THE HOWLING NUISANCE

Evening Post, Volume CVIII, Issue 148, 19 December 1929, Page 34

THE HOWLING NUISANCE

■SOMETHING CAN BE DONE

... ; - The "Wellington Radio Society, at its ;;iast meeting, again expressed concern •;at the prevalence of. ....the '"howling J.rvalve" nuisance, and, probably cor'■rectly, tho-blamo was laidprincipally ■Vat the feet of beginners using homeJbuilt receivers of the simple regenerative typo, though it was suggested that .some -trade-produced sets were responsible for part of the interference. In ,'.Great Britain this shocking nuisance %ia comparatively rare, for a number of ,'. ■ One is. that the broadcasting ■'authorities- themselves waged a constant warfare, by propaganda and direct faction, against >it.- Another is that, as an outcome of the severe official atti';tude, receivers of the simple regenera.'■tive type were not recommended for -.^construction without ample warning. In •' (New Zealand, the propagandist section 'of such.warfare has been very weak . jand practically confined to the volunjtary services of radio writers. Some !*'direct, action," but very little, owing ■to thet scanty resources available, has ■ibeen carried out by .the P. and T. De•partment. The1 Broadcasting Company viitself has "done" nothing appreciable to ;'-check the vUSBa of/ interfering receivers ','or- even to "advise- against their use. On "the.,other hand, a ypiing beginner, ambitious.to build his own valve receiver, 'isiEarmore likely-than not to be given a set of directions which one would 'suppose were-TTefinitely designed to turn him into a public nuisance. Every howling receiver is liable to ■care somebody out of buying a receiver of his own: try it by inviting a friend to listen to your big new set • on a "silent night"! The. prevalence of the nuisance must have cost the trade and th,e> Broadcasting Company a very large amount of money, and it could have been and can be very greatly reduced;, if not abolished, by very simple means. Every beginner has to purchase paits. for his set; and consequently comes.into direct contact -with the dealery one of the parties interested in Ms future good behaviour. In the jnterests,'of his own business the dealer should the beginner with a circuit diagram, or a choice of them, suitable for a receiver that cannot cause interference, and an effective notice that certain types of circuit are definitely prohibited. (It is not sufficient merely to quote the regulations.) It is not everyone who is able, at first, to build a set -with a satisfactory neutralised stage of radio-frequency amy plification; and such a stage improperly adjusted is of little use to the owner and is a source of interference. She cheapness and economy of valves is guch,-however, that a perfectly simple remedy is within the reach of all; that is to-place in front of a regenerative detector circuit what has been called a '.'blocking valve.'' This feeds the detector^ circuit in the same way as a regular high-frequency stage, but has no tuning-circuit before it; the aerial is connected directly to the grid, which is also'\ connected to the negative end of the: filament by a Srili leak of about half a megohm. The extra cost of the valve, socket, and grid leak is quite small,.and the result is a set that cannot radiate and is a little more sensitive than without the extra valve. "With proper, choice of valve'the sensitivity may b> increased a good deal. Unfortunately there is no absolute protection. One of the first things the i owner of such a set is likely to do is ' to put in a wave-trap to "cut Wellington out,' 3 while he tries to get 4YA and'2^C. The chances are that this ■will turn the set'into a fierce oscillator ;at whatever frequency the wavetrap is set to; and tho urgent necessity for.propaganda becomes obvious again. The famous adjuration of Captain Eekersley, '■■ late of tho 8.8.C., should be used-persistently, "Don't Do It!" The writer has often urged, and does bo again, that a very powerful remedy against the howling valve nuisance ■would be tho abolition of the silent nights.' The wickedest howling is always heard in "Wellington on a Wednesday, unless 2YA puts;, on a special transmission; "and the. reason':.is clear: simple ieceix|rs in the hands of those, clumsy people' -who "do itV will not receive distant stations clearly while the local station is running.; Various arguments in favour of the silent night have been advanced, but the ofliy one ;that really has any weight is that of the extra eost,and to do the company justice this has not, to the writer's knowledge, been-used. The other arguments will not stand. One is that the silent night gives the feeble receiver achance to get outside- Wellington. Those who do the howling are not getting anywhere at all; .and those who are not, no matter •what:type of set they own, are prevented from doing so by the howlers. We may., look forward to the .usual post-Christinas outbreak, of' oscillators.