Laboratory Jottings

Radio Record, Volume IV, Issue 37, 27 March 1931, Page 12

Laboratory Jottings

Report Upon _ the "Ultimate" Receiver

*PHROUGH the courtesy of H. Nimmo and Sons, Ltd., Wellington, we have had an opportunity of testing the "Uiltimate" long and short-wave receiver, and have been convinced that, for New ZeaJand conditions, this is an ideal set. It employs two stages of screen grid, gridleak detector, first stage audio, and second stage audio with two H406 in push-pull. The circuit has been specially designed for Philips valves, which are used throughout. lug-in coils are pro-‘vided-to cover two bands of short-wave and broadcast. The internal design of the set speaks very highly for the designer. It is neat, attractive and well finished. The tuning dial reaction and a balancing condenser are bo be found on the front panel, while on the inside we have a rejector tone control and an aerial balancing condenser. These are to be'set in position once only, when the set is installed, and need not be altered for subsequent use. The sensitivity of the set is quite equal to our standard receiver with three Stages of screen grid. The use of regeneration brings in many stations which are just normally on the borderline of audibility. During the afternoon upon which we installed the set we were surprised to bring in Auckland at quite fair strength. This is quite a feat for our particular location, and the set proved that this was quite an ordinary performance for it. It gave us all the New Zealand "A" class stations during the afternoon (Auckland and Dunedin, of course, were weak until about 6 o’clock), and after about 8 o’clock at night, the Australian stations came in at great strength. We had quite a big collection of them for the few days the set was in our possession. The Japs. could be brought in quite easily, and the use of regeneration certainly facilitates DX hunting, The selectivity of the set was all that was to be desired. By a careful adjustment of the rejector, we could separate 2FC and 3L0 from Wellington. This, we might remark, is quite a feat, for it is usual to have a fairly strong background on these stations, but the "Ulti-

mate" kept this down to a minimum; in fact, with a short aerial, we could get a dead spot between Wellington and 250, Sydney, a most unusual state of affairs, The rejector did not to any great extent reduce volume. It certainly did on. Wellington, but this was a most desirable feature. , Dhe tone of the set is good. The H406’s have a distinct tone, and produce very pleasing results when used in combination with the Jensen moving coil speaker provided with the set. There is an absence of boominess which is characteristic of some types of sets. The tone is always pleasing. Owing to the absence of a separate volume control, detuning on 2YA was necessary, and strangely enough this did not alter fidelity. Upon all other stations, regeneration proved itself to be an excellent control. For the test upon shortwave we handed the set over to Mr. F. W. Sellens, of Northland, who is one of the best-known shortwave listeners in New Zealand. Mr. Sellens says: "I was surprised at the volume at which I could receive the stations. W8xXAL, New Jersey, and Saigon, China, were at quite good speaker strength, with about three feet of wire for an aerial, while with a proper aerial these stations were too loud for an ordin-ary-sized room, even with very little reaction." .

This fact we desired to endorse our. selves. Saigon and W8XAL provided real entertainment. There was no ques: tion of novelty, the music came in clear and strong, and coming from such a distance, it was really enjoyable. The announcer_ in Boundbrook, New Jersey, sounded more like one in Christchurch. Mr. Sellens continues :- "Other statio-s heard at good volume were :-RV15, S* ria; WOXF,~° Chicago; WSXK, V.itsburg; Zeesen, Germany; W2XAI’, Schenectady; VK2MB, Sydney; GBP, England; G5SW, England ; 12RO, Rome; 7LQ. Nairobi; WIXAZ, Springfield, Mass.; HRB, Honduras. A number of amateurs and unidentified duplex telephone stations. "In addition to the above, several were audible, but the noise level was too high. This is not a long list of stations, but a few that were on the air during the limited period I had the receiver. "Although there are three tuned circuits, two stages of screen-grid frequency tuning is very simple, being controlled by a vernier dial operating ganged con-

densers. Any operator without previous experience, could,. with the ‘Ultimate,’ enjoy programmes from the principal shortwave stations in all parts ‘of the world, After a little practice in tuning, it will be possible to bring in many of the weaker stations. It is not possible to give the volume of the stations heard with the ‘R’ system, as this is designed for phone reception, R9 only being the speaker volume. The ‘Ultimate’ is not constructed for other than loudspeaker reception. . If the signal is receivable this receiver will amplify it sufficiently to give loudspeaker results."