[Repeater-Builder] Re: Uniden Key
And here's what Takigen offers http://www.takigen.com/english/contents/eyesearch/search.do?name=D-057 LW --- In Repeater-Builder@yahoogroups.com, Mike Morris WA6ILQ wa6...@... wrote: The key photos from both Scott Zimmerman and Kevin Valentino are up on the keys Page The name cast into the key blank looks like Takigen (it's a Japanese radio, do you really expect something from Chicago Lock ?), and I can't make out the third digit of the key number - it's 02(something)0. Mike WA6ILQ
RE: [Repeater-Builder] Zetron 38A not sending reverse burst
I use several Z-38A controllers in ham applications. I get around the squelch crash problem by setting the Z-38A to stop sending a PL tone as soon as a user unkeys. The short tail is still there from the repeater, but the lack of a tone to a receiver lets the audio shut off while carrier is still present, and does not generate a squelch crash. I believe Nate calls this a 'chicken burst' though I have never heard that term before - A second benefit of shutting off the tone after a user unkeys is that it allows in-band links with no ping-pong effects due to the tails talking to each other. 73 - Jim W5ZIT --- On Wed, 11/18/09, Eric Lemmon wb6...@verizon.net wrote: From: Eric Lemmon wb6...@verizon.net Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.com Date: Wednesday, November 18, 2009, 1:09 PM You have discovered one of many dirty little secrets that apply to aftermarket tone panels. When designing the 38A tone panel, and many other products, Zetron overlooked the fact that reverse burst is essential in the repeated audio. From a close examination of the 38A manual and schematics, it appears that it will decode CTCSS reverse burst and CDCSS turnoff code, and MAY generate CDCSS turnoff code, but I see no evidence that it can generate reverse burst. That alone is a major shortcoming! Zetron is not the only manufacturer that ignored reverse burst encoding when designing a community repeater controller. Instrument Associates, which produced the i20R On-site Repeater Controller for the Motorola GR1225 desktop repeater, did likewise. I did not realize this until I found that squelch crashes were immediately heard as soon as I put the i20R in service. Although some fans of the old Highway Patrol shows starring Broderick Crawford may enjoy the sound of a squelch crash, I do not, nor do any of my radio users. That i20R was pulled from service immediately, and put on the shelf! There are two different formats for CTCSS reverse burst STE (Squelch Tail Elimination) that are defined in TIA-603-C, the international standard for land-mobile radio performance and design. One format, used principally by Motorola, uses a 120-degree phase shift, while the other format, used by Kenwood and many others, uses a 180-degree phase shift. Since modern radios often use digital signal processing to encode and decode low-speed data (CTCSS and CDCSS), it is all too easy to design a circuit that responds perfectly to 180-degree phase shift but ignores 120-degree phase shift, and vice-versa. Zetron and others couldn't be bothered to create a CTCSS encoder that could be switched between the two reverse-burst formats, so they just ignored the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ yahoogroups. com [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of wspx472 Sent: Wednesday, November 18, 2009 10:15 AM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Zetron 38A not sending reverse burst I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it?
[Repeater-Builder] Re: Zetron 38A not sending reverse burst
I tried that but decided not to go that route for now. The reason is that I need that hang time to tell how well I am hearing the repeater. It is 900 MHz and users are few and far between. If usage picks up, I will probably turn off PL during the hang time. I want to try it a while like it is but I am still thinking about with doing away with the controller and just having a PL decoder and ID'er. The ComSpec TS-64 does send reverse burst. --- In Repeater-Builder@yahoogroups.com, Jim Brown w5...@... wrote: I use several Z-38A controllers in ham applications. I get around the squelch crash problem by setting the Z-38A to stop sending a PL tone as soon as a user unkeys. The short tail is still there from the repeater, but the lack of a tone to a receiver lets the audio shut off while carrier is still present, and does not generate a squelch crash. I believe Nate calls this a 'chicken burst' though I have never heard that term before - A second benefit of shutting off the tone after a user unkeys is that it allows in-band links with no ping-pong effects due to the tails talking to each other. 73 - Jim W5ZIT --- On Wed, 11/18/09, Eric Lemmon wb6...@... wrote: From: Eric Lemmon wb6...@... Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.com Date: Wednesday, November 18, 2009, 1:09 PM  You have discovered one of many dirty little secrets that apply to aftermarket tone panels. When designing the 38A tone panel, and many other products, Zetron overlooked the fact that reverse burst is essential in the repeated audio. From a close examination of the 38A manual and schematics, it appears that it will decode CTCSS reverse burst and CDCSS turnoff code, and MAY generate CDCSS turnoff code, but I see no evidence that it can generate reverse burst. That alone is a major shortcoming! Zetron is not the only manufacturer that ignored reverse burst encoding when designing a community repeater controller. Instrument Associates, which produced the i20R On-site Repeater Controller for the Motorola GR1225 desktop repeater, did likewise. I did not realize this until I found that squelch crashes were immediately heard as soon as I put the i20R in service. Although some fans of the old Highway Patrol shows starring Broderick Crawford may enjoy the sound of a squelch crash, I do not, nor do any of my radio users. That i20R was pulled from service immediately, and put on the shelf! There are two different formats for CTCSS reverse burst STE (Squelch Tail Elimination) that are defined in TIA-603-C, the international standard for land-mobile radio performance and design. One format, used principally by Motorola, uses a 120-degree phase shift, while the other format, used by Kenwood and many others, uses a 180-degree phase shift. Since modern radios often use digital signal processing to encode and decode low-speed data (CTCSS and CDCSS), it is all too easy to design a circuit that responds perfectly to 180-degree phase shift but ignores 120-degree phase shift, and vice-versa. Zetron and others couldn't be bothered to create a CTCSS encoder that could be switched between the two reverse-burst formats, so they just ignored the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ yahoogroups. com [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of wspx472 Sent: Wednesday, November 18, 2009 10:15 AM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Zetron 38A not sending reverse burst I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it?
[Repeater-Builder] Re: Zetron 38A not sending reverse burst
From my experience, the Model 38 and 48 will not do reverse burst. I did however use a Arcomm audio delay board and accomplished the same results. http://www.arcomcontrollers.com/rc210/rad.html Then I decided I want a repeater controller capable of additional ports and dropped the Model 48 I was using and went with the Arcom RC-210 and Com Spec SS-64 encoders with reverse burst built-in. http://www.com-spec.com/ss64.htm Randy --- In Repeater-Builder@yahoogroups.com, wspx472 wpxs...@... wrote: I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it?
Re: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
Anybody have a 38Max they want to sell me cheap? (he he... now that we're on an anti-Zetron thread :) :) On Nov 19, 2009, at 9:13 AM, wb0vhb wrote: From my experience, the Model 38 and 48 will not do reverse burst. I did however use a Arcomm audio delay board and accomplished the same results. http://www.arcomcontrollers.com/rc210/rad.html Then I decided I want a repeater controller capable of additional ports and dropped the Model 48 I was using and went with the Arcom RC-210 and Com Spec SS-64 encoders with reverse burst built-in. http://www.com-spec.com/ss64.htm Randy --- In Repeater-Builder@yahoogroups.com, wspx472 wpxs...@... wrote: I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it? -- Cort Buffington H: +1-785-838-3034 M: +1-785-865-7206 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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
[Repeater-Builder] Antenna Pattern Question
I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP
Re: [Repeater-Builder] Antenna Pattern Question
It wouldn't be impossible that an applications engineer at the factory might be able to assist. Decibel went to Andrew and now is CommScope. Chuck WB2EDV - Original Message - From: Dan Hancock To: repeater builders Sent: Thursday, November 19, 2009 11:42 AM Subject: [Repeater-Builder] Antenna Pattern Question I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP -- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.707 / Virus Database: 270.14.73/2513 - Release Date: 11/19/09 02:51:00
RE: [Repeater-Builder] Antenna Pattern Question
Comprod makes dipole arrays with a screen reflector, at least for VHF, not sure about UHF. I'm looking in the catalog and it shows a backside null close to 20 dB down from the main lobe. The screen reflector should be nominally about 1/4 wave behind the radiator for maximum forward gain. It could be modeled fairly easily. How wide of a forward beamwidth do you want? Would a couple of corner reflectors be a better way to go? --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dan Hancock Sent: Thursday, November 19, 2009 11:43 AM To: repeater builders Subject: [Repeater-Builder] Antenna Pattern Question I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/19/09 07:51:00
Re: [Repeater-Builder] Antenna Pattern Question
I was thinking about the possibility of him converting the DB-411 into a corner reflector. Might work. Get the info from the Decibel corner reflector and apply it to the DB-411. Chuck WB2EDV - Original Message - From: Jeff DePolo j...@broadsci.com To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 19, 2009 11:49 AM Subject: RE: [Repeater-Builder] Antenna Pattern Question Comprod makes dipole arrays with a screen reflector, at least for VHF, not sure about UHF. I'm looking in the catalog and it shows a backside null close to 20 dB down from the main lobe. The screen reflector should be nominally about 1/4 wave behind the radiator for maximum forward gain. It could be modeled fairly easily. How wide of a forward beamwidth do you want? Would a couple of corner reflectors be a better way to go? --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dan Hancock Sent: Thursday, November 19, 2009 11:43 AM To: repeater builders Subject: [Repeater-Builder] Antenna Pattern Question I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/19/09 07:51:00 Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.707 / Virus Database: 270.14.73/2513 - Release Date: 11/19/09 02:51:00
Re: [Repeater-Builder] Antenna Pattern Question
I have DB 664 (VHF) clamped directly to a tower leg with all elements facing one direction and it works nearly as well off the back side range wise. I think you will have to go with a real corner reflector to knock it down any noticeable amount. Experiment away and let us know your findings. tom Dan Hancock wrote: I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.73/2513 - Release Date: 11/19/09 07:51:00
[Repeater-Builder] Wanted UHF MVP
Hi guys, I have been reading this list for a long time and now its time to take the plunge. I need to build a portable UHF repeater for my SAR team. So, I am looking for a UHF MVP. I will pay a reasonable price and shipping to Atlanta, 30317 I am looking forward to trying this and I will be asking more questions, this is only the first. Please reply directly to sarpaul(at)gmail(dot)com. Thanks! Paul KI4ADT www.atsar.org
[Repeater-Builder] Re: Antenna Pattern Question
I'm basically looking to null an area of about 45 degrees behind the antenna. Kinda like I want omni coverage except for this 45 degree area. I don't think beans will cut it. I'll check Comprod's web site. Thanks and 73, Dan N8DJP --- In Repeater-Builder@yahoogroups.com, Jeff DePolo j...@... wrote: Comprod makes dipole arrays with a screen reflector, at least for VHF, not sure about UHF. I'm looking in the catalog and it shows a backside null close to 20 dB down from the main lobe. The screen reflector should be nominally about 1/4 wave behind the radiator for maximum forward gain. It could be modeled fairly easily. How wide of a forward beamwidth do you want? Would a couple of corner reflectors be a better way to go? --- Jeff -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dan Hancock Sent: Thursday, November 19, 2009 11:43 AM To: repeater builders Subject: [Repeater-Builder] Antenna Pattern Question I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.425 / Virus Database: 270.14.61/2498 - Release Date: 11/19/09 07:51:00
RE: [Repeater-Builder] LDG Voter RVS-8 Mystery
Tom and Skip identified the problem as input levels being too high. I got this straightened out, and the problem is solved. Thanks for the suggestions. I appreciate the help. John AF4PD -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of John Transue Sent: Saturday, November 07, 2009 10:14 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] LDG Voter RVS-8 Mystery -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Thomas Oliver Sent: Saturday, November 07, 2009 7:45 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] LDG Voter RVS-8 Mystery I would first try bypassing the voter and hook the link receiver directly to the 850 to make sure levels are good. There should be no reason you have low audio out of the controller the 850 normally has gobs of audio and has to be knocked down with a resistor of considerable ohmage in order not to overdrive a transmitter. As someone else stated the oscilloscope is your friend here. Note the levels on the input and output of the controller with the scope when it is working properly then put the voter back in and compare. tom Tom, Thanks for the suggestion. Both you and Skip have zeroed in on input levels as a possible problem. I will check this out. John Yahoo! Groups Links __ NOD32 4582 (20091107) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com Yahoo! Groups Links __ NOD32 4582 (20091107) Information __ This message was checked by NOD32 antivirus system. http://www.eset.com
RE: [Repeater-Builder] Uniden Key
must have lost some res on the upload. key stamped: TAKIGEN 0200, other side has strange symbols nothing i can explain, 4 of them. maybe japaneese? --- On Wed, 11/18/09, Mike Morris WA6ILQ wa6...@gmail.com wrote: From: Mike Morris WA6ILQ wa6...@gmail.com Subject: RE: [Repeater-Builder] Uniden Key To: Repeater-Builder@yahoogroups.com Date: Wednesday, November 18, 2009, 10:55 PM The key photos from both Scott Zimmerman and Kevin Valentino are up on the keys Page The name cast into the key blank looks like Takigen (it's a Japanese radio, do you really expect something from Chicago Lock ?), and I can't make out the third digit of the key number - it's 02(something) 0. Mike WA6ILQ
[Repeater-Builder] uniden key
just looked through the Takigen site. looks like it is model # c-104 it is an 0200 key just as mine is hope this helps kevin
[Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Skipp, Here's the WA1ZDX info www.ccdx.org/zedyx/mods/db212.htm Actually this one is on Repeater Builder http://www.repeater-builder.com/db/db-212-assembly-and-mounting-instructions-(andrew).pdf Spec from Andrew on the DB212 http://www.stealth.ae/plugins/custompages/detinf.php?id=322id_categories=115 More Andrew info http://www.hol4g.com/webpdf/DBB_CAT29-PG318-319_01.PDF Info on modifying a DB201 and DB212 for 10 and 6 meters http://www.xanaduu.com/db201/ Ken WA6OSB
Re: [Repeater-Builder] Antenna Pattern Question
Dan, Before you make any decisions about selecting any specific antenna for your application, you need to know or specify top or side mounting. Then you'll need to consider any and all metallic objects present in the near environment of the antenna because they constitute reflective or parasitic sources that can have a profound impact on the actual far field radiation pattern obtained. I have done a lot of NEC modeling in order to make a more informed scientific estimations of how these factors modify the final radiation pattern before attempting to choose any specific antenna for a given application vs. placement and orientation about the tower. NEC modeling is only and good as the modelers ability to accurately construct a model that truly depict the real world electrical environment of the antenna. It's doubtful that you would ever get an antenna manufacturer to model, or to guarantee a particular pattern outside of those field patterns derived from their antenna test range due to the complexity of modeling and of offering such service. Cellular and other similar providers largely employ directional panel arrays are virtually free of any significant radiation in the direction of the tower, supporting structure, or other antennas in the near environment. Therefore, their engineers don't need to consider the unwanted effects of parasitic radiation sources external to the array. Unfortunately, those of us relegated to VHF and UHF systems end up illuminating a rather large area of the tower resulting in a complex number of parasitic radiation sources that change the resultant pattern that otherwise might radiate per the text books if located in free space. Bill, WA8WG - Original Message - From: Dan Hancock To: repeater builders Sent: Thursday, November 19, 2009 10:42 AM Subject: [Repeater-Builder] Antenna Pattern Question I have a repeater that I need to have as tight a cardiod pattern as possible. I have looked at the dipole antennas such as the DB-411 and they don't really shut down the back door quite enough. Does anyone have any antenna modeling software that would show the result of adding an 18 wide screen to the back side of the mast on the DB-411? Does anyone have any experience in home-brewing a modification like this? Dan Hancock N8DJP
[Repeater-Builder] Yaesu FTR-2410A tuning
I'm recrystalling this unit and am working on the TX. The first part of the tuning procedure states to monitor a circuit point with a VTVM but there is no test point to connect to. Worse, the only way to physically get a connection to this point is to completely disassemble the TX, which doesn't make much sense to me. Maybe the problem is with me. Is anyone familiar with these things? Thanks. 73 Paul - KC0HST
RE: [Repeater-Builder] Re: Zetron 38A not sending reverse burst
The TS-64 does indeed encode a reverse burst STE signal. Unfortunately, it has the 180-degree phase shift, because that is really easy to do. It cannot encode a 120-degree phase shift, so that means it is fairly useless with Motorola and a few other radio brands. When I contacted Comm Spec about this a few years ago, the engineer I spoke with seemed not to know that there are two standard reverse burst formats. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wspx472 Sent: Thursday, November 19, 2009 6:47 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Zetron 38A not sending reverse burst I tried that but decided not to go that route for now. The reason is that I need that hang time to tell how well I am hearing the repeater. It is 900 MHz and users are few and far between. If usage picks up, I will probably turn off PL during the hang time. I want to try it a while like it is but I am still thinking about with doing away with the controller and just having a PL decoder and ID'er. The ComSpec TS-64 does send reverse burst. --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Jim Brown w5...@... wrote: I use several Z-38A controllers in ham applications. I get around the squelch crash problem by setting the Z-38A to stop sending a PL tone as soon as a user unkeys. The short tail is still there from the repeater, but the lack of a tone to a receiver lets the audio shut off while carrier is still present, and does not generate a squelch crash. I believe Nate calls this a 'chicken burst' though I have never heard that term before - A second benefit of shutting off the tone after a user unkeys is that it allows in-band links with no ping-pong effects due to the tails talking to each other. 73 - Jim W5ZIT --- On Wed, 11/18/09, Eric Lemmon wb6...@... wrote: From: Eric Lemmon wb6...@... Subject: RE: [Repeater-Builder] Zetron 38A not sending reverse burst To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Date: Wednesday, November 18, 2009, 1:09 PM  You have discovered one of many dirty little secrets that apply to aftermarket tone panels. When designing the 38A tone panel, and many other products, Zetron overlooked the fact that reverse burst is essential in the repeated audio. From a close examination of the 38A manual and schematics, it appears that it will decode CTCSS reverse burst and CDCSS turnoff code, and MAY generate CDCSS turnoff code, but I see no evidence that it can generate reverse burst. That alone is a major shortcoming! Zetron is not the only manufacturer that ignored reverse burst encoding when designing a community repeater controller. Instrument Associates, which produced the i20R On-site Repeater Controller for the Motorola GR1225 desktop repeater, did likewise. I did not realize this until I found that squelch crashes were immediately heard as soon as I put the i20R in service. Although some fans of the old Highway Patrol shows starring Broderick Crawford may enjoy the sound of a squelch crash, I do not, nor do any of my radio users. That i20R was pulled from service immediately, and put on the shelf! There are two different formats for CTCSS reverse burst STE (Squelch Tail Elimination) that are defined in TIA-603-C, the international standard for land-mobile radio performance and design. One format, used principally by Motorola, uses a 120-degree phase shift, while the other format, used by Kenwood and many others, uses a 180-degree phase shift. Since modern radios often use digital signal processing to encode and decode low-speed data (CTCSS and CDCSS), it is all too easy to design a circuit that responds perfectly to 180-degree phase shift but ignores 120-degree phase shift, and vice-versa. Zetron and others couldn't be bothered to create a CTCSS encoder that could be switched between the two reverse-burst formats, so they just ignored the problem. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@ yahoogroups. com [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of wspx472 Sent: Wednesday, November 18, 2009 10:15 AM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Zetron 38A not sending reverse burst I am trying to get a repeater going using a 38A and find that it doesn't send reverse burst. I thought I saw that it did in the manual but upon looking again, all I see is where it responds to reverse burst. Does anyone know for sure if it is supposed to send reverse burst? If so, how do I get it to do it?
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
