Re: [Repeater-Builder] Re: PL (CTCSS) Filter
At 3/21/2009 06:20, you wrote: Hi Bob, Cut a long story short .. looks like I did not actually finish the circuit which with my memory is no surprise. While working on the second build have found that the 1500 caps between pins 1 and 5 are missing as are the connections to pins 4 and 11. I think the reason was that I did not know what the values were exactly. Sorry about this but could you tell me what the value is. Regards, Doug - GM7SVK The cap values are properly called out on the schematic. Pins 4 11 are the supply connections for the op amp. Pin 4 is +12V pin 11 is ground. BTW, although the TL084 should work fine, there are better op amp choices available these days. I personally like the TLV2374 for its rail-to-rail in/out capability, low crossover distortion low cost. Then again if all you have in your parts bin is an LM324 it should work fine for testing purposes. Bob NO6B
Re: [Repeater-Builder] Re: PL (CTCSS) Filter
At 3/21/2009 08:38, you wrote: Thank you Bob, Sorry to display my ignorance but 1500 what, nf, pf? Doug They're 1500 pF, as called out in the schematic (the pF is below the 1500 in Chuck's schematic). Bob NO6B
Re: [Repeater-Builder] Re: PL (CTCSS) Filter
At 3/21/2009 06:20, you wrote: Hi Bob, Cut a long story short .. looks like I did not actually finish the circuit which with my memory is no surprise. While working on the second build have found that the 1500 caps between pins 1 and 5 are missing as are the connections to pins 4 and 11. I think the reason was that I did not know what the values were exactly. Sorry about this but could you tell me what the value is. OK, I see the problem: the schematic on Repeater-Builder is missing the complete capacitor values - thanks for pointing this out, Bob M. Here's the correct schematic. Sorry for the confusion. Bob NO6Battachment: CTCSS HPF-WB2EDV.png
Re: [Repeater-Builder] Re: PL (CTCSS) Filter
At 3/19/2009 08:18, you wrote: Hi Doug, Many years ago I had a similar situation. Instead of using the N06B filter I used the built in hi-pass filter in a Comm Spec PL encoder/decoder board. It is very similar to the NO6B filter. Actually the reason I developed my own HPF was because of the poor performance of the filter in the CommSpec board. It's transient response is poor, causing a ringing boxy sound around 400 Hz. My design is an adaptation of the HPF used in the Sigtone C1116 CTCSS board. All I did was move the 3 dB point down from 300 Hz to ~210 Hz, since I don't use any of the higher CTCSS tones didn't want to filter the audio any more than necessary, since some of the outgoing paths end up being HPF'd again downstream by 300 Hz cutoff HPFs. Even at 151.4 Hz the attenuation is about 20 dB - good enough for me. What was happening was that the filter was introducing twist (subtle distortion) to the DTMF waveform. IIRC both the CommSpec Sigtone designs are flat once you're well within the voice band (600 Hz higher). But if 2 or more CommSpec filters are cascaded in a system the high pass rolloff may be high enough to attenuate some of the low DTMF tones. But that's not your problem if you're using my design. I suggest looking at the output of the filter with a scope to see if there's any ultrasonic oscillation that could be confusing the DTMF decoder downstream. You do have that 27k or some value of resistor = 1k on the output op amp (pin 8), right? An output isolation resistance is required to prevent external capacitive loading from causing that op amp to oscillate. Bob NO6B
RE: [Repeater-Builder] Re: PL (CTCSS) Filter
Somehow my mailer treated this thread and the message I just replied to about the same topic as different... so I didn't see that Bob had replied to you, nor your reply that you were working on a rebuild. You can probably ignore what I sent if you're already on to figuring out what's wrong with your circuit! (GRIN) It still applies, but you're already there. 73, Nate WY0X -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Doug Hutchison Sent: Friday, March 20, 2009 8:33 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: PL (CTCSS) Filter Thank you both. Yes Bob have the 27k but seem to have made a mistake in the build somewhere in that the scope shows CTCSS still present on the output. Looks like there is some attenuation taking place, reducing all audio passing through by about a third. Cannot as yet see my error - will try a new build and advise. Best regards, Doug - GM7SVK
Re: [Repeater-Builder] Re: PL/CTCSS Filter
Thanks for sharing the circuit. Now someone needs to design a printed circuit board for it and make it available to those not having the wherewithal to make their own. Chuck WB2EDV - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 27, 2003 12:05 PM Subject: [Repeater-Builder] Re: PL/CTCSS Filter I've seen a lot of posts on this subject but no posting of an actual filter schematic. Here's mine. It includes a de-emphasis section for flat audio response systems; omit if using pre-emphasized audio in your controller. As John pointed out in an earlier post, the performance of the HPF in the ComSpec TS-32 leaves a bit to be desired. Yes it will strip CTCSS tones nicely, but it has a poor transient response will ring around 400 Hz. This is the reason systems using this filter have a boxy sound. For my system I decided to use the filter in the Sigtone C1116 decoder. I redesigned the filter to cut off a bit low in frequency (210 Hz) in order to slightly improve system audio quality, since I didn't need brick-wall filtering at the higher tone freqs. that I don't use. Happy Thanksgiving everyone! Bob NO6B Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: PL/CTCSS Filter
On Thu, 27 Nov 2003 13:09:44 -0500, Chuck Kelsey wrote: Thanks for sharing the circuit. Now someone needs to design a printed circuit board for it and make it available to those not having the wherewithal to make their own. Just breadboard it Chuck. It only uses one chip (the TL084 is a quad opamp) along with the passive components. Just putting one together as we speak, so I can see how much difference there is between it and the TS-32 :) Tedd Doda, VE3TJD Lazer Audio and Electronics Baden, Ontario, Canada Way to go Matt! (#17) Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: PL/CTCSS Filter
I know, I know. But a nice little printed circuit board makes it really neat and professional. Keep us posted on your results. Chuck - Original Message - From: Tedd Doda [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 27, 2003 2:21 PM Subject: Re: [Repeater-Builder] Re: PL/CTCSS Filter On Thu, 27 Nov 2003 13:09:44 -0500, Chuck Kelsey wrote: Thanks for sharing the circuit. Now someone needs to design a printed circuit board for it and make it available to those not having the wherewithal to make their own. Just breadboard it Chuck. It only uses one chip (the TL084 is a quad opamp) along with the passive components. Just putting one together as we speak, so I can see how much difference there is between it and the TS-32 :) Tedd Doda, VE3TJD Lazer Audio and Electronics Baden, Ontario, Canada Way to go Matt! (#17) Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: PL/CTCSS Filter
[EMAIL PROTECTED] wrote: I've seen a lot of posts on this subject but no posting of an actual filter schematic. Here's mine. This is now an available article on Repeater Builder: http://www.repeater-builder.com/pl-filter/ More to come as soon as I can find the copy of the schematic... Kevin Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: PL/CTCSS Filter
Just breadboard it Chuck. It only uses one chip (the TL084 is a quad opamp) along with the passive components. If you have a controller that does de-emphasis or you don't want it, a dual opamp like the TL062 should be sufficient. That's what I'll be using. Adi -- Adi Linden | va3adi | [EMAIL PROTECTED] | http://adis.ca +-+ IRLP Node 2590 in Sioux Lookout, Ontario Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
