PL / CG (CTCSS) Filter Information Index

PL / CG (CTCSS) Filter Information Index
The links below will allow you to build several working subaudible tone filters.
Information compiled by Mike Morris WA6ILQ
If anyone would like to donate additional information for this page
please send it to (the callsign above) at repeater-builder dot com

No warranty as to the quality or usefulness of the filter circuits below is expressed by Repeater Builder

From the owner of the Scom company:

There was a discussion on Repeater-Builder a while ago about the advantages and disadvantages of various commercial CTCSS highpass filters. S-COM's analog guru, Virgil, W0INK, did a careful analysis of five common highpass filter designs: Communications Specialists TS-32, Communications Specialists TS-64, the stock Motorola Micor PL filter, the Motorola MSR2000 PL filter, and the GE CG filter. The results are certainly interesting. His paper can be found at http://www.scomcontrollers.com/downloads/ctcsssreject&hpfilters.pdf.

A repeat audio board designed for the GE Master Exec II from Micro Computer Concepts 171k JPG file donated by Ron Wright N9EE
Note that the page is oriented for printing, not viewing.

A High Pass PL Tone Filter By Bob Dengler NO6B

A High Pass PL Tone Filter By Kevin Custer W3KKC

The PL filter from a Motorola Motrac receiver audio-squech board By Kevin Custer W3KKC
We use it in Micors

GE's Mastr Exec II tone board from LBI30854 which replaced LBI4143
This board has the tone encoder, tone decoder and tone filter . Look for the section on the "Tone Reject Filter".

Mastr-Pro Aux Receiver chassis This link goes to LBI4172 which is for a rack-mount power supply chassis for the Mastr-Pro series of receivers. One option was a line amplifier that came in tone and non-tone versions. Look for the section that describes "Line Amplifier A503/A504". A503 does not have the filter, A504 has it. Just print those two schematic pages and compare them.

Mastr-Pro base station / repeater power supply chassis This is LBI4423, and contains the line amplifier information for the 4EA24A12 and A13 chassis: the A12 version is used in carrier squelch stations (non-tone), and the A13 is for stations with Channel Guard tone decoders, filters and line amplifiers. Simply compare the two schematics.

Another one of GE's tone filter boards Another look at how GE did it (from LBI30727, not sure which radio it's for).

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Page created 14-Sep-2004 by Kevin K Custer W3KKC