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The BOLD text quoted above is only half right. The LPF does not present 50 ohms impedance to the harmonics and that I agree with. None of the harmonic energy is reflected back to the source, that being the transmitter. A LPF consists of series and parallel circuits. The series circuits are from the main transmission path to ground and in effect short out the harmonic energy to ground. None of it goes back to the transmitter. The parallel circuit components offer a very high impedance inline with the transmission path and basically force that energy to seek another path and that path is via a series circuit to ground. Again, none of it goes back to the transmitter.

One a note: I noticed an ad that stated the following,

"All RF amplifiers will "react" in some way when a low pass filter is attached. This reaction is mainly caused by reflected harmonics. All RF amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor causing reduced efficency and output power. The transistor will also run hotter."

Perhaps this piece of misinformation this is a reason many CB'ers don't want to use a LPF on their amps.

<blockquote data-quote="Captain Kilowatt" data-source="post: 263100" data-attributes="member: 39">The BOLD text quoted above is only half right. The LPF does not present 50 ohms impedance to the harmonics and that I agree with. None of the harmonic energy is reflected back to the source, that being the transmitter. A LPF consists of series and parallel circuits. The series circuits are from the main transmission path to ground and in effect short out the harmonic energy to ground. None of it goes back to the transmitter. The parallel circuit components offer a very high impedance inline with the transmission path and basically force that energy to seek another path and that path is via a series circuit to ground. Again, none of it goes back to the transmitter.One a note: I noticed an ad that stated the following,&quot;All RF amplifiers will &quot;react&quot; in some way when a low pass filter is&nbsp; attached. This reaction is mainly caused by reflected harmonics. All RF&nbsp; amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor&nbsp; causing reduced efficency and output power. The transistor will also&nbsp; run hotter.&quot;&nbsp;Perhaps this piece of misinformation this is a reason many CB&#039;ers don&#039;t want to use a LPF on their amps.&nbsp;&nbsp; <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f617.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":whistle:" title="Whistling&nbsp; &nbsp; :whistle:"&nbsp; data-smilie="29"data-shortname=":whistle:" /></blockquote>

[QUOTE="Captain Kilowatt, post: 263100, member: 39"] The [B]BOLD[/B] text quoted above is only half right. The LPF does not present 50 ohms impedance to the harmonics and that I agree with. None of the harmonic energy is reflected back to the source, that being the transmitter. A LPF consists of series and parallel circuits. The series circuits are from the main transmission path to ground and in effect short out the harmonic energy to ground. None of it goes back to the transmitter. The parallel circuit components offer a very high impedance inline with the transmission path and basically force that energy to seek another path and that path is via a series circuit to ground. Again, none of it goes back to the transmitter. One a note: I noticed an ad that stated the following, "All RF amplifiers will "react" in some way when a low pass filter is attached. This reaction is mainly caused by reflected harmonics. All RF amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor causing reduced efficency and output power. The transistor will also run hotter." Perhaps this piece of misinformation this is a reason many CB'ers don't want to use a LPF on their amps. :whistle: [/QUOTE]

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