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RADIO DIGEST — Illustrated
February 16, '1924
AS HAS been previously stated, the supply of commercial wave traps is unusually small. It is surprising that so few manufacturers are making device which will help so many fans. .'ially those in crowded cities where '.he numerous powerful broadcasting stas not only interfere with one another but also present a solid wall of interference which few sets can pierce to bring in the long distance stations.
In addition, in order to reduce the price,
the wave trap is so simplified that its
mum efficiency is lost.
Another wave trap, known as the "Aux
iliary Tuner," is manufactured by S. A.
Twitchell of Minneapolis, Minn. The com
ponent parts of this unit are quite a little more numerous than would be expected in such an instrument, but an examination and test emphasizes the efficiency of its unusual construction.
Best results are obtained by connecting the ground to the left-hand binding post, while the right-hand post is connected to the ground of the receiving set. The righthand switch controls the coupling of two windings on the trap coil, trap 4 being the loose and trap 6 the tight coupling. The condenser is very sensitive and care should be taken not to pass the station by turning too fast.
The left-hand switch is a form of loadins coil that has the effect of loading the antenna circuit in instances where it is desired to reduce the coupling in the tuner of the receiving set.
This tuner may also be connected in parallel with the receiving set, sometimes with better results.
Notes on Phantom Receiver
In answer to many letters on the Phantom receiver I wish to give the following information which is of value to anyone constructing this set.
The circuit works well on a canoe or any type of boat, by tacking on about 2 feet of 1-inch wide copper ribbon below the waterline for a ground and supporting a small aerial above the heads of the occupants. On larger boats there are always metal objects that can be used as a ground. A good aerial may be constructed by winding some hard-drawn number 14 copper wire on a 1-inch form like a spring and stretching this out above the 'canoe.
The tuner is not necessarily limited to any one design of coupler, but may be of any type so long as it is tapped as specified in the article. Almost every experimenter has some old coupler that can be rewound using 26 to 28 dec. on the stator and number 30 dec. on the rotor. The 180° types of couplers are best, as screws and nuts may be used on the edge of th« rotor for taps and flexible wires to lead to the s.witch points on the panel. The diameter of the stator may be anywhere from 3 to 4 inches, with a rotor to match. The rotor and stator may be bank-wound using larger wire to advantage.
The grid leak was constructed by using the black paper tape in an old CRL grid leak and lowering the resistance of the paper with an extra-soft lead pencil until the results conformed to that specified in the article.
1XP is a private experimental station and does not manufacture or sell any of the parts. These parts are special and will have to be constructed by the experimenter unless some manufacturer puts them on the market.
This circuit greatly reduces static (QRN) and to judge by the number of people who have mentioned it in their letters seems to have given satisfaction. — Leon W. Bishop, Athol, Mass.
The average cost of upkeep for Radio equipment is about $10 a year.
"What a difference just a few cents make !'
BRINGS IN EVERYTHING!
BEAUTIFUL MAHOGANY NEUTRODYNE
f 1 7 HEN you get this magnificent looking set hooked up you will be able to hear all stations VV without interference. All parts are same as illustrated in Radio Digest, Feb. 2nd. Panel is mahogany with beautiful Tate dials — a set fitted for the most exclusive home.
Panel drilled, all parts mounted on panel and baseboard ready for wiring PAY NO MONEY ^^^g« Only
Just Pay tHe Postman __—^^^B^p \ ' !p9 1 g| J * '. . ,J| fr s *s. PA
with all the following parts:
2 22'/2 VoK « Battery $0.00
$86.00 I Fuitone Loud Speaker 9.50
5 Genuine DX Tron Tubes $25.00
I 110 Ampere Storage Battery 18.00
I DeLuxe Homecharger .• 18.00
I Genuine Baldwin Headset 12.00
I Complete Aerial Equipment 1.50
I 45 Volt B Battery 5.50
The above parts and equipment complete would cost you $144.00! Our Price $125.00 It Works— NEUTRODYNE— All Standard Parts
3 Rheostats, 30 ohms $2.00 2 Transformers $9.50
I Rheostat, 6 ohms 90
3 Air Core R. F. Transformers, mounted on eon
densers, and 2 balancing condensers 20.00
I Potentiometer, 600 ohms 1.85
3 Jacks 2.70
I Condenser 40
I Grid Leak 65
5 Sockets 5.00
9 Readem Binding Posts 85
I 8x26 Mahogany Panel 3.64
4 Bezels , .80
3 Dials 4.50
I Baseboard 50
24 ft. Square Brass Bus Wire 60
Only $45.50 with blue prints FREE.
Complete Parts — MILOPLEX — 2-Step Amplifier Mounted on baseboard and paneL LIST $21.06 OUR PRICE ONLY $16.50
1 Panel 7x9xiV' $1.26 2 Sockets $2.00 1 Baseboard $9.25
2 Webster's 4-1 Trans 2 Double Circuit Jacks... 1.80 1 Cabinet Mahogany
formers 9.59 1 Set Readem Engraved Finish 3 J»
2 30 Ohm Rheostats 2.00 Binding Posts 75
The above mentioned parts will include any Ohm Rheostat and All-American Transformers if desired.
Complete Parts — MILOPLEX — Cabinet FREE
I .0005 Variable Condenser, Vernier. $6.00
I Estru Variometer 5.00
I .00025 Variable Condenser 2.00
I Variable Grid Leak 75
1 .00025 Mica Fixed Condenser 40
2 .002 Phone Condensers 80
3 3'A-inch Dials, each 75c 2.25
I Potentiometer, 1850 ohms 2.20
I Rheostat 1 .00
Socket Bakelite Base $0.90
I Bakelite Panel, 9XI4X-,'. 2.50
I WD-12 Tube 6.50
I B Battery, large, 22'/2 volt 3.00
3 Dry Cells 1.35
12 ft. sq. brass Bus wire 30
I Set Readem Binding Posts 75
print FREE enly
order for complete
Everything in Radio Write Us
We Are Responsible Folks, Money Promptly and Cheerfully Refunded If You Are Not Satisfied
All Orders Mailed Promptly. Parcel Post Prepaid on $5.00 or Owr.
No Stamps Accepted.
Quality Merchandise at Low Prices
Economical Radio House
4600 LINCOLN AVENUE, CHICAGO
We Personally Guarantee AD Goods
A receiving antenna for broadcast reception should never be over 100 feet long and 75 feet *viU be found better as a rule. A single wire of this length means just added advantage of greater I
■X will be found better as a rule. A single j* /Z-jL/t *»
; just as much distant reception oath the fo. \S (jZtJUAr&£&"ia
iter selectivity. e 17
Flewelling Is the recognized authority on quality Radio Apparatus. Naturally any part produced under his name ■will be up to his high standard. It is a lot safer to boy the parts designed by Flewelling; and made on* der his personal supervision — for nothing takes the place of the "genuine." These parts are manufactured exclusively by
RUELL MANUFACTURING pOMPANT
2977 Cottage Grove Ave. CHICAGO