Большинство советов японского радиолюбителя Kazuhiro Sunamura JF1OZL вполне понятны из рисунков. Впрочем, тексты легко вогнать в переводчик.
We are handmader. We use our handmade transmitter. If the picture tube of the TV set of your house shows you a figure with many stripes , when you use your transmitter. Then we call TVI " Terevision Interferance" has come on.
Mode 1 : Harmonic of transmitter comes on the antenna of TV. *** tvi1.gif
When we use the 21MHz CW transmitter, the five times harmonics of the radiated signal becomes 105MHz. It is third channel of VHF television on Japan. Connect the good shielded dummy load on the connector of your transmitter! After that , if you can not see the TVI, then you can recognize the TVI is caused by this mode. In order to reject this mode, use a low pass filter between the antenna and the transmitter of your shack. You can learn how to make it on the another page of my homepage.
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Mode2 : Radio signal conducts through the AC line.*** tvi2.gif
If the radio signal is conducted to the AC line of your home from your transmitter , then it comes to the TV set of your and your neighbers. It will cause the TVI. Connect the good shielded dummy load on the connector of your transmitter! Even after that , if you can see the TVI, then you can recognize the TVI is caused by this mode. Or, supply power from removed battery from your car! After that the interferance disappears, then you can recognize the TVI is caused by this reason. In order to reject this mode, use a line filter made by troidal core. Turn 13 turns of it on the FT114-43 core!
Mode3 : You must recognize that the TV set do not have shield. tvi3.gif
The printed board of TV set's is located on the plastic case with no shield. The convertor block may be shielded. But the IF amplifier and video amplifier of TV set will be not shielded. Therefore if you make your transmitter without any shield, The circuit of transmitter and the circuit of the TV will make influence directly each other. That causes TVI. Use Good shielded aluminium case to your transmitter. Do not use plastic case to the transmitter.
Mode 4 : Radiate from key code of your CW transmitter. */** tvi4.gif
If you make CW transmitter with zero bias final transistor , and keying it on the emitter of it, it will cause this mode. The high frequency electric signal flows on the wire between the transmitter case and the key on your desk, the signal will be radiated from the wire. It will cause TVI. The signal flows on this line will have many harmonics , because the transistor acts intermittently. Connect the emitter on the ground directly! Even after it , if you see the TVI, then you can recognize the TVI is caused by this reason. To avoid this mode, keying must be made on buffer or driver of the transmitter.
Already I have indicated four mode of TVI.
Mode 1 : Harmonic of transmitter comes on the antenna of TV.
Mode2 : Radio signal conducts through the AC line.
Mode3 : You must recognize that the TV set do not have shield.
Mode 4 : Radiate from key code of your CW transmitter.
You will be able to guess that there are many another mode causes TVI. For example , radiated signal from power line of the transmitter come on the antenna of TV receiver. And you must take care of that many another reason causes TVI on the same time.