1935 Radio Constructor's Guide Now On Sale
18 RECEIVERS OF ALL KINDS FEATURED IN ENLARGED 192PAGE MANUAL FOR HOME BUILDERS: TWO PRESENTATION BLUEPRINTS.
Wy HIS year’s "Radio Guide’-the eighth edition-is now off the press, and is easily the finest yet published. In last year’s hand-book twelve sets were described; this year’s contains full constructional details of no fewer than eighteen complete receivers and power amplifiers, besides numerous useful radio devices ranging from a Reiss microphone to a singlevalve superhet shortwave converter. There are nine sections in all, the first being an introductory one. In it. is given a host of practical tips which all experjmenters, particularly. beginners, will find yery useful. ‘The next section. deals with broadcast band re-, ceivers,"both battery and a.c, operated, aig of superhet and t.r.f: types. ~All are picked receivers, up-to-the-minute in design, and are described and illustrated in such detail that anyone with a vestige of radio knowledge should not have the slightest difficulty in building them successfully, Perhaps the most popular of. these sets will be the "Tom. Thumb Two," not only because it is the simplest and cheapest. to: build, but -also because, though only a4 two-valver, it gives re« markable results. It is: an all-waver, and will bring in stations all over the world -with excellent clarity and surprising "punch." Among the other battery models are the "Golden Superhet Six" and. the Radiokes ‘12/84B" Dualwave Superhet, two receivers which have the range, selectivity and sensitivity of many commercial a.ec. receivers using the same number of valves. The "Commander Hight" is one of the a.e. receivers which is sure to be popular. It uses eight valves and is thoroughly up-to-date in design. Pushpull 45’s are’ used in the output, ensuring high tonal fidelity combined with low cost.. Another fine set is the "Comet Superhet Five,’ which is one of the most remarkable receivers ever designed in this country.) As a special gift to readers, blue-prints of both these receivers are included with each copy of the "Guide." In the next section, two up-to-date power amplifiers are described. The smaller-the "Baby Grand"-uses a 57 first audio stage, direct-coupled to. a 56 driving a pair of 45’s in resistance push-pull. The quality of reproduction is aboye reproach, while the volume is sufficient for a smali dance hall, It is both cheap and simple to build, and uses only standard parts. ' The 20-watt "Public Address" ampli- ’ fier was primarily designed for servicemen. It uses a 57 first audio ampli-
fier, resistance capacity coupled to a pair of 56's in pushpull, which are in turn resistance capacity coupled to a pair of 50’s in the output,
Next follows a comprehensive section dealing with the design of all types of aerials-broadcast, shortwave and all-wave. Special attention is paid to the latest noise-reducing doublets for all-wave operation, The next section deals with meters, and in it are given worked examples showing how to find solutions to such problems as calculating shunts and series resistors, multiplying voltage and current ranges, determining the internal resistance of d.c. voltmeters and ammeters, the way to use a d.c, milliammeter as a d.c. yoltmeter, and the:method of constructing an ohmmeter for d.c. resistance measurements. _ Five up-to-date shortwave receivers and a five-metre transceiver are described in the shortwave section, which follows next. The "Haglet Two" is a compact little two-valver using a 57 as leaky-grid detector, with electron regeneration, and a 56 output stage. Though only small, it can be depended on to bring in the main shortwave stations of the world at excellent ’phone strength. A powerful but simple-to-build shartwave superhet-the "Night Flight Short-waver’-follows next. This set uses plug-in coils, and, unlike the usual run of shortwave superhets designed for home construction, it is neither tricky to build nor uncertain in operation. Regeneration applied to the I.F. stage gives high gain and excellent selectivity. One of the latest type 15 indirectlyheated screen-grid battery valves is used as detector in the battery model of the "Sky-Hawk Short-wave Four" to enable electron-coupled reaction to be obtained as simply and effectively as in ae, receivers. The valves used are 82 r.f. stage, 15 detector, 30 first audio amplifier, and PM22A output pentode. Provision is made for plugging in the ‘phones following the 380, and for switching off the output pentode, thus conserving battery current when speaker reproduction is not required. This is easily the most powerful battery four-valve shortwaver that has yet been described in this-country. The a.c. version of the "Sky-Hawk" uses a 58 rf, amplifier, 57 leaky-grid
detector, with electron-coupled feaction; 56 audio stage and 2A5 as output pentode, As with the battery model, the ’phones can be plugged in after the (Continued in Col, 2 next page.)
first audio stage and the output pentode cut out for headphone listening. Both models of the "Sky-Hawk Shortwave Four" use ganged tuning ,condensers. The "Viking Short-waver" is a threevalve shortwave receiver which can be operated either from a separate power pack or, alternatively, can derive its power from an a.c. broadcast set. Constructional details of a five-metre transceiver have been included in this year’s "Guide" because one of the newest and most fascinating fields for .experimenting in radio lies in ultra-short-wave transmission and reception. With the simplest of equipment, it is possible to obtain first-class voice transmission and reception over distances varying from 10 to 30 miles, depending on the topography of the intervening country. Experimenters will find Section 6 one of the most interesting in the book. In it are given full details for making a Reiss microphone, "B" class amplifier, a one-valve shortwave, converter, & power-pack for shortwave sets, an aerial tuner for DX work, a "B" eliminator for auto-sets, simple power line filter, a selective crystal set, and a single and double wave-trap. In addition there are two comprehensive practical articles dealing with charging accumulators at home and learning the Morse code. In Section 7 are given a wide variety of radio hints, alphabetically arranged, while Section 8 contains valuable reference chart tables. A station list is also published, giving the most powerful broadeast stations in the world which are best heard in New Zealand. The stations are arranged in frequency order to permit of easy identification. Next follows a similar list of the most powerful shortwave stations in the world, together with full operating schedules. The final section contains a radio alphabet, in which are given brief definitions of terms most commonly found in radio. This year the "Guide" has been printed on higher-grade paper than in previous years, and has been enlarged by 82 pages. Because of these improvements it has been found necessary to restore the price to the half-a-crown once charged for it, but a _ glance through the contents will soon prove. to readers that this year’s "Guide" represents the best value ever given, in this country at least, in any technical radio publication.
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Radio Record, Volume VIII, Issue 42, 26 April 1935, Page 47
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1,1431935 Radio Constructor's Guide Now On Sale Radio Record, Volume VIII, Issue 42, 26 April 1935, Page 47
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