Radio Digest (Oct 1923-July 1924)

* 10 RADIO DIGEST — Illustrated April 5, 102U OPERATION, TROUBLES ntinued i. 9) enters the earth is the best. ■-.mended tor ground con len insulated near •neter. Pipes of the heating system i oid results ii" actually con trlc light wires, and protected by an approved lightning arrester. This arrester l;as two terminals, one of which connects to the aerial and the other of which connects to a ground. For this ground, a water pipe should be used. The wire must not be smaller than the aerial wire and in no ease smaller than Number 14. It need nected to the earth but are liable to take a much longer path in getting there. The connection to the pipe should be well made by cleaning a section of the pipe all the way around until it is bright, and then using a standard ground clamp tightly fitted over this clean place. The regulations of the Fire Underwriters in regard to the installation of a receiving station are not hard to conform with. An antenna properly installed is more of a protection from lightning than a hazard. The regulations, in brief, say that the aerial shall be put up in a strong and durable manner, at least not run over or under any wires carrying more than 500 volts, kept five inches away from all elec not be insulated wire or held away from the walls. This same wire can be used for the earth terminal of the receiver if desired. _ .. Connections Having erected the antenna and made your choice of vacuum tubes you are now ready to connect the set. Inside the Type 225 set are two sets of binding post strips as shown in the diagram. The strip on the left, marked A and E is for the antenna and ground connections. The strip on the right contains five binding posts for the battery connections. It is very important to connect the various batteries as indicated. The poles on the battery are generally marked. The numerals on some B batteries indicate the voltage of the Considering -^V OUR new reproducer is now under consideration by thousands of radio enthusiasts throughout the country. Singularly, many of the most expert are making quick decisions and below we quote from an opinion, entirely unsolicited, given us by Mr. C. E. Mattson, Baltimore. "I gave the sample a test at one of the radio stores. About 15 customers crowded round and all agreed it was equal to the $35.00 and won by several lengths against the $30.00 . My own opinion is that the M-G is going to be the greatest hit in radio this and next season ." Within five days (date of going to press) from receiving above, we have had orders for immediate shipment, aggregating exactly 146 complete reproducers and a large quantity of extra units for other makes of horns and phonographs from Mr. Mattson and his customers. PRICES. An Explanation We have been reluctantly obliged to slightly increase oar price, and to prospective pnrchasers a foil explanation will be mailed en receipt of a postal card. Complete with (gold plated) unit and cord, ready for CIO f\(\ attaching «J>l£ .UU West of the Rockies 12.65 Unit only (gold plated) with cord ready for attaching 5.00 Unit only (nickel plated) with cord ready for attaching 4.00 THE MOZART-GRAND CO. NEWARK, N. J. Manufacturers of Fine Instruments U. S. A. terminal with respect to the negative lead. The positive pole of the battery should be connected to the plus binding post and the negative pole of the battery to the minus binding post. The whole connection is shown in the figure and you should have no difficulty in following this diagram. The next step is to insert the vacuum tubes in the sockets, making sure that a satisfactory connection is made and that the bayonet catch locks the tube in. Occasionally, a tube will not be inserted correctly in the socket and a' loose connection means noises and poor results. After the tubes have been inserted, the telephone receivers should be connected to the jack by means of a plug. Turn the rheostat Number 4 from left to right, as shown by the arrow in the first diagram. Turning the rheostat increases the current flowing through the vacuum tubes. The amplifier rheostat Number 5 can be turned almost fully on while the detector rheostat Number 4 must be adjusted to give the most satisfactory results. The method of adjusting is as follows: First, start with a detector voltage of 22^ for the TJV-200 tube and with the regeneration knob Number 3 set as zero, turn the rheostat Number 4 to the right until a slight noise is heard in the telephone re ceiver. The tube should be operated just below the hissing point. After you have heard some signals, you will find that the B battery voltage can be varied from 2254 down to as low as 15, but some intermediate voltage may give the most satisfactory results. Each time the B battery voltage is varied, adjust the detector filament rheostat Number 4. The combination of detector B battery and filament current is the real key to the successful operation of the outfit. Such a combination varies with different tubes and sometimes different operators select different combinations. You should learn how to adjust the detector voltage to get the best result. This can always be done by listening to signals and operating just below the hissing point on the detector. It is economical, especially with the XXV201A tubes, to adjust the amplifier rheostats as low as possible 'without sacrificing signal strength. Voltages above 80 for the B battery give greater volume but at somewhat of a sacrifice in quality. The rheostats may be advanced slightly above the usual point as the storage battery begins to become run down and turned back when a fresh battery is used, but other than this, the rheostats require no adjusting. (Continued on page 22) SUPER VALUES WHAT'S NEW IN RADIO? Farrand's Super-Pliodyne NINE TUBE RECEIVER Uses Six Stages of Tuned Radio Frequency with but Two Controls Write for complete details and price list of parts to build this new receiver HANES-ZENER Located at 42nd St. and Broadway, New York City Always first in marketing the NEW THINGS in RADIO Resistances ORIGINAL and GENUINE P. L. 100,000 OHMS, 30.000 OHMS, 80,000 OHMS, 25,000 OHMS, 50,000 OHMS, 12,000 OHMS, 48,000 OHMS, 1,000 OHMS, LIST PRICE $100 1 EACH DEALERS! WRITE FOR OUR DISCOUNTS COCKADAY Erla Two Tube Reflex Four-Circuit Receiver All Parts for This Circuit 3000 MILES $40.70 Parts as specified by Mr. Cockaday Including Mahogany Cabinet 1 — Cockaday Coil 2 — Amsco 26-Plate Condensers Parts are Genuine and same as specified 2 — Amplex Grid-Densers by Erla 1 — Bradley Leak, yt to 10 meg. 1 — Amsco 6 ohm Rheostat 3 — Amsco 20 ohm Rheostats 1 — Pacent Single Jack 2 — Pacent Double Jacks Power Amplifier 2 — Amertran Transformers 1 — Como Push-Pull Transformer — Input 1 — Como Push-Pull Transformer — Output FOR $19.00 2 — Switch Levers 11 — Switch Points INCLUDING 2— Switch Stops 1 Panel 7x11 1 — Dubilier Condenser — .0005 1 — Dubilier Condenser — .00025 with Mount 2 Sockets 1 — Durham Variable Grid Leak 1 Rheostat 3 — Lavite Resistances — 48,000 ohms 7 Erby Engraved B Posts 1 — Amsco 400 ohm Potentiometer 2 Fahnestock Clips 1 Pair Como Push-Pull Transformers 1—7x24 Panel 1— 3"x2i/4" Sub Panel 1— 12"xl2" Panel List Price, $23.90 Our Price $59.00 We will wire this amplifier for you for an additional charge of $4.00. We Have Just Received a New Shipment of THE NEW MODEL D. N. K. & K. PHONES MADE IN GERMANY Our Price $6.50 WE GIVE A 20% DISCOUNT on All Standard Radio Apparatus Not Listed Above All Mail Orders Shipped Promptly Send Money Order, Including Postage The Radio Mail Order House— Know* for Low Prices WRITE FOR OUR CATALOG "B" ^ 1480 Broadway, Corner 42nd St., New York City