| OCR Text |
Show By-Pass Condensers an Aid to Radio Receiver There are a number of places in a receiver where by-puss condensers should be used to hefp improve its operation. By-pass or blocking condensers con-densers keep the radio frequency currents cur-rents in the part of the circuit where they belong. If the radio frequency or high frequency current strays into the audio frequency or low frequency part of the circuit, you will get howls and noises and generally poor performance per-formance from your set. In fact, If very much radio frequency gets through to the audio you may not be able to operate the receiver at all. By-pass condensers should be used across any part that has a high resistance re-sistance or impedence to provide an easy path for the radio frequency current. A by-pass condenser should always be provided across the "A" and "B" batteries. When the batteries bat-teries are new the resistance Is not extremely high, but after they have been In use for some time this resistance re-sistance rises rapidly and some means must be provided to counteract this effect. A fairly large capacity must be used from one-half to two mfd. The larger the better. Connect the condenser between the 45-volt plus and the negative filament and between the 90-volt plus and the negative filament. fila-ment. Even with a new battery these condensers will improve reception, but their effect will be particularly noticeable notice-able with batteries that have been used a short time. Use good quality condensers and make sure they are not leaking. To test for leakage connect a 90-volt battery across the condenser for a few seconds, then, after setting aside for about 15 minutes, touch the condenser con-denser contacts with a pair of phone tips. If there Is no click heard in phones then the condenser is leaking. leak-ing. If, however, you hear a click, it Is O. K. The next place a blocking condenser con-denser should be tried Is across the primaries of the audio transformers. Very often a small amount of radio frequency current will get through from the detector and will pass through the primary of the transformer trans-former unless an easier path Is provided pro-vided for It. A condenser of from .0025 to .01 should be used. The best value will be found by trying various vari-ous capacities. |
