[Repeater-Builder] Re: Repeater Range : Estimate Program Available
As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). Power and frequency do not really play that much into it. This has been mentioned in many stories of a repeater running just on the exciter and not many noticed. Once you get past the radio horizon, you cannot practically increase the power to get more distance. So a radio transmitting with an antenna on a 200 foot tower will give about 20 miles of coverage. VHF goes a little farther than UHF, but it's not by a lot. RadioMobile does a great job of factoring in many other things like TX power, RX sensitivity, frequency, coax and duplexer losses and some antenna modeling. After the learning curve, you can closely approximate typical systems with ease. Dwayne Kincaid WD8OYG Ya I use it at work too. Its better than at least 1/2 of the commercial products available. Quite amazing considering a Ham out of Quebec programmed it. Jesse On 8/29/07, Nate Duehr [EMAIL PROTECTED] wrote: skipp025 wrote: OK Groovy Guys and Gals, Is there a simple rule of thumb radio range versus frequency and power level type computer program/software on the web? Maybe some software that also considers generic repeater operation from x-height agl with input frequency and power values. My friend doesn't need or really want a program with involved graphics or Lat Long issues. Most of his Ham Radio work is actually FM Simplex on flat ground and he's really interested in using the program for both VHF High and Low Bands as a very rough estimate of expected operational range (on flat ground) in miles. Your turn... Thanks in advance... skipp Even though he doesn't need it, I think spending the effort to learn how to drive RadioMobile is time well spent, if you're into looking at paths, coverage, etc. For a free program, it's really not bad at all. And it'd give him something to grow into after he mastered the basics. Nate WY0X
Re: [Repeater-Builder] Re: [AR902Mhz Repeater-Builder] PURC 5000 questions
Correct! There is a rule for FCC Commercial radio type acceptance that radios can not be front panel programmed. -- Original Message -- Received: Wed, 29 Aug 2007 07:33:03 PM CDT From: Bob M. [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: [AR902Mhz Repeater-Builder] PURC 5000 questions There's probably some FCC rule that prohibits commercial stuff from being front-panel programmable by other than the manufacturer or a radio technician. Nucleus paging transmitters have a DIP switch inside that disables frequency programming. Some radios require a special dongle to be attached to allow freqs to be entered. So I figured that the PURC is no different and while it's capable of being programmed, there's a mechanism in place to inhibit it to all but those who should know what they're doing. Bob M. == --- Jim [EMAIL PROTECTED] wrote: Bob M. wrote: A third has an actual numeric keypad on the front panel, but it's usually locked so it can't easily be changed. Either a password or flipping a DIP switch inside the unit would be necessary to allow frequency programming. The default password is 5000, and I have yet to see one where it had been changed. But yes, I remember there is a dip switch or push-on jumper that can disable the keypad. -- Jim Barbour WD8CHL Park yourself in front of a world of choices in alternative vehicles. Visit the Yahoo! Auto Green Center. http://autos.yahoo.com/green_center/
Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
Height = elevation AMSL of the antenna, HAAT, or AGL (which would make no sense)? Joe M. ldgelectronics wrote: As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet).
Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote: As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). It's a rule of thumb, but isn't nearly as accurate as doing the real engineering on a system. Power and frequency do not really play that much into it. This has been mentioned in many stories of a repeater running just on the exciter and not many noticed. Once you get past the radio horizon, you cannot practically increase the power to get more distance. Humbug. Please tell all the VUCC holders at VHF and up that, and see if they laugh pretty hard. You can't just increase transmitter power, though -- you have to increase the overall gain of the system on both transmit and receive. The biggest bang for the buck in dB? The antenna system. Ask any Moonbounce specialist, or satellite chaser. They'll tell you the same thing. Ever seen the size/effort involved in a 2m EME array for CW? So a radio transmitting with an antenna on a 200 foot tower will give about 20 miles of coverage. With an average gain antenna, average feedline, and average power levels on both ends. VHF goes a little farther than UHF, but it's not by a lot. Only part of the story. Try 220 MHz. It'll out-perform VHF by a large margin, in most cases. Why? Noise floor is lower in densely populated areas. (This won't hold as true out in the sticks.) RadioMobile does a great job of factoring in many other things like TX power, RX sensitivity, frequency, coax and duplexer losses and some antenna modeling. After the learning curve, you can closely approximate typical systems with ease. Yes! That's real engineering. The problem is... most people think that the rule of thumb is some kind of law, and don't bother doing the real calculations. Will this low-loss coax help my system? Will a bigger antenna or one with more directional characteristics help? Additionally, between 2m and UHF, most people run MUCH higher gain antennas, because they fit in the same physical space. One's UHF station can out-perform one's VHF station by a mile (no pun intended) if it has similarly sized antennas. I think rules-of-thumb in most things are great AFTER you do the math and know what their limitations are. If you haven't done that, they're a crutch and/or worse, a perceived limitation that really isn't there. A mediocre repeater, not tuned/optimized on a relatively low gain antenna with average system losses (cheap feedline, smaller antenna) out here on a mountain top (5000' HAAT) will perform approximately to your rule of thumb. A repeater with excellent receiver sensitivity by adding a good low-noise pre-amp (GaAsFET or PHEMT), very low loss feedline (7/8 hardline or better), and a relatively high gain antenna (perhaps with slight down-tilt) will perform FLAWLESSLY at your rule-of-thumb radio horizon and be useable for another 25-50 miles beyond that. Especially if the mobile user is also blessed with a better than average gain antenna with a nice pattern as close to the horizon as possible! Give that mobile an optimized yagi, and they'll be working the repeater far into the next state out here, and our states aren't very small! http://www.repeater-builder.com/antenna/3db.html - A good article on the topic and the trade-offs for a repeater. Many people simply won't take the time, expense, and effort to do that level of engineering work on a repeater -- or a home station. But those that will, are rewarded with communications capability far beyond where the rule-of-thumb says it shouldn't work anymore. Like I mentioned above, the VUCC roles tell the tail. Never limit the new guy's imagination with a rule-of-thumb. Show them the TOP operator's achievements and tell 'em it's attainable by anyone with enough time, resources, and patient application of ALL the radio theory they can learn. Apply what those guys know to your repeaters and it'll make a significant improvement in performance, at the edges. ALWAYS recommend that anyone upgrading a station or building a repeater put their maximum effort into the antenna and antenna system. As my first Elmer used to say, The antenna makes the radio. -- Nate Duehr, WY0X [EMAIL PROTECTED]
Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
On Aug 30, 2007, at 1:20 AM, MCH wrote: Height = elevation AMSL of the antenna, HAAT, or AGL (which would make no sense)? I assumed HAAT for my calculations and that number seemed to be the most sane, after trying a few. But I think the resulting number is generous for a badly-built repeater, and too small for a well-built one. -- Nate Duehr, WY0X [EMAIL PROTECTED]
Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
To All Interested: I would invite you attention to a paper presented by Kenneth Bullington, Radio Propagation at Frequencies Above 30 Meagcycles in the October 1947 Proceedings of the I.R.E. - Waves and Electronics Section. Most all radio propagation prediction methods over the years have been based on the findings of his research for this paper. A GE Mobile Radio Data File Bulletin (10003-1), VHF and UHF Propagation, was published in July 1962 for use by engineers and technicians for the prediction of radio coverage. Along with this bulletin a hard paper/plastic slide rule was manufactured by GE for its sales personnel to predict radio coverage. Motorola sales people liked to get a hold of it and use it also; Range and Signal Strength Calculator for 2 Way Radio.There was a second version put together by GE in 1977; Range and Transmitter Power Calculator. If you can find them, either of these slide rules can give adequate results with radio range calculations. With the general usage of computers in the 1980's many propagation programs appeared on the market, some use digitized USGA maps while others take a more simplistic approach. You get what you pay for! This Data File may be available on line, I am not sure if it is. Fred W5VAY - Original Message - From: ldgelectronics To: Repeater-Builder@yahoogroups.com Sent: Thursday, August 30, 2007 1:35 AM Subject: [Repeater-Builder] Re: Repeater Range : Estimate Program Available As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). Power and frequency do not really play that much into it. This has been mentioned in many stories of a repeater running just on the exciter and not many noticed. Once you get past the radio horizon, you cannot practically increase the power to get more distance. So a radio transmitting with an antenna on a 200 foot tower will give about 20 miles of coverage. VHF goes a little farther than UHF, but it's not by a lot. RadioMobile does a great job of factoring in many other things like TX power, RX sensitivity, frequency, coax and duplexer losses and some antenna modeling. After the learning curve, you can closely approximate typical systems with ease. Dwayne Kincaid WD8OYG Ya I use it at work too. Its better than at least 1/2 of the commercial products available. Quite amazing considering a Ham out of Quebec programmed it. Jesse On 8/29/07, Nate Duehr [EMAIL PROTECTED] wrote: skipp025 wrote: OK Groovy Guys and Gals, Is there a simple rule of thumb radio range versus frequency and power level type computer program/software on the web? Maybe some software that also considers generic repeater operation from x-height agl with input frequency and power values. My friend doesn't need or really want a program with involved graphics or Lat Long issues. Most of his Ham Radio work is actually FM Simplex on flat ground and he's really interested in using the program for both VHF High and Low Bands as a very rough estimate of expected operational range (on flat ground) in miles. Your turn... Thanks in advance... skipp Even though he doesn't need it, I think spending the effort to learn how to drive RadioMobile is time well spent, if you're into looking at paths, coverage, etc. For a free program, it's really not bad at all. And it'd give him something to grow into after he mastered the basics. Nate WY0X
[Repeater-Builder] OT- Weather Radio Recall
This is a bit off-topic, but I thought it would be important to get the word out as life safety is involved... Tom W9SRV NEWS from CPSC U.S. Consumer Product Safety Commission Office of Information and Public Affairs Washington, DC 20207 FOR IMMEDIATE RELEASE August 29, 2007 Release #07-292 Firm's Recall Hotline: (800) 203-4921 CPSC Recall Hotline: (800) 638-2772 CPSC Media Contact: (301) 504-7908 Weather Radios Recalled by Oregon Scientific Due to Failure to Receive National Weather Service Alerts WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. Name of Product: Oregon Scientific Weather Radios Units: About 66,000 Manufacturer: Oregon Scientific Inc., of Tualatin, Ore. Hazard: The radios could fail to receive National Weather Service alert signals in certain areas of the country. In the event of severe weather, this failure could put a consumer's life and property at risk. Incidents/Injuries: None reported. Description: This recall involves the following Weather Radios and Weather Stations: NAME MODEL All Hazards Portable Weather Alert Radio WR103NX Portable Public Alert Radio WR108 Public Alert Weather Station WRB308 John Deere Public Alert Weather Station WRB308J No other models are included in this recall. Sold at: Retail stores nationwide, including some electronics and sporting goods stores, online retailers and in catalogs from December 2005 through June 2007 for between $30 and $150. Manufactured in: China Remedy: Consumers should not rely on the recalled weather radios to receive emergency information. Consumers should contact Oregon Scientific for instructions on returning the radio to receive a free replacement. Consumer Contact: For additional information, contact Oregon Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday through Friday or visit the firm's Web site at www2.oregonscientific.com To see this recall on CPSC's web site, including pictures of the recalled products, please go to: http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html
Re: [Repeater-Builder] Re: subaudibe tones..
MCH wrote: Which results in OH 'claiming' 30 of the 32 (or 38) available tones. That leaves 2 or 8 tones for everyone else. Not a particularly fair or reasonable plan. Joe M. ?? -- Jim Barbour WD8CHL
Re: [Repeater-Builder] OT- Weather Radio Recall
tgundo2003 wrote: This is a bit off-topic, but I thought it would be important to get the word out as life safety is involved... Tom W9SRV Firm's Recall Hotline: (800) 203-4921 CPSC Recall Hotline: (800) 638-2772 CPSC Media Contact: (301) 504-7908 Weather Radios Recalled by Oregon Scientific Due to Failure to Receive National Weather Service Alerts I've never cared for Oregon Scientific-they're the ones that put all those wireless weather stations in the middle of the 433 MHz ham band-and are getting away with it! My father tells me that 430-440 is totally useless at his house in rural N. AZ because of all the unlicensed wireless junk. Manufactured in: China Why does that NOT surprise me? -- Jim Barbour WD8CHL
Re: [Repeater-Builder] Re: Duplexer input and output power
Ok Skipp, and Jesse, So, I supposed that the specification of such, should be presented by the manufacturers of the said, and with the said, right! Or there is a general concept for duplexers, as in both examples, .1 to 3dB Jesse, and Skipp input loss 15 to 35% And which will be more accurate to work from dB or %. I always try to get a good balance when I'm tuning duplexers, most times I ended up taking a loss on the power for a better result on the receiver side, is this the best way to go? Or it depends on your situation, whether or not the extra power would effect your weakest signal! (most times a final touch up is done at the repeater site, it always make me feel like a perfectionist) Sometimes I still depend on my ears, then take a look at the test gears, 99% of the time I go with my ears because the difference don't be much when the duplexers are setup to the test gear figures. So, is the figurers always the right thing to work with, or they are just guides for a Tech with a bad hearing? v44kai.Joel. - Original Message - Fom: Jesse Lloyd To: Repeater-Builder@yahoogroups.com Sent: Wednesday, August 29, 2007 12:54 PM Subject: Re: [Repeater-Builder] Re: Duplexer input and output power Ya, duplexers will have insertion loss. Typically you get more insertion loss with more rejection, so its a balancing act. Insertion loss can range from .1 dB (very good) to 3 dB. Typically if I can get a duplexer to less than a dB I'm happy. Insertion loss (dB) = 10 log ( PIN / POUT ) So Pout = Pin x 10^(Insertion Loss/10) So for 50 Watts: .1 dB = 48.9 Watts .3 = 46.7 .5 = 44.6 .8 = 41.6 1 = 39.7 1.2 = 37.9 1.5 = 35.4 2 = 31.5 2.5 = 28.1 3 = 25 Jesse On 8/29/07, skipp025 [EMAIL PROTECTED] wrote: Hi Joel, In the real world it depends on the duplexer type, size, quality, operation and setup values, which may be fixed or adjustable. Just throwing out a generic rule of thumb... you will find many duplexers lose about 15% to 35% of the input power. One would hope for near zero loss but that will never happen. A common quality duplexer has adjustable probes or coax ports (the name used is based on the duplexer type), which often trade what we generic call insertion loss for increased performance. Loss through a duplexer is not always a linear graph of power in vs power out. Just to put something out... be happy if a properly setup and working duplexer delivers 75% to maybe 95% of the input power. Be grateful if you receive better than 85% of the rated power. A really tight duplexer might eat as much as 35% to 40% of your input power and there are much worse possible examples. cheers, s. Joel [EMAIL PROTECTED] wrote: Is there a table or formula or ratio for power input to a duplexer, to the resulting output power of the said? For instance, if I put 10, 20, 50, 100 watts to the input, what should be the output, with a 50 Ohms at the load? example 10,20, 50, 100 watts in = x output @ 50 Ohms. BASED ON A PROPERLY TUNED DUPLEXER I think someone had a short for-instance on this, can't find it, and will like some insight on this. v44kai.Joel. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date: 8/28/2007 4:29 PM
Re: [Repeater-Builder] OT- Weather Radio Recall
Thanks!! On 8/30/07, tgundo2003 [EMAIL PROTECTED] wrote: This is a bit off-topic, but I thought it would be important to get the word out as life safety is involved... Tom W9SRV NEWS from CPSC U.S. Consumer Product Safety Commission Office of Information and Public Affairs Washington, DC 20207 FOR IMMEDIATE RELEASE August 29, 2007 Release #07-292 Firm's Recall Hotline: (800) 203-4921 CPSC Recall Hotline: (800) 638-2772 CPSC Media Contact: (301) 504-7908 Weather Radios Recalled by Oregon Scientific Due to Failure to Receive National Weather Service Alerts WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. Name of Product: Oregon Scientific Weather Radios Units: About 66,000 Manufacturer: Oregon Scientific Inc., of Tualatin, Ore. Hazard: The radios could fail to receive National Weather Service alert signals in certain areas of the country. In the event of severe weather, this failure could put a consumer's life and property at risk. Incidents/Injuries: None reported. Description: This recall involves the following Weather Radios and Weather Stations: NAME MODEL All Hazards Portable Weather Alert Radio WR103NX Portable Public Alert Radio WR108 Public Alert Weather Station WRB308 John Deere Public Alert Weather Station WRB308J No other models are included in this recall. Sold at: Retail stores nationwide, including some electronics and sporting goods stores, online retailers and in catalogs from December 2005 through June 2007 for between $30 and $150. Manufactured in: China Remedy: Consumers should not rely on the recalled weather radios to receive emergency information. Consumers should contact Oregon Scientific for instructions on returning the radio to receive a free replacement. Consumer Contact: For additional information, contact Oregon Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday through Friday or visit the firm's Web site at www2.oregonscientific.com To see this recall on CPSC's web site, including pictures of the recalled products, please go to: http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html
Re: Re: [Repeater-Builder] Re: Duplexer input and output power
Joel, I aggree the major is the equipment working. If it aint broke don't fix it. Test gear measurments allow determining the source of a problem if there is a problem. If your ears say it aint working what is not working and in this case might not be the duplexer. Yes the test gear measurements do make a big difference. In a repeater there is so much that has to work. 73, ron, n9ee/r ps: with the start of this discussion has anyone said what type, model, etc of duplexer it is??? Might be a clue. From: Joel [EMAIL PROTECTED] Date: 2007/08/29 Wed PM 03:49:32 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Duplexer input and output power Ok Skipp, and Jesse, So, I supposed that the specification of such, should be presented by the manufacturers of the said, and with the said, right! Or there is a general concept for duplexers, as in both examples, .1 to 3dB Jesse, and Skipp input loss 15 to 35% And which will be more accurate to work from dB or %. I always try to get a good balance when I'm tuning duplexers, most times I ended up taking a loss on the power for a better result on the receiver side, is this the best way to go? Or it depends on your situation, whether or not the extra power would effect your weakest signal! (most times a final touch up is done at the repeater site, it always make me feel like a perfectionist) Sometimes I still depend on my ears, then take a look at the test gears, 99% of the time I go with my ears because the difference don't be much when the duplexers are setup to the test gear figures. So, is the figurers always the right thing to work with, or they are just guides for a Tech with a bad hearing? v44kai.Joel. - Original Message - Fom: Jesse Lloyd To: Repeater-Builder@yahoogroups.comSent: Wednesday, August 29, 2007 12:54 PM Subject: Re: [Repeater-Builder] Re: Duplexer input and output power Ya, duplexers will have insertion loss. Typically you get more insertion loss with more rejection, so its a balancing act. Insertion loss can range from .1 dB (very good) to 3 dB. Typically if I can get a duplexer to less than a dB I'm happy. Insertion loss (dB) = 10 log ( PIN / POUT ) So Pout = Pin x 10^(Insertion Loss/10) So for 50 Watts: .1 dB = 48.9 Watts .3 = 46.7 .5 = 44.6 .8 = 41.6 1 = 39.7 1.2 = 37.9 1.5 = 35.4 2 = 31.5 2.5 = 28.1 3 = 25 Jesse On 8/29/07, skipp025 [EMAIL PROTECTED] wrote: Hi Joel, In the real world it depends on the duplexer type, size, quality, operation and setup values, which may be fixed or adjustable. Just throwing out a generic rule of thumb... you will find many duplexers lose about 15% to 35% of the input power. One would hope for near zero loss but that will never happen. A common quality duplexer has adjustable probes or coax ports (the name used is based on the duplexer type), which often trade what we generic call insertion loss for increased performance. Loss through a duplexer is not always a linear graph of power in vs power out. Just to put something out... be happy if a properly setup and working duplexer delivers 75% to maybe 95% of the input power. Be grateful if you receive better than 85% of the rated power. A really tight duplexer might eat as much as 35% to 40% of your input power and there are much worse possible examples. cheers, s. Joel[EMAIL PROTECTED] wrote: Is there a table or formula or ratio for power input to a duplexer, to the resulting output power of the said? For instance, if I put 10, 20, 50, 100 watts to the input, what should be the output, with a 50 Ohms at the load? example 10,20, 50, 100 watts in = x output @ 50 Ohms. BASED ON A PROPERLY TUNED DUPLEXER I think someone had a short for-instance on this, can't find it, and will like some insight on this. v44kai.Joel. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date: 8/28/2007 4:29 PM Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
Nate, Totally aggree with you. HAAT, true HAAT, is the real factor. Coverage of a repeater is determined by HAAT. I've been told by a repeater owner and users a repeater is say 850 ft high. Turns out they were giving referenced to ASL and the ground ASL was 800 ft, hi. Kinda down the same lines as one stating when they are monitoring a repeater a user will turn their beam in the direction of a users location. 73, ron, n9ee/r From: Nate Duehr [EMAIL PROTECTED] Date: 2007/08/30 Thu AM 03:44:32 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available On Aug 30, 2007, at 1:20 AM, MCH wrote: Height = elevation AMSL of the antenna, HAAT, or AGL (which would make no sense)? I assumed HAAT for my calculations and that number seemed to be the most sane, after trying a few. But I think the resulting number is generous for a badly-built repeater, and too small for a well-built one. -- Nate Duehr, WY0X [EMAIL PROTECTED] Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote: As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). This equation is ok, but for a perfect spheer. Is a good place to start. Here in FL where max altitude is about 330 ft ASL it works pretty well although the lower the antenna the worse the actual coverage results. We have plenty of repeaters at 200 ft that have noticably better coverage than 20 miles with a mobile. Also one has to take in account of the user's station. The equation is to the horizon so a user with height over the horizon can also increase coverage. 73, ron, n9ee/r Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] OT- Weather Radio Recall
Quote: “for between $30 and $150.” WOW!! Consumer beware………huh Randy -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of tgundo2003 Sent: Thursday, August 30, 2007 9:30 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] OT- Weather Radio Recall This is a bit off-topic, but I thought it would be important to get the word out as life safety is involved... Tom W9SRV NEWS from CPSC U.S. Consumer Product Safety Commission Office of Information and Public Affairs Washington, DC 20207 FOR IMMEDIATE RELEASE August 29, 2007 Release #07-292 Firm's Recall Hotline: (800) 203-4921 CPSC Recall Hotline: (800) 638-2772 CPSC Media Contact: (301) 504-7908 Weather Radios Recalled by Oregon Scientific Due to Failure to Receive National Weather Service Alerts WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. Name of Product: Oregon Scientific Weather Radios Units: About 66,000 Manufacturer: Oregon Scientific Inc., of Tualatin, Ore. Hazard: The radios could fail to receive National Weather Service alert signals in certain areas of the country. In the event of severe weather, this failure could put a consumer's life and property at risk. Incidents/Injuries: None reported. Description: This recall involves the following Weather Radios and Weather Stations: NAME MODEL All Hazards Portable Weather Alert Radio WR103NX Portable Public Alert Radio WR108 Public Alert Weather Station WRB308 John Deere Public Alert Weather Station WRB308J No other models are included in this recall. Sold at: Retail stores nationwide, including some electronics and sporting goods stores, online retailers and in catalogs from December 2005 through June 2007 for between $30 and $150. Manufactured in: China Remedy: Consumers should not rely on the recalled weather radios to receive emergency information. Consumers should contact Oregon Scientific for instructions on returning the radio to receive a free replacement. Consumer Contact: For additional information, contact Oregon Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday through Friday or visit the firm's Web site at www2.oregonscientif-ic.com To see this recall on CPSC's web site, including pictures of the recalled products, please go to: HYPERLINK http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.htmlhttp://www.cpsc.-gov /cpscpub/-prerel/prhtml07/-07292.html No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00 AM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00 AM
Re: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Gary, AC power line transmission theory is very different than RF. In RF radiation and propagation down the line follows a much different science. Also in AC lines the load is continously changing and at 60 Hz it takes large Ls and Cs to make much difference. AC power is more concerned with power factor than radiation. This can lead to more voltage and current, at the same time, out than at the source. There are some concerns of very long grid lines with transmission, but plays a much less factor than at RF. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/29 Wed PM 09:03:50 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers Transmission line theory is transmission line theory. It doesn't matter what the frequency is it all works the same. Power line transmission engineers worry about the same things in power transmission as do RF engineers. Only the wavelength is different. IR drops in feed lines is much less than a factor than the LC/dielectric type losses. Again frequency shows this. 100 W at 10 MHz and 1000 MHz will have radically different losses yet both have the same I and V and R. A feed line at 10 MHz has a totally different R loss than the same feed line used at 1000 MHz. It does NOT have the same R at different frequencies. It has the same Z (surge or characteristic impedance) at all frequencies but not the same series resistance R. The resistance increases because of skin effect the higher the frequency is. This is where loss comes from. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Wednesday, August 29, 2007 9:32 AM To: Repeater-Builder@yahoogroups.com Subject: Re: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ralph, Transmission line theory for RF and AC power is totally different. In AC power lines little is paid attention to as for transmission except for R losses and power factor. Yes up the voltage/lower the current and the IR loss goes down. For RF this is totally different for the RF propergatesdown the line, not just passes as voltage and currents. This is why feedlines have specific impedances and loads used. One can have any impedance of coax or twin feeds one wants...that is if you have the material and space for it. One can get off the shelf 75 Ohm twin lead. Using 50 or 75 Ohm has more to do with stability especially at RF. IR drops in feedlines is much less than a factor than the LC/dielectric type losses. Again frequency shows this. 100 W at 10 MHz and 1000 MHz will have radically different losses yet both have the same I and V and R. 73, ron, n9ee/r From: Ralph Mowery [EMAIL PROTECTED] Date: 2007/08/27 Mon AM 09:20:07 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers --- Ron Wright [EMAIL PROTECTED] wrote: Jesse, Then why do twin feeders have much less loss than coax??? Skin affect is even more of a factor there due to the differences in the area of the outer shield in coax vs the twin feeders wire. Maybe it is because of the larger C coupling in the coax due to the larger surface area of the shield. Coax has a lower R even with skin effect than twin line feeders. Skin affect is a factor, but a small one compared to the LC factor. 73, ron, n9ee/r It is not open wire or coax that determins the power loss. It is the impedance of the line and the size of the conductors for frequencies up to 1000 Mhz or so. To transfer 1000 watts of power , the voltage will be higher and the current lower in most prectical open wire lines. That is because the impedance will be around 300 to 600 ohms. Coax is usually 50 or 70 ohms. To get 1000 watts of power through that impedance line it requires less voltage and more current. This is the principal of regular 60 hz power line transmission. Up the voltage to a few hundred thousand volts and the current will go down. This lowers the losses. I don't care to take time to do the calculations, but if you take some small guage wire (say # 20) and space it close to make about 200 ohms line and figuer the loss, it may be higher than some 1 inch or even 1/2 inch hardline. At frequencies below around 1000 Mhz the major loss is the IsqR loss in all lines. Radiation is a very small part. In coax there is a point in which the current on the shield is not flowing but jumping from point to point where the shield wires cross. This causes some resistance. That is partly why the foil shielded coax and hardline is lower in loss than regular coax. __ Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out.
[Repeater-Builder] Re: Duplexer input and output power
Telewave once told me their TPRD 4 bottle 5 inch duplexer insertion loss per side... target value is about 1.2 to 1.5 dB per side, which works out to about 35 watts output with 50 watts input. One can often see those figures in play out in the real world. Work with what ever value best describes what idea you want to convey. Percentage is not one normally seen as a technical value but most of the generic world understands it. cheers, skipp Joel [EMAIL PROTECTED] wrote: Ok Skipp, and Jesse, So, I supposed that the specification of such, should be presented by the manufacturers of the said, and with the said, right! Or there is a general concept for duplexers, as in both examples, .1 to 3dB Jesse, and Skipp input loss 15 to 35% And which will be more accurate to work from dB or %. I always try to get a good balance when I'm tuning duplexers, most times I ended up taking a loss on the power for a better result on the receiver side, is this the best way to go? Or it depends on your situation, whether or not the extra power would effect your weakest signal! (most times a final touch up is done at the repeater site, it always make me feel like a perfectionist) Sometimes I still depend on my ears, then take a look at the test gears, 99% of the time I go with my ears because the difference don't be much when the duplexers are setup to the test gear figures. So, is the figurers always the right thing to work with, or they are just guides for a Tech with a bad hearing? v44kai.Joel. - Original Message - Fom: Jesse Lloyd To: Repeater-Builder@yahoogroups.com Sent: Wednesday, August 29, 2007 12:54 PM Subject: Re: [Repeater-Builder] Re: Duplexer input and output power Ya, duplexers will have insertion loss. Typically you get more insertion loss with more rejection, so its a balancing act. Insertion loss can range from .1 dB (very good) to 3 dB. Typically if I can get a duplexer to less than a dB I'm happy. Insertion loss (dB) = 10 log ( PIN / POUT ) So Pout = Pin x 10^(Insertion Loss/10) So for 50 Watts: .1 dB = 48.9 Watts .3 = 46.7 .5 = 44.6 .8 = 41.6 1 = 39.7 1.2 = 37.9 1.5 = 35.4 2 = 31.5 2.5 = 28.1 3 = 25 Jesse On 8/29/07, skipp025 [EMAIL PROTECTED] wrote: Hi Joel, In the real world it depends on the duplexer type, size, quality, operation and setup values, which may be fixed or adjustable. Just throwing out a generic rule of thumb... you will find many duplexers lose about 15% to 35% of the input power. One would hope for near zero loss but that will never happen. A common quality duplexer has adjustable probes or coax ports (the name used is based on the duplexer type), which often trade what we generic call insertion loss for increased performance. Loss through a duplexer is not always a linear graph of power in vs power out. Just to put something out... be happy if a properly setup and working duplexer delivers 75% to maybe 95% of the input power. Be grateful if you receive better than 85% of the rated power. A really tight duplexer might eat as much as 35% to 40% of your input power and there are much worse possible examples. cheers, s. Joel v44kai@ wrote: Is there a table or formula or ratio for power input to a duplexer, to the resulting output power of the said? For instance, if I put 10, 20, 50, 100 watts to the input, what should be the output, with a 50 Ohms at the load? example 10,20, 50, 100 watts in = x output @ 50 Ohms. BASED ON A PROPERLY TUNED DUPLEXER I think someone had a short for-instance on this, can't find it, and will like some insight on this. v44kai.Joel. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date: 8/28/2007 4:29 PM
Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Gary, I've measured RG59 cable terminated into a 75 Ohm resistive load with a variable freq impedance meter. We found the coax stopped being 75 Ohms below about 0.5 MHz. The cable manufacture also verified this. Other engineers in our department knew of this as well. We were designing security systems using video and the vertical and harizonal sync signals became very distored over long, 2500 ft. RG59 cables and this was the major reason. We had to design circuits that corrected this, but the cable had the problem. I am sure different RG59 cables have different low freq bandwidths. RG11 would also be different as well as cable TV cable. All coax has a lower and upper frequency range. Since we deal with radio this is not much of a factor until one gets real low or GHz levels. Coax also has the problem of a upper freq limit due to it's outer shield becomes large enough to act as wave guide. One will see upper freq specs will be lower the larger cable. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/29 Wed PM 09:23:57 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers As far as bandwidth goes,,, where do you get this .5 MHz for rg59 cable as a lower limit? Open wire lines begin to radiate as frequency is increased to the point where the line spacing becomes an appreciable portion of a wave length due to the time it takes for propagation of fields between wires. 73 Gary K4FMX Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Ron Wright Sent: Thursday, August 30, 2007 11:48 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, Coax also has the problem of a upper freq limit due to it's outer shield becomes large enough to act as wave guide. One will see upper freq specs will be lower the larger cable. 73, ron, n9ee/r Recent Activity a.. 14New Members b.. 3New Files Visit Your Group Share Photos Put your favorite photos and more online. Yoga Resources on Yahoo! Groups Take the stress out of your life. Endurance Zone on Yahoo! Groups Communities about higher endurance. . Yep, try 2.4ghz ATV using 1-7/8 heliax... not a happy combo.. LOL! 73 Mike Perryman www.k5jmp.us
Re: [Repeater-Builder] Re: Duplexer input and output power
--- Joel [EMAIL PROTECTED] wrote: Ok Skipp, and Jesse, So, I supposed that the specification of such, should be presented by the manufacturers of the said, and with the said, right! Or there is a general concept for duplexers, as in both examples, .1 to 3dB Jesse, and Skipp input loss 15 to 35% And which will be more accurate to work from dB or %. I always try to get a good balance when I'm tuning duplexers, most times I ended up taking a loss on the power for a better result on the receiver side, is this the best way to go? Or it depends on your situation, whether or not the extra power would effect your weakest signal! (most times a final touch up is done at the repeater site, it always make me feel like a perfectionist) Sometimes I still depend on my ears, then take a look at the test gears, 99% of the time I go with my ears because the difference don't be much when the duplexers are setup to the test gear figures. So, is the figurers always the right thing to work with, or they are just guides for a Tech with a bad hearing? v44kai.Joel. The percent and dB are the same thing. They are just the same numbers expressed in different ways. Just as distances can be expressed in miles, feet, meters, or other units. One is not more accurate , but some units are easier to work with. Most of the time it is easier to work with Db than percentages. They will just directly add or subtract. You might state a large distance in miles or kilometers instead of feet or millimeters. Neither is more accurate, just easier to state something as 10.1 miles instead of 53328 feet. especially when extreme accuracy is not required. You should tune the duplexer for the best signal and deepest notch. You then take whatever loss you get. If it is too much you change the coupling loops in the cans and try again. While going from 1 db to 2 db of power loss seems like a lot if you use a watt meter, it is really not that much in the performance of a system. What will kill the system is the desense of the receiver by the transmitter. If you have to detune a duplexer for less out of the transmitter to eliminate the desense, you are doing something wrong or the duplexer may not be up to the job to start with. Usually trying to use a 4 cavity duplexer to separate a 600 kHz 2 meter repeater will not work with transistor equipment, especially if the receiver is very good. It may work if everything is tuned just right, but if it rains ,a bird lands on the antenna or any other thing, it degrades enough to desense the receiver. It is always best to touch up a duplexer hooked up to the actual repeater and antenna system. Almost no system will be exec tally 50 ohms like the test setup. If putting in 100 watts to most 2 meter duplexers gives me about 70 watts out I am satisfied. Depending on the duplexer you may get less. One 6 cavity duplexer I have is set up for a high rejection of about 120 db. To get this I had to take a factory rated loss of 3 db. This only gives me 50 watts out. So anything between 50 and 75 watts out with 100 watts in is only the differance in about a 2 db to 3 db loss , or one dB of differance. The db differance does not seem to be much , but the actual power differance does. In actual use, the range will be almost the same. If you have a calibrated signal generator just try to see if you can tell much by the quiting differance of 1 dB. I do some weak signal work and 1 db may make the differance in a contact, but that is for very weak signals and not the casual usages most hams will be using. Pinpoint customers who are looking for what you sell. http://searchmarketing.yahoo.com/
RE: [Repeater-Builder] OT- Weather Radio Recall
On that topic I found that a pager works just as well: http://www.iinc.com/ggcomm/pager.html Been using one for quite a while now with good results. Dakota Summerhawk -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of R. K. Brumback Sent: Thursday, August 30, 2007 9:29 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] OT- Weather Radio Recall Quote: for between $30 and $150. WOW!! Consumer beware...huh Randy -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of tgundo2003 Sent: Thursday, August 30, 2007 9:30 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] OT- Weather Radio Recall This is a bit off-topic, but I thought it would be important to get the word out as life safety is involved... Tom W9SRV NEWS from CPSC U.S. Consumer Product Safety Commission Office of Information and Public Affairs Washington, DC 20207 FOR IMMEDIATE RELEASE August 29, 2007 Release #07-292 Firm's Recall Hotline: (800) 203-4921 CPSC Recall Hotline: (800) 638-2772 CPSC Media Contact: (301) 504-7908 Weather Radios Recalled by Oregon Scientific Due to Failure to Receive National Weather Service Alerts WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. Name of Product: Oregon Scientific Weather Radios Units: About 66,000 Manufacturer: Oregon Scientific Inc., of Tualatin, Ore. Hazard: The radios could fail to receive National Weather Service alert signals in certain areas of the country. In the event of severe weather, this failure could put a consumer's life and property at risk. Incidents/Injuries: None reported. Description: This recall involves the following Weather Radios and Weather Stations: NAME MODEL All Hazards Portable Weather Alert Radio WR103NX Portable Public Alert Radio WR108 Public Alert Weather Station WRB308 John Deere Public Alert Weather Station WRB308J No other models are included in this recall. Sold at: Retail stores nationwide, including some electronics and sporting goods stores, online retailers and in catalogs from December 2005 through June 2007 for between $30 and $150. Manufactured in: China Remedy: Consumers should not rely on the recalled weather radios to receive emergency information. Consumers should contact Oregon Scientific for instructions on returning the radio to receive a free replacement. Consumer Contact: For additional information, contact Oregon Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday through Friday or visit the firm's Web site at www2.oregonscientific.com To see this recall on CPSC's web site, including pictures of the recalled products, please go to: http://www.cpsc. http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html gov/cpscpub/prerel/prhtml07/07292.html No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00 AM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00 AM
[Repeater-Builder] Re: Repeater Range : Estimate Program Available
As a quick and dirty method, the radio horizon (RH) is: Distance (in miles) = Square Root of (2 * height in feet). This equation is ok, but for a perfect spheer. Is a good place to start. Here in FL where max altitude is about 330 ft ASL it works pretty well although the lower the antenna the worse the actual coverage results. We have plenty of repeaters at 200 ft that have noticably better coverage than 20 miles with a mobile. I agree that it's not the perfect formula, but if someone is asking the question of how much power do I need, then they need to look at the height formula first to get them in the ball park. When it comes to range, nothing matters more than height. Doubling the height increases the range by about 50%. With power, you have to 10 times the effective power to double the range (until the RH limit). Since the original question was for flat terrain, the RH will be real close. HAAT = AGL. Dwayne Kincaid WD8OYG
Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
--- Ron Wright [EMAIL PROTECTED] wrote: On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote: As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). This equation is ok, but for a perfect spheer. Is a good place to start. Here in FL where max altitude is about 330 ft ASL it works pretty well although the lower the antenna the worse the actual coverage results. We have plenty of repeaters at 200 ft that have noticably better coverage than 20 miles with a mobile. Also one has to take in account of the user's station. The equation is to the horizon so a user with height over the horizon can also increase coverage. 73, ron, n9ee/r The quick and dirty method at the top is not entirely correct. For relative flat land the visual range to the horizon in miles is the sqrt of the height in feet. That is just for one station. You have to do the same for the other station and add the results together. Then there is a factor of about 1.2 to 1.5 this distance has to be multiplied by for the radio horizon instead of the vusual horizon. For the repeater station antenna at 200 feet, it would be 14 miles to the horizon plus a mobile antenna of 5 feet heigth to get 2.2 miles which would be 16.2 miles. Then multiply that by the radio wave bending factor of 1.2 to 1.5 to get 19.4 to 24.3 miles. It does not take much of a rise in the road when the rest of the land is flat to get the mobile station up a few feet and this can add a lot to the range. If the road goes up just 25 feet more the range will go up around 5 more miles. Pinpoint customers who are looking for what you sell. http://searchmarketing.yahoo.com/
RE: [Repeater-Builder] Duplexers
At 8/29/2007 06:40 PM, you wrote: If you have two watt meters and an antenna matching device you can put one wattmeter between the transmitter and the matching device and tune it for minimum reflected power on the first meter. Then with a second meter between the tuner and the mismatched load you can see the second wattmeter that is reading the reflected power. The second wattmeter will have a higher forward power reading than the first due to the added re-reflected power. This doesn't sound right either, as there should be no reflected power at the antenna if it's been matched further down the line. The tuner would be adjusted so as to create a conjugate impedance of the antenna at the end of the feeding coax, thus eliminating the mismatch. My guess is that the higher power reading on the wattmeter is due to the weird impedances it's seeing on both its input output. Bob NO6B Hi Bob, Please read again what I wrote. I am not sure that you are following how the meters are in the circuit. Remember that whatever you do at the transmitter end of a transmission line has no affect on what is going on in the line itself. The only thing that will change the swr on the line is what you do at the load. 73 Gary K4FMX OK, after talking to a senior RF engineer at lunch here at work I think I understand what's going on. The part that threw me was having the matching circuit in the middle of the feedline the fact that any reflected power from the load MUST be totally re-reflected back by the matching circuit, otherwise there would be power reflected back to the TX, which by definition does not occur in this example. Because of the multiple re-reflections between the matching circuit load resulting in multiple waves back forth within that coax section, typical single-wave thinking doesn't apply. I guess it's a useful way to illustrate why coax gets lossier if you use a tuner far from the antenna. Bob NO6B
[Repeater-Builder] Tuning Midland 70-1632B XTR moblie radio tuning to ham band
We are looking to use a couple of Midland 70-1632B UHF radios to link to our tower location for interconnect of other repeaters. Any one know the secret of getting them to go out of band and lock. I have tried to retune the two pots to 1.5 volts but for some reason they do not want to stay. Our received or input is on 443.725 and transmit or output is 448.725 any ideas? Thanks Herschel N9KPA
Re: RE: [Repeater-Builder] Duplexers
Bob, It is better to have someone so one can set down and talk to. This e-mail is great for bringing the world together, but face to face is much better except for most of the ugly Hams I hang out with. The problem with a tuner is the feedline losses, but better than no tuner at all unless got resonant antennas. On HF this is harder to do if one moves about. Putting the tuner at the antenna is a solution, but then get into remote application. Some tuners are automatic and tune whenever they see higher than say 1.5:1 SWR. 73, ron, n9ee/r From: Bob Dengler [EMAIL PROTECTED] Date: 2007/08/30 Thu PM 12:53:11 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Duplexers OK, after talking to a senior RF engineer at lunch here at work I think I understand what's going on. The part that threw me was having the matching circuit in the middle of the feedline the fact that any reflected power from the load MUST be totally re-reflected back by the matching circuit, otherwise there would be power reflected back to the TX, which by definition does not occur in this example. Because of the multiple re-reflections between the matching circuit load resulting in multiple waves back forth within that coax section, typical single-wave thinking doesn't apply. I guess it's a useful way to illustrate why coax gets lossier if you use a tuner far from the antenna. Bob NO6B Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
Ralph, I am sure the equation is Distance (in miles) = Square Root of (2 * height in feet) not Distance (in miles) = Square Root (height in feet). From: Ralph Mowery [EMAIL PROTECTED] Date: 2007/08/30 Thu PM 12:12:53 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available --- Ron Wright [EMAIL PROTECTED] wrote: On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote: As a quick and dirty method, the radio horizon is: Distance (in miles) = Square Root of (2 * height in feet). This equation is ok, but for a perfect spheer. Is a good place to start. Here in FL where max altitude is about 330 ft ASL it works pretty well although the lower the antenna the worse the actual coverage results. We have plenty of repeaters at 200 ft that have noticably better coverage than 20 miles with a mobile. Also one has to take in account of the user's station. The equation is to the horizon so a user with height over the horizon can also increase coverage. 73, ron, n9ee/r The quick and dirty method at the top is not entirely correct. For relative flat land the visual range to the horizon in miles is the sqrt of the height in feet. That is just for one station. You have to do the same for the other station and add the results together. Then there is a factor of about 1.2 to 1.5 this distance has to be multiplied by for the radio horizon instead of the vusual horizon. For the repeater station antenna at 200 feet, it would be 14 miles to the horizon plus a mobile antenna of 5 feet heigth to get 2.2 miles which would be 16.2 miles. Then multiply that by the radio wave bending factor of 1.2 to 1.5 to get 19.4 to 24.3 miles. It does not take much of a rise in the road when the rest of the land is flat to get the mobile station up a few feet and this can add a lot to the range. If the road goes up just 25 feet more the range will go up around 5 more miles. __ Pinpoint customers who are looking for what you sell. http://searchmarketing.yahoo.com/ Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Hi Ron, Think about what goes on in power and RF transmission. Radiation is a problem in power distribution just like it is in RF. Propagation down the line is a concern in power distribution the same as RF. If you compare 160 meter transmitter/tuner L and C values to those of values used at 2 meters there is a large difference there also. Power distribution is just a lower frequency. Standing waves on power distribution lines are just as important as those on RF lines. Standing waves on power distribution produce hot spots in lines just like RF does. The only difference is the wave length is much longer at 60 Hz and you need to travel a much greater distance to see the effects but the effect are the same. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, August 30, 2007 10:54 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, AC power line transmission theory is very different than RF. In RF radiation and propagation down the line follows a much different science. Also in AC lines the load is continously changing and at 60 Hz it takes large Ls and Cs to make much difference. AC power is more concerned with power factor than radiation. This can lead to more voltage and current, at the same time, out than at the source. There are some concerns of very long grid lines with transmission, but plays a much less factor than at RF. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/29 Wed PM 09:03:50 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers Transmission line theory is transmission line theory. It doesn't matter what the frequency is it all works the same. Power line transmission engineers worry about the same things in power transmission as do RF engineers. Only the wavelength is different. IR drops in feed lines is much less than a factor than the LC/dielectric type losses. Again frequency shows this. 100 W at 10 MHz and 1000 MHz will have radically different losses yet both have the same I and V and R. A feed line at 10 MHz has a totally different R loss than the same feed line used at 1000 MHz. It does NOT have the same R at different frequencies. It has the same Z (surge or characteristic impedance) at all frequencies but not the same series resistance R. The resistance increases because of skin effect the higher the frequency is. This is where loss comes from. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Wednesday, August 29, 2007 9:32 AM To: Repeater-Builder@yahoogroups.com Subject: Re: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ralph, Transmission line theory for RF and AC power is totally different. In AC power lines little is paid attention to as for transmission except for R losses and power factor. Yes up the voltage/lower the current and the IR loss goes down. For RF this is totally different for the RF propergatesdown the line, not just passes as voltage and currents. This is why feedlines have specific impedances and loads used. One can have any impedance of coax or twin feeds one wants...that is if you have the material and space for it. One can get off the shelf 75 Ohm twin lead. Using 50 or 75 Ohm has more to do with stability especially at RF. IR drops in feedlines is much less than a factor than the LC/dielectric type losses. Again frequency shows this. 100 W at 10 MHz and 1000 MHz will have radically different losses yet both have the same I and V and R. 73, ron, n9ee/r From: Ralph Mowery [EMAIL PROTECTED] Date: 2007/08/27 Mon AM 09:20:07 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers --- Ron Wright [EMAIL PROTECTED] wrote: Jesse, Then why do twin feeders have much less loss than coax??? Skin affect is even more of a factor there due to the differences in the area of the outer shield in coax vs the twin feeders wire. Maybe it is because of the larger C coupling in the coax due to the larger surface area of the shield. Coax has a lower R even with skin effect than twin line feeders. Skin affect is a factor, but a small one compared to the LC factor. 73, ron, n9ee/r It is not open wire or coax that determins the power loss. It is the impedance of the line and the size of the conductors for frequencies up to 1000 Mhz or so. To transfer 1000 watts of power , the voltage will be higher and the current lower in most prectical open wire lines. That is because the impedance will be around 300 to 600 ohms. Coax is usually 50 or 70 ohms. To get
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
Perhaps they should mark the jacket with 'Contains no copper' to deture cell site theft as well. On 8/30/07, skipp025 [EMAIL PROTECTED] wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements. Yahoo! Groups Links
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
skipp025 wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements. Damn, I assume that the connectors aren't the same, then? Our stash of LDF5 connectors is going to be worthless after a time... if that's the case. G. Thanks for the warning Skipp. Nate WY0X
Re: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
--- Ron Wright [EMAIL PROTECTED] wrote: Ralph, I am sure the equation is Distance (in miles) = Square Root of (2 * height in feet) not Distance (in miles) = Square Root (height in feet). Then my refferance (ARRL Antenna Book 1974 version page 11) must be wrong. They give it as 1.415 * sqrt height, not 2 times the heigth. You may be getting the two times if you have two antennas at the same height. You have to use the formula two times, one for each antenna and then add them together for the total distance. The 1.415 is a multiplier for radio wave bending around the curve of the earth and may need to be differant for differant kinds of earth. Building a website is a piece of cake. Yahoo! Small Business gives you all the tools to get online. http://smallbusiness.yahoo.com/webhosting
[Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements.
RE: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
I have had a 125 Ft. of Andrews LDF 450 ½ in On My 444.75 Repeater for over 15 Yrs. it actually got bent a little during a Move I put 3 Popsicle Sticks on it and Tape SWR Is Still 1.1 , I just wonder if they Switch to alum if it will cause some kind of reaction of Dissimilar Metals on the Connectors , Oh I know what they will do Drop the price of the Coax and raise the Price of special connectors . Happy Repeater Building Don KA9QJG
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
--- DCFluX [EMAIL PROTECTED] wrote: Perhaps they should mark the jacket with 'Contains no copper' to deture cell site theft as well. I think the price of aluminum is up enough also to make it worth while to scrap. I have heard of reports of aluminum siding being ripped off. Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7
[Repeater-Builder] Contains No Copper!
Contains no copper I live just south of Orland Park, IL (Andrew's old Corporate office) I had the opportunity a few years back to pick up some LDF5. While on the property I saw 2 - 30 yard dumpsters side by side by one of the manufacturing buildings. The 1 dumpster had all sizes of scrap, bent, damaged heliax from 1/4 superflex to 3+ inch air cable. It was ready to overflow, and no piece was larger than 6 ft. The other 30 yard dumpster was almost full of pure scrap copper from the manufacturing process. The noon time sun made the dumpster look like it was on fire from the shiny copper! Blinded by the light! What a sight! 73 Brian, WD9HSY Your kid may be an Honor Student, Your Kid may be a Great Athlete, Your Kid may be a Doctor or a Lawyer, But My kid is in the US Air Force plays with ICBM's, Inter Continental Ballistic Missiles, What was your Lat. and Long. ? ** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
At 8/30/2007 03:45 PM, you wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements. Under my previous site manager, aluminum hardline was banned from the site. Bob NO6B
RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
I wonder what you were using to measure the impedance of the cable with below .5 MHz? Some cable especially rg59 types have copper clad steel center conductors. If the copper clad is very thin low frequencies can penetrate the copper clad and get into the steel where the loss can go up substantially. If you are using that cable to transform an impedance the additional lose can make the impedance transformation something other than expected. The impedance will be closer to the characteristic impedance of the cable rather than the expected transformation impedance. But to have the characteristic impedance fall apart at .5 MHz would be a mystery. 75 ohm cable is used extensively in video base band applications where flat low frequency response is needed. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Thursday, August 30, 2007 10:48 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, I've measured RG59 cable terminated into a 75 Ohm resistive load with a variable freq impedance meter. We found the coax stopped being 75 Ohms below about 0.5 MHz. The cable manufacture also verified this. Other engineers in our department knew of this as well. We were designing security systems using video and the vertical and harizonal sync signals became very distored over long, 2500 ft. RG59 cables and this was the major reason. We had to design circuits that corrected this, but the cable had the problem. I am sure different RG59 cables have different low freq bandwidths. RG11 would also be different as well as cable TV cable. All coax has a lower and upper frequency range. Since we deal with radio this is not much of a factor until one gets real low or GHz levels. Coax also has the problem of a upper freq limit due to it's outer shield becomes large enough to act as wave guide. One will see upper freq specs will be lower the larger cable. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/29 Wed PM 09:23:57 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers As far as bandwidth goes,,, where do you get this .5 MHz for rg59 cable as a lower limit? Open wire lines begin to radiate as frequency is increased to the point where the line spacing becomes an appreciable portion of a wave length due to the time it takes for propagation of fields between wires. 73 Gary K4FMX Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links
RE: [Repeater-Builder] Re: Repeater Range : Estimate Program Available
Fred, et al: The General Electric Datafile Bulletin 10003-1 is available for download here: www.repeater-builder.com/ge/datafile-bulletin/df-10003-01.pdf These two files are also needed to perform the calculations: www.repeater-builder.com/ge/datafile-bulletin/df-10003-03.pdf www.repeater-builder.com/ge/datafile-bulletin/ecp-159.pdf 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Fred Seamans Sent: Thursday, August 30, 2007 6:11 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available To All Interested: I would invite you attention to a paper presented by Kenneth Bullington, Radio Propagation at Frequencies Above 30 Meagcycles in the October 1947 Proceedings of the I.R.E. - Waves and Electronics Section. Most all radio propagation prediction methods over the years have been based on the findings of his research for this paper. A GE Mobile Radio Data File Bulletin (10003-1), VHF and UHF Propagation, was published in July 1962 for use by engineers and technicians for the prediction of radio coverage. Along with this bulletin a hard paper/plastic slide rule was manufactured by GE for its sales personnel to predict radio coverage. Motorola sales people liked to get a hold of it and use it also; Range and Signal Strength Calculator for 2 Way Radio.There was a second version put together by GE in 1977; Range and Transmitter Power Calculator. If you can find them, either of these slide rules can give adequate results with radio range calculations. With the general usage of computers in the 1980's many propagation programs appeared on the market, some use digitized USGA maps while others take a more simplistic approach. You get what you pay for! This Data File may be available on line, I am not sure if it is. Fred W5VAY
RE: [Repeater-Builder] Duplexers
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Bob Dengler Sent: Thursday, August 30, 2007 12:53 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Duplexers At 8/29/2007 06:40 PM, you wrote: If you have two watt meters and an antenna matching device you can put one wattmeter between the transmitter and the matching device and tune it for minimum reflected power on the first meter. Then with a second meter between the tuner and the mismatched load you can see the second wattmeter that is reading the reflected power. The second wattmeter will have a higher forward power reading than the first due to the added re- reflected power. This doesn't sound right either, as there should be no reflected power at the antenna if it's been matched further down the line. The tuner would be adjusted so as to create a conjugate impedance of the antenna at the end of the feeding coax, thus eliminating the mismatch. My guess is that the higher power reading on the wattmeter is due to the weird impedances it's seeing on both its input output. Bob NO6B Hi Bob, Please read again what I wrote. I am not sure that you are following how the meters are in the circuit. Remember that whatever you do at the transmitter end of a transmission line has no affect on what is going on in the line itself. The only thing that will change the swr on the line is what you do at the load. 73 Gary K4FMX OK, after talking to a senior RF engineer at lunch here at work I think I understand what's going on. The part that threw me was having the matching circuit in the middle of the feedline the fact that any reflected power from the load MUST be totally re-reflected back by the matching circuit, otherwise there would be power reflected back to the TX, which by definition does not occur in this example. Because of the multiple re-reflections between the matching circuit load resulting in multiple waves back forth within that coax section, typical single-wave thinking doesn't apply. I guess it's a useful way to illustrate why coax gets lossier if you use a tuner far from the antenna. Bob NO6B Yes coax is lossier with reflected power on it. The part of the power that gets reflected from the antenna back toward the transmitter gets attenuated a second time by whatever lose the cable has to begin with. Then when that portion of the power gets re-reflected at the transmitter end and is on its way back to the antenna again it suffers attenuation a 3rd time by the coax so all the re-reflected power does not make it back to the antenna. Then a portion of the re-reflected power gets reflected again back toward the transmitter along with the new wave of power. This repeats itself again and again adding to the loss but after a few round trips of bouncing up and down the feed line most of it gets radiated and some has gotten attenuated to a miniscule amount. Of course this process is continuously repeated as power is constantly applied from the transmitter. But my reason for using the first wattmeter and the tuner was to have a nearly perfect flat load on the transmitter so that one could see the true power coming out of the transmitter. The second wattmeter after the tuner will then show the higher power which would be the sum of the forward and re-reflected power so it could be seen that reflected power does indeed get re-reflected at the transmitter (in this case at the tuner)and makes its way back to the antenna. In common applications with just a single wattmeter and no tuner involved where there is reflected power on the line the wattmeter in the forward position will show the forward power plus the re-reflected power. To find power out of the transmitter you would subtract the reflected power shown in the reverse position from the indicated forward power on the meter. This works over a wide range of impedances with a bird wattmeter. 73 Gary K4FMX
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
Isn't LDF a copper shield with an aluminum core that has copper coating on it? Jesse On 8/30/07, Bob Dengler [EMAIL PROTECTED] wrote: At 8/30/2007 03:45 PM, you wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX� product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as direct replacements. Under my previous site manager, aluminum hardline was banned from the site. Bob NO6B
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
I just looked at the Andrew spec sheet for AVA5-50, which is the Andrew Virtual Air replacement for LDF5-50, and the two cables appear to identical. The AVA5-50 has a copper tube inner conductor and a corrugated copper outer conductor. I suspect that the thickness of both inner and outer conductors has been reduced, which accounts for the lighter weight, but there is no aluminum involved. It appears the Heliax AL is the aluminum version of Heliax LDF5-50. As Jesse pointed out, the smaller Heliax sizes such as LDF2 and LDF4 do use a copper-clad solid aluminum center conductor. Larger sizes have hollow copper tubes as center conductors. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Thursday, August 30, 2007 8:00 PM To: Repeater-Builder@yahoogroups.com Subject: [Norton AntiSpam] Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry Isn't LDF a copper shield with an aluminum core that has copper coating on it? Jesse On 8/30/07, Bob Dengler [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] wrote: At 8/30/2007 03:45 PM, you wrote: The Wal Mart effect* makes it to the Communications Feed-Line industry (*Global Economy) enjoy, s. [paste text] Building upon the market success of its two most significant cable products, Andrew Corporation has announced they will be streamlining its long-running and market-leading HELIAX product portfolio by discontinuing its LDF series cable and featuring alternative products that offer higher value. Andrew will cease regular production of LDF5 and LDF7 series coaxial cables on December 31, 2007 with equivalently sized HELIAX Andrew Virtual Air (AVA ) and HELIAX AL aluminum series cables serving as direct replacements. Under my previous site manager, aluminum hardline was banned from the site. Bob NO6B
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
Our local FD has been plagued by theives stealing the aluminum cans from our can trailer. It must be worth it. And the content of Heliax (no matter what you call it) has to be higher than a thin walled can. Joe M. Ralph Mowery wrote: --- DCFluX [EMAIL PROTECTED] wrote: Perhaps they should mark the jacket with 'Contains no copper' to deture cell site theft as well. I think the price of aluminum is up enough also to make it worth while to scrap. I have heard of reports of aluminum siding being ripped off. Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 Yahoo! Groups Links
Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry
At 12:25 AM 2007-08-31 -0400, you wrote: Our local FD has been plagued by theives stealing the aluminum cans from our can trailer. FWIW one ham club I know of have some kind of plug in cable connecting their building alarm system with the ARES/event trailer. What kind of sensors and such I have no idea. Tony
