Re: [Repeater-Builder] Micor Bi-Level Squelch Circuit
I wonder if it is a noise floor problem. How does it act on a service monitor when it is not hooked to an antenna picking up high levels of noise? tom [Original Message] From: Adam Feuer feu...@optonline.net To: Repeater-Builder@yahoogroups.com Date: 7/12/2009 7:30:11 AM Subject: Re: [Repeater-Builder] Micor Bi-Level Squelch Circuit I am a very big fan of the Micor bi-level squelch. It's action is second to none on my 440 and 900 system however, I too am having the exact same problem on my 29.540 receiver in carrier squelch. I just will not take anyone into the noise but rather near quieting signals just pop out and disapear under the squelch. I have tried cleaning all of the pins and swapping out the audio control module but nothing seems to help. Interesting enough, this is NOT happening on my 6 meter Spectra Tac! At the moment, I have placed my 29.540 Spectra Tac aside and replaced it with a GE Mastr II auxiliary receiver on 10 meters. The results are much better as pertains to the squelch, but this is not to start a Micor vs. Mastr II comparison.something is just not right on 10 meters with a Spectra Tac receiver. If it can work on all of the other bands (especially six meters!) it should work on 10. If anyone has any suggestions, perhaps some part changes on the audio control module, they would be greatly appreciated! Adam N2ACF kq2h wrote: I've been impressed with the operation of the Micor bi-level squelch circuit based on the M7716 IC. I use Micor Spectra-Tac receivers exclusively on 440, 902, 6 Meters and 222 MHz (VHF to 222 conversion) with excellent results. However, I am perplexed by 10 Meters. The Spectra-Tac squelch circuit doesn't work well at all. It squelches up on fading signals that aren't all that noisy and drops out for no apparant reason. It appears that the squelch is set too high, but it isn't. I've tried different audio/squelch modules, receiver boards and housings. Even the IMTS modification which defeats the short squelch tail doesn't help the situation. When a UHF reciever is substituted in place of the 10 Meter receiver, the squelch circuit works fine. An old 25-30 MHz Motrac receiver, with its simple 3 transistor squelch circuit, works perfectly on 10 Meters. There are no problems with drop outs. The receiver squelch remains open well into the noise. This leads me to believe that the Micor bi-level circuit needs to be optimized for 10 Meters. Does anyone know of any component value changes in the Micor bi-level circuit to optimize operation on 10 Meters? Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] Micor Bi-Level Squelch Circuit
I am a very big fan of the Micor bi-level squelch. It's action is second to none on my 440 and 900 system however, I too am having the exact same problem on my 29.540 receiver in carrier squelch. I just will not take anyone into the noise but rather near quieting signals just pop out and disapear under the squelch. I have tried cleaning all of the pins and swapping out the audio control module but nothing seems to help. Interesting enough, this is NOT happening on my 6 meter Spectra Tac! At the moment, I have placed my 29.540 Spectra Tac aside and replaced it with a GE Mastr II auxiliary receiver on 10 meters. The results are much better as pertains to the squelch, but this is not to start a Micor vs. Mastr II comparison.something is just not right on 10 meters with a Spectra Tac receiver. If it can work on all of the other bands (especially six meters!) it should work on 10. If anyone has any suggestions, perhaps some part changes on the audio control module, they would be greatly appreciated! Adam N2ACF kq2h wrote: I've been impressed with the operation of the Micor bi-level squelch circuit based on the M7716 IC. I use Micor Spectra-Tac receivers exclusively on 440, 902, 6 Meters and 222 MHz (VHF to 222 conversion) with excellent results. However, I am perplexed by 10 Meters. The Spectra-Tac squelch circuit doesn't work well at all. It squelches up on fading signals that aren't all that noisy and drops out for no apparant reason. It appears that the squelch is set too high, but it isn't. I've tried different audio/squelch modules, receiver boards and housings. Even the IMTS modification which defeats the short squelch tail doesn't help the situation. When a UHF reciever is substituted in place of the 10 Meter receiver, the squelch circuit works fine. An old 25-30 MHz Motrac receiver, with its simple 3 transistor squelch circuit, works perfectly on 10 Meters. There are no problems with drop outs. The receiver squelch remains open well into the noise. This leads me to believe that the Micor bi-level circuit needs to be optimized for 10 Meters. Does anyone know of any component value changes in the Micor bi-level circuit to optimize operation on 10 Meters? Yahoo! Groups Links
RE: [Repeater-Builder] Micor Bi-Level Squelch Circuit
Alex, if memory serves, the component differences for the lowband audio/squelch board are documented in the manual. I don't remember if the station and mobile boards both have different components for lowband, or if it was just the station. I also don't remember if the SpectraTAC audio board had different components in the squelch circuit, or if it was on the Micor mobile or station that did. When I get back to the shop I can dig out manuals. I forget if the component differences were related solely to altering the action of the Micor squelch in and of itself, or if they were also a function of the different AF response (particularly HF noise output) of the lowband Sensitron receiver. The Micor squelch circuit is, IMHO, still the best there ever was. However, the long squelch can be a bit too long in some cases when you're using an audio delay board to mute squelch tails. What ends up happening is that if you set the delay long enough to fully mute long squelch tails that sometimes users that are DFQ who un-key quickly will have their last word chopped off because the short-squelch turn-off is much shorter than the audio delay duration. Although it defeats the purpose of the bi-level squelch, what I usually do is defeat the short squelch logic and set the delay accordingly. I don't have my notes in front of me, but the mod involves adding a resistor to pull down one of the lines coming off the 7716 to result in the detected noise level always falling in the long squelch voltage range as seen by the comparator. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of kq2h Sent: Thursday, July 09, 2009 6:13 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor Bi-Level Squelch Circuit I've been impressed with the operation of the Micor bi-level squelch circuit based on the M7716 IC. I use Micor Spectra-Tac receivers exclusively on 440, 902, 6 Meters and 222 MHz (VHF to 222 conversion) with excellent results. However, I am perplexed by 10 Meters. The Spectra-Tac squelch circuit doesn't work well at all. It squelches up on fading signals that aren't all that noisy and drops out for no apparant reason. It appears that the squelch is set too high, but it isn't. I've tried different audio/squelch modules, receiver boards and housings. Even the IMTS modification which defeats the short squelch tail doesn't help the situation. When a UHF reciever is substituted in place of the 10 Meter receiver, the squelch circuit works fine. An old 25-30 MHz Motrac receiver, with its simple 3 transistor squelch circuit, works perfectly on 10 Meters. There are no problems with drop outs. The receiver squelch remains open well into the noise. This leads me to believe that the Micor bi-level circuit needs to be optimized for 10 Meters. Does anyone know of any component value changes in the Micor bi-level circuit to optimize operation on 10 Meters? Checked by AVG - www.avg.com Version: 8.5.375 / Virus Database: 270.13.12/2233 - Release Date: 07/12/09 08:20:00
[Repeater-Builder] Micor Bi-Level Squelch Circuit
I've been impressed with the operation of the Micor bi-level squelch circuit based on the M7716 IC. I use Micor Spectra-Tac receivers exclusively on 440, 902, 6 Meters and 222 MHz (VHF to 222 conversion) with excellent results. However, I am perplexed by 10 Meters. The Spectra-Tac squelch circuit doesn't work well at all. It squelches up on fading signals that aren't all that noisy and drops out for no apparant reason. It appears that the squelch is set too high, but it isn't. I've tried different audio/squelch modules, receiver boards and housings. Even the IMTS modification which defeats the short squelch tail doesn't help the situation. When a UHF reciever is substituted in place of the 10 Meter receiver, the squelch circuit works fine. An old 25-30 MHz Motrac receiver, with its simple 3 transistor squelch circuit, works perfectly on 10 Meters. There are no problems with drop outs. The receiver squelch remains open well into the noise. This leads me to believe that the Micor bi-level circuit needs to be optimized for 10 Meters. Does anyone know of any component value changes in the Micor bi-level circuit to optimize operation on 10 Meters?
Re: [Repeater-Builder] Micor Bi-Level Squelch Circuit
Try cleaning all the RF schielding and IF schielding connections for that receiver. Those low-band Micor receivers had issues where they occasionally started having squelch and sensitivity problems when those contacts became less than perfect. I've used Micor receivers on 10 meter FM and had them work well with the squelch circuit. -- Original Message -- Received: Sat, 11 Jul 2009 09:44:51 PM PDT From: kq2h k...@yahoo.com To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor Bi-Level Squelch Circuit I've been impressed with the operation of the Micor bi-level squelch circuit based on the M7716 IC. I use Micor Spectra-Tac receivers exclusively on 440, 902, 6 Meters and 222 MHz (VHF to 222 conversion) with excellent results. However, I am perplexed by 10 Meters. The Spectra-Tac squelch circuit doesn't work well at all. It squelches up on fading signals that aren't all that noisy and drops out for no apparant reason. It appears that the squelch is set too high, but it isn't. I've tried different audio/squelch modules, receiver boards and housings. Even the IMTS modification which defeats the short squelch tail doesn't help the situation. When a UHF reciever is substituted in place of the 10 Meter receiver, the squelch circuit works fine. An old 25-30 MHz Motrac receiver, with its simple 3 transistor squelch circuit, works perfectly on 10 Meters. There are no problems with drop outs. The receiver squelch remains open well into the noise. This leads me to believe that the Micor bi-level circuit needs to be optimized for 10 Meters. Does anyone know of any component value changes in the Micor bi-level circuit to optimize operation on 10 Meters?
