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Revamping the Silver Super-Heterodyne
501
If uv-2Oi-A, ov-2, uv-199, or Dv~3 tubes are used, the Benjamin spring sockets will work in very nicely. These sockets absorb all vibration and eliminate almost entirely the ringing noise often experienced with such tubes. In addition, these sockets are excellent from an electrical and mechanical standpoint.
If standard 4-inch dials are used on the condensers, they can be tuned satisfactorily either by means of a pencil with an eraser rotated against the edge of the dial and the panel, or by tuning the dial with the fingers on the outside edge instead of on the knob. If vernier dials are used, the Apex, which is geared about 10 to i, is extremely satisfactory and is to be recommended. The Eztoon is also a good dial, except that the vernier action covers only a few degrees, after which the entire dial must be rotated and the vernier re-adjusted. Any other good standard vernier dial without "back-lash" or play in it will be satisfactory.
Jefferson No. 41 transformers may be used in the set although Thordarson 3^ to i transformers seem fully as satisfactory as the Jefferson.
The Thordarsons may be used in either
3^ to i for both stages or if a very great volume is anticipated a 3^ to i in the second stage and a 2 to i of the new type in the third stage.
For details of the construction of the set. the reader is referred to the unusually complete construction article on the portable set in RADIO BROADCAST for October, 1924. Methods of construction in both sets are quite similar.
HINTS ON ASSEMBLY
ALL PARTS are placed on the baseboard and panel, and should be located according to the photographs. After the panel has been prepared, the proper parts should be placed on it and the sub-base screwed in position. The parts to go on the sub-base should be placed in their proper positions, and their locations marked, care being taken to see that they are so situated that the wiring will be easy and that tubes will not strike meters, etc. or the location of any parts on the sub-base conflict with parts on the panel.
All wiring that it is possible to do on the panel should be done before the panel is attached to the sub-base on which the sockets,
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B9CH AFC B45+ RFC
FIG. 4
A placement diagram of the units in the receiver