em, this little plug will be pulled!)

Back to the radio . . .

The cabinet is just slightly smaller than the SW-3 it sort of suggests, and close inspection of that Velvet Vernier will tell you it was repaired with non-original parts, like the "nose-cone", once a polished brass piece, was damaged from within seizing the dial shaft, and had to be drilled off carefully, so as not to damage the bakelite escutcheon, and the shaft works covered with a bakelite nose which happens to be an old steam-control knob from an iron. But, it's not horrible, and the vernier works great, now.

Like the first R-dyne, the "Model A", this "B" model has only three controls on the face, and no fine tune. Using a 50pf variable and the Velvet 5:1 vernier eliminates the need. 3 mc tunes nice and slowly with this arrangement, and the converter operates with a 14 - 18 mc input. Consequently, this is a 19m. SW and 20m. amateur band receiver. The IF tunes 3.0 - 3.2, which means i get 14.0 - 14.2 with a 17mc xtal (17000kc.) I can also get 20.0 - 20.2mc if i wanted, but i would have to take some windings off the front-end LC to do this effectively, and i have no interest there. Perhaps, later, i will make a rig to cover 17, 15, 12, and 10 meters.

You might note from the bird's-eye view that the coils are above chassis in the B version, and are not shielded. Again, i found shielding an unecessary hassle, the steel chassis seems to do just fine. The 6SN7 closest to the center- front coil (oriented to the left center in this image) is a very hot tube, temp wise, but it has very little effect on the coil, which happens to be the IF/ detector coil. The terminal strip just to the right of this coil has the grid- leak wired on it. This turned out be be a good way to keep the grid circuit of the detector away from the filament wiring underneath, which ran unavoidably near this circuit, had it been left underchassis.

As in the previous version, i am using a plate-to-voice-coil transformer for low impedance headsets. My next rig will give the user a choice between high and low impedances. Those white wires you see are the leads to the power input, the B+, Filament and Ground. This radio was designed to use a bolt-on 30 inch aeral, and provision exists for a regular coax line to attach as well, but as a portable with a whip, it works great! I use this as a table-top receiver, casual listening, but it performs well as a CW receiver used with a transmitter.

The third image is the bottomside of the "chassis", which is really only an aluminium plate held in place by two stand-offs to the rear, and the front panel. Clockwise from upper left is the antenna input variable, around 150pf, the regen pot (yes, i know, no throttle cap . . . how inefficient of me. . .)and below it, the 6SN7 detector / audio stage. Remember, the grid circuit of the detector is on top of the deck. That RF choke you see there is honestly something that i forgot to remove, because the audio resistance is actually determined by the variable pot reactance/regen pot. If that choke was, say, 70 hy, it might make a difference, but not 2.5 mH. It will be removed for my next transmitter project, and the primary of an audio transformer put in it's place.

Proceeding clockwise we come to the 6C5 oscillator, note the ceramic xtal socket, and finally the mixer tube, the 6J5. Power, ground, and filaments are routed to that terminal strip to the lower right edge of the chassis, from whence it is cabled to the rear apron accesses. Notice that despite it's diminuative size, there is still plenty of room to put a soldering iron without torching off some nearby wire. Just the way i like it . . . simple, straightforward, and lotsa room. Like under the hood of a six-cylinder 1955 Belaire. You can stand between the engine and the firewall.

This next image shows another up-close look at the upper deck, from the 6SN7 side. Next to it, in the middle, is the mixer coil. You can see that the whole first layer is covered with tape. That first level winding is the secondary, the detector grid coil and tickler. The exposed winding is the primary, from the mixer. You can see that 50pf tuning cap easily. Next coil over is the front end LC, and that red wire is connecting it to the grid cap of the 6J7. You can just see the band xtal in the shadow to the right of the 6J7.

This has been my 19 and 20 metre work-horse. As was the "A" model, this has proven to be a very useful, functional receiver for what i designed it for: toss on a hotel nightstand, clip a wire to the window screen and you're off! Or, use the bolt-on 30 in. aerial. I have no standby switch for use with a transmitter, but i use a separate antenna for the transmitter anyway, so it's a simple matter of grounding out the antenna input, unless i am running substantial power, in which case an RC paralleled across a B+ standby switch at the power supply would do fine.