RADIO NOTES

Te Awamutu Courier, Volume 53, Issue 3822, 16 October 1936, Page 9

RADIO NOTES

SPRING CLEAN YOUR RADIO. Spring will soon be here (writes ‘ Spark Gap” in the October issue of The Australian Journal), and with it the necessity for giving a real overhaul to the radio-receiver. Let us begin with the power supply. If this be drawn from the mains, it may soon be disposed of. Check the flexible cord for breaks or partial breaks; even broken pieces of the fine wire that go to make up the flexible cable tend to cause noises in the receiver. Make sure that the adaptor makes good, firm contact with its socket. An indifferent contact at this point is a sure noise maker. Now for the battery operated receiver. The A battery should be in good condition. The majority of battery operated sets these days are powered by an accumulator. The top of the battery should be well cleaned. Maybe some sulphation is noticeable here. Probably also the terminals have been corroded to some extent. Strong ammonia water should be used for cleaning the tops of the batteries and the terminal screws. It may be necessary to use a knife to scrape off some of the corrosion in order to get anywhere near the raw metal. Where the connecting wire is jammed under a net the metal should be thoroughly cleaned.

The B battery should now receive attention. Check the voltage whilst the receiver is working. A 45 volt battery will operate the receiver with a reading as low as 30 volts, but it is a good plan to discard a battery when its voltage drops below 35, as a partially exhausted battery tends to introduce in the receiver.

The C battery should now be checked. This also is probably of the dry type. Normallr the readings for a C battery should be 3 and 41, or 11, 3, 45, 6 and 71, depending on the make of the battery. If a test, after several hours work, shows that a 4 volt battery has dropped to 31 or lower, the battery should be discarded.

Now test the valves. If any valve is suspected of not doing its full work,

I it should be replaced by another and the result noted. With a nail file, touch up either the bottoms or sides of tiie pins on the valves, depending on the type of socket springs provided.

Now proceed to clean up the sockets, especially the flat portions of the bases between the terminals. All dust should be wiped from these flat surfaces, in order to prevent any unwanted leakage. Tighten up the nuts on all four or more terminals of each socket (if the connections are not soldered), and see that each nut makes good, even contact with the wire joined to it.

It is now time to examine the variable condensers. The plates of the condenser should be turned out of mesh and the dust between the plates removed by means of an ordinary pipe cleaner. All dust and dirt should be cleaned from the small bars that bold the stator plates, as it is here that leakage and noises can become very pronounced.

With a soft brush, clean every particle of dust from the chassis and the various other instruments. Make sure that every connection is mechanically perfect and that no two bare wires are making contact in unwanted places. If you are using a superheterodyne type of receiver, be careful not to alter the small trimming condensers, as once these have been changed it is very difficult to return them to the correct position without an elaborate set of instruments.

Perhaps at this stage it would be wise to examine the aerial and earth. Make sure that the aerial is taut and is not swinging against any metal work. Test the earth connection to see that tiie joint between the earth lead and the metal plate is not corroded. A couple of buckets of water thrown on the earth plate will ensure a good contact with the ground.

It will be found that a few minutes spent on your receiver will have made a wonderful difference to the reception. It will be clear and minus the nasty crackles and scratchings that previously had been noticed; probably the volume will be greatly improved; and maybe that distant station, previously barely audible, will romp in in great style.