Questions and Answers

Radio Record, 3 July 1936, Page 49

Questions and Answers

"PoOINES" (Laumarunui): he transmission line ig given us 110 feet in order that there need be no transformer at the aerial itself. If the instructions concétning ‘the matching of! the aerial aud transmission to the trausformer are earried out carefully the results will. be very good indeed. "CS C.." (Hikurangi): The double * doublet would be a bit better for you for shortwave work, and about the same for broadeast as the one you have vat present. , { «A: Two plates are used in each cell, ‘"TYUZZLUD" (Wellington) : You should certainly have an aerial and earth to get the best out of the set you have. ‘J£ these are installed properly the results \should be much better than in the case of / your old set. Because your old set gave reception on the smaller stations. you mention, that does not mean that it was more sensitive, as it is only a matter of shielding. As to a noise eliminator, the serviceman who puts up the aerial can advise.-you concerning that, and whether in your-case it would be beneficial. "ALL WAVE" (Porangahau): In the "Radio Constructor’s .Guide" for 1986 there is a compact B class amplifier which would probably suit your requirements, The least expensive method would be to hire one for the occasion that you have in mind, " P.I." (Kerepeehi): ‘Che analyser *that you ask for was described in the January 1933 "Radio Times," but this would not be suitable, without many ebanges, for the modern valves. As there are So many efficient analysers and testers on the market at very reasonable prices, it is doubtful whether one could build as efficient a tester for as low a cost. "J R." (Dominion Road, Auckland): * If you by-pass the portion of the yoltage divider that is between the tap to the phones and chassis, you should obtain the desired result. This portion of the voltage divider is at present part of the plate resistance, and. has signal voltages developed across it. A condenser of abcut 0:5 mfd will suffice. A.: The interference would not be influenced by the details.of the coils .and the only cure seems to be the judicious ise of an axe on the offending party! ‘The 7{ reception of shortwaves is quite possible, rn with the local station on the air, "‘PECEPTION" (Lower Hutt): The extra lead-in would be better inside and as you have a‘fairly short leadin, it would pay you to cut it off short and try to get it to match to the transformer. If the longer length gives better results then you can join up again without much trouble.

A: Yes, the dotted lines refer ‘to the shield, The condenser that is overheating sounds very suspitious, and as the ticking you describe alsu points to a faulty condenser, we would suggest a replacement there. "Y ALODINA" (Auckland): The effeet of the copper sphere would: be nil, and-it would. be only a waste of . time publing it iu the aerial. The main trouble .seems to be that you bhaye tov long a lead-in for the broadcast inverted L aerial. If the 42-foot mast could be erected nearer the house then the action of the shielded ‘lead-in would be much better, and especially on shortwave. An aerial longer than. 100 feet, including leadin, is seldom advantageous, especially in the tewns. . |

Slow" (Wellington); Yes, the * stability and sensitivity ele. would be better for the change. A: The 465 k.e. would be . bétter’ in eyour case. The valve arrangement would be quite good. but suggest that you use a 1C6 for the frequency converter, und a more conventional circuit with it. The autodyne circuit you show is not too satisfactory, and we would not advise its use,