RADIO AND ITS RECEIVERS

Sun (Auckland), Volume IV, Issue 1007, 25 June 1930, Page 6

RADIO AND ITS RECEIVERS

Conducted for THE SUN Dy

R. F. HAYCOCK

IZH HAMILTON

TRANSMITTING HOURS

DETAILS OF STATION

Highly satisfactory results are reported by radio enthusiasts concerning the transmissions from IZH, the Hamilton B class station operated by Mr. G. S. Anchor.

The plant is located at Radio House, Victoria Street, Hamilton. The wavelength is 479.5 metres, 650 kilocycles. Hours of transmissions are: Monday, Wednesday and Friday, 12 noon to 1 p.m.; Tuesdays and Thursdays, 12.30 p.m. to 2 p.m. (Thursday, special request session); Saturday, 11.30 a.m. to 12.30 p.m. Every Wednesday Mr. F. V. Stephens, of the W.E.A., talks about “World Affairs,” answering any problems the listeners are interested in. A Wednesday night session will be started as soon as arrangements for a studio have been made. The midday musical session is much appreciated by listeuers-in in the Waikato, and reports from Whangarei, Thames, Wellington and Nelson show that the station is “getting out” well. The transmitter, which is built in an oak cabinet with glass sides and top, uses a 50 watt valve in the Hartley circuit. This oscillator is modulated by one of the latest Philips 50watt modulator valves, using the Heising system. The plate voltage at present is about 750, supplied by two 2Sl’s in a fullwave circuit, but an Esco motor generator is shortly to be installed. The input is 42 watts.

Two pick-ups and a double turntable are used for playing records, and one of the latest Philips microphones for speech. The pick-ups require two stages of amplification before being fed into the modulator, and the microphone requires three stages.

PENTODE VALVES

OLD FRIEND IN NEW GUISE

. The American radio journals have recently beeu very much occupied by discussions on the merits of the wonderful “new” valve which has been evolved in the laboratory of a prominent American valve manufacturer. Perusal of the articles in question brings the somewhat startling disclosure that the valve in question is none other than our old friend the “Pentode,” already well known in New Zealand radio communities. As a matter of fact, it is now some two years since the first Pentode valve —the Mullard “Pentone”—-arrived in New Zealand, and ever since that time its popularity has been steadily increasing.

The manufacturers have just placed on the market a “Super-Pentone” valve (PM24A) for use with a 4-volt accumulator or In a mains receiver having a 4-volt supply. This wonderful new “Super-Pentone” will undoubtedly be warmly welcomed in New Zealand, where the efficiency, economy and reliability of the all-British valve is an accepted fact.

Station KFOX Longbeach, California, lias been on the air as late as 10.30 p.m. (New Zealand time) recently; they sign off at 3 a.m., standard Pacific time, and play “Three O’clock in the morning/' and then announce that they are going off the air for two hours, opening again at 5 a.m. for “early morning exercises.”

One of the latest nuxlern radio practice is the tl..** White system of amplification is a direct-coupled system, the ni of one valve being direotlv conn. , to the grid of the succeeding with no transforme. < r ronde*"®* between, thus producing a system* 41 able of both amplification and de't*®" tion-amplificat ion. In place ol o' transformer or condenser a resists * coupling is used, and the Loftin-wv? system is capable of amplifying , quencies between the range of sn “*■ iO.OOO cycles. audio amplification has been asw? ated with good quality fr- :i early radio times, and this jAT grade audio channel may be usedi par* as a detector-amplifier for raj? use, as a gramophone amplifier as? broad band amplifier for televislonToi photo-electric cell operation, and » the transmitting end. as the moduli; tion amplifier.