20 Meter CW transmitter

whawaii

Joined Apr 21, 2009
1
Oh, I see. That's really interesting. So you essentially amplify a harmonic and filter it out?
I know i'm responding to this years down the road, but here goes anyway -

Ding, Ding, Ding! Winner, Winner - Chicken Dinner!

That is how the RF Section of Remote Controllers work. The crystals used are from the 20 Meter Band 14.4 - 14.6MHz for the 72MHz Band & 15.08 - 15.2MHz for the 75MHz Band. They use the 5th Harmonic of the crystal by filtering out the fundamental & the first few harmonics, in the early stages before the Driver, & then use Low Pass Filtering on the final output. Here are two drawings of the same circuit. I find the Hand Drawing a bit easier to follow.

BTW - These are the FM versions of the circuit. The AM versions are wired slightly different. The manufactures basically used the same circuit board for both, just changing a few components for the two different modulations.
72MHz FM Module.gifFP_TP_FM.jpg
 
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