how to check a tank circuit

[paulrevelcet]

Is there any way to check if a tank circuit is working? it is supposed to vibrate at around 180MHZ, it is powered by a 9volt battery and I would like to check it. I dont have a frequency counter, But I do have an Oscope, duel channel 30MHZ.

[Chris Smith]

The out put value should be higher than the input value. The scope will show the oscillations as well as the voltage peaks, but the values should be higher on the out put side, than on the in, in order to be a gain. A tank circuit is generally not just an oscillator.

[russlk]

Your 30 mHz scope is not going to be any use. If you have a receiver that will tune the frequency, you can hear the quieting that happens when you tune to the unmodulated carrier, or you can modulate it and listen for the modulation. If you just want to know if it is oscillating, measure the base and emitter voltage of the oscillator. The base will be negative relative to the emitter if it is working (NPN transistor)and positive 1/2 volt if it is not working.

[Dimbulb]

Hello I think you have a fair question.
On my television which is USA variety that uses an external antenna.<p>On channel 8 you should be able to adjust it to 180 Mhz. When the transmitter is on and coupled to the antenna input or using an antenna to antenna coupling you might say the picture should go from fuzzy to a blurp when it picks up the signal. To be certain turn the transmitter on and off and observe the reception.

[paulrevelcet]

Thanks alot.

[Chris Smith]

Even your slower scope will show activity and gain. <p>You wont be able to see any resolution of the signal, other than what looks like hash lines, but those lines will show the signal never the less.

[Rodney]

Use a grid Dip meter.

[Edd]

<<But I do have an Oscope, duel channel 30MHZ>>….which channel usually wins?<p>With your having a scope, surprised no one mentioned just taking the 1x probe and clipping in a 1N914/4148 diode, with its other lead close connected to the probes typical 6 in gnd lead. Diode loading and filtering being provided by the probes RC components. Put the scopes vert amp into the lowest mv range, DC coupling mode, auto triggering , slow hoz time base. Then just bring the diode up ll to the tank coil and watch the progressive detected DC level shift on the scope trace, IF the circuit is ossifrying.<p>73's de Edd
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<p>[ May 10, 2004: Message edited by: Edd Whatley ]</p>

[Chris Smith]

Isnt that what I said Fred, I mean Ed? <p>Hash