[Repeater-Builder] Re: Give Away - Motorola Micor VHF/UHF Mobiles GE Low Band Mobiles
Looks like I'm moving to Texas! ;p
[Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Re: Simrex - GLB Pre-Selector Verus You're actually comparing two different boxes. no6b@ wrote: Nope - comparing GLB vs. GaAsFET/pass cavity combo Still not the equivalent box... you're still missing the post active-device stages. I don't need them. But I suppose one could add a 2nd pass cavity AFTER the preamp. I've never had to do that in ~30 years of repeater building. I have used post preamplifier filters in the interest of managing extremely high signal levels. Care to publish your results here? Why don't you tell us what you found? I've asked more than once for some reason you're reluctant to publish your results. I can't help but be even more suspicious of the GLB. Because of time... I can post things only when I have the available time and quickly replying in detail requires that I should probably review my notes. If those notes are not readily at hand you will obviously just have to wait. Lacking the hard data, I'm going to do a little guesswork here: a typical GaAsFET preamp has 17 dB of gain @ 440 MHz. The GLB Preamplifier I repaired has a dual gate Mosfet. The version I received had a blown device so I replaced it. With different amounts of bias I could actually get up to nearly 25dB. The NF of the device alone depending on the bias was anywhere from about .7 to 1.2 dB again depending on the bias. The Simrex preselector has a spec'd overall gain of 8 dB. Which is similar to what I ended up with after replacing the bad Mosfet and selecting a bias point resulting in a gain of about 9.2dB through the box. All other things being equal, the combined loss of the resonators in the preselector would then be 9 dB. Kevin says the distribution is 2 stages before 2 after. The 224 MHz version I have here is 1 before and 3 trailing stages. If all the stages are equivalent, then the pre-active device loss is 4.5 dB. Assume 0.5 dB NF of the actual GaAsFET device, I come up with 5 dB NF. Am I close? Using your above figures with one pre-device stage... figure about 2.3dB and .7 for 3dB NF at 224 MHz. Yeah, but the numbers are off. To properly compare the two you'd need to use more than one pass-cavity. At least one additional cavity (min) following the active device and to really be honest, more than one trailing BP Cavity. See above, Kevin's post. In many cases, the trailing cavity isn't needed. But not in every case... If you're trying to manage extremely high signal levels the trailing filters can greatly help filter unwanted RF. A single pass cavity usually has enough out-of-band rejection to be totally adequate on its own - no post-preamp filtering needed. The post-preamp filtering can and does contribute in the management (not necessarily the prevention) of high signal levels issues. ..only for RXs that need it. I guess I'm a bit biased because I use real RXs (GEs), so the only protection needed is for the preamp going in front of it. Depends a lot on the specific situation... the last real GE receiver front end I swept had a modestly wide front- end. Although it might have survived only better than some other brand and model receivers there are situations where post preamplifier filtering before the receiver would be a real benefit. Then again, the fact that post-device filtering is used in the GLB makes me worry about the actual selectivity ahead of that device. If there's only 1 or 2 resonators ahead of it, that's not much protection. A 1/4 wave bottle will provide much more rejection ahead of that first amp, and with less loss hence lower NF. There are 2 resonators in front of the Active Device. The higher Q of a 1/4 wave cavity is obviously better. The honest to thyself person should determine the NF difference, which is probably not a huge amount. Once again, I'm still waiting for the NF numbers. See the above... IMO the Simrex amplified preselector is a space-saving compromise, nothing more. Bob NO6B Sure, it's a compromise that works well for what they are. I'd probably (and do) park a Simrex or GLB Pre-selectors in front of less than bullet-proof receivers. Something else to consider: if your less than bullet-proof RX has good sensitivity, a preamp isn't even needed - just throw a pass cavity in front of it. Simple cheap, you'll probably still end up with better sensitivity than if you used the Simrex preselector. Bob NO6B Because a number of less than bullet proof receivers don't have great sensitivity. And the response (shape) of a pass cavity is different than a multi-stage pre-selector. s.
[Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
The better skirts are mucho desired. n...@... wrote: As you so often like to state, it all depends on the application - in many cases it simply isn't necessary. And in many cases it's beneficial to have better skirts... But there are other solutions: if you want a brute-force window filter they're out there too. I have a few 5 MHz wide 1 dB loss UHF filters sitting on the shelf here that I acquired at the Dayton Ft. Tuthill hamfests. ~$40 each. Seems like a good deal... but the 5MHz band-width is only (for me) usable in some system applications. Some of those applications where the 5MHz band-width would be excessive but the expected Simrex band-width would not be... Again, the loss is low enough that in most cases a leading preamp simply isn't needed. Leading or Post Preamp? Kind of makes it look like helicals are a sin doesn't it... Ever wonder why the MVP/MastrII Micors are so deaf compared to more modern RXs? Nope... I haven't measured the loss of the UHF helical assembly, but the VHFHB front-end helicals have ~6 dB of loss. In all those radios, their own helicals effectively are all the post-preamp filtering you'll ever need. No it isn't... if you sweep the front end of Micor you'll find it's actually fairly wide. I seem to remember sweeping some GE Receivers and their front ends were relatively wide on the order of at least a few MHz. From Memory I seem to remember the Micor being at least 4MHz wide. The GLB preselector preamp has 4 helical stages of unknown (unknown to me) coupling. Depends on the Pre-selector Model and age of the box ... I have GLB units here with two pre-device stages and three post-device stages. And I have versions with a more traditional helical design and others with more of a lumped parts layout. A 2-Meter version I have lots of pictures of has 1 stage of pre-selection and four trailing stages. The active device is an MRF-901. OK. MRF-901 NF @ 2M is ~1 dB, so maybe 2-3 dB NF for the unit. And that jives with my informal recorded notes for the 224 MHz GLB Pre-selector with a dual gate Mosfet. Not bad for VHFHB, but having only 1 little resonator in front of the active device doesn't offer it much OOB protection. Better put a (gasp) PASS CAVITY in front of it! ;) To quote someone who recently wrote: As you so often like to state, it all depends on the application - in many cases it simply isn't necessary. However, In more than a few real world situations you might really need the filter pre-selection a lot more than the most optimum NF. A practical trade of pre-selection for a slightly higher noise figure can and does sometimes make the difference in a usable radio system. OK fine. But again, we DON'T KNOW the noise figure for the device. It's not mandatory to know the NF for every situation, only helpful for those specific situations where making a logical assumption is not allowed. Furthermore, since the filtering distribution varies with the model, it's very difficult to predict the dynamic range characteristics of the unit. True along with the different active devices. Fun to play with? Yes. Can solve some IMD/overload problems? Certainly. But not a tool for any seriously engineered RF system. Bob NO6B Really depends a lot on whose money you're spending. I've seen a lot of seriously engineered RF systems that don't work very well out there in the real world. s.
Re: [Repeater-Builder] Give Away - Motorola Micor VHF/UHF Mobiles GE Low Band Mobiles
hummm we are so far we would have used this Motorola Micor VHF mobile converted to a 147.080MHz repeater here 73/s all gervais ve2ckn From: Dave Cochran Sent: Saturday, July 31, 2010 9:00 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Give Away - Motorola Micor VHF/UHF Mobiles GE Low Band Mobiles Only 5 hours or so drive from me. and we could really use the equipment down here. I'll talk with a couple of guys and see if I can find a co-pilot or two. Dave - N0TRQ On Sat, Jul 31, 2010 at 5:28 PM, rrath rr...@charter.net wrote: Me three. Rod kc7vqr Me too !! On Sat, Jul 31, 2010 at 4:56 PM, Scott Zimmerman n3...@repeater- builder.com wrote: If only I lived in Texas.. Humph!! Scott Scott Zimmerman Amateur Radio Call N3XCC 474 Barnett Road Boswell, PA 15531 wb5dcu wrote: I am cleaning out the shack and I have the following radios I would like to give away: 7 - Motorola Micor VHF Mobiles 5 - Motorola Micor UHF Mobiles 1 - Motorola Q2904A UHF Industrial repeater 1 - Motorola Syntor UHF 1 - Motorola Mitrek UHF 1 - GE Master II Low Band mobile with accessories 1 - GE Master PRO Low Band mobile with accessories 1 - Motorola Micor VHF mobile converted to a 147.080MHz repeater mounted in BUD cabinet with NHRC-2 controller. Some of the Micor's are parts radios, they were given to our repeater group by a local 2 way shop that was going out of business. The 147.08 repeater was taken out of service about 5 years ago. It was working when we replaced it with a new repeater. These are free, take all or none. I will NOT ship, local pick up only. I live in Sherman Texas which is located north of Dallas Texas on US Highway 75. Contact me by email at wb5d...@verizon.net Yahoo! Groups Links -- Always drink upstream from the herd.
[Repeater-Builder] Narrowbanding
Florida Repeater Coordinator proposes narrowbanding: http://www.florida-repeaters.org/FRC%202meter%20narrowband%20policy%20released%207-18-10.pdf
RE: [Repeater-Builder] Re: Give Away - Motorola Micor VHF/UHF Mobiles GE Low Band Mobiles
Did you get wifeys permission yet ? To: Repeater-Builder@yahoogroups.com From: noahsi...@hotmail.com Date: Sun, 1 Aug 2010 05:06:51 + Subject: [Repeater-Builder] Re: Give Away - Motorola Micor VHF/UHF Mobiles GE Low Band Mobiles Looks like I'm moving to Texas! ;p
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
At 8/1/2010 01:15, you wrote: But there are other solutions: if you want a brute-force window filter they're out there too. I have a few 5 MHz wide 1 dB loss UHF filters sitting on the shelf here that I acquired at the Dayton Ft. Tuthill hamfests. ~$40 each. Seems like a good deal... but the 5MHz band-width is only (for me) usable in some system applications. Some of those applications where the 5MHz band-width would be excessive but the expected Simrex band-width would not be... Then we're back to the pass cavity solution. Just saying there are other inexpensive, well-engineered options out there. Again, the loss is low enough that in most cases a leading preamp simply isn't needed. Leading or Post Preamp? Leading meaning pre-preamp. Kind of makes it look like helicals are a sin doesn't it... Ever wonder why the MVP/MastrII Micors are so deaf compared to more modern RXs? Nope... I haven't measured the loss of the UHF helical assembly, but the VHFHB front-end helicals have ~6 dB of loss. In all those radios, their own helicals effectively are all the post-preamp filtering you'll ever need. No it isn't... if you sweep the front end of Micor you'll find it's actually fairly wide. I seem to remember sweeping some GE Receivers and their front ends were relatively wide on the order of at least a few MHz. From Memory I seem to remember the Micor being at least 4MHz wide. The VHF HB MVP front-end helical assembly has a 3 dB BW of 1.8 MHz. At 40 dB down the BW is 5.7 MHz. Granted the selectivity curves of the Simrex preselector curves are narrower, but keep in mind that they are in fact misleading, since most of that selectivity is AFTER the preamp stage. Add to that the fact that the mixer in the GE radios has very high dynamic range (remember, the stock GEs don't have a gain stage ahead of the mixer), you likely end up INCREASING the GE's susceptibility to IMD by using one. The GLB preselector preamp has 4 helical stages of unknown (unknown to me) coupling. Depends on the Pre-selector Model and age of the box ... I have GLB units here with two pre-device stages and three post-device stages. And I have versions with a more traditional helical design and others with more of a lumped parts layout. A 2-Meter version I have lots of pictures of has 1 stage of pre-selection and four trailing stages. The active device is an MRF-901. OK. MRF-901 NF @ 2M is ~1 dB, so maybe 2-3 dB NF for the unit. And that jives with my informal recorded notes for the 224 MHz GLB Pre-selector with a dual gate Mosfet. Not bad for VHFHB, but having only 1 little resonator in front of the active device doesn't offer it much OOB protection. Better put a (gasp) PASS CAVITY in front of it! ;) To quote someone who recently wrote: As you so often like to state, it all depends on the application - in many cases it simply isn't necessary. Agreed: in the above example the Simrex preselector isn't necessary: simply omit it use just a pass cavity. However, In more than a few real world situations you might really need the filter pre-selection a lot more than the most optimum NF. A practical trade of pre-selection for a slightly higher noise figure can and does sometimes make the difference in a usable radio system. OK fine. But again, we DON'T KNOW the noise figure for the device. It's not mandatory to know the NF for every situation, only helpful for those specific situations where making a logical assumption is not allowed. Kind of like saying you don't need to know how much output power your TX is running, so long as your users can hear it. Fun to play with? Yes. Can solve some IMD/overload problems? Certainly. But not a tool for any seriously engineered RF system. Bob NO6B Really depends a lot on whose money you're spending. I've seen a lot of seriously engineered RF systems that don't work very well out there in the real world. ...and in almost every case I've seen this, it's due to the engineering failing to take into account all of the real-world parameters. If your models are flawed, everything falls apart. Bob NO6B
RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation at a location with an on-site tower is to ensure that all utilities pass through a window where a common ground reference exists. Ideally, the tower should be right next to the facility, so that the same ground reference is used for both. The power transformer that feeds the control room should be in that room, not hundreds of feet away, and the secondary neutral of that transformer should be bonded to the same ground that is used by the telephones, radio system, cable TV, satellite system, and raised-floor supports. If executed properly, the design of the control room creates a Faraday Cage within which all occupants are safe from injury due to GPR (Ground Potential Rise) from a nearby lightning strike. Likewise, all the electronics within the control room are protected against surge damage. It is obvious from the news report that the dispatcher was injured because her headset was at a different potential from her body. The GPR resulting from lightning striking the tower led to thousands of volts difference between the radio control system (the headset) and the floor and counter in the control room- and the chair she was sitting in. It is also obvious that this difference in potential could not exist if the tower and the adjacent control room were grounded in accordance with industry safety standards. Some common sense and credible engineering skills are essential elements in a proper control room design. Many moons ago (late 60's), I was Chief Engineer at radio station WLRW, a 50 kW FM station at Champaign-Urbana, Illinois. During my watch, the station control room was relocated to a building next door. It was my job to supervise the cabling installation within the building and to the transmitter at the base of the tower, which was just over 100 feet away. All of the remote circuits and network feeds came through a grounding window that was common with the power and the tower grounding system. I remember arguing with the Illinois Power foreman about how we needed a separate transformer to power the station, and it had to be installed right at the side of the control room and not in a vault several hundred feet away. The value of designing the entire installation to comply with established industry standards and sound engineering practices was proven many times, when the tower was struck by lightning during a storm, and no damage or injury occurred. Although the station was on automation most of the day, we had live talent from late afternoon to early morning, and at least one lightning strike occurred while on-air talent was at the board and wearing headphones. The lights blinked, but the board operator felt nothing and the show went on. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tracomm Sent: Thursday, July 29, 2010 9:48 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] OT- Dispatcher injured by lightning strike A dispatcher was treated for electrical shock on May 2 after lightning sent a power surge through the dispatcher's headset. http://richmondregister.com/localnews/x1255109983/Lightning-surge-injures-91 1-dispatcher http://richmondregister.com/localnews/x1255109983/Lightning-surge-injures-9 11-dispatcher
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Care to hazard a guess on the percentage of facilities (radio/tv, two-way) that aren't done right? A few years ago this happened near here - a radio personality wearing headphones taken to the hospital following a lightning strike to the tower outside the radio station. Chuck WB2EDV - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 01, 2010 11:42 AM Subject: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation at a location with an on-site tower is to ensure that all utilities pass through a window where a common ground reference exists. Ideally, the tower should be right next to the facility, so that the same ground reference is used for both. The power transformer that feeds the control room should be in that room, not hundreds of feet away, and the secondary neutral of that transformer should be bonded to the same ground that is used by the telephones, radio system, cable TV, satellite system, and raised-floor supports. If executed properly, the design of the control room creates a Faraday Cage within which all occupants are safe from injury due to GPR (Ground Potential Rise) from a nearby lightning strike. Likewise, all the electronics within the control room are protected against surge damage. It is obvious from the news report that the dispatcher was injured because her headset was at a different potential from her body. The GPR resulting from lightning striking the tower led to thousands of volts difference between the radio control system (the headset) and the floor and counter in the control room- and the chair she was sitting in. It is also obvious that this difference in potential could not exist if the tower and the adjacent control room were grounded in accordance with industry safety standards. Some common sense and credible engineering skills are essential elements in a proper control room design. Many moons ago (late 60's), I was Chief Engineer at radio station WLRW, a 50 kW FM station at Champaign-Urbana, Illinois. During my watch, the station control room was relocated to a building next door. It was my job to supervise the cabling installation within the building and to the transmitter at the base of the tower, which was just over 100 feet away. All of the remote circuits and network feeds came through a grounding window that was common with the power and the tower grounding system. I remember arguing with the Illinois Power foreman about how we needed a separate transformer to power the station, and it had to be installed right at the side of the control room and not in a vault several hundred feet away. The value of designing the entire installation to comply with established industry standards and sound engineering practices was proven many times, when the tower was struck by lightning during a storm, and no damage or injury occurred. Although the station was on automation most of the day, we had live talent from late afternoon to early morning, and at least one lightning strike occurred while on-air talent was at the board and wearing headphones. The lights blinked, but the board operator felt nothing and the show went on. 73, Eric Lemmon WB6FLY
Re: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Had a similiar problem when I was chief engineer at an AM-FM radio station. The antenna tower was within 250 ft of the building. The prior engineer connected a copper strap from the automation equipment to one of the tower legs. Whenever we had a lightning strike on the tower you can see the lightning dance across the equipment. Due to the lightning many time I had to replace parts in the automation controller. I finally found the copper strap and removed it from the tower. No longer did I get any calls due to lightning causing automation equipment failure. I then got the owner to get an engineering crew to measure the tower to ground and found that the original grounding was falling and needed to be fixed. After that no longer had issues either with the FM transmitter or TV transmitter at that site. Also added lightning protestion on the AC coming into the building. David Aug 1, 2010 03:43:37 PM, Repeater-Builder@yahoogroups.com wrote: Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation at a location with an on-site tower is to ensure that all utilities pass through a window where a common ground reference exists. Ideally, the tower should be right next to the facility, so that the same ground reference is used for both. The power transformer that feeds the control room should be in that room, not hundreds of feet away, and the secondary neutral of that transformer should be bonded to the same ground that is used by the telephones, radio system, cable TV, satellite system, and raised-floor supports. If executed properly, the design of the control room creates a Faraday Cage within which all occupants are safe from injury due to GPR (Ground Potential Rise) from a nearby lightning strike. Likewise, all the electronics within the control room are protected against surge damage. It is obvious from the news report that the dispatcher was injured because her headset was at a different potential from her body. The GPR resulting from lightning striking the tower led to thousands of volts difference between the radio control system (the headset) and the floor and counter in the control room- and the chair she was sitting in. It is also obvious that this difference in potential could not exist if the tower and the adjacent control room were grounded in accordance with industry safety standards. Some common sense and credible engineering skills are essential elements in a proper control room design. Many moons ago (late 60's), I was Chief Engineer at radio station WLRW, a 50 kW FM station at Champaign-Urbana, Illinois. During my watch, the station control room was relocated to a building next door. It was my job to supervise the cabling installation within the building and to the transmitter at the base of the tower, which was just over 100 feet away. All of the remote circuits and network feeds came through a grounding window that was common with the power and the tower grounding system. I remember arguing with the Illinois Power foreman about how we needed a separate transformer to power the station, and it had to be installed right at the side of the control room and not in a vault several hundred feet away. The value of designing the entire installation to comply with established industry standards and sound engineering practices was proven many times, when the tower was struck by lightning during a storm, and no damage or injury occurred. Although the station was on automation most of the day, we had live talent from late afternoon to early morning, and at least one lightning strike occurred while on-air talent was at the board and wearing headphones. The lights blinked, but the board operator felt nothing and the show went on. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tracomm Sent: Thursday, July 29, 2010 9:48 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] OT- Dispatcher injured by lightning strike A dispatcher was treated for electrical shock on May 2 after lightning sent a power surge through the dispatcher's headset. http://richmondregister.com/localnews/x1255109983/Lightning-surge-injures-91 1-dispatcher http://richmondregister.com/localnews/x1255109983/Lightning-surge-injures-9 11-dispatcher
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
What concerns me more than anythingso many experts yet this sort of thing still happens...(in many fields)!!! Hindsight is great!! D On 01/08/2010 17:24:18, Chuck Kelsey (wb2...@roadrunner.com) wrote: Care to hazard a guess on the percentage of facilities (radio/tv, two-way) that aren't done right? A few years ago this happened near here - a radio personality wearing headphones taken to the hospital following a lightning strike to the tower outside the radio station. Chuck WB2EDV - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 01, 2010 11:42 AM Subject: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
And I only see it getting worse as everyone 'has' to cut corners/costs. Chuck WB2EDV - Original Message - From: Doug Hutchison specialq@ntlworld.com To: repeater-builder@yahoogroups.com Sent: Sunday, August 01, 2010 12:53 PM Subject: Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike What concerns me more than anythingso many experts yet this sort of thing still happens...(in many fields)!!! Hindsight is great!! D On 01/08/2010 17:24:18, Chuck Kelsey (wb2...@roadrunner.com) wrote: Care to hazard a guess on the percentage of facilities (radio/tv, two-way) that aren't done right? A few years ago this happened near here - a radio personality wearing headphones taken to the hospital following a lightning strike to the tower outside the radio station. Chuck WB2EDV - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 01, 2010 11:42 AM Subject: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3043 - Release Date: 08/01/10 02:34:00
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Yup.we are only a number after all!! D On 01/08/2010 18:04:12, Chuck Kelsey (wb2...@roadrunner.com) wrote: And I only see it getting worse as everyone 'has' to cut corners/costs. Chuck WB2EDV - Original Message - From: Doug Hutchison specialq@ntlworld.com To: repeater-builder@yahoogroups.com Sent: Sunday, August 01, 2010 12:53 PM Subject: Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike What concerns me more than anythingso many experts yet this sort of thing still happens...(in many fields)!!! Hindsight is great!! D On 01/08/2010 17:24:18, Chuck Kelsey (wb2...@roadrunner.com) wrote: Care to hazard a guess on the percentage of facilities (radio/tv, two-way) that aren't done right? A few years ago this happened near here - a radio personality wearing headphones taken to the hospital following a lightning strike to the tower outside the radio station. Chuck WB2EDV - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
When the expert label starts to get thrown around too much I like to quote one of my math teachers in junior high school whose definition of expert is worth remembering to deflate any over sized egos. Ex is a has been and a Spurt is a drop under pressure Milt N3LTQ Quoting Doug Hutchison specialq@ntlworld.com: What concerns me more than anythingso many experts yet this sort of thing still happens...(in many fields)!!! Hindsight is great!! D On 01/08/2010 17:24:18, Chuck Kelsey (wb2...@roadrunner.com) wrote: Care to hazard a guess on the percentage of facilities (radio/tv, two-way) that aren't done right? A few years ago this happened near here - a radio personality wearing headphones taken to the hospital following a lightning strike to the tower outside the radio station. Chuck WB2EDV - Original Message - From: Eric Lemmon wb6...@verizon.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 01, 2010 11:42 AM Subject: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike Whenever I read a report like this, I have mixed emotions. I am surprised that the injury occurred, which is impossible if the facility was properly designed and islanded in accordance with numerous standards, including NFPA 70, NFPA 780, and the Motorola R56 Manual. I am also angry that an official issued the statement that ...the communications system, including its 400-foot radio tower, are grounded in accordance with industry safety standards. That official, and the idiots who designed the communications center, should be fired and/or brought up on criminal charges. The key to a safe installation Yahoo! Groups Links
RE: [Repeater-Builder] DSP404 beta 5.18 released
It looks like a kernel update and some cleanup. The notes are buried in the Wiki. I posted to the DSP reflector but it appears that the post are moderated as it has not shown up. Alan, Steve, or Matt will probably let us know next week. Stan From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Saturday, July 31, 2010 10:31 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DSP404 beta 5.18 released I didn't seen any release notes on Linkcomm's site. What's new in this release? -- Tim :wq On Jul 31, 2010, at 7:27 PM, Stanley Stanukinos wrote: Those of you that are running the Link DSP404 a Beta release is out version 5.18. I have loaded it on my controller and so far so good. The fist bug is in the comm. Set up.. I am running Vista business on a laptop with a real serial port and it does not show or allow the com port to be selected, however it still works on com 1. The first time I selected T on the left side I received a memory error but have not been able to reproduce it. I also have seen some stuttering in the audio between the controller and the laptop I am using on the local network. The controller is connected directly to the wireless router and I am connecting wirelessly with the laptop. So there may be more issues around or just my setup. Stan
RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Yup...thats just what I mean...experts.bah humbug!! D On 01/08/2010 19:44:48, Eric Lemmon (wb6...@verizon.net) wrote: That is so true! When you add corporate ego to the mix, things get really murky. A case in point: Back in the mid-eighties, one very large and well-known computer equipment manufacturer was contracted to install some facility monitoring equipment at Space Launch Complex Six at Vandenberg AFB, a site that was to be (until the Challenger disaster) the west-coast Space Shuttle launch pad. The monitoring equipment was divided into two major pieces, on separate floors of the Launch Control Center and about 200 feet apart. From the moment the system was energized, a number of data channels had 60 Hz common-mode noise corrupting the data on the RS-422 circuits. My crew was attempting to investigate the noise issue, when we discovered that the supplier's technicians had deliberately floated the upstairs cabinets by using insulating washers and plastic sheets to avoid contacting any grounded facility items such as embedded rebar. When advised by our AHJ (Authority Having Jurisdiction) inspector that the installation violated Article 250 of the NEC, the manufacturer's engineer explained that this was the way his company did these installations, and- here's the corporate ego part- they had been doing%2
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
Often times it's a well-meaning individual that simply doesn't understand (like me - LOL) and there are plenty of inspectors out there that don't know either. The corporate reasons for doing things wrong speak for themselves. Life is full of mis-information. Chuck WB2EDV - Original Message - From: Doug Hutchison specialq@ntlworld.com To: repeater-builder@yahoogroups.com Sent: Sunday, August 01, 2010 3:26 PM Subject: RE: [Repeater-Builder] OT- Dispatcher injured by lightning strike Yup...thats just what I mean...experts.bah humbug!! D
[Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Re: Simrex - GLB Pre-Selector Pre-Amplifier n...@... wrote: Then we're back to the pass cavity solution. Just saying there are other inexpensive, well-engineered options out there. Sure, the pass cavity is one of many possible options. The VHF HB MVP front-end helical assembly has a 3 dB BW of 1.8 MHz. At 40 dB down the BW is 5.7 MHz. Granted the selectivity curves of the Simrex pre-selector curves are narrower, but keep in mind that they are in fact misleading, since most of that selectivity is AFTER the preamp stage. My question to you is... what function would you think the multiple section/stage post active device selectivity serves? Add to that the fact that the mixer in the GE radios has very high dynamic range (remember, the stock GEs don't have a gain stage ahead of the mixer), you likely end up INCREASING the GE's susceptibility to IMD by using one. Depends on what you park in front of the receiver. in the above example the Simrex preselector isn't necessary: simply omit it use just a pass cavity. Once again a pass cavity is totally different compared to the Simrex GLB Preselector tuned circuits. To equate the two layouts you would need to add trailing resonant filters, which are in many examples tighter/sharper than the front end selectivity of the following receiver. If I tried to provide some type of speculative explanation regarding the Simrex GLB Preselector Management and/or control of extremely high level inputs, IMD and unwanted signals through the trailing helicals... you'll probably jump on the not a well-engineered label again. So I'm not even going to try and I'm pretty much outta this subject thread after this reply post. It's not mandatory to know the NF for every situation, only helpful for those specific situations where making a logical assumption is not allowed. Kind of like saying you don't need to know how much output power your TX is running, so long as your users can hear it. Sure... kind of If I assume the Tx Power of a 100 watt Power Amplifier is within 15% of its nominal rated value based on indicated current draw, supply voltage, a spectral view and knowing the output path to the antenna is working properly... I should be able to make a logical assumption users within a normal expected coverage area should be able to hear the machine... even though I've never measured the output with an accurate watt meter. Fun to play with? Yes. Can solve some IMD/overload problems? Certainly. But not a tool for any seriously engineered RF system. Bob NO6B Really depends a lot on whose money you're spending. I've seen a lot of seriously engineered RF systems that don't work very well out there in the real world. ... and in almost every case I've seen this, it's due to the engineering failing to take into account all of the real-world parameters. If your models are flawed, everything falls apart. Bob NO6B In the most (unfortunately to many) recent examples of poorly preforming RF Systems I've seen up close were due to the lack of the Engineers, interest, experience knowledge not including the mention of the bureaucracy or incompetence placing that person on the project. s. That's it for me... cheers
Re: [Repeater-Builder] OT- Dispatcher injured by lightning strike
n5sx...@charter.net wrote: I must admit that I don't see the problem with the sensitive equipment not finding ground thru the floor! In the 1980 I have some telephone central offices built by TRW. Each of the equipment racks were mounted on thick plastic sheets, and the mounting bolts were inserted thru insulating shoulder washers. Each equipment rack had a dedicate home run ground back to the main central office ground buss plate. All worked well, with no lightning problems. Some many years later I was still working for the same telephone company when I was asked to go back to that office to see why the new equipment addition would not work. It was needed badly as the C.O. was out of lines and needed this expansion to work. A quick inspection showed that the new equipment had been mounted directly to the concrete floor with out the insulation kit. I had the CO crew there help jack the rack up and slide a rubber floor mat under it for temporary insulation. We verified that the ground strap was correctly installed, and when we returned that equipment cabinet to service , it came up and worked fine. The equipment installer was forced to return at night to correct his problems. So not everything should be chassis grounded to the floor. Jeff
[Repeater-Builder] Re: DSP404 beta 5.18 released
I found what looks like unfinished release notes on the Wiki here: http://linkcomm.com/wiki/index.php?title=DSP4_V5.18_Changes --- In Repeater-Builder@yahoogroups.com, Stanley Stanukinos ka5...@... wrote: It looks like a kernel update and some cleanup. The notes are buried in the Wiki. I posted to the DSP reflector but it appears that the post are moderated as it has not shown up. Alan, Steve, or Matt will probably let us know next week. Stan From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Sawyer Sent: Saturday, July 31, 2010 10:31 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DSP404 beta 5.18 released I didn't seen any release notes on Linkcomm's site. What's new in this release? -- Tim :wq On Jul 31, 2010, at 7:27 PM, Stanley Stanukinos wrote: Those of you that are running the Link DSP404 a Beta release is out version 5.18. I have loaded it on my controller and so far so good. The fist bug is in the comm. Set up.. I am running Vista business on a laptop with a real serial port and it does not show or allow the com port to be selected, however it still works on com 1. The first time I selected T on the left side I received a memory error but have not been able to reproduce it. I also have seen some stuttering in the audio between the controller and the laptop I am using on the local network. The controller is connected directly to the wireless router and I am connecting wirelessly with the laptop. So there may be more issues around or just my setup. Stan
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
martinfriedman67 wrote: Our Amateur radio club's Motorola MSR 2000 continuous duty amp needs repair. I cant figure out how to remove the amp board from the heat sink. I removed all screws from corners as well as the transistors. It seems to be held by the center, just below the tall air variable cap. I tried heating the solder in the area but, no joy. I don't want to crack the board. The drawings in the manual I found here do not show even the screw holes. Thanks in advance, 73, Marty (WB2BEW) Look for the via that carries the power supply connections to the board. Sounds like they are holding you back. Kevin
