Stromberg - Carlson 29
The chassis wiring diagram of this model, which appears on page 2-15 of Rider's revised Volume II; page 614 - R of the early edition; and page 2401 of the Rider - Combination Manual, is not clear in one or two places. So that no doubt will be in your mind when checking over two of the condenser banks,

Are showing herewith enlarged drawings of the bank having eleven condensers, in the upper right-hand side of the diagram, and the nine-con denser bank that is shown in about the middle of the page. You can identify their positions on the wiring diagram by the apparatus in the vicinity and by the color and position of the leads. Notice that the top of the sketch shown here goes to the right-hand side of the diagram in your Manual.

Philco Model 144

Effective April 15,1935 the center tap is removed from the filament winding on the power transformer. If a hum is experienced in reception, connect a 20 - ohm, wire-wound resistor across the filament winding, with center cap of resistor grounded. This set is shown on page 5-41 in Rider's Manual Volume V.

" X " Models in The Sparton Line
Some of the Sparton model numbers conclude with the letter " X ". The fol lowing data will no doubt be of value when seeking equivalent circuits in Rider's Manuals. In some instances, the " X " denotes a receiver intended for export sale and containing a special power transformer. In other cases, the letter " X " denotes some addition to the basic circuit. Model 27 - X is the model 18 chassis used in a model 27 cabinet. (Rider

Manuals Sparton page 3-10, 3-11, 4-2, 4-3.)
Model 67 - X is the same as the model 67 with a special power trans former and is intended for export. (Rider Manual Sparton 5-10, 5-11, 5-12.)
Model 73 - BX is an export model.
Model 80 - X is the same as the model 80, with a special power trans former and is intended for export. (Rider Manual Spatton 5-15, 5-16, 5.17, 5-18.)
Model 81 - X is the same as the model 81, with the addition of a wave trap (Rider Manual Sparton 4-16.)
Model 82 - X is the same as model 82, with the addition of a wave trap. (Rider Manual Sparton page 4-17.)

Stromberg - Carlson 55,56
The i-f, peak of these models, the schematic of which appears on page 4-10 of Rider's Volume IV, is 175 kc. Please make a notation of this on the above-mentioned schematic.

Bosch 239
Please make a note that Model 239 is similar electrically to the Bosch models 236 and 237, the servicing data on which are found on page 3-11 in Rider's Volume III and on page 2531 in the Rider - Combination Manual. This Model 239 was used in a table installation and the only difference between it and the other models mentioned is that the antenna and ground leads were braided together with the power supply cord in Model 239.

Howard Grand
Please make a notation that the power unit shown on Howard page 6-16 of Rider's Volume VI is for Series 2 of this model, as well as Series 1.

Packard Bell 34
If this set should need to be readjusted, the procedure is as follows: Set dial to about 1700 kc. and connect the output of a signal generator, set at the same frequency, to the antenna. Adjust the trimmer condensers of the r-f. and detector stages for maximum output. All adjustments at 1000 kc. and 600 kc. are made by bending the outside rotor plates of the variable condenser tuning the r-f. stage. The schematic diagram of this receiver will be found on page Ord of Rider's Volume VI.

Crosley 815
We have received word from the manufacturer that no servicing data has ever been issued for the 815, but if you get one in the shop look up Model 8B3, on page 6-10 in Volume VI of Rider's Manuals. We are advised that the 8B3 is practically the same as the 815.

Atwater Kent 145,325
The schematic diagram shown on page 5-7 of Rider's Volume V is for the early model but the note at the bottom of the diagram covers the changes that were made in the late model. The elimination of the condenser, C4, in the frequency-changing switch in the late models necessitated a rearrangement of the parts. The chassis layout for the late model is shown in the accompanying illustration.

The bottom view of the chassis used in A - K, Models 145 and 325 of the late type