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5282
Posted: March 25, 2010 11:48 pm
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What is the benefit to use the rfc1 and rfc3 on this fm transmitter ?

When their tendency weak output alot?
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Sch3mat1c
Posted: March 26, 2010 08:24 am
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RFC1 and RFC3 ensure those transistors run in class C.


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CWB
Posted: March 26, 2010 12:54 pm
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yep ... a very deep class "C" .

if the bandwidth of the LC circuits is not wide enough the sloped response will cause AM'ing (effectively) in the output .
this is where some of these designs fall short ... the "Q" of the LC is too high for the modulation index .
misalignment can contribute to the problem .


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5282
Posted: March 26, 2010 01:06 pm
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thank all
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5282
Posted: March 26, 2010 09:00 pm
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what kind of transistor can i use in this fm transmitter tr2
Not 2n2219

This post has been edited by 5282 on March 26, 2010 09:01 pm
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tekwiz
Posted: March 26, 2010 09:55 pm
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QUOTE (5282 @ March 26, 2010 12:00 pm)
what kind of transistor can i use in this fm transmitter tr2
  Not 2n2219

Virtually any VHF small signal NPN silicon transistor will work. Frequency capability information is in the transistor's datasheet.


BTW: The purpose of most RFCs is to block RF while passing DC. The opposite of what a decoupling capacitor does.


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5282
Posted: March 26, 2010 10:33 pm
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thank tekwiz
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