RADIO

Southland Times, Issue 20172, 7 May 1927, Page 11

RADIO

(Conducted by “Reflex.”) Readers are invited to contribute items of local interest for publication • in these columns and to ask for advice upon any matters over which they may have some doubt. Letters should be addressed to “Reflex,” care of Times Office, and should reach the office not later than mid-day on Monday for insertion the following Wednesday. ANSWERS TO CORRESPONDENTS W. J. R. (Invercargill) writes stating that he has been experiencing interference from his neighbour s receiving set, and asks for advice as to the remedy. I would advise him to place his aerial at right angles to that of his neighbour. Although this may not completely eliminate the trouble, it will quite probably minimise the nuisance. “Buzz” (Orepuki).-—Your letter will be dealt with next week. LAST WEEK’S COLUMN Unfortunately the usual radio column had to be deleted last week on account of the space devoted to the municipal elections. HOWLING VALVES Listener-in writes as follows— Reflex. Sir, —Your criticism of my letter in last week’s radio column in which I compared a radiating set to a car without brakes was no doub.t merited, but you don’t seem to realise what a curse the howling valve is. Take last night (Sunday) for instance. The valves drowned any music there was. The operators were not getting music themselves and were spoiling it for those who could. Why should we tolerate this state of affairs when it can so easily be cured ? The number of refractory sets in operation in the district is not great, but quite sufficient to spoil one’s entertainment. The cost of converting these sets would not be great and would be off set by the increased efficiency of the set and the boon conferred on other listeners. I fail to see how the barring (until they are converted) of radiating sets is going to have other than a stimulating effect on the expansion of radio. In conversation with a radio salesman last week he said he had lost three sales recently because his clients would not tolerate the howling valves. Why should they?—l am, etc., LISTENER-IN. 23/4/27. Listener-in states that he does not think I realise what a curse the howling valve is, and at the same time seems to pity me for my ignorance. Unfortunately I have experienced it too often. I was not listen-ing-in on the day referred to, but doubtless there have been nights that have been just as bad. It is hard on the man who is punctual in the paying of his license and who takes every care to see that he does not. oscillate over the top of his neighbour not so thoughtful as himself. A novice does not always know when his set is howling, and for his benefit I reproduce a few hints by a New Plymouth correspondent of the New Zealand Radio—“ Whenever the ‘carrier wave’ of a station is heard (he states), the receiving set is howling and causing interference to all BCL’s in the vicinity. Do not tune by picking up the ‘carrier’ first. “When a station is ‘tuned in’ move the secondary condenser to the left until the station fades out; then turn to the right in the same manner. If the ‘carrier’ is heard at either side* the set is still howling slightly and the condenser should be returned to the point where maximum signals are received, and the tickler coil moved a little further away from the secondary coil. “It will be an advantage to do away with the aerial condenser altogether tuning in is quicker and signals louder without it. It can be incorporated in a wave-trap if the user is near a broadcast station. “A handle about Bin long should be attached to the knob of the secondary condenser (a lead pencil wired to the knob will do) ; this will act as a vernier, and will enable the set to be worked with the hands well away from the coil and condenser, as well as eliminating hand capacity.’ More than 18 volts should not be used on the plate of the detector valve.” Listener-in has not so far seemed to realise that I am not against the step he proposes save from a viewpoint of cost, and have already admitted that such a step would be an advantage to all radio fans. Take for instance a two-valve set. To convert this into a non-radiating set, the cost would be approximately 30/-, including of course the cost of the transformer and on the assumption that he manufactures his own coils. There are few youngsters who could afford that amount. As far as I can see the remedy lies with the Post and Telegraph Department in the appointment of a radio inspector equipped with a direction-finding device. The efficiency of such a course can be vouched for by the following paragraph— Apparently it is possible to track down oscillators in a city! Windsor (England) “howlers” received a shock recently when the Post Office oscillator-locating van bore down on them as a result of complaints of oscillation from listeners in that district. Several offenders were located, and the engineers found that in every case the use of reaction was being abused. Our correspondent’s last point is a knotty one and nothing further can be said on this count. —Reflex. Reflex. Sir, —Last Sunday evening I tuned in three American stations—KGO, Oakland; KPO, San Francisco; KNX, Los Angeles, on my 5-tube Browning Drake, with only a twenty-foot aerial. Difficulty was experienced in getting the calls because of strong induction and howling valves. Re the latter, I saw that a correspondent, “Listener-in,” advocated the universal use of non-radiating sets which you disapproved of because it would keep many young fellows out of the “game.” Well, all I can say is this, that howling valves have kept more people from installing a radio than anything else. Just imagine the uninitiated going to purchase a set and hearing nothing but squeals. Do you think they would buy one? Certainly not. Radio in New Zealand is becoming as common as the gramophone, and in order to compete with it must deliver trouble-free and noise-free service. There is one particular fiend who is becoming an absolute nuisance. He cannot be hearing anything himself the way he wanders up and down the dials. Surely the P. and T. Department can do something. It isn't as if they don't know about it. I think “Listener-in’s” analogy was particularly appropriate.—l am etc., H. F. ROSS. 58 Nith street, Invercargill, 23/4/27. “NEW ZEALAND RADIO” The April publication of New Zealand Radio has just come to hand. The high standard set when the journal was first published has been maintained, and there has been no deminution in the quality or quantity of the news matters. Included in this issue are several features of special interest, notably a report on the New Zealand Radio one-valve receiver suggesting a variable grid leak; the third and last of a series of articles describing eight easily-built economical receivers to suit all pockets; correspondence from all parts of the Dominion, and other articles of a descriptive and general nature.

The journal is one which can be safely recommended to anyone interested in the science of radio.

CHANGE IN WAVE LENGTHS Advice has been received from the Post and Telegraph Department that as from Tuesday, April 26, the wave-lengths of the Dunedin and Christchurch stations was altered as under—3YA (Christchurch), 405 metres. 4YA (Dunedin), 435 metres. The wave-length of the existing Wellington station, it was stated, would remain as at present, but, when the new station is in operation, the code coil will be altered to 2YA, and the station will operate on a wavelength of 380 metres. B BATTERY HINTS Batteries should be kept in a cool, dry 1 place. Where heavy-consumption valves I are used they should not be placed too close to the receiver. When reading the voltages, use a good type of voltmeter. Keep the tops of B batteries perfectly clean. Where two stages of audio-frequency amplification are used do not omit the C ! battery; it will not only increase the life of the B batteries but will improve the tone. WHALERS’ RADIO TESTS The following item is taken from the Waikato Times under the date of April 14. Great interest was aroused by the announcement of the radio test being made by the Norwegian whaling ship C. A. Lari son, bound from Wellington to San Fran- | cisco. In response to the request for re- ' ports as to further transmissions from the i vessel, Mr. R. F. Haycock received numer- | ous reports on Tuesday from all over the district and the information gained is being I forwarded to the Chief Telegraph Engineer at Wellington. Last night the vessel was heard at about 6.30 p.m. The announcer repeated the call letters A.R.G.L., and the name of the vessel. He also called Hullo, Mr. Percy, Hullo, G.B.Y. Hullo, Wellington, and added that the vessel’s position was long. 170 degrees W., lat. 29.55., and that the distance from Wellington was approximately 1100 miles. His announcements were interspersed with gramophone selections, all of which were heard at good loudspeaker strength. Before closing down, the operator said he would appreciate reports on 600 metres (the commercial wavelength) and that if he heard that Wellington and G.B.Y. were hearing him he would be on the air again to-night. In view of the fact that he is only using small power, it is remarkable how clear and loud his signals are, and based on the volume of the transmission last night he j should be heard quite easily for at least another week. The C. A. Larsen, like the remainder of the Norwegian whaling vessels is equipped with a k.w. Marconi radiophone which compared with the power used by the big broadcasting station is very small. The whaler was heard clearly until 1800 odd miles from Wellington. The succeeding night the vessel was again heard when the estimated distance was 2000. CARE OF COMPONENTS Care of radio components is a matter that is all too frequently neglected by the users of wireless sets, and, under the caption, “Take Care of Radio Components,” Mr C. Slade, in the Sydney Daily Telegraph, gives some valuable advice to amateurs regarding the attention which should be given to their B batteries.

Do not be misled (writes Mr Slade) as to the condition of the storage battery by the fact that it will light the valves. Even in a state of discharge it will do this—i.e., even when the hydrometer gives a reading which indicates a flat battery. It is very risky to allow a storage battery to drop too low; sulphation of the plates is sure to take place if you ignore this rule. With a storage battery it is just as important to see that there is enough electrolyte as it is to watch for the condition of the battery itself. The plates should be covered with electrolyte at all times. When you remove one of the three caps you should not be able to see the plates, unless because of conditions of excellent light you can penetrate the covering of the electrolyte. Remember, too, that each cap represents one of the three cells, and that the electrolyte in all three cells should be tested with the hydrometer. The charging rate of a storage battery is also very important. Readers who have their own battery-chargers should see that the rate does not exceed that recommend ed by the manufacturer of the battery. When charging a battery leave the caps off the top of the cells, thus exposing the electrolyte to the air of the room. Some slight fumes that develop during the charging process thus are dissipated in the air; otherwise they might accumulate and be rather intensive. Under some conditions, if allowed to become intensive, they will damage the containers. The vast majority of B.C. listeners use dry cell B batteries, and whijn these batteries become exhausted they are discarded. With B batteries the amperage, or size, is an important factor, and, generally speaking, it is far more economical to buy a large amperage B battery than a small one, in spite of the extra cost. Never use an ammeter to read the condition of a B battery. good type of voltmeter should be the only test, the reading of which should be taken while the receiver is operating. B batteries are made in 221 and 45 volt sizes. To add up the voltages, connect them in series—that is, the plus terminal of one to the negative terminal of the other. There will be two terminals left—the minus (or negative) terminal of the first battery, and the plus of the last. Remember, there will be no other minus terminal—not even the minus terminal of the second battery, which is marked minus, for that has now been converted to a plus 45-volt or 224-volt, as the case may be; also the actual voltages are not the voltage that are marked on the batteries, except in the case of the first battery. Let us take an example: Suppose you have a 45-volt B battery. Now. if you connect this to the negative terminal of another 45-volt battery, the first battery terminal markings are correct, but the second battery terminal markings represent the reading marked thereon plus 45 volts — that is, the voltage of the preceding battery is added to it.