fect alinement of the condensers. Where the under-subpanel wiring runs from back to front, small holes are drilled to pass the wire, making possible permanent separation and neat arrangement of the various leads. After wiring as much as possible of the subpanel without the front panel, prepare the front panel for mounting. Care should be taken in the mounting that the driving mechanism of the drum dial is placed in the collar of the bracket before the panel is faced up to the subpanel assembly, after which the front panel may be pulled up with screws through the brackets. Now, with a screwdriver inserted to spread the lips of the drum driver, the dial may be slid along the condenser shaft and into the aperture and the drive mechanism released on it. At the same time the dials should be turned so as to read 100 with the condenser plates all the way in. and the dial locked in place on the shaft. The remainder of the wiring to the potentiometer and switch-rheostat may now be completed and the receiver tested.
All sockets of the receiver are to be supplied with UX-201A or CX-301A tubes, except the power-tube socket located nearest the back edge of the subpanel; this tube may be UX-112 or UX-171, as indicated in the schematic diagram. Note that the C-battery necessary for the UX-112 is 9 volts and, if the UX-171 tube is used, 27 volts of C-battery are required.
Due to the careful matching of the units, the set will not require any major adjustments for efficient operation over the entire waveband or, if any slight balancing is found necessary, this may easily be done with the small balancing condensers mentioned. Connect the A, B and C-batteries in the manner shown in the diagram on page 126, also the aerial and ground, and turn on the filament switch; this is done by turning on the rheostat, which also turns off all the tubes in the set when turned to the extreme left. When tuning for a station, keep both dials in step and when the station is located, adjust the left-hand dial independently for loudest and clearest signal; the volume is then controlled by the potentiometer.
An enlarged blueprint of the wiring diagram, shown on page 126, together with full-size drilling templates of the front and subpanel, may be obtained from Popular Mechanics radio department, 200 E. Ontario st.. Chicago, for 25 cents. Specify blueprint No. 125.
Material List
- 1 front panel, 3.16 by 7 by 24 in.
- 1 subpanel, 3.16 by 9 by 23 in.
- 1 Aero U16 kit of four coils.
- 2 SM drum dials.
- 2 SM, type 220, a.f. transformers.
- 4 Hammarlund .0005 mid. condensers.
- 1 Benjamin, or similar type, spring-suspended socket.
- 5 SM No. 511 sockets.
- 2 Tobe, or similar type, 1-mfd. fixed condensers.
- 1 Carter, or similar type, .001 mfd. fixed condenser.
- 1 .00025-mid. grid condenser, Carter or similar type.
- 1 Yaxley, or similar type, switch rheostat, 6 ohms.
- 1 Yaxley, or similar type, potentiometer, 200 ohms.
- 1 Yaxley, or similar type, fixed resistance, 1 ohm.
- 1 Polymet EZ, or similar type, gridleak mounting.
- 1 Tobe, or similar type, 2-meg. gridleak.
- 11 XL, or similar type, lettered binding posts.
- 10-in. round brass rod, 1⁄4 in. in diameter, or 3 Hammarlund insulated flexible couplings, busbar, No. 14 round, tinned-copper type, machine screws, nuts, etc.
- 5 doz. soldering lugs, long, round hole type.
Snap Terminals on Battery Leads
Good electrical and mechanical connections are the features claimed for the "snap" type of battery terminal shown in the illustration. Small round-head studs are provided on the receiver instead of regular binding posts, and the terminals snap tightly on these studs. A multi-terminal can also be obtained. for use when two or three leads must be connected to the same stud. Vibration does not loosen these fasteners, as is the case with leads that are attached to the common type of binding post.
