Re: [Repeater-Builder] Re: unsubscribe (reading yahoo group posts - a butter way - no popcorn)
On Aug 14, 2010, at 7:01 PM, Chuck Kelsey wrote: I'm the opposite. I want all my email dumped in one inbox. I'm afraid if it gets sorted to different folders, something's bound to get missed. Just like the mailman puts all my snail mail in one mailbox. Works just fine. Same reason I prefer list servers to forums - I don't want to have to go and look somewhere. Chuck WB2EDV All the mail in the individual folders is tagged as new and almost all modern mail clients show counts of new mail per folder. If not that, there's always smart folders which all now do also -- All New Mail, no matter what folder it's in. If the mail is light for the day, I just go there... It's virtually impossible to miss something, but it will show you your real priorities in mail reading if you sort to folders. Frankly, sometimes RB (sorry Kevin Scott) sits for weeks when the real mail gets busy. The little number next to the folder keeps counting up with new messages as a reminder that I need to get to them, eventually... but not now. I've been unsuccessful thus far in getting all the way to Inbox Zero ( http://inboxzero.com/inboxzero/ ) but it's a smart long-term goal... -- Nate Duehr, WY0X n...@natetech.com
Properly designed PAs (was: Re: [Repeater-Builder] Coax length, etc.)
On Aug 14, 2010, at 9:45 PM, Jeff DePolo wrote: I disagree. I would accept the notion that the transmitter may not be happy (and I put that in quotes not to mock you, but becuase I can't come up with a better word either) because it is not *properly matched* when looking into a 50+j0 load. This indicates a deficiency in the amplifier; if it were designed and working right, it *should* make rated power when terminated in a 50 ohm load on-channel. Okay, I'd love to go off on a side tangent here for a moment. (By the way, loving the discussion. Learning from it.) Jeff, out of all the PAs you've seen out there, both commonly used and not-so-common... which ones (in your opinion) are properly designed (when working right)? I have this feeling that most, if not all, have various problems... but you've seen a heck of a lot more of them in-service than I have. Which ones behave the best, as regards to this other discussion that's going on about making them happy. In other words, which ones have you bought/used that you hooked up, and forgot about them completely because you knew they'd just work. I ask, because this is always the kind of mature, well-developed tech I'm looking for. Price is still a factor, but when you find something that just works... it's truly grand in the tech world, for all sorts of reasons that tend to degrade what something was intended to be, vs. what it really ended up being. I'm also curious to see if your recommendations are new gear, or 20+ year old gear. I really like MASTR II Stations, but I will admit to some consternation over how the PAs *sometimes* act. We've had 'em run for a decade, and we've had 'em pop like light bulbs every few months. Yes, the problem is often in the duplexer/feedline/antenna system when this happens, but it's also often subtle and not exactly easy to find. I'm wondering to myself, (and now out loud)... Is there a PA out there that wouldn't have cared or been un-happy? Bonus points for it monitoring its own happiness and turning on an alarm light, closing a contact, etc. Is the answer to this question the Crescend amps perhaps? How did their acquisition of Vocom affect their quality? I haven't looked lately, did they mix up the model line and keep the Vocom stuff? Just some questioning thoughts, not very well thought out, at almost 1AM... -- Nate Duehr, WY0X n...@natetech.com
Re: [Repeater-Builder] Coax length, etc.
On Aug 14, 2010, at 9:45 PM, Jeff DePolo wrote: Well, kinda. Many duplexers are spec'ed for 1.5:1 (14 dB RL) input VSWR max. Fortunately, I rarely see any that are that bad. I'll gladly trade off a tenth of a dB of insertion loss for several (if not 10 or more) dB of return loss improvement when I'm tuning on the VNA, but some hams are greedy and don't think along those lines when they're tuning... Actually I think that even though Service Monitors have finally become *relatively* commonplace in the Ham Shack, the VNA is not something most hams have seen or know how to use. (I would count myself in that group.) Like Service Monitors used to be before the flood of HPs on eBay in the last few years, I hear rumors of great deals on VNAs, and yet never see them in any way plentiful, easy to acquire, or affordable, but then again I'm also not exactly looking that hard, and perhaps I'm missing one of those everyone knows about Bob's VNA Warehouse! kinds of sources for such things. I do find it interesting (sorry another side-thought) that a great many *professionals* don't seem to have access to them, nor can convince their employers to purchase them. I have heard the excitement in professional RF Engineer's voices when their company finally acquires one... and seen 'em load up the car with stuff they've always wanted to put on the VNA. A few years ago, anyway. Are they more common than I think? From Jeff's comments and other's off-list, they're obviously the right tool for the job, and tuning duplexers without them seems similar to messing around with taking the engine out of a car without an engine hoist, but unlike engine hoists -- professional RF shops don't even seem to regularly own a VNA or have anyone on staff qualified/trained on how to use one. Can't count the number of cell site and other RF techs I've talked to over the years who were just happy as clams when they finally got TDR equipment to check cables too. What's up with the RF industry not buying these things by the truckload? Too spendy? -- Nate Duehr, WY0X n...@natetech.com
Re: [Repeater-Builder] Coax length, etc.
Hi Kevin: Regarding temperature, our club has a site, no A/C or heat, where temperatures inside the shelter can get below +20 deg F in winter, and well over 130 deg F in the summer heat. I can't imagine filter tuning not changing under such conditions, Invar or not. I can see over time where tuning might walk off the reservation. But I bow to your greater experience with cavity duplexers. Another chance? Which part, erroneous readings, don't directly measure power, or the voltmeter part? Sure, what the heck. ;-) I've had Bird 43's, and calibrated line sections with matched elements for that matter, give erroneous reflected power readings depending upon what was going on with the transmission line. By erroneous, I mean it was usually a reading that was, for example, excessively high versus what we knew was going on, such as a straight piece of rigid line or coax terminated into a known good load. On rare occasion, we found we slipped a bullet or had a bad connector. More often, relocating the instrument somewhere else along the line resolved those bad readings. RF calorimeters can measure power directly. But unless they've one hidden in them somewhere, ThruLine meters can not. Just because the Commission might accept wattmeter readings, or Bird says so, doesn't make it so. As for the voltmeter part, check out page 6 of the Bird 43 manual (page 18 of the PDF), a copy of which you'll recall is here: http://www.repeater-builder.com/bird/pdf/bird-43-wattmeter-2004.pdf I respectfully submit what is shown is a schematic/diagram of a directional coupler attached to a voltmeter as an indicator. An induced RF voltage sample is rectified, filtered and applied through a dropping resistor to a shunt-connected ammeter. By definition, a voltmeter is the shunt-connected ammeter with series resistor part. But don't take my word for it. Take a peek at Chapter 25 in any recent ARRL Handbook (this works for my 2007 copy anyway). Is it less a voltmeter because the induced voltage tracks current on the line? Want to call it an ammeter or current meter then, after all that's what the actual meter movement is? I submit this particular voltmeter happens to be calibrated to read average power at 50 ohms impedance, and it does this quite well within its limitations. I now await your thrashing. Please be gentle. ;-) Like the manual says, the Bird 43 is fast, convenient and accurate. I agree it's fast and convenient. I'll agree it's accurate with the caveats expressed. It beats lugging a slotted line around, and it beats every other meter like it, IMHO, including my old Daiwa dual-metered POS wattmeter. ;-) Oh, BTW, the emperor has no clothes either. :-P 73, Russ WB8ZCC On 8/14/2010 10:11 PM, Kevin Custer wrote: Russ Hines wrote: Some related comments, if you don't mind. Temperature changes seem to be the biggest detuner of largely mechanical devices like cavity duplexers. We often send our repeaters off to live in less-than-ideal environments, then expect cavity input/output impedances to remain as we measured them in the shop? Don't think so. I largely disagree. Most modern duplexer designs (within the last 25 years or so) use compensating elements to make the duplexer or cavity temperature stable. Invar is a nickel-steel alloy that exhibits about 1/10 the thermal expansion as a common carbon steel counterpart. Invar is used to make the tuning rod - many times it's threaded. The rest of the duplexer or cavity is usually made of similar metals and generally thermal expansion occurs across these components equally, resulting in extremely low frequency drift over its rated operating temperature. Our in-line power meters, like our trusted Bird 43, do not directly measure power. They're really voltage meters calibrated in watts at a specific impedance. That's why they can be fooled into displaying an erroneous reflected power reading, perhaps lulling us into a sense of security that the VSWR on the line is acceptable when it may not be. What? Maybe you would like to have another chance at that one Kevin Custer
Re: [Repeater-Builder] new member introduction
On Sat, Aug 14, 2010 at 20:32, Nate Duehr n...@natetech.com wrote: Very little, typically. Almost all have solid-state components that would be utterly dead after an EMP. Tube gear that survives EMP better is virtually all gone. And user radios are required for any repeater to be useful, and they'd all be totally dead too. Nate, your assessment then is that all repeaters within range of an EMP would be wiped out? snip So... the rest of your posting sure sounds like an advertisement for another list, which is generally bad Netiquette, unless the lists had something a little bit more in common. If an EMP can wipe out all repeaters, I would say that EMP has everything to do with repeaters. snip even though your From is a pseudonym. Personally, I find pseudonym-bearers on the Internet usually need this advice: If you want to be somebody else, change you mind. Seriously. Or at least have the pseudonym match something you are, or something you do. My email address is ZephyrNYC. Zephyr is the West Wind, and was my first DJ name. NYC is for the city of my birth. I would say that matches who I am and something that I do. If all repeaters can be wiped out by an EMP, the only way I can think of to prepare for one then is to store spare repeater components inside a Faraday cage or similar container and hope that there isn't a successive EMP after the first one. 73, Frank kF2ANK Security is mostly a superstition. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing. ~ Helen Keller http://en.wikipedia.org/wiki/Helen_keller - Amateur Radio Portable Operations Group http://groups.yahoo.com/group/ARPortable/ - EMP (Electro-Magnetic Pulse) Preparedness http://groups.yahoo.com/group/EMPprepare/ - Great Outdoors Radio Club http://groups.yahoo.com/group/gorc/ - Ham Radio Help Group http://groups.yahoo.com/group/HamRadioHelpGroup/ - Military and Commercial Portable Radios http://groups.yahoo.com/group/milpack/ - Survival Communications http://groups.yahoo.com/group/survivalcomm/
Re: [Repeater-Builder] Coax length, etc.
I don't know about that. Anritsu SiteMaster and CellMaster test sets are fairly common test equipment available to cell techs here in Connecticut. Whether they use them (or know how) is another thing. Joe On 8/15/2010 2:59 AM, Nate Duehr wrote: What's up with the RF industry not buying these things by the truckload? Too spendy?
RE: [Repeater-Builder] Coax length, etc.
But why? If all of the power (or, let's hope, at least 99.99% of it) is on-channel, *should* a properly-designed and properly-functioning transmitter misbehave due to the poor match a duplexer presents at frequencies far removed from the channel center? Well yes, properly designed transmitter. But how much do you want to pay for it? Me personally? I'll pay for a transmitter that works, and works right. The way I see it, repeaters are like cars. You have to get your car inspected for safety. Your car doesn't pass safety inspection? You can't drive it on the public roads, lest you'd be putting other people at risk. Same with a repeater transmitter. If it's unstable and has the potential for causing interference other systems (ham repeaters, public safety, aviation, etc.), it shouldn't be on the air. Either fix it, or if you can't afford to fix it, take it down. I don't want some scmuck driving a beat-up 1972 pickup down the interstate in front of me and having his rear bumper fall off any more than I want somebody putting some clunker up on a mountantop and having it go spurious and interfering with EMS or ATC. That's just the way I see it, sorry if that rubs some people the wrong way. A built in isolator will solve all of those problems as an example. Maybe. An isolator will help flatten the load on, and around, the carrier frequency, but isolators, too, have a finite VSWR bandwidth, they won't provide a perfect load across the entire spectrum. And if you can afford an isolator, you can probably afford a better PA. It is almost impossible for a high Q cavity to not present some reactance away from the tuned frequency. It's not almost impossible, it's definately impossible. If it didn't then it would not have any selectivity. Right. The random length cable of course transforms that reactance to something that the transmitter may or may not be comfortable with as discussed above. Just to clarify, the complex Z is being transformed (both R and jX), not just the reactive component. The thing with random-length cables is just that - they're random. How do we know what cable length is going to make the transmitter happy? Does the transmitter like more XL or more XC, or bigger R's or smaller R's, and at what frequency, because as I'm sure you know, the complex Z is going vary wildly at different frequencies, due to the duplexer's Z, its behavior as a transformer with respect to the load Z at the antenna port, the antenna feedline acting as a transformer with respect to the antenna feedpoint Z, and the cable between the PA and the duplexer also acting as a transformer, so you end up with this complex system of cascaded transformers. Chances are if the PA is that picky, its behavior may also change with temperature, voltage, who knows what else. Antenna feedpoint Z's change with environmental conditions (precipitation, icing, etc.). Feedline electrical lengths (phase) change with temperature, so the resulting Z at the duplexer antenna port is also going to change. There are *so many variables* that will constantly be changing over time that what may seem to work when you walk off the site may fail miserably months, days, maybe even hours later after you think you've found that magic cable length. At least with an isolator we've taken the bulk of those external variables out of the equation - I can agree with that. But, call me a fundamentalist, I still believe that a PA should work, and work right, when it sees 50 ohms on-channel no matter what's happening off-channel. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
Actually I think that even though Service Monitors have finally become *relatively* commonplace in the Ham Shack, the VNA is not something most hams have seen or know how to use. For $100, Rick's (Amtronix) return loss bridge is a must-have for anyone that has a SM with a SA/TG. With it, there's no longer any excuse for not being able to tune cavities properly for maximum return loss. Like Service Monitors used to be before the flood of HPs on eBay in the last few years, I hear rumors of great deals on VNAs, and yet never see them in any way plentiful, easy to acquire, or affordable, but then again I'm also not exactly looking that hard, and perhaps I'm missing one of those everyone knows about Bob's VNA Warehouse! kinds of sources for such things. Hey, I didn't say they were cheap, nor that everybody can or should own one. There's nothing more enjoyable than tuning up a $100 duplexer from Dayton on a $50,000 network analyzer, especially when it's a 3-porter and you don't even have to swap cables around :-) --- Jeff WN3A
RE: Properly designed PAs (was: Re: [Repeater-Builder] Coax length, etc.)
Jeff, out of all the PAs you've seen out there, both commonly used and not-so-common... which ones (in your opinion) are properly designed (when working right)? I think a lot of them, generally speaking, are properly designed. That's not to say that some of them don't have some downsides or specific, recurring points of failure (to wit: the beloved Mastr II output strap connection failure). I'd name manufacturers that are on my $^!+ list, but I'd rather not do that here, but I will say that most of them are the made-for-amateur brands. I've had great luck with just about anything Micor (and, I have to say, significantly better long-term results with Micor over M2, sorry GE fans). Crescend and *newer* TPL amps have been good to me. EFJ CR1010 PA's have also been workhorses. I have this feeling that most, if not all, have various problems... but you've seen a heck of a lot more of them in-service than I have. Well, I dunno, there are probably others on this list in the two-way business that have seen more than me. I do broadcast for a living; I'm generally an RF guy, my interest in repeaters is just a subset of that. I have a bunch of ham repeaters (20-some I think), and maintain a bunch for other individuals/clubs, and have built or maintained many for others over the years, but I'm sure there are others that do two-way on a daily basis that can give more points of reference as far as recurring problems with other brands/models that I'm not as familiar with. I ask, because this is always the kind of mature, well-developed tech I'm looking for. Price is still a factor, but when you find something that just works... it's truly grand in the tech world, for all sorts of reasons that tend to degrade what something was intended to be, vs. what it really ended up being. To me, the cost of the radio hardware is the least of my worries. I'm not saying that to sound like an alpha-hotel. I look at it this way. I've got all of these repeaters to deal with. I have no free time the way it is. When one breaks, that means I have to take a day off work (or away from family, or away from something else) to go deal with it. It probably means a few hundred miles of driving. And, more than likely, if it's a major failure, I'm probably going to have to make a return trip, doubling the time/cost. So do I really want to take a chance on low-grade hardware up front? No way. Whoever said time is money was an idiot. Time is worth inifinitely times more than money. You can make more money. You can even borrow money. Hell, if you were desparate you could even steal money. You can't do any of those things with time. Time is the one resource you can't make more of. And, for me, I've never had enough time to get everything done that I want to get done. Life's too short to waste time on high-maintenance equipment. I'm also curious to see if your recommendations are new gear, or 20+ year old gear. Both. While I still believe the glory days of two-way turned out the best damned equipment ever made, there is still some decent stuff being made today. I really like MASTR II Stations, but I will admit to some consternation over how the PAs *sometimes* act. We've had 'em run for a decade, and we've had 'em pop like light bulbs every few months. With the exception of the PA's, they generally just run. 100 watt UHF M2 PA's have been rather disappointing for me, both with and without matching networks, with or without isolators. 75 watters seem to run forever. Highband and lowband, much fewer problems. I have a bunch of the 200 watt solid state M2 stations, and have pulled them all out (except for one, which is coming out in a week or two), they're just a nightmare to keep all three PA's working all the time. Is the answer to this question the Crescend amps perhaps? I've been happy with them. I have 7 or 8 of the previous-vintage UHF Crescend/Milcoms (the gold-alodined ones that you're probably familiar with) on the air, and they've been fine, running in the 150-175 watt range. I ordered a couple 100 watt highband amps for a local club about a year ago, they seem OK. I have a bunch of their 900 MHz linear amps in use on STL's and they've been solid. I wouldn't hesitate to buy them. How did their acquisition of Vocom affect their quality? They did change their design, and talking to their engineers a few months ago, they're doing some re-designs due to some of the devices they had been using going on EOL, so more changes will be forthcoming. Some of the older pre-Crescend Vocom amps weren't very good. I haven't looked lately, did they mix up the model line and keep the Vocom stuff? They still have the Vocom line which they market as a lower-cost alternative. I like the TPL RXR series because they are extremely simple. They also have one device per board, so in the event that you have a device fail or burn up a collector trace or something, you only have
[Repeater-Builder] Digital repeater sidebands??
Hi folks We have a digital repeater in the 420-430 MHz subband that is being installed shortly on our site. I am concerned about the possible interference to systems in the 440-450Mhz subband on the same site. What experience have you folks had with similar systems and installations? What is the typical sideband levels from commercial digital repeaters at 10MHz+ spacing? FYI this site is owned by our club and we have full control over the installations on it including the commercial customers who lease space on it. I just want to know what to look for when this new system is installed. Burt VE2BMQ
Re: [Repeater-Builder] Digital repeater sidebands??
I just realized that we also have another commercial analog repeater in the 420-430MHz band, so close in sidebands would also be a concern. Burt VE2BMQ Burt Lang wrote: Hi folks We have a digital repeater in the 420-430 MHz subband that is being installed shortly on our site. I am concerned about the possible interference to systems in the 440-450Mhz subband on the same site. What experience have you folks had with similar systems and installations? What is the typical sideband levels from commercial digital repeaters at 10MHz+ spacing? FYI this site is owned by our club and we have full control over the installations on it including the commercial customers who lease space on it. I just want to know what to look for when this new system is installed. Burt VE2BMQ Yahoo! Groups Links
Re: [Repeater-Builder] Digital repeater sidebands??
I guess you say what type of modulation and bandwidth are you using for the new Digital Repeater? Should not be any problem. The digital modulation mask are getting more efficient in the use of the spectrum as channel bandwidth get narrower. The name of the game is to get more spectrum efficiency. Just because you go digital the RF rules of the game should not change. They say Digital modulation is less inclined to discernible interference than analog FM. I have not seen any problems when taking trunked systems from Analog FM to Digital P25. I have several mixed mode systems and again have never seen any inter-modulation issues come up when going to digital mode. In general I think the Digital P25 mode gives much better quality audio over a larger part of the coverage area. Something commercial especially public safety users want. Peter On Sun, Aug 15, 2010 at 10:46 AM, Burt Lang b...@gorum.ca wrote: Hi folks We have a digital repeater in the 420-430 MHz subband that is being installed shortly on our site. I am concerned about the possible interference to systems in the 440-450Mhz subband on the same site. What experience have you folks had with similar systems and installations? What is the typical sideband levels from commercial digital repeaters at 10MHz+ spacing? FYI this site is owned by our club and we have full control over the installations on it including the commercial customers who lease space on it. I just want to know what to look for when this new system is installed. Burt VE2BMQ
RE: [Repeater-Builder] Coax length, etc.
I've brought that issue up a few times, and usually get the blank radio shack salesman type of stare. -- Original Message -- Received: Sat, 14 Aug 2010 08:45:47 PM PDT From: Jeff DePolo j...@broadsci.com There is no simple rule of thumb, and if anybody tells you that there is, ask them how do you account for the unknown-length of coax that's *inside* your transmitter/amplifier before it gets to the antenna jack. --- Jeff WN3A
RE: [Repeater-Builder] Coax length, etc.
Russ, Of course the Bird 43 does not measure power directly. But it does sample voltage AND current on the line in amounts that are combined to indicate power. It is a directional coupler. The only time you will have a problem with it deviating from its accuracy is when the directivity becomes too low such as when the line impedance is way off from its design 50 ohms. As I said before it will read power accurately even if the transmission line is no a 50 ohm line. The manual even tells you that you can use it to measure line loss with an open at the far end of the line. Please read chapter 2 theory of operation of the Bird manual that you show the reference to. Then read it again! 73 Gary K4FMX Another chance? Which part, erroneous readings, don't directly measure power, or the voltmeter part? Sure, what the heck. ;-) I've had Bird 43's, and calibrated line sections with matched elements for that matter, give erroneous reflected power readings depending upon what was going on with the transmission line. By erroneous, I mean it was usually a reading that was, for example, excessively high versus what we knew was going on, such as a straight piece of rigid line or coax terminated into a known good load. On rare occasion, we found we slipped a bullet or had a bad connector. More often, relocating the instrument somewhere else along the line resolved those bad readings. RF calorimeters can measure power directly. But unless they've one hidden in them somewhere, ThruLine meters can not. Just because the Commission might accept wattmeter readings, or Bird says so, doesn't make it so. As for the voltmeter part, check out page 6 of the Bird 43 manual (page 18 of the PDF), a copy of which you'll recall is here: http://www.repeater-builder.com/bird/pdf/bird-43-wattmeter-2004.pdf I respectfully submit what is shown is a schematic/diagram of a directional coupler attached to a voltmeter as an indicator. An induced RF voltage sample is rectified, filtered and applied through a dropping resistor to a shunt-connected ammeter. By definition, a voltmeter is the shunt-connected ammeter with series resistor part. But don't take my word for it. Take a peek at Chapter 25 in any recent ARRL Handbook (this works for my 2007 copy anyway). Is it less a voltmeter because the induced voltage tracks current on the line? Want to call it an ammeter or current meter then, after all that's what the actual meter movement is? I submit this particular voltmeter happens to be calibrated to read average power at 50 ohms impedance, and it does this quite well within its limitations. I now await your thrashing. Please be gentle. ;-) Like the manual says, the Bird 43 is fast, convenient and accurate. I agree it's fast and convenient. I'll agree it's accurate with the caveats expressed. It beats lugging a slotted line around, and it beats every other meter like it, IMHO, including my old Daiwa dual-metered POS wattmeter. ;-) Oh, BTW, the emperor has no clothes either. :-P 73, Russ WB8ZCC
RE: {Disarmed} [Repeater-Builder] Re: Coax length, etc.
Quote from Skip:
Just reading this thread gives me a headache...
Skip, you are not the only one reaching for the Advil. When I read it, I
thought, OH NO, here it goes again.
Randy
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of skipp025
Sent: Friday, August 13, 2010 11:55 PM
To: Repeater-Builder@yahoogroups.com
Subject: {Disarmed} [Repeater-Builder] Re: Coax length, etc.
Man..!
Just reading this thread gives me a headache...
Glad I'm not in the middle of it...
:-)
s.
Re: [Repeater-Builder] new member introduction
On Sunday 15 August 2010 02:27:17 ZephyrNYC wrote: On Sat, Aug 14, 2010 at 20:32, Nate Duehr n...@natetech.com wrote: Very little, typically. Almost all have solid-state components that would be utterly dead after an EMP. Tube gear that survives EMP better is virtually all gone. And user radios are required for any repeater to be useful, and they'd all be totally dead too. Nate, your assessment then is that all repeaters within range of an EMP would be wiped out? Having talking with some folks who were charged with calculating the effects of EMP, a rough guideline is that anything you want to survive be buried in at least 20 feet underground, and more is better. An EMP is going to seriously screw us up. I think radio communications is farther down the list of problems if we get hit by one. Food, for one is going to be hard to move around. Of course, stuff things in the ground will work, gven the effort, AND not having a second one, say a month after the first, when you've taken items out of storage and are using them. Lately I'll point out that unless a lot of folks prepare in this way, it won't much matter if you've saved some stuff, will it.. snip So... the rest of your posting sure sounds like an advertisement for another list, which is generally bad Netiquette, unless the lists had something a little bit more in common. If an EMP can wipe out all repeaters, I would say that EMP has everything to do with repeaters. snip even though your From is a pseudonym. Personally, I find pseudonym-bearers on the Internet usually need this advice: If you want to be somebody else, change you mind. Seriously. Or at least have the pseudonym match something you are, or something you do. My email address is ZephyrNYC. Zephyr is the West Wind, and was my first DJ name. NYC is for the city of my birth. I would say that matches who I am and something that I do. If all repeaters can be wiped out by an EMP, the only way I can think of to prepare for one then is to store spare repeater components inside a Faraday cage or similar container and hope that there isn't a successive EMP after the first one. 73, Frank kF2ANK Security is mostly a superstition. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing. ~ Helen Keller http://en.wikipedia.org/wiki/Helen_keller - Amateur Radio Portable Operations Group http://groups.yahoo.com/group/ARPortable/ - EMP (Electro-Magnetic Pulse) Preparedness http://groups.yahoo.com/group/EMPprepare/ - Great Outdoors Radio Club http://groups.yahoo.com/group/gorc/ - Ham Radio Help Group http://groups.yahoo.com/group/HamRadioHelpGroup/ - Military and Commercial Portable Radios http://groups.yahoo.com/group/milpack/ - Survival Communications http://groups.yahoo.com/group/survivalcomm/ -- STeve Andre' wb8wsf en82 Disease Control Warden Dept. of Political Science Michigan State University A day without Windows is like a day without a nuclear incident.
[Repeater-Builder] Re: Repeater Stuff For Sale!
80 in for 200 out --- In Repeater-Builder@yahoogroups.com, Maire-Radios maire-rad...@... wrote: what is the input power on the 200 watt Vocom amp? K+John - Original Message - From: n2len To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 14, 2010 9:24 PM Subject: [Repeater-Builder] Repeater Stuff For Sale! Motorola RKR-1225 VHF Repeater with Rack Mount Currently programmed for Hamsplit $475 Shipped and Insured Motorola R-1225 UHF Repeater Just Radio and Control Head Unit Hamsplit down to 444MHZ $425 Shipped and Insured Cat 400 Linking Controller and RME-200L Rack Mount with Ed-400W Windows Programming Software $325 Shipped and Insured Cat RLS-1000B Remote Link Switch Board with RME-200L Rack Mount Enclosure. $125.00 Shipped Pacific Research RI-310 Repeater Controller Ror the VXR-5000 Repeater Direct Replacement for the stock Internal Controller Plug Play $400.00 Shipped TPL RXR Series VHF 150 Watt Repeater Amplifier Rack Mount/Fan $375.00 Shipped TPL RXR Series UHF 100 Watt Repeater Amplifier Rack Mount/Fan $350.00 Shipped Two Vocom UHF Repeater Amplifiers Working Condition of both Unknown 100 Watt Factory 462.925 UVC100-10RF $125 Shipped Vocom UHF Repeater Amplifier Working Condition Unknown 200 Watt Factory 462.925 UVC200-80RFF Rack Mount/Fan PAYMENT PAYPAL! E-mail too: n2...@...
RE: [Repeater-Builder] RG-142, RG-400 va RG-223
I should have mentioned that RG-223 has a solid silver-coated copper center conductor, while RG-400 has a stranded silver-coated center conductor, which makes RG-400 better suited where flexibility counts. RG-142 has a solid steel center conductor that is solver coated and copper clad, but it should not be used where it will be flexed after installation. The big disadvantage of RG-223 is the power-handling capability. RG-223 is rated for just 86 watts at 400 MHz, while RG-400 (and RG-142) are rated for 1100 watts at 400 MHz. RG-223 has 50% greater attenuation at 50 MHz and 15% greater attenuation at 400 MHz. RG-223 will be okay in most applications, but the power-handling limitations and its attenuation should be considered. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Wednesday, August 11, 2010 5:20 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] RG-142, RG-400 va RG-223 Sid, RG-223 will be fine, provided that you use silver-plated connectors that are specifically designed for that cable, and avoid using any barrels or between-series adapters. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Sid Sent: Wednesday, August 11, 2010 11:51 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] RG-142, RG-400 va RG-223 I have seen a lot of jumpers, interconning cables, duplexer cables, etc made using RG-142 and RG-400 (the 400 is preferred). However, RG-223 is also silver, double shielded,very flexible, and also about RG-58 size. Any reason why RG-223 would not work just as well; other than it is not a teflon cable? Sid.
RE: [Repeater-Builder] Coax length, etc.
Agreed!! Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Eric Lemmon (major snippage) This discussion is both informative and quite entertaining! 73, Eric Lemmon WB6FLY
Re: [Repeater-Builder] Tait T800 Series II
At 10:10 AM 8/13/2010, Steve wrote: Hi the T800,s both series one and two are great, series one uses eproms series two is an eeprom programmed using a single data line via an rj11 skt on the front and rear. In the UK a series two sells for around 400ukp a low band series one for around 200ukp. ---Thanks for the input Steve. The one I was looking at is supposedly a new demo and the guy wants $975 for it Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em!
Re: [Repeater-Builder] Coax length, etc.
I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO, it's really messy. It can't tell the difference between a 1:1 VSWR and a 2:1 VSWR (both will calculate out to 1.4:1) on a 70 ohm line. That's not accuracy, that's nearly useless. BTW, my POS Daiwa can show me a 100% reflected condition, just like the Bird. And just like the Bird, it doesn't indicate if that's an open or a short. I believe Bird wants us to believe that their meter is faster and more convenient (it is) yet as accurate as a slotted line and calorimeter (sorry, nope). It's a calibrated voltmeter, not a network analyzer. For most everyday, mundane RF chores, it's just dandy as we don't really need high accuracy. And as long as line impedances stay reasonably close to 50 ohms, it turns out accuracy is pretty good, too. Certainly not bad for a portable instrument, and that's the point. If we remember what its limitations are, we should be good to go. That's why I own one and want more. Okay, I'm done picking nits. It's the next yahoo's turn. ;-) 73, Russ WB8ZCC On 8/15/2010 2:08 PM, Gary Schafer wrote: Russ, Of course the Bird 43 does not measure power directly. But it does sample voltage AND current on the line in amounts that are combined to indicate power. It is a directional coupler. The only time you will have a problem with it deviating from its accuracy is when the directivity becomes too low such as when the line impedance is way off from its design 50 ohms. As I said before it will read power accurately even if the transmission line is no a 50 ohm line. The manual even tells you that you can use it to measure line loss with an open at the far end of the line. Please read chapter 2 theory of operation of the Bird manual that you show the reference to. Then read it again! 73 Gary K4FMX Another chance? Which part, erroneous readings, don't directly measure power, or the voltmeter part? Sure, what the heck. ;-) I've had Bird 43's, and calibrated line sections with matched elements for that matter, give erroneous reflected power readings depending upon what was going on with the transmission line. By erroneous, I mean it was usually a reading that was, for example, excessively high versus what we knew was going on, such as a straight piece of rigid line or coax terminated into a known good load. On rare occasion, we found we slipped a bullet or had a bad connector. More often, relocating the instrument somewhere else along the line resolved those bad readings. RF calorimeters can measure power directly. But unless they've one hidden in them somewhere, ThruLine meters can not. Just because the Commission might accept wattmeter readings, or Bird says so, doesn't make it so. As for the voltmeter part, check out page 6 of the Bird 43 manual (page 18 of the PDF), a copy of which you'll recall is here: http://www.repeater-builder.com/bird/pdf/bird-43-wattmeter-2004.pdf I respectfully submit what is shown is a schematic/diagram of a directional coupler attached to a voltmeter as an indicator. An induced RF voltage sample is rectified, filtered and applied through a dropping resistor to a shunt-connected ammeter. By definition, a voltmeter is the shunt-connected ammeter with series resistor part. But don't take my word for it. Take a peek at Chapter 25 in any recent ARRL Handbook (this works
Re: [Repeater-Builder] Tait T800 Series II
Hi glad to help. That price is a bit high,ex demo or not, it is still secondhand and I would imagine $800-850 to be a fair price 73 Steve - Original Message - From: Ken Arck ah...@ah6le.net To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 15, 2010 10:53 PM Subject: Re: [Repeater-Builder] Tait T800 Series II At 10:10 AM 8/13/2010, Steve wrote: Hi the T800,s both series one and two are great, series one uses eproms series two is an eeprom programmed using a single data line via an rj11 skt on the front and rear. In the UK a series two sells for around 400ukp a low band series one for around 200ukp. ---Thanks for the input Steve. The one I was looking at is supposedly a new demo and the guy wants $975 for it Ken -- President and CTO - Arcom Communications Makers of repeater controllers and accessories. http://www.arcomcontrollers.com/ Authorized Dealers for Kenwood and Telewave and we offer complete repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net We don't just make 'em. We use 'em! Yahoo! Groups Links
Re: [Repeater-Builder] Henry C100D10R Repeater Amplifier Fuse Rating ?
Fuses protect wiring. Equipment should be fused to match the power handling level of the leads that supply it. For a 100 watt mobile, I would choose 10ga wire (unless the leads needed to be quite long) and fuse it at 30amps. 73 Paul - Original Message - From: hfd_firefighter I have one that came with a 15 amp fuse that blows whenever I apply more than 5 watts drive. I suspect that the fuse should be around 20 - 40 amps as the power supply requirement is 25 amps. Anyone know the proper fuse rating for this amp? What is a typical rating for a 100 watt mobile transmitter? I wanted to change the fuse to something larger to see if I can get rated power out, I'm running at 30 watts now with 3 watts drive and the 15 amp fuse. Thanks in advance Jim WA1SOT.
RE: [Repeater-Builder] Coax length, etc.
Hi again Russ, _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO, it's really messy. It can't tell the difference between a 1:1 VSWR and a 2:1 VSWR (both will calculate out to 1.4:1) on a 70 ohm line. That's not accuracy, that's nearly useless. Yes it gets a little tricky to find VSWR with a non 50 ohm line. But most of the time we really don't care what it is. I say we don't care because it is rare that the 50 ohm Bird meter gets used in a non 50 ohm transmission line. With a 50 ohm line things work out nicely to find power and VSWR no matter what kind of reflection the load presents. BTW, my POS Daiwa can show me a 100% reflected condition, just like the Bird. And just like the Bird, it doesn't indicate if that's an open or a short. So what? If you need to know that then you are using the wrong instrument. I believe Bird wants us to believe that their meter is faster and more convenient (it is) yet as accurate as a slotted line and calorimeter (sorry, nope). It's a calibrated voltmeter, not a network analyzer. Try doing the same thing with a voltmeter. :) No one claims it to be anything other than a simple wattmeter. It is not a super accurate at measuring power either. It is claimed to be 5% of full scale reading. That means with a 100 watt slug the best accuracy that you can depend on is +- 5 watts anywhere on the scale. So at 25 watts on the meter scale it could be as low as 20 watts or as much as 30 watts. But for what it is it works very well. For most everyday, mundane RF chores, it's just dandy as we don't really need high accuracy. And as long as line impedances stay reasonably close to 50 ohms, it turns out accuracy is pretty good, too. Again, line impedance doesn't matter for power measurement. 73 Gary K4FMX Certainly not bad for a portable instrument, and that's the point. If we remember what its limitations are, we should be good to go. That's why I own one and want more. Okay, I'm done picking
Re: [Repeater-Builder] Coax length, etc.
Last round. Hi again, Gary. ;-) On 8/15/2010 7:09 PM, Gary Schafer wrote: Hi again Russ, *From:* Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] *On Behalf Of *Russ Hines *Sent:* Sunday, August 15, 2010 4:54 PM *To:* Repeater-Builder@yahoogroups.com *Subject:* Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. Yeah, and? The Bird does it better. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. That's correct. As I said, the 43 isn't a slotted line. Regarding VSWR, all in-line meters make an attempt at this, some have fancy cross-needle indicators where VSWR is represented at the intersection of the needles. How else would you do determine VSWR with such a device? That was a rhetorical question. ;-) As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. Thanks, Gary, that's right. The meter is calibrated at 50 ohms impedance. When the line impedance isn't 50 ohms, you can't just look at the meter, the meter scale is no longer accurate, is it? Subtracting reflected from forward is a given, and never at issue here. Well, impedance does matter. At the characteristic impedance of the meter, line, load, etc., seems a waste of time to subtract nothing, you'll see right away there's no reflected power. ;-) If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Gary, you seem to be contradicting yourself. A paragraph ago you said the ratio of voltage and current work out to the power at 50 ohms. Now we don't care what the impedance is? We either do or don't. As for me, I choose to care 'cuz that's the kind of guy I am. ;-) I understand the coupling, both are present, agreed. But if impedance didn't matter, then the meter would indicate power accurately regardless of line impedance. That's simply not so. The Bird manual even says it's not so. It's limited by its own line section. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO, it's really messy. It can't tell the difference between a 1:1 VSWR and a 2:1 VSWR (both will calculate out to 1.4:1) on a 70 ohm line. That's not accuracy, that's nearly useless. Yes it gets a little tricky to find VSWR with a non 50 ohm line. But most of the time we really don't care what it is. I say we don't care because it is rare that the 50
Re: [Repeater-Builder] Coax length, etc.
Russ Hines wrote: Hi Kevin: Regarding temperature, our club has a site, no A/C or heat, where temperatures inside the shelter can get below +20 deg F in winter, and well over 130 deg F in the summer heat. I can't imagine filter tuning not changing under such conditions, Invar or not. I can see over time where tuning might walk off the reservation. But I bow to your greater experience with cavity duplexers. Duplexer tuning is not the only thing you'd need to worry about with temperature extremes you reference. The radio set might have a hard time with +130 shelter temp. That could easily relate to radio temperatures exceeding the ability of some equipment manufacturers to remain stable. Filters will change with temperature - it's a fact. The amount they change is, I suppose, what's under question. Most commercially made units have a temperature rating of -30 to +60 degrees C. This means the duplexer will remain within its ratings between those extremes. Most of us engineer our repeater systems to have some amount of isolation headroom. Headroom is necessary for several reasons, temperature variations are likely the biggest reason, along with icing of the antenna. I have a site using a Wacom WP-641 and 250 watt transmitter. This site sees -25 degree F temperatures in the winter and +85 degree F temperatures in the summer - outside shelter. The shelter is not climate controlled. The duplexer loss is 1.5 dB or 29%. This relates to 72.5 watts going up as heat. If the repeater is in transmit for a long time, the temperature in the building can approach +100 degrees ambient. Now, add the heat generated by the loss of the duplexer, and the duplexer becomes very hot to the touch. Even at these temperature extremes, the repeater is completely happy with the isolation provided by the duplexer. You state that over time the tuning might walk off the reservation. This seems to allude to the duplexer changing tuning and not coming back to its settings after it has returned to the temperature it was tuned at. If this is the case, the duplexer design is faulty - period. Another chance? Which part, erroneous readings, don't directly measure power, or the voltmeter part? Sure, what the heck. ;-) I've had Bird 43's, and calibrated line sections with matched elements for that matter, give erroneous reflected power readings depending upon what was going on with the transmission line. By erroneous, I mean it was usually a reading that was, for example, excessively high versus what we knew was going on, such as a straight piece of rigid line or coax terminated into a known good load. On rare occasion, we found we slipped a bullet or had a bad connector. More often, relocating the instrument somewhere else along the line resolved those bad readings. If you were able to move the meter and have differing determined power readings, something IS/WAS very wrong. But, maybe you aren't using the instrument correctly? To paraphrase the manual, the reflected power must be subtracted from the forward power to determine the actual power delivered to the load. If you move the meter about the line, it is possible that the power shown on the meter will change, but, if you read the reflected at the same spot, and determine the power - it should always subtract to the same determined power reading. RF calorimeters can measure power directly. But unless they've one hidden in them somewhere, ThruLine meters can not. Just because the Commission might accept wattmeter readings, or Bird says so, doesn't make it so. While I'll agree that the Bird doesn't measure power directly, it still measures power, quite accurately, no matter the impedance of the connected line. Bird claims the meter to be accurate within 5% of full scale reading. While it might not be as accurate as a VNA, it doesn't cost as much either. Let's revisit what you originally wrote: /Our in-line power meters, like our trusted Bird 43, do not directly measure power./ No argument here... / They're really voltage meters calibrated in watts at a specific impedance. / When you were reading the manual, you missed something - read on... As for the voltmeter part, check out page 6 of the Bird 43 manual (page 18 of the PDF), a copy of which you'll recall is here: http://www.repeater-builder.com/bird/pdf/bird-43-wattmeter-2004.pdf I respectfully submit what is shown is a schematic/diagram of a directional coupler attached to a voltmeter as an indicator. An induced RF voltage sample is rectified, filtered and applied through a dropping resistor to a shunt-connected ammeter. By definition, a voltmeter is the shunt-connected ammeter with series resistor part. But don't take my word for it. Take a peek at Chapter 25 in any recent ARRL Handbook (this works for my 2007 copy anyway). Is it less a voltmeter because the induced voltage tracks current on the line? Want
RE: [Repeater-Builder] Coax length, etc.
I don't know if you really don't get it or you are just trying to be controversial. I tend to think a little of both. Either way, I give up. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 7:37 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. Last round. Hi again, Gary. ;-) On 8/15/2010 7:09 PM, Gary Schafer wrote: Hi again Russ, _ From: mailto:Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. Yeah, and? The Bird does it better. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. That's correct. As I said, the 43 isn't a slotted line. Regarding VSWR, all in-line meters make an attempt at this, some have fancy cross-needle indicators where VSWR is represented at the intersection of the needles. How else would you do determine VSWR with such a device? That was a rhetorical question. ;-) As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. Thanks, Gary, that's right. The meter is calibrated at 50 ohms impedance. When the line impedance isn't 50 ohms, you can't just look at the meter, the meter scale is no longer accurate, is it? Subtracting reflected from forward is a given, and never at issue here. Well, impedance does matter. At the characteristic impedance of the meter, line, load, etc., seems a waste of time to subtract nothing, you'll see right away there's no reflected power. ;-) If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Gary, you seem to be contradicting yourself. A paragraph ago you said the ratio of voltage and current work out to the power at 50 ohms. Now we don't care what the impedance is? We either do or don't. As for me, I choose to care 'cuz that's the kind of guy I am. ;-) I understand the coupling, both are present, agreed. But if impedance didn't matter, then the meter would indicate power accurately regardless of line impedance. That's simply not so. The Bird manual even says it's not so. It's limited by its own line section. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO,
Re: [Repeater-Builder] Tait T800 Series II
Ken Arck wrote: At 10:10 AM 8/13/2010, Steve wrote: Hi the T800,s both series one and two are great, series one uses eproms series two is an eeprom programmed using a single data line via an rj11 skt on the front and rear. In the UK a series two sells for around 400ukp a low band series one for around 200ukp. ---Thanks for the input Steve. The one I was looking at is supposedly a new demo and the guy wants $975 for it Ken Ken, The other concern with it is it has a wide band receiver (T855-20) and a narrow band transmitter (T857-26). I am not familiar with the -26 and cannot find much info on it beyond USA only and used with QuasiSync systems (Tait's version of simulcast). Modifying a -25 to -20 is pretty straight forward, but I don't know what is involved with the -26. Ed Yoho W6YJ
RE: [Repeater-Builder] Coax length, etc.
I know I'm going to regret stepping into this one, but since when has that stopped me before... Thanks, Gary, for admitting the 43 doesn't measure power directly. What do you mean by measure power directly? If you're talking about comparing a thruline measurement against absorptive/calorimetric techniques, then that's apples and oranges, one is measuring power in a transmission line (either with or without reflections present), the other is measuring power absorbed into a load, big difference. Please clarify what you mean by measuring power directly so at least we're all on the same page. Of course, it is a directional coupler, no argument. That makes it a reflectometer No, it's not a reflectometer, it can't do forward and reverse measurements concurrently. If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point Not without knowing the phase between the two it couldn't. BTW, my POS Daiwa can show me a 100% reflected condition, just like the Bird. And just like the Bird, it doesn't indicate if that's an open or a short. A Bird isn't a VSWR bridge, it's a directional wattmeter. Yes, it can be used in a roundabout way to measure/calculate VSWR, but it's not a VSWR meter. Sidebar. I grit my teeth when I hear someone on the radio say my SWR meter shows I'm putting out 100 watts. Since when does a SWR meter measure power!???! Do you use your bathroom scale to check your blood pressure? Egads. I'm not taking a stance here (at least not yet) on the relative merits of the Bird 43 or other thruline-type wattmeter line sections or elements, I'm just trying to get a handle on the matter that is the subject of debate... --- Jeff WN3A
[Repeater-Builder] antenna plan
I'm looking for input on an antenna plan. Currently have a Diamond X500HNA on a water tank. Antenna is mounted on a mast, clamped to the fill pipe on the side of the tank, with base of antenna just above the top of the tank in order to maintain a circular pattern. See the picture attached, taken of the west side of the tank. I'd like to change to an ellliptical pattern that favors the bigger town in the county which is roughly at 270 deg west and about 6 miles away. The fill pipe is located on this side of the tank. I'd like to put a Decibel 2-bay folded dipole (model?) that I already have, on our mast so that it is above the tank. I'd like to position the dipoles so that one is at about 30 deg NE and the other is at about 150 deg SE. Here's where the elliptical part comes in. I'd like to take a yagi or corner reflector and mount it lower, at the railing or a short distance up the mast, and point it at the town I'd like to focus on at 270 deg west. It would be fed together with the Decibel using a coaxial power divider. The vertical distance from the bottom of the Decibel and the directional antenna would be about 25 feet. I'm thinking that someone has done this before. How does it perform? Can you put antennas to work together like this and come up with a nice egg-shaped pattern without deep nulls? I am willing to spend time working to get accurate phasing lines fabricated for the power divider. Will I run into problems with patterns shifting because of any slight impedance mismatches between the phasing lines and the feedpoints of the antennas? In simple terms, what I'm shooting for is base/mobile coverage out to about 25-30 miles from the NW clockwise around to the SW, and handheld coverage in the town to the west in my elliptical 'blob'. I realize that there are a lot of other variables involved in coverage area such as output power, sensitivity, feedline loss, haat, and so on. Thanks for your input. 73 Paul - KC0HSTattachment: P4120024.JPG
Re: [Repeater-Builder] Coax length, etc.
Sorry, Gary. I have a bad tendency to question what's put in front of me. That includes what I call the girl copy I read in product manuals and brochures. FWIW, girl copy refers to the rarely-true supposed personal information about the particular lady-of-the-month in certain men's magazines. ;-) I appreciated the banter, take care, Gary. 73, Russ WB8ZCC On 8/15/2010 9:20 PM, Gary Schafer wrote: I don't know if you really don't get it or you are just trying to be controversial. I tend to think a little of both. Either way, I give up. 73 Gary K4FMX *From:* Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] *On Behalf Of *Russ Hines *Sent:* Sunday, August 15, 2010 7:37 PM *To:* Repeater-Builder@yahoogroups.com *Subject:* Re: [Repeater-Builder] Coax length, etc. Last round. Hi again, Gary. ;-) On 8/15/2010 7:09 PM, Gary Schafer wrote: Hi again Russ, *From:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com] *On Behalf Of *Russ Hines *Sent:* Sunday, August 15, 2010 4:54 PM *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Subject:* Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. Yeah, and? The Bird does it better. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. That's correct. As I said, the 43 isn't a slotted line. Regarding VSWR, all in-line meters make an attempt at this, some have fancy cross-needle indicators where VSWR is represented at the intersection of the needles. How else would you do determine VSWR with such a device? That was a rhetorical question. ;-) As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. Thanks, Gary, that's right. The meter is calibrated at 50 ohms impedance. When the line impedance isn't 50 ohms, you can't just look at the meter, the meter scale is no longer accurate, is it? Subtracting reflected from forward is a given, and never at issue here. Well, impedance does matter. At the characteristic impedance of the meter, line, load, etc., seems a waste of time to subtract nothing, you'll see right away there's no reflected power. ;-) If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Gary, you
[Repeater-Builder] repeater builder for 1.2 fn atv
Looking for video id, photo sequencer, 2-8 watts out so that I may attach 20watt final amp. Also what controller may be used most affectively. I need a good jobber that may head me in the direction. Eastern Pa. 800' level ant. de WB3DTG, Bethlehem, Pa. fn20hq73
[Repeater-Builder] Re: Tait T800 Series II
Hi Ed, The differences I see between the -25 and -26 are minor. Caps and resistors in the Low Pass Filter audio stage and a different 12.8Mhz reference with a voltage tuning pin, where the standard didn't have it. The specifications of the reference are same otherwise, 1ppm -20 to +70. If you are going from -25 or -26 to -20, just change the components to the -20 values. Yes, they were defined changes for FCC, according to the book. niteviser --- In Repeater-Builder@yahoogroups.com, Ed Yoho w6yj_ya...@... wrote: Ken Arck wrote: At 10:10 AM 8/13/2010, Steve wrote: Hi the T800,s both series one and two are great, series one uses eproms series two is an eeprom programmed using a single data line via an rj11 skt on the front and rear. In the UK a series two sells for around 400ukp a low band series one for around 200ukp. ---Thanks for the input Steve. The one I was looking at is supposedly a new demo and the guy wants $975 for it Ken Ken, The other concern with it is it has a wide band receiver (T855-20) and a narrow band transmitter (T857-26). I am not familiar with the -26 and cannot find much info on it beyond USA only and used with QuasiSync systems (Tait's version of simulcast). Modifying a -25 to -20 is pretty straight forward, but I don't know what is involved with the -26. Ed Yoho W6YJ
Re: [Repeater-Builder] Re: Tait T800 Series II
niteviser wrote: Hi Ed, The differences I see between the -25 and -26 are minor. Caps and resistors in the Low Pass Filter audio stage and a different 12.8Mhz reference with a voltage tuning pin, where the standard didn't have it. The specifications of the reference are same otherwise, 1ppm -20 to +70. If you are going from -25 or -26 to -20, just change the components to the -20 values. Yes, they were defined changes for FCC, according to the book. niteviser Aha. Any chance of a PDF with the -26 documentation? What pin on the DB25 is the tuning pin brought out to? I also assume the voltage tuning pin needs to be tied to a stable reference. The series II schematic shows the FM pin (VCXO adjust) tied to a divider from +5V (not the most stable reference point). Thanks, Ed Yoho W6YJ
[Repeater-Builder] Re: Henry C100D10R Repeater Amplifier Fuse Rating ?
It is good to keep in mind that a fuse provides full protection only to the conductors downstream of the fuse, i.e. between the fuse and the load. While we often thing we are protecting the wire between the fuse and the point of supply, it gives only limited protection in that portion of the circuit. Using a fuse to provide OVERLOAD protection is a bit different than provideing OVERCURRENT protection. Worst case scenario is a short circuit in the circut ahead of the fuse. The fuse of course provides no protection there. ( And that does happen ) Where is all that smoke coming from?? Wes AE6ZM VE7ELE GROL/RADAR ARRL Technical Specialist Lincoln, CA CM98iv --- In Repeater-Builder@yahoogroups.com, Paul Holm p...@... wrote: Fuses protect wiring. Equipment should be fused to match the power handling level of the leads that supply it. For a 100 watt mobile, I would choose 10ga wire (unless the leads needed to be quite long) and fuse it at 30amps. 73 Paul
[Repeater-Builder] Re: Tait T800 Series II
Ed, The tuning pin is the FM pin of the 12.8MHz module. There were several 12.8 MHz references some with 3 pins and then some with 4 pins which used the half rail to set the frequency mid point. It was quite acceptable to program to the closest frequency on the Eprom and pull the reference either by altering the voltage or adjusting to get the offset. It is still then 1ppm stable. Can you tell me which PCB version you have 220-01398-??, I'll she what I have available. niteviser --- In Repeater-Builder@yahoogroups.com, Ed Yoho w6yj_ya...@... wrote: niteviser wrote: Hi Ed, The differences I see between the -25 and -26 are minor. Caps and resistors in the Low Pass Filter audio stage and a different 12.8Mhz reference with a voltage tuning pin, where the standard didn't have it. The specifications of the reference are same otherwise, 1ppm -20 to +70. If you are going from -25 or -26 to -20, just change the components to the -20 values. Yes, they were defined changes for FCC, according to the book. niteviser Aha. Any chance of a PDF with the -26 documentation? What pin on the DB25 is the tuning pin brought out to? I also assume the voltage tuning pin needs to be tied to a stable reference. The series II schematic shows the FM pin (VCXO adjust) tied to a divider from +5V (not the most stable reference point). Thanks, Ed Yoho W6YJ
[Repeater-Builder] Re: Fs: (/\/\)otorola UHF Desktrac
I don't know about your neck of the woods, but one of the local ham groups picked up a Desktrac already tuned on the ham band to their frequency for $125 with the service manual. It does not have enough of a transmit duty cycle for their semi-busy ham system so it is sitting on the shelf. First $100 will take it off their hands, so they are hard to sell here on the West Coast, even when they are cheap. Good Luck and I hope you find a buyer for your unit. Joe - WA7JAW --- In Repeater-Builder@yahoogroups.com, kc8gpd kc8...@... wrote: Um Ok, I want this gone. Tried swapping it, and selling it so how low do i have to go before someone will bite. not that i will necessarily let it go extremely cheap, but i am just curious about how low i have to go to get it sold. also want to know the reasoning of why it is so hard to get it sold since GMRS and Ham are still wideband. i will also toss in a small cushcraft uhf ringo as well. again will swap to a rebandable p25 mobile scanner or ??? here are pic's http://img405.imageshack.us/i/sales8910018.jpg/ http://img188.imageshack.us/i/sales8910017.jpg/ http://img842.imageshack.us/i/sales8910016.jpg/ http://img683.imageshack.us/i/sales8910015.jpg/ http://img706.imageshack.us/i/sales8910021.jpg/
