Re: [Repeater-Builder] Micor repeater audio
Jeff DePolo wrote: your input Mike I don't have a real answer for you, but it's interesting that I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station? You're probably seeing the peak in the PL filter's response. If you remove the PL filter and config the A/S board for carrier squelch operation, you'll probably see relatively flat response up to about 2.5 kHz where the splatter filter starts to take over. --- Jeff WN3A Yeah, I thought of that before I tested actually, Jeff. I was using the SCom controller to generate the tones directly to the transmitter in the normal repeat path. But overall repeat audio is about the same. That's a good point for everybody! Jim
Re: [Repeater-Builder] Micor repeater audio
I know no one cares to see my graphs... But I posted another one anyways. Thank you for this little nugget! I suspected the PL filter as well Threw those resistors on tonight, and while the difference in response measured is not that great, the difference to the ear is huge! This really cleaned up the audio on my box on the bench. Measuring a pure sine wave will probably not show the real effects the ringing has on speech and other complex waveforms, likely validating my observation that the speech is significantly cleaned up. Thanks again for the great experience shared with the group! Tom W9SRV Jeff is right on the nose here I have swept the MICOR and MOTRAC PL filters and there is a defined peak around 400 Hz. It is likely caused by the self resonance of the 6 Henry chokes and associated support components which create the tuned network used in the filter. This can be tamed down (filter made to be flatter in response) to some degree by placing a 220K resistor across the choke(s). See Here: http://www.repeater-builder.com/rbtip/plf.html Kevin Custer
RE: [Repeater-Builder] Micor repeater audio
mzfb2001 wrote: I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike I don't have a real answer for you, but it's interesting that I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station? You're probably seeing the peak in the PL filter's response. If you remove the PL filter and config the A/S board for carrier squelch operation, you'll probably see relatively flat response up to about 2.5 kHz where the splatter filter starts to take over. --- Jeff WN3A
Re: [Repeater-Builder] Micor repeater audio
Jeff DePolo wrote: I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station? You're probably seeing the peak in the PL filter's response. If you remove the PL filter and config the A/S board for carrier squelch operation, you'll probably see relatively flat response up to about 2.5 kHz where the splatter filter starts to take over. --- Jeff WN3A Jeff is right on the nose here I have swept the MICOR and MOTRAC PL filters and there is a defined peak around 400 Hz. It is likely caused by the self resonance of the 6 Henry chokes and associated support components which create the tuned network used in the filter. This can be tamed down (filter made to be flatter in response) to some degree by placing a 220K resistor across the choke(s). See Here: http://www.repeater-builder.com/rbtip/plf.html Kevin Custer
Re: [Repeater-Builder] Micor repeater audio
Hi Guys, W0INK studied and reported on that topic some time ago: http://www.scomcontrollers.com/downloads/ctcsssrejecthpfilters.pdf 73, Bob Bob Schmid, WA9FBO, Member S-COM, LLC PO Box 1546 LaPorte, CO 80535-1546 970-416-6505 phone 970-419-3222 fax www.scomcontrollers.com -Original Message- From: Kevin Custer kug...@kuggie.com To: Repeater-Builder@yahoogroups.com Sent: Wed, Nov 18, 2009 9:54 am Subject: Re: [Repeater-Builder] Micor repeater audio Jeff DePolo wrote: I have had he opposite experience with the two most recent Micor UHF stations I ut on-line. Both have a peak very near to 400 Hz, and roll ff several B/octave above that. Setting for 3 in/3 out @ 1KHz, I get bt 4 out @ 00 hz, and abt, oh, 1.5 or so at 3K. nyone else noticed a peak around 400 Hz on a UHF Micor station? You're probably seeing the peak in the PL filter's response. If you remove he PL filter and config the A/S board for carrier squelch operation, you'll robably see relatively flat response up to about 2.5 kHz where the splatter filter starts to take over. --- Jeff WN3A Jeff is right on the nose here I have swept the MICOR and MOTRAC PL filters and there is a defined peak around 400 Hz. It is likely caused by the self resonance of the 6 Henry chokes and associated support components which create the tuned network used in the filter. This can be tamed down (filter made to be flatter in response) to some degree by placing a 220K resistor across the choke(s). See Here: http://www.repeater-builder.com/rbtip/plf.html Kevin Custer
Re: [Repeater-Builder] Micor repeater audio
mzfb2001 wrote: I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike I don't have a real answer for you, but it's interesting that I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station?
Re: [Repeater-Builder] Micor repeater audio
Yes, I just measured mine out last week (again) and I believe I have the same thing. I will measure it exactly tommorow and post my findings. Tom W9SRV --- On Mon, 11/16/09, wd8chl wd8...@gmail.com wrote: From: wd8chl wd8...@gmail.com Subject: Re: [Repeater-Builder] Micor repeater audio To: Repeater-Builder@yahoogroups.com Date: Monday, November 16, 2009, 11:55 PM mzfb2001 wrote: I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike I don't have a real answer for you, but it's interesting that I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station? Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.com
Re: [Repeater-Builder] Micor repeater audio
I stand corrected. I just checked mine on the bench. Injected signal from my audio generator into the Exciter (pin 24 on the TX interconnect board). Set the output of the generator to acheive 3k deviation at 1k. Then checked the 1/3 octaves from 160 to 6300. I posted the graph in the files section of the group, but I found the peak at 1600Hz. I suppose I could do this again into the PL input to go around the stock audio processing, but this is the way I am going to use it.. However, I believe the audio tailoring I am hearing is actually caused on the RX side of things. The other file I posted in the group a few weeks ago (When I was checking adm vs non-adm) was measued by outputting a constant 3k dev on the service monitor at multiple audio frequencies and measuring the audio input going into the exciter thru the RX and 7K controller with an AC voltmeter. You will see on that graph there is most definatly a bump at 200-400Hz. I can double check, but the last time i swept a straight 7k it was pretty flat in audio response, so the tailoring must be caused by the RX or the AS board and the PL filtering (Which I am using). I'm sure Kevin or someone else out here smarter than me has a logical explainationI'll wait to read it. Tom W9SRV --- On Tue, 11/17/09, TGundo 2003 tgundo2...@yahoo.com wrote: From: TGundo 2003 tgundo2...@yahoo.com Subject: Re: [Repeater-Builder] Micor repeater audio To: Repeater-Builder@yahoogroups.com Date: Tuesday, November 17, 2009, 12:04 AM Yes, I just measured mine out last week (again) and I believe I have the same thing. I will measure it exactly tommorow and post my findings. Tom W9SRV --- On Mon, 11/16/09, wd8chl wd8...@gmail.com wrote: From: wd8chl wd8...@gmail.com Subject: Re: [Repeater-Builder] Micor repeater audio To: Repeater-Builder@yahoogroups.com Date: Monday, November 16, 2009, 11:55 PM mzfb2001 wrote: I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike I don't have a real answer for you, but it's interesting that I have had the opposite experience with the two most recent Micor UHF stations I put on-line. Both have a peak very near to 400 Hz, and roll off several dB/octave above that. Setting for 3 in/3 out @ 1KHz, I get abt 4 out @ 400 hz, and abt, oh, 1.5 or so at 3K. Anyone else noticed a peak around 400 Hz on a UHF Micor station? Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.com Yahoo! Groups Links repeater-builder-fullfeatu...@yahoogroups.com
RE: [Repeater-Builder] Micor repeater audio
First if it is all stock. I would go through the cards and replace the electrolytic caps in the audio path. Or just shot gun all the caps. As old as they are it would be good. I do this when I rebuild any micor or mastr repeater. I have a couple of stock micors up and have them sounding fine. Others may have some suggestions to add. -Kevin -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of mzfb2001 Sent: Saturday, November 14, 2009 12:51 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor repeater audio I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike Yahoo! Groups Links
Re: [Repeater-Builder] Micor repeater audio
mzfb2001 wrote: I was looking in the files section and may have missed it, but I am looking to improve the transmit audio quality on my UHF transmiter. I've noticed that the audio is lacking in lows its not tinny but its not what I would call normal audio from a Micor. The audio levels and on frequency adjustments have made and to seem to be on the money. This is an unmodified repeater station using stock cards and no controller. The receiver is stock and the frequency has been changed to the 440mhz band. The audio coming out of the receiver has fine audio quality. Just looking for your thoughts or ideas. Thanks for your input Mike I'd make sure the channel element is not limiting the quality of your audio. Consider doing a sweep of the frequency response at several deviation levels and see what you have. I've seen re-crystaled elements that were less than good. Kevin
