Re: [Repeater-Builder] Wacom WP-639 Duplexer question
On 9/8/2010 6:11 PM, RichardK wrote: Good evening, our club has a Wacom WP-639 four can duplexer as part of our repeater system. Input Fq is 147.915 and Output Fq is 147.315. We have a 600kHz (+) offset. Very simply, our main problem is when we run the transmitter at full power 100 watts, there is a HUGE desense on the receive side of things. When we drop the transmitter power level to around 20-50 watts, the receive side opens WAY up to a large area where people can get into the repeater. As we begin to bring up the transmitter power, white noise begins to appear and the receive side starts to desense again. All the cables have been switched to double sheilded cables and all the same wavelength in length. We have the duplexer seperated sheilded from the transmitter preamp parts. We have not replaced the antenna feed coax with double sheilded coax yet. Antenna is a Hustler G7 atop a 55' mast. The duplexer was retuned just over 1 year ago. Any suggestions as to what we could look into next? Some of us believe the problem is with the tuning of the duplexer receive cans. Thank you very much. The Wacom WP-639 is insufficient for 100 solid state watts, unless you run a GE MASTR II PLL exciter and no preamp. You will either need to replace the duplexer with another unit capable of properly isolating 100 solid state watts, add additional filters, change to a less noisy transmitter and amplifier (tubes are better - no I'm not kidding). Kevin Custer - W3KKC
Re: [Repeater-Builder] ariels
On 8/29/2010 1:15 PM, Doug Hutchison wrote: Ariel? Antenna maybe? C'mon guys. Be careful Doug. The poster is from the United Kingdom, where they use the term Ariel, not Antenna. You know what it means, so let it go. This list is not just for Americans, as we have many members from other Countries. Kevin Custer List Owner
Re: [Repeater-Builder] Running a Mastr II Repeater QRP
On 8/30/2010 6:01 PM, Chuck Kelsey wrote: I agree with Jeff 100%. Me three... Kevin
Re: [Repeater-Builder] Coax length, etc.
to call it an ammeter or current meter then, after all that's what the actual meter movement is? Talked yourself right around the circle there. ;-) You didn't say anything about CURRENT in your first post. While it reads voltage, it also reads current. These two are combined to read power. 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. No - they measure current and voltage and display power in watts, no matter what the impedance is. / 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./ Sorry - I don't agree. Kevin Custer
Re: [Repeater-Builder] Coax length, etc.
Jeff DePolo wrote: Because the impedance is not matched between the transmitter and duplexer, the 'apparent' loss of the duplexer is greater than the manufacturers stated loss of the duplexer. Changing the cable length is not changing the loss of the duplexer, it's changing the power that is accepted at the transmitter port of the duplexer by matching the output impedance of the transmitter to the input impedance of the transmitter port of the duplexer. But if the duplexer is tuned to 50 ohms, and the cable is 50 ohms, varying the cable length isn't going to change the Z seen by the transmitter. Or are you suggesting the duplexer is purposely de-tuned from 50 ohms? Purposely, accidentally, by lack of good design - people not having the right equipment to tune it correctly - whatever. And also that by varying the cable length between the transmitter and the duplexer that you can vary the reflected power on that same line? Yes. With all due respect, that's not possible, regardless of what the Z is of the duplexer. The only time it could have an effect on the reflected power would be if the transmitter/PA were spurious, and the amplitude/frequency of the spurs changed with varying load Z, and I think we can both agree that if that's the case, we have bigger fish to fry. And this is where I believe the duplexer manufacturers are covering their butt. They don't want the problem with complex reactance presented by the duplexer to be their problem. Not that I don't agree, because it's usually the transmitter that is really at fault. Joe Ham buys a new duplexer and hooks it up to his 110 Watt MASTR II repeater and gets 50 watts out the antenna port. He does his homework and realizes that he should only be loosing 29% with the 1.5 dB of insertion loss stated in the paperwork - but he's loosing over 50%. The duplexer manufacturer supposedly engineered and tuned it for a 50 Ohm system. He knows that the cable he connected to the transmitter is good, because when he disconnects the end going to the transmitter port of the duplexer and connects it to his Bird 43 terminated with a good load - it reads 110 watts. Now, is the transmitter becoming spurious and the cable length being changed in length satisfies the match between the duplexer and transmitter - I don't know... All I can tell you is I have followed the suggestions written in the WACOM manual and it has worked. I had one instance of a ham radio club loosing PA's left and right on their 2M machine. They told me of the situation and I offered to do a little testing. The 110 watt PA would put out 110 watts into a Bird and dummy, but only 45 watts was coming out the antenna port of the duplexer. At the time I didn't own a spectrum analyzer. The repeater wouldn't duplex without desense. I changed the length of the line between the PA and duplexer until I got the power to read about 75 Watts as I remember. That was 13 years and they still have the same PA - no desense either. Not to belabor the point, but whatever the VSWR is on a length of transmission line, that's the VSWR that's on the line *regardless of length*. You can't change the VSWR by changing the length of the line. As you vary the length, you go round n' round the Smith Chart in a constant VSWR circle, with the Z repeating cyclicly every half-wavelength, but you've still got a complex Z that nets a 1:5:1 VSWR relative to 50 ohms at the end of whatever length of line you choose (cable loss effects notwithstanding). There are an infinite number of complex Z's that yield a 1.5:1 VSWR - cut the line to any random length and you'll hit one of them. In a situation where the duplexer and transmitter have differing impedances, and a cable optimized in length matches these impedances, the mismatch at the duplexer is minimized, therefore the power reflected by the duplexer is minimized. I think what you're really saying is that the mismatch at the *input to the matching section* (i.e. the cable between the PA and the duplexer), NOT the mismatch at the duplexer, is minimized. Sorry - that is what I meant to say. Many of us use converted commercial gear in the ham band. Many don't take the time to properly convert the receiver and especially the transmitter to properly operate in the adjacent ham band. So, when you run a 150.8 to 174 MHz amplifier in the 2M ham band or a 450 to 470 MHz amplifier in the UHF ham band is it going to represent a good 50 Ohm impedance? Likely not... We need to realize that most duplexer manufacturers know what they are doing and their products are presenting a 50 ohm match on its intended frequencies - unless somebody has adjusted on it. But, because the duplexer is not a perfect load, it creates reactance and the transmitter/PA may not like it. If it doesn't like it, it may become spurious. If it becomes spurious, it isn't putting out all of its power
Re: [Repeater-Builder] Coax length, etc.
Kevin Custer wrote: Joe Ham buys a new duplexer and hooks it up to his 110 Watt MASTR II repeater and gets 50 watts out the antenna port. He does his homework and realizes that he should only be loosing 29% Wow -* loosing -* that should have been losing - that's what I get for being in a hurry
Re: [Repeater-Builder] Coax length, etc.
Kevin Custer wrote: I had one instance of a ham radio club loosing PA's left and right on their 2M machine. Indeed - I am loosing my mind - grin K
Re: [Repeater-Builder] Coax length, etc.
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] Coax length, etc.
Ross Johnson wrote: So will someone post a simple rule of thumb... If you have the option of optimizing cable length from PA to first cavity, IE you haven't made them yet what's the best simple rule of thumb to follow to build them to avoid reactance. 1/2wl if allowed minus coupling loop depth? Or is that past a simple thumb. Simple rule - there is none. The length can be determined experimentally as outlined in several publications of various duplexer manufacturers. I use the length I need to do a good job - then, if the transmitter is unhappy, I build a cable long enough to do the job and satisfy the transmitter. Kevin
Re: [Repeater-Builder] Coax length, etc.
Jeff DePolo wrote: Maybe I'm not understanding right. Are you saying that by varying the cable length between the transmitter and the duplexer that you can affect the insertion loss of the duplexer? No. Because the impedance is not matched between the transmitter and duplexer, the 'apparent' loss of the duplexer is greater than the manufacturers stated loss of the duplexer. Changing the cable length is not changing the loss of the duplexer, it's changing the power that is accepted at the transmitter port of the duplexer by matching the output impedance of the transmitter to the input impedance of the transmitter port of the duplexer. And also that by varying the cable length between the transmitter and the duplexer that you can vary the reflected power on that same line? Yes. In a situation where the duplexer and transmitter have differing impedances, and a cable optimized in length matches these impedances, the mismatch at the duplexer is minimized, therefore the power reflected by the duplexer is minimized. Please tell me I'm reading this wrong...I've been on the road a long time and working a lot of long hours, so it's quite possible... --- Jeff WN3A I have found that when you get a transmitter that is 'picky' about the length of interconnecting cable, power being read at the output port of the duplexer is low and you cannot alter the tuning of the cavity closest to the transmitter to make things right. In other words, the place where lowest VSWR and maximum power transfer occurs is at two completely different places, and power transfer is not up where it should be (transmitter makes 100 watts into a dummy load but only shows 50 watts on the output port of the duplexer that has a stated 1.5 dB loss (29 %)). As you get close to the 'optimum' cable length, the lowest VSWR and maximum power transfer occur near the same place when tuning the cavity closest to the transmitter. I usually pay more attention to what is coming out the antenna port of the duplexer - first. Then, when things are right, comparing forward power going to the duplexer and power going to a good dummy load will be very close the same, since matching the impedance of the transmitter to the impedance of the duplexer was accomplished by some means. I use a compensation cable along with my Bird so that the samplers transmission line length is nullified in the line under test. This compensation cable results in exactly 1/2 WL including the samplers transmission line. Compensation cable lengths are outlined in the manual for the Bird 43. Kevin
Re: [Repeater-Builder] Need low power PA mod help for VHF MVP
Thomas Oliver wrote: I am in need of a 2-5 watt range amp to drive an external amplifier, the stock VHF MVP amp is adjustable from 8-25 watts output, I think by bypassing Q202 I will be close to my goal. I need to know where to connect the coax to keep Q201 from getting mad. I have done this on UHF MVP's before but the VHF amp is coupled differently between stages. Schematic here: www.repeater-builder.com/ge/lbi-library/lbi-30143a.pdf Try removing Q202 and placing a coupling capacitor between the pads where the Base and Collector were. Something between 100 and 470 pF should do it. I'd use a silver mica with short leads. Kevin
Re: [Repeater-Builder] Mirage B-320-G as a Repeater Amp
Bob - AF6D wrote: Before adding a Mirage 320 our TKR 750 was putting out 50 watts into a 6 cavity Wacom WP-642 at the cost of 2-3dB loss on TX (as the spec sheet said.) The cans are tuned right on the money and the Hustler G5-144 fed with LMR-400 is 1.1:1. This has worked for over a year just fine (except for grungy weak signal audio.) Now add the Mirage B-320-G 200 watt amplifier. It seems to work just fine outside of the repeater chain. On its low setting 3 watts will drive it to 200 watts. On its high setting 50 watts will drive it to 200 watts. We plan on adding two fans on the heat sinks and rack mounting it and running it with only 25 watts drive. The power meter lights up all the way to the red. But as soon as we tune it all up and connect it to the duplexer the Mirage SWR/Drive trips and the amp goes to sleep. A SWR meter between the repeater and the amp shows 1.1:1. The amp to the duplexer shows 1.1:1. The duplexer to the antenna shows 1.1:1. I've lost my mojo. Waz up? We'll assume the Mirage amplifier is either tuned to a 50 Ohm output impedance by any internal adjustments or there are no adjustments to tune the amplifier to match the load. That being said, it is possible that the Mirage Amplifier doesn't like the reactive load presented by the duplexer. If so, you will need to do one (or more) of the following: 1.) Use an impedance matcher (sometimes referred to as Z-Matcher) capable of handling the output power of the amplifier. http://www.repeater-builder.com/db/pdfs/db-z-matcher-tuning-info.pdf http://www.repeater-builder.com/antenna/duplexer-cabling-lengths.html 2.) Use an Isolator or Circulator tuned to your transmitter frequency properly sized to absorb the reflected power. You still might have to use #1 or #3 to aide in matching so you aren't wasting the power reflected back to the transmitter or the power not being transferred to the duplexer, out the antenna port, as seen as a loss greater than the 2 to 3 dB stated by the manufacturer for this duplexer and your interconnecting cabling. 3.) Optimize the cable length from the amplifier to the transmitter port of the duplexer to maximize the return loss (create a better match). http://www.repeater-builder.com/antenna/duplexer-cabling-lengths.html Please also read the note about cabling lengths between the repeater and the duplexer in the section on page 4 of the following document: http://www.repeater-builder.com/wacom/wp6xx-vhf-tuning-instructions-remec.pdf Watch for word wrap... Doing #3 might require doing #4. 4.) Optimize the tuning of the first cavity of the duplexer from the factory setting. BE CAREFUL HERE... Assuming no one has ever tuned the duplexer from its factory settings, and assuming the factory knew what they were doing and tuned the duplexer correctly (tuned it for maximum return loss (best match at 50 Ohms on your frequencies) and best response, or a compromise of both - usually the case in a factory tuned Wacom product. Realize if any cavity is/was re-tuned at any point you are altering the response intended by the factory. It is possible, however, to optimize the cable length and lightly retouch the tuning the first cavity to fix the situation you have encountered. Optimizing the cable length will shift the impedance to create an acceptable match between the amplifier and the transmitter port of the duplexer and retouching the first transmitter cavity will nullify the reactance presented by the line. If you are not willing to re-tune the duplexer, then only consider the solutions in #1 or #2. I'm hopeful Jeff DePolo or Allan Crites will look this over and add correct what ever I missed. Kevin Custer
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
radi...@aol.com wrote: Hi Kevin, The desense is a staticy reception of weaker signals( ie an HT at 25 miles) It had gotten worse as it started to affect strong signals too. If the transmitter was turned off, the repeater could hear just fine. Problem is intermittent and often followed a rainy day. We replaced EVERYTHING A UHF repeater on the same tower is unaffected. At this point we think the new antenna is failing. Tower sections have been bonded grounds improved etc etc To know whether or not the problem is the antenna system, do a desensitization test directly at the antenna port of the duplexer using a good load and a lossy tee or other acceptable method like a coupler slug installed into the Bird Watt meter. If you don't know how to perform a desense test, there are several articles on the website that will assist you. If this proves good, then you have more work to do on the outside. Let us know... Kevin
Re: [Repeater-Builder] Re: Coax length, etc.
motarolla_doctor wrote: Kevin, I am using your coaxial matching section on a couple of antennas with good results. Great article on RB and not too hard to build MD, I wish I could take the credit, but the original concept was from a friend W8ZD - I just improved upon his concept. For those interested in what we are referring to, or, have availability of large (free) CATV hardline and want to use it in 50 Ohm service, go here: http://www.repeater-builder.com/projects/matchingstubs.html Thanks, Kevin
Re: [Repeater-Builder] Re: Dissasembly of msr 2000 continuous duty amp. How?
wb6dgn wrote: There is a process I use to easily see which stage is bad. Reply if you need more help. Maybe you'd consider posting it here? Always looking for better ways to do things. Tom DGN Verify you have drive to the PA by looking to see how much is coming out of it or any filters that follow. Then take the watt meter and put it on the antenna connector and terminate the meter with a suitable load. I use a Bird 43 with matching 100 watt dummy load. I usually start with a 10 or 25 watt slug no matter the size of the PA. If the correct drive is coming from the exciter, make sure the correct voltages are present on the stages of the PA. PNP RF transistors are used in the MICOR VHF PA, so put your thinking cap on upside down. If you have a hand-held radio, tune it to the frequency of the transmitter, and remove the rubber duck and set it off to the side - out of arms reach. Key the defective radio and touch the base of the first transistor in the PA with the metal blade of the Motorola MICOR tuning tool. Watch the S-Meter on the hand-held or listen for quieting. On my Yaesu FT530, I normally get about 1/2 scale S-Meter reading on the base of the first stage. Keeping the radio keyed, touch the collector - the S-Meter reading should be considerably stronger and quieter. If not, you might have found your problem. Anyway, continue doing this down through the stages until you find the bad one - moving the hand-held radio back away as need to add loss. Once you find the stage that has no apparent gain, take a small capacitor (a few hundred pF) and trim the leads so you can use it to bridge across the base to the collector. The leads only need to be long enough to be able to go across the transistor to couple energy at the base to the collector. If the stage is bad, you will see the PA make *some* power - there will be some indication on the watt meter. The transistor, when bridged shows output power, is likely bad and needs replaced. This method can generically to troubleshoot other makes and models of PA's. DISCLAIMER: I have worked on some ill engineered equipment that will go spurious and blow up if you touch one of the RF transistor conductors with some metallic object. This has never happened to me with a MICOR or MASTR II PA, but has with Spectrum and some other junk. Do This At Your Own Risk!! In the MICOR, the first or second stages are usually the culprit, unless something has taken out the final stages, which should only be replaced as a whole, with matched units, if one or more are found to be bad. Kevin Custer
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
radi...@aol.com wrote: Hi Kevin, I have confirmed that 2 of the 4 finals are bad. both are on one side of the push pull. Both open base connection One has collector to emitter short. The other open emitter. I have not yet checked the drivers I might be able to test them without removal. I have a friend trying to scare up a Mitrek Aside from the transistors which I know are hard to find, and the cooked 12 ohm resistors, Is there something else I need to look for? I doubt it. Usually the resistors go because of the imbalance from one or more of the transistors failing. I recommend replacing all of the output together with matched gain transistors, if you choose to repair the PA. We think it was an intermittent Duplexer or antenna issue that caused it to blow. We have since replaced the repeater, amp, and duplexer but a desense condition has returned after a few weeks. The antenna is a 4 bay folded dipole on a 100 foot tower. this Antenna replaced a Stationmaster only about 3 years ago. Tower is Rohn 45? guyed with Phillystrand. Thanks for your help. Marty What kind of desense? Does the repeater properly duplex on a known good dummy load? Kevin
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
radi...@aol.com wrote: Sucess! I completely cleaned and re tinned my Weller 8100 tip, added some solder, and got heat transfer to pop it up. I was not aware of the fish paper that the wires came thru. Now to troubleshoot the amp. It probably has some blown transistors as well as the cooked caps and 12 ohm resistors across some of the finals. We do have a Motorola test set, I have done component level work in the past, but this is out of my league. Kevin, I may take you up on your offer for further help. Thanks to all who responded. 73, Marty Consider obtaining a used MICOR mobile (usually can be gotten for $5 to $50) having a power amplifier board of the desired size and transplant it onto your heatsink. The PA assembly for this mobile radio is identical to the one(s) used on the continuous duty MICOR and MSR2000 power amplifiers. Or, just figure out which stage is bad and replace the transistor(s) that have failed. There is a process I use to easily see which stage is bad. Reply if you need more help. Kevin
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
Tom Parker wrote: Why has no one suggested replacing the guts of this beast with a Mitrek PA? Why? Kevin
Re: [Repeater-Builder] Coax length, etc.
Russ Hines wrote: Thanks, guys, a good topic and one that always seems to come up. And it sparks more questions and comments, of course. The cable length issue is a brother to if you don't like your VSWR, change the point along the transmission line where you're measuring it. By changing the length of the line, we're creating a transmission line transformer (a good thing) but we're limited by its length (not so good). It seems to me the mentioned circulator/isolator at the output of the xmtr is a better fix, as reflections coming back from the duplexer is absorbed by the circulator's load, the xmtr is generally happy, and we're no longer limited where we can put things in a rack or elsewhere. For amateurs, coming up with usable VHF circulators seems to be difficult and usually expensive, and coax always seems to be cheaper. Has anyone had luck finding a source for reasonbly priced VHF circulators, or success in rolling their own? Also, I noted in the pamphlet Kevin referenced that the unused duplexer port was left open (Figs. 1 2). I guess if the isolation is already greater than the load's return loss, it doesn't matter, at least at the reject frequency. But it seems to me one could possibly create problems for oneself by not terminating the unused open port. Just a thought. Maybe I work better knowing there's a load there. ;-) Your comments, please. 73, Russ WB8ZCC I think we all agree that a real impedance matching device is the best approach, but hams (generally speaking) are cheap. Many will spend two days hacking on a piece of RG-214 before spending fifty or a hundred bucks on a different (better?) solution. Allan Crites and I are currently in discussion which will be used as the basis of a RB web article that will explain exactly what is happening, why it happens, and why an 'optimized' cable length can be used to transfer power ending up with the stated loss of the duplexer and have little reflected power toward the transmitter - so long as the duplexer is tuned properly and exhibits good return loss on the frequency it's designed to pass. Kevin Custer
Re: [Repeater-Builder] Coax length
Doug Hutchison wrote: Does the length of coax connecting cable between repeater and filters matter? Yes - and no. Please read the note about cabling lengths between the repeater and the duplexer in the section on page 4 of the following document: http://www.repeater-builder.com/wacom/wp6xx-vhf-tuning-instructions-remec.pdf Watch for word wrap... Kevin Custer
Re: [Repeater-Builder] Re: Dissasembly of msr 2000 continuous duty amp. How?
Bill wrote: Apparently no one here got the moto memo on working with giant heat-sinks. First you only need a 30-40 watt iron to work on them as moto did at the factory The secret is.. raising the heat-sink to about 3-400 degrees while you are working on what needs to be done. PS .. don't touch it with fingers or arms. This technique also lowers possibility of cracking the ceramics. I usually lay out everything that has to be done in advance with extra planning. Hey, I didn't say it was going to be quick... . Bill Atlanta The amplifier in question is a MSR2000 VHF, not UHF - no ceramics to worry about - no oven required. Kevin
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
radi...@aol.com wrote: Thanks Kevin, I think you are on to something. The areas that are pinned down seem to be close to where the power supply wires enter the board from the underside. I am wondering if the wires are glued down with RTV or something. Cautious prying is still not getting me anywhere. Marty Get a friend. Using two solder guns (Weller 8200 or like) heat both joints where the feed-through pins come through. Pull straight up when you have both heated well enough that the solder is fully molten. This process can be done with one gun/iron, but it's difficult at best; as you have to alternately heat and pry which puts a good bit of strain on the board until it becomes free. You could also try a de-soldering tool cleaning out the holes where the feed-throughs protrude from the board, but again, this can be difficult to remove the solder that lays under the board depending on the amount of heat you apply and the quality of your de-soldering pump. Kevin
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
radi...@aol.com wrote: OK Kevin, I had already tried the desoldering with a really good Pace unit, but the heat did not transfer well. I will get a buddy to help and use my Weller guns. I have a big 250 watt one here somewhere. Marty Let us know how you make out - or, if you need more help... Kevin
Re: [Repeater-Builder] Dissasembly of msr 2000 continuous duty amp. How?
martinfriedman67 wrote: Our Amateur radio club's Motorola MSR 2000 continuous duty amp needs repair. I cant figure out how to remove the amp board from the heat sink. I removed all screws from corners as well as the transistors. It seems to be held by the center, just below the tall air variable cap. I tried heating the solder in the area but, no joy. I don't want to crack the board. The drawings in the manual I found here do not show even the screw holes. Thanks in advance, 73, Marty (WB2BEW) Look for the via that carries the power supply connections to the board. Sounds like they are holding you back. Kevin
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Joe wrote: Hello Bob, I agree that the GLB is a space saving device, but don't you think that the multistage helical coil stages in the preselector with beat a single cavity in skirts and out-of-band rejection? Curves for the GLB are available here: http://www.repeater-builder.com/glb/glb-preselector-order-form.pdf While the skirts and OBR of the GLB might beat a single cavity, many times it isn't necessary - especially if the receiver that follows is able to cope with high out of band signals and the preamp that follows the cavity has a high overload point. The problem is, like any receiver that has several helicals in cascade before the first active stage, the loss that precedes the active stage has a majority role in the overall NF of the system that follows. It matters little what the quality of the active stage is, because the loss has already determined (for the most part) the system Noise Figure. The GLB preselector preamp has 4 helical stages of unknown (unknown to me) coupling. If they are over-coupled (and I believe they are not looking at the response curves) only a few dB of loss will occur before the active stage. If they are lightly coupled (which I believe is true) then several dB of loss occurs ahead of the active stage. Every dB of loss ahead of the first active stage ADDS to the system NF - period. This loss can NEVER be recovered no matter how good the preamp is that follows. Kevin
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
Kevin wrote: The problem is, like any receiver that has several helicals in cascade before the first active stage, the loss that precedes the active stage has a majority role in the overall NF of the system that follows. It matters little what the quality of the active stage is, because the loss has already determined (for the most part) the system Noise Figure. Skipp wrote: Kind of makes it look like helicals are a sin doesn't it... Hamtronics thinks it's a sin - that's why their receivers have some of the best sensitivity numbers of all of the stuff we commonly build repeater from. However, their receivers get hammered in high RF density locations, and the result is the need of some added filtering ahead of it. This is where the GLB can and does provide an improvement. I speak with experience here. I have used many Hamtronics receivers and GLB preselector/preamps (that I bought new) over the years. If you are lucky enough to have a really clean repeater site, the Hamtronics receiver line will work fine with no added preselection. I bought the GLB's primarily for protection to the repeater receiver when I was using a frequency agile in-band remote base. Many times it was possible to link to repeaters on the adjacent channel when I had the GLB in place. The addition of the GLB wasn't without its drawbacks though. My Hamtronics receiver would hear at -125 dBm for 12 dB SINAD stock with no preamp or preselection (the first GaAs device is basically unprotected). Running an in-band remote base anywhere within a MHz or so of the repeater input would desensitize the Hamtronics repeater receiver. After installing the GLB, I could link to repeaters 15 kHz away from my input with very little desense from the remote base transmitter. Anything over 60 kHz had no affect on repeater receiver sensitivity. The link beams were 50 to 100 feet below the repeater antenna and I normally run 5 watts on the Icom 900 stack. A 2-Meter version I have lots of pictures of has 1 stage of pre-selection and four trailing stages. The active device is an MRF-901. And the coupling for this model is a slightly different method than some (not all) of the other models I have looked at. Are you sure that's not 4 section preceding the device and 1 following? In more than a few real world situations you might really need the filter pre-selection a lot more than the most optimum NF. A practical trade of pre-selection for a slightly higher noise figure can and does sometimes make the difference in a usable radio system. No argument here If the site noise figure is worse than the NF of the GLB, adding it won't hurt your actual effective receiver sensitivity, and the added filtering can be a real boost. However, I'm blessed with sites that allow me to realize most of the sensitivity from a good preamp - with not much ahead of it (now that I don't do much RF linking). Kevin
Re: [Repeater-Builder] Repeater trans mit levels at the receiver?
n...@no6b.com wrote: At 7/31/2010 09:31, you wrote: Joe - the picture was inside the e-mail. Bob - it is an SO-239 Tee, and it is into a dummy load. (checked on 2 different ones). Longshot, but try replacing the T, preferably with a silver-plated one. I know I've had old PL259/SO239 elbows generate desense when I tried using them on the duplexer output of my 2 meter portapeater. Cutting apart some cheap UHF elbows manufactured by a famous CB company revealed a spring between the contacts. Great for CB, not so great for VHF/UHF. Use Amphenol or Kings - costs more, but tastes great - less filling Kevin
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Tim, I have a two meter repeater that outputs 250 watts (approximately +54 dBm) into the duplexer. After the 93 dB of rejection that the duplexer provides for shear power reduction toward the receiver port, -39 dBm of transmitter power leaves the duplexer receiver port - headed toward the receiver. The repeater is a Motorola MICOR VHF equipped with a MICOR preamp. Bench sensitivity is -125 dBm for 12 dB SINAD. The duplexer is a stock Wacom WP-641. This repeater normally uses a tube type power amplifier to achieve the 250 watt level. Using the tube power amp, no desense occurs on the repeater. I also have a the stock 110 watt MICOR power amplifier (solid state) that can be switched in. The repeater has a slight amount of desense when running the solid state PA. Why? It's obviously not the shear amount of power, as it has been reduced over 3 dB. The culprit is /transmitter side-band noise/. The solid-state power amplifier provides no additional protection of the amount of transmitter side-band noise being produced by the exciter, in fact, being wide-band in nature, the solid-state unit amplifies the noise. The tube power amplifier, however, is a High Q (very narrow band - tuned to the exact transmit frequency) device only providing power gain on the 'desired' repeater output frequency, and reducing (or at least not amplifying) the transmitter side-band noise appearing on the receiver frequency. From your explanation below, I don't believe shear power is ruining your ability to duplex, but rater the amount of transmitter side-band noise reaching the receiver. To prove this, install a notch cavity in the transmit leg tuned to the receiver frequency. If your duplexer isn't capable of allowing the present radio equipment to properly duplex, either the duplexer needs replaced, or you can change the type of transmitter to something else - no, I'm not suggesting tube-type. General Electric built a VHF exciter that has 22 dB less transmitter side band noise (600 kHz from its primary carrier) than most multiplier counterparts (like your Motorola MICOR). Using it is like installing a 22 dB notch filter between the exciter (transmitter) and receiver where side-band noise is concerned. This exciter is the MASTR II PLL. To comment on the folks privately emailing you telling you a MICOR receiver cannot handle an off frequency carrier of -53 - they are full of it - period. The answer is HOW CLEAN the adjacent frequency signal is. If the adjacent carrier is full of noise, and that noise falls on the frequency the receiver is listening to - then no the receiver can't handle it, but that's a totally different thing ruining your lunch - comparing apples to oranges. Hope this helps... Kevin Custer Hi guys, Took some time away from the project... loosing too many hairs. Ok, I've gotten another receiver strip, and it has the specified sensitivity per Mot. Guess I want to bounce some ideas around with those of you who are more learned in the arts! With 250mW (+24dBm) into the transmit port... antenna port is a quality 50 ohm load, I see -72dBM at the receiver port. (pretty much what I expect.. 1.8dB loss through the xmit side, 100dB notch through the RX side. With it all hooked up receiving an input signal of about 0.7uV, application of the 250mw to the transmitter side will cause noise in the receiver, although not much. So, it appears that if I add an additional 30dB notch (another 'can'), the problem at high power may go away. If I compare what 50 watts with an additional can would be (-130dB) to what I get with 250mW current notch (100dB), then it looks like I just need to add an additional can. 50 w = +47dBm - 130dB future notch = -83dBm at receiver. 250mw = +24 - 100dB current notch = -76dBm With the current notch @ 50 watts, I see a receive signal of -53dBm. Some have said that the Micor can handle that, while others (off-line) have said no way. This setup appears to support the opinion that -53 is still way too much. Any comments and thoughts would be most appreciated! Thanks, Tim
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Tim wrote: Hi Kevin, Thanks for the info. I've used the PLL MastrII exciter on a couple of systems also. Now, since this duplexer is of the 'notch' variety, I already have about 100db of notch (on the TX side) that is tuned to the RX freq. Shouldn't this be enough? Yes, 100 dB of duplexer isolation should be plenty - something is obviously a amiss. How dirty is the transmitter (spectral purity)?
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Larry - I didn't. The 250 watts is produced by a GE MASTR Pro/II 4EF5A1 capable of 330 watts continuous. The MICOR high-band tube amplifier, IMHO, is junk compared to the GE 4CX250R based VHF power amplifier. The 4EF5A1 is designed to operate from 144 to 174 MHz. without modification. Obtaining proper drive for it was the fun part. Read all about it here: http://www.kuggie.com/ahra/hmft.html Pictures of it here: http://www.kuggie.com/ahra/hmft.html Kevin Kevin - how did you get the MICOR 250 Watt VHF Amplifier to go down to 2-Meters? Or was it a factory 140-150 MHz range unit originally? I see plenty of the 100-watt (I think they're a TLD-1692) amps that are factory 2-Meter range PA decks (I have a few spares, in case I ever need them) but haven't ever seen a factory 140-150 range 1/4 KW PA. I know they do exist, and a few people have them. I just haven't found one, or found anyone who can move the 150-170 MHz range units down to 2-Meters. Thanks and 73, LJ
Re: [Repeater-Builder] Re: Simrex - GLB Pre-Selector Pre-Amplifier
skipp025 wrote: The less gain is related to the internal filtering stages, not the device. I would expect the version with the GasFet to have the typical expected NF for that device. Any other available active devices to have Noise Figures commensurate with their typical expected values (for those devices). I doubt it. But without any real NF numbers, it's all guesswork. I have measured all the original GLB Pre-selectors and their performance values are very realistic (no surprises). I wouldn't expect a surprise/difference if I ordered the GasFet equipped Simrex Pre-selector. What you are missing is that ANY losses ahead of the first active stage add to the noise figure of the system - directly. So, while filtering exists in the GLB device, so does loss, and this loss is more than what is experienced when using a quality large diameter cavity. Many times Skipp you tell us there is no free lunch, and the same applies to the comparison of selectivity and loss between the GLB and a quality cavity followed by a good active stage. Real world test. Take a Hamtronics receiver (no preamp) and do a basic bench sensitivity test to obtain a baseline. If you find something around -123 dBm your in the right ballpark. Now install a bi-polar GLB preselector/preamp in front and measure the sensitivity again - you'll find you have lost several dB of bench sensitivity - at least 3 or 4 dB. Take the same receiver and add a quality 1/4 bottle with a good preamp (your choice - something with 1.5 dB NF or less) and do the test again. Now, the receiver hears at -123 to -127 dBm (dependent mainly upon the quality of the preamp that follows) because the filter hasn't severely ruined the system NF ahead of the first active stage. Even though the GLB has gain, the noise figure of the design has already determined the sensitivity that will be realized by the receiver that follows. The GLB preselector/preamp should not be considered for adding basic sensitivity, because it's possible (depending on how good the receiver is to begin with) the opposite will happen - however, it will protect a receiver that lacks good front-end filtering, like the Hamtronics. Like everything, the situation helps to dictate what equipment will give the best results. Kevin
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Tim wrote: Using the Micor's exciter - about 270mW. Cannot see any spurs/noise within 80dB of the main carrier. I wonder Most of the MICOR exciters I have converted to 6M result in more than 270 mW of power - in fact, 400 to 600 mW is common. I wonder if something is amiss at the exciter, like a bad crystal or stage not peaked correctly generating noise. If you have a 6M hand-held or mobile rig capable of transmitting on your repeater output frequency, try substituting it for the MICOR and see what happens to your receiver with one of these transmitting instead. Kevin
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Steve wrote: Hi Kev would it be feasable to use a sig gen cranked right up ? Depends on how clean the signal generator is. I'd think it doesn't have enough smoke (output capability) to really be beneficial Many generators have a strong carrier (here we go again) adjacent from the desired carrier by few, several, many kHz/MHz. Also, depending on make/model, it may not be as clean (spurious emissions) as a tuned circuit (read MICOR exciter). I wonder how many of the -53 naysayers have or have used a Cushman CE-3? LOL! The folks that have looked at the output of one of these on a spectrum analyzer will get it. K
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Tim wrote: Actually, the output is about +26dBm, so it's closer to 400mW. Good - that's more like it. I've also tried a VX-5 on low power, and got the same result. Obviously, something is wrong with the operation of your duplexer or interconnecting cabling. I really don't think it's providing the isolation you believe it is... Can you explain in detail how you are determining the notch depth of the duplexer. Also, what exactly are you using for the components of the duplexer? If it's the coax stub type, which article have you followed? Thanks, Kevin
Re: [Repeater-Builder] Repeater transmit levels at the receiver?
Tim wrote: Hi Kevin, Yes, the original used RG-58.. couldn't see using it. Figured it would give me desense! As far as the amount of notch, I was surprised that the total was more than each one added, Don't be - it's common for the apparent notch to be deeper than the measured addition of individual cavities - added together. Don't be fooled, the depth was there the whole time (no black magic here), it just wasn't all being realized in the test set-up. Proper interconnect cable lengths can do a bunch for notch depths. but with 50 watts coming out of the antenna port, I see -55dBm at the RX port. - kinda made me think the original measurements were ok. What you see coming out the RX port depends on several factors: How good the match of the attached equipment is - at the frequency being tested, and the phase angle of the connecting cable. Other factors play a part too, but these two play the bigger part. I cut them to 35 each. (visible coax showing between each end of the PL-259). Not exactly to length. Might affect performance a bit. I wouldn't have chosen UHF connectors for building the duplexer. IMHO, their construction leaves a lot to be desired when trying to optimize a duplexer for maximum performance, unless you take their inherent flaws into consideration when using them. Wacom built a good duplexer which uses UHF connectors, but they actually used those properties to their advantage. 35 inches, plus the amount inside the connector results in approximately 37-1/2 inches of interconnecting cable. From my calculations, I have extrapolated your optimum notch depth to appear on 54.44 MHz. I believe, with RG-142 coax, that a length longer than 38 inches will be needed, depending on your exact frequency. From your photo, I believe some of your problem to be the UHF connector and how you have it mounted. A solid ground all around the connector is important to achieve a low impedance (low inductive reactance) connection. I have always preferred the Utah Cap approach for building the Heliax duplexer. It allows you to realize most/all of the potential of the stub. The thicker the copper (within reason) the better. Also - it looks like you might be using only one connector per stub. If this is true, and you are using a UHF tee connector with the stub - it won't work as expected. The electrical length of the tee will throw the whole thing off - this might be your biggest problem with your design/construction. Kevin
Re: [Repeater-Builder] Re: Repeater receiver testing
allan crites wrote: Kevin, I'm sorry to have to tell you this but I think your calculator batteries need to be changed. 0 dBM = 0.2236 volts in a 50 Ohm circuit. +20 dBM is indeed 100 mW and P=EI and inserting 100 mW into the Eq. for Volts in a 50 Ohm system, E= the sq. rt. of the quantity (.100 x 50) = sq. rt. of 5 = .707 V. or 707 mV. not the 2.24 V. you indicated. Not sure what planet you are from Allan, but since you admit that 0 dBm is .2236 Volts, and everyone knows that an increase in power by 10 dB is the same as multiplying that figure by 10, I'm correct - you are way off. Even if the rcvr had an input Z of 50 Ohms (without any X component at the operating freq. which I doubt but let's accept that as so) , the rcvr input Z at a freq. removed by 6 MHz can hardly be assummed to be any thing close to 50 Ohms and is more likely to be highly + or -X therefor not absorbing or accepting any input signal and your analysis lacks merit. My statement said power hitting the input port, I said nothing about power being accepted or absorbed into the receiver, therefore again - I'm correct - you are way off. Let me remind you that, on this particular email list, I (we) strive for accuracy. I don't just come up with some crap to make things interesting - I've been 'doing' duplex radio systems since I was 14 - I'm now 46, so you do the math, correctly this time. You state my analysis lacks merit. Unless you have tried the the experiment I refer to - and have found something different to report, why don't you try keeping your off base thoughts and inaccurate calculations/information to yourself. If this seems to come off as a hot headed warning - you have read this post correctly. (I'm the list owner (in case you haven't figured that out)). By the way, the GE PLL exciter has 22 dB less phase noise at 600 kHz from its primary carrier than does its multiplier counterpart, you can bet it's way more than that at 6 MHz. End of thread - everyone please more forward. Kevin Custer
Re: [Repeater-Builder] Re: Repeater receiver testing
yes I know -55db is I think around 399 microvolts which will flatten any receiver, I sure hope not; there are many signals coming down my antenna that are that strong. In fact, my 440 repeater 13 miles away is at about that level at my antenna connector. Reminds me of a test I did with a GE MASTR Pro VHF receiver (stock - no preamp - ER-41C) and a GE MASTR II PLL exciter (stock - 200 mW output) and a tee connector. Receiver and exciter on each end of the tee (with short cables) and antenna/service monitor on the center. As I remember, the frequencies were about 6 MHz apart and the 'repeater' would duplex reasonably well considering no filtering was used between the units. Of course, I'm not saying there wasn't desense, but it worked - pretty well. Obviously, the 200 mW was split into two paths and who knows how much was hitting the input port of the receiver, but lets say half of it was - 100 mW. That power level is +20 dBm. I can almost guarantee you that transmitter side band noise is what created the desense - not the shear power of the transmitter. +20 dBm is 2,240,000 ?V or 2.24 volts of RF. My receive antenna for the UHF remote receivers is top mounted across the tower face beside the VHF stick. The VHF repeater runs 250 watts. 4 watts of VHF power appears at the splitter (in the shelter - including feedline loss) which feeds the 4 UHF receivers. The splitter (old CATV type) gets warm - you figure out how much VHF power is getting to each UHF receiver grin. Kevin Custer
Re: [Repeater-Builder] 6 Meter Heliax Duplexers
Tim wrote: I think I've found a way to make it work. 1. Got some brass tubing that is just about the same diameter as the rg-8's center conductor poly. (might have to use some silicon grease to make it slide a bit easier). Tip... I made a lot of antennas using hobby brass tubing. I found that the center conductor and dielectric from quality RG-8 was slightly too large for the (5/16?) hobby brass, HOWEVER, the center conductor and dielectric from legacy Radio Shack solid dielectric coax sleeved in with a nice snug fit. The RS coax was of poor quality (in my opinion) because of the lack of adequate shielding, but this made good use of otherwise poor quality cable. YMMV. Kevin Custer
Re: [Repeater-Builder] MASTR II LOW BAND TUNING
Jeff DePolo wrote: I took a quick look at them, and what stands out like a sore thumb is 1.6 db insertion loss with a 150 watt power rating. That means they'll be dissipating close to 50 watts in such a small package. Doesn't give me a warm and fuzzy feeling... --- Jeff WN3A Warm likely - maybe even hot, but certainly not fuzzy. - - Sort of like a cheap soldering iron. Kevin
Re: [Repeater-Builder] Simulcast Information on-line
skipp025 wrote: For those of you who'd like to see a few different examples of various Simulcast Systems explained. http://www.simulcastsolutions.com/case-studies.htm Another explanation is available here: http://www.repeater-builder.com/k7pp/index.html Kevin Custer
Re: [Repeater-Builder] Quantar Simulcast Issue
Jeff DePolo wrote: To get the RF phase accuracy you're implying that is required would mean that everything in the RF path would have to guarantee that phase relationship. That means the same length RF interconnect cables inside the cabinet, same RF feedline length (or full-wavelength multiples thereof), same antenna type, etc. Even if you could guarantee that kind of accuracy at the time of installation, thermal effects would quickly throw it way off (cables expanding/contracting with temperature for example). Not to mention the propagation delay will vary a whole lot with temperature, humidity, etc. Just not gotta happen And in practice, we know it isn't going to happen, so we purposely set the frequency difference between transmitters that overlap in coverage to about 20 Hz. This negates most negative effects of two transmitters being real close but not dead on frequency or angle. Transmitters that are very close to one another will cause PL tone decoders in the users radio to not reliably open, not to mention to weird audio artifacts that are produced/heard. At 20 Hertz, or so, CTCSS tone decoders work fine and radios' speakers don't emit a horrible beat note. Kevin
Re: [Repeater-Builder] Astron RS50 Power Supply
Jeff DePolo wrote: Everyone is entitled to make an ass out of himself now and then, but you're abusing the privilege... Now that's funny... BTW: I had set the dudes posting privileges to Moderated, but Scott decided to toss him - - Scott wins. Onward and Upward. Kevin Custer
Re: [Repeater-Builder] Lost 10 volts in a Master II UHF Repeater
Scott Zimmerman wrote: --- That reminds me of a story Kevin told about when he worked in a CB shop. A guy came in and said he mounted his radio and now it didn't work. Kevin went out to investigate and found the guy drilled two holes right straight through the radio and used two lag bolts to fasten it to the dash!! It sure wasn't going anywhere in a crash!! Yup..Radio was a week old - and totally ruined. Dude comes in to the CB shop I was working at when I was 14; wants a CB right now, and doesn't have the time to have it installed. So, we ran the power and antenna wires and laid it on the passenger seat until he could return to have it mounted. He comes back a week later to 'complain' that the radio no longer works. He had taken some time at his delivery lay-over to professionally mount his new radio to the under side of the dash. I went out and saw the bolt heads (with nice washers I might add) on the under side of the case of the radio. He drilled 2 mounting holes right through both sides of the case (and circuit board) and mounted that radio to the dash. It sure looked good, and it wasn't going anywhere, but the radio failed to operate after he wiped out most of the VCO and audio amplifier components with the 1/2 drill bit. True story - sigh Kevin
Re: [Repeater-Builder] Re: Micor ?
Ryan, A, Your problem is likely not the Station Control Module. I'm just guessing, but I'd say JU401 needs installed on the exciter. This circuit is sort-of a loop back - meaning PTT cannot occur on the exciter unless Keyed A+ is delivered to the exciter, and brought back to the SCM, where it is used to create Keyed A-. This is done so the exciter will not transmit until the channel element has had time to be enabled and become stable. Keyed A+ is either run through the PL encoder (which someone my have removed) or through JU401 if the encoder is absent. See if the jumper has been cut or removed on the exciter. If so, replace it or install a PL encoder board. Kevin Hi Kevin and group, I get PTT on pin 9 and 10. before i replace parts the manual says about Q8 and a CR5 as problems any thoughts ? Ryan n3ssl --- In Repeater-Builder@yahoogroups.com, Kevin Custer kug...@... wrote: n3ssl wrote: Hi Group, I have a Vhf Micor unified station that was modfied prior to ownership. The Mods for the Station control module were performed as on the RB site. The problem I am having is there is no PTT on pin 5 of the back plane. Is there something i should check ? The Station control module is the TLN 4635 Ryan n3ssl Ryan, Can you PTT from any of the other inputs? Kevin
Re: [Repeater-Builder] Micor ?
n3ssl wrote: Hi Group, I have a Vhf Micor unified station that was modfied prior to ownership. The Mods for the Station control module were performed as on the RB site. The problem I am having is there is no PTT on pin 5 of the back plane. Is there something i should check ? The Station control module is the TLN 4635 Ryan n3ssl Ryan, Can you PTT from any of the other inputs? Kevin
Re: [Repeater-Builder] Linear Modulation EPROM files
DCFluX wrote: Working on converting a Linear Modulation (Similar to ACSSB) 220 Trunking repeater to Amateur Radio applications, but I need your help. I am experimenting with a LMC3005 repeater, also known as the Viking LX. I believe the RF and Signal processing boards are similar to the ones found in the LMM3115 mobile radio if that is what you have. Possible suspect brands of manufacture are: Intek Global Linear Modulation Technology Midland Securicor Radiocoms Pty. Ltd. RoameR One EF Johnson For some reason the repeater I have is missing the EPROMs from the Trunking Channel Controller module. It is the one that has the 7 segment display and LEDs that sits in between the Exciter and Receiver modules. It is labeled They are labeled IC13, IC20 and IC21. 13 and 20 should be a 27C256 and IC21 is a battery backed up clock module M48T18. The LM/Viking LX Repeater (relabeled Securicor) I have has IC20 missing as well, but does have IC21- the clock module, and IC13 the EPROM. It was supposedly operational when it was pulled from service, so I don't believe you'll need IC20. I don't have any way to read them, but if you want, I'll pull and send them to you as long as I get them back. Kevin
Re: [Repeater-Builder] Linear Modulation EPROM files
DCFluX wrote: Can you power one up and see what the display says? Mine all show and have a solid squelch that blinks off about once every 2 seconds. Maybe there is something critical in the RAM module and the battery went dead. As I understand it there is an elaborate power up thing that gets displayed. and the switches should be functional. Holding mode down during power up should make the module run in a diagnostic mode. Replied directly K
[Repeater-Builder] Problems reaching the RB website sigh
I got several personal emails about not being able to reach the Repeater Builder site this morning. Google has reported the site has been hacked and most browsers redirect you to a big warning page. I scanned the supposed infected pages, http://repeater-builder.com and http://www.repeater-builder.com with AVG link scanner http://www.avg.com.au/resources/web-page-scanner/. I also looked at the .htaccess file and other content to make sure there isn't anything going on. I found NOTHING that resembled malware or suspicious links, forwarders, scripts, etc. I have submitted for re-evaluation on both Google and another independent evaluator - stopbadware.org. If you look at the help sites, this BS generates a LOT of business for companies that scan sites for money. We shall see what the re-evaluations say. Realize I changed NOTHING on the website, and I believe it has been clean all along. If the site proved to be clean on these subsequent scans, I can only assume there is collusion between Google and businesses that scan websites for money. I have no proof of this - it's just an observation. Kevin
Re: [Repeater-Builder] Problems reaching the RB website sigh
La Rue Communications wrote: Right on Kevin - Thanks for staying on top of this. I checked all my browsers, I have about 10 on both my Mac and PCs and got no errors. Warning page redirects are only happening to people that have or use (subscribe to) Google add-ons and similar software. The RB site has been tested by several others and unless there is infection deep within the site (and there could be, but I really don't think so), no one should be at risk for navigating the site. AVG link scanner says the site is safe, as well as other anti-virus and anti-malware services being run on the site. The message I got from Google used wording like The site /may/ be compromised and The site could have been mis-identified. Again, all of my webmasters are doing what we can to insure the site is safe to navigate. I'll post any updates I have as I can. Thanks everyone for your understanding... Kevin
[Repeater-Builder] The Repeater Builder website....
So, here is the conclusion to today's events following the supposed repeater-builder.com site hack. We have processed your request for review of your website, http://repeater-builder.com/. At this time, none of our data partners are reporting badware activity related to the site. Any warnings displayed by our partners about your site have either already been removed or should be removed shortly. In addition, the report(s) about this site in StopBadware's Clearinghouse have been moved from active to archived. For tips on keeping your website clean and secure, please visit: http://stopbadware.org/home/security If you have further questions, please visit our online help discussion community: BadwareBusters.org http://BadwareBusters.org. The StopBadware Team The whole thing was a BS scam to try to gain business from a bogus warning. So much for Google being your friend Webmasters BEWARE! Oh yea - Firefox resolves the site again. Tell everyone they are safe now (you do feel safer now don't you?) sigh W3KKC .. Long day, I'm going to bed.
[Repeater-Builder] Nice article on the Molotora Gontor
Bob Meister has written a nice article on the Molotora Gontor for RB. http://www.repeater-builder.com/molotora/gontor/gontor.html Thanks go out to Bob for his efforts! Kevin Custer
Re: [Repeater-Builder] HP E8285A Cellular Test Sets
Dawn wrote: I checked the archives and noticed there was scant mention of these units. For the money, these seem like a dream come true. From what I understand, once set up in the test mode, they have most all of the function of the HP-8920 series minus the following: No Edacs,LTR or any signaling formats or DPL except raw tone generation and DTMF. Three watt limitation No frequency count on Spec A screen Pre-set squelch or none. Otherwise these function as a complete service monitor from 100kc-1 gig and another second band to 1.7gig. I also gather that with a suitable thruline or similar power attenuator, the wattmeter indication can be adjusted to read correctly removing the 3 watt limitation. If all this is correct and with an external multi format tone generator such as Motorola's or Cromco's and a Multiformat tone reader such as Opto's or Connect System's boxes, you pretty much have the entire enchilada por poco dinero. Am I missing something or is this quite possibly a fantastic deal due to the shere amount of orphaned CDMA/TDMA test sets since GSM? Anyone have one of these? The 100 kc-1 gig isn't part of Agilent's specs. Is this a hack or was this a function of earlier units? Any info or caveats appreciated on these units. I bought one recently on eBay. It had, what the seller referred to as, a 'jittery' display. It also has the desired Option 102 (spectrum analyzer / tracking generator. They can be branded either HP or Agilent. Some later models aren't able to tune below 800 MHz, as the downconverter and input modules 'may' not be calibrated by the factory for operation in this portion of the spectrum. Also, the firmware on the newer units doesn't support operation below 800 and some other functionality. The unit I was watching looked pretty good, had 102, and I took the plunge... There is a guy in Lakewood NY that is very knowledgeable on HP / Agilent equipment (as well as some other brands). His name is Rick Bowman, and he owns Amtronix Instruments. Before purchasing my unit, I asked Rick all of the same questions you are wondering about. Basically, if you buy one from eBay or another surplus source, it isn't known if you will have a 'good one' until someone like Rick takes a look and determines what it needs. I lucked out. Even though the unit I have has a serial number above what Rick considered would be okay for operation below 800, mine didn't require a different downconverter or input module. It did require a firmware downgrade and I had him run it through calibration. The display jitter was caused by some bad capacitors on the display board. If you have one of these and the display is jittery, don't run it as it will eventually take out the regulators on the display board. My display is a little burned - common I'm told for these machines. Rick has these units already 'fixed up' from time to time for around $700.00. He is currently out of stock on these, but expects to be getting some in soon. My suggestion is to get on his waiting list. Rick is a good guy to deal with. His prices are fair and his work second to none. In the past, I have used the HP 8920A/B and my HP E8285A is very similar in operation. Basically it doesn't have the items you mentioned above, but does have a few things that the 8920 doesn't. It is a good machine, and for the price, you can't beat it for a good monitor. I'm told all E8285A's have the high-stability reference oscillator. Here's a page that does a comparison between them: http://www.amtronix.com/e8285a.htm Rick can be reached at: http://www.amtronix.com/ Kevin Custer
Re: [Repeater-Builder] Doug Hall 4RV Voter
Nicholas Cerreto wrote: Hello! Does anyone have a service manual for the Doug Hall Voter 4RV Voter? Not likely...A manual with schematic is not offered by Hall. If you need it repaired, try shotgunning the IC's or send it back to them for repair. Kevin Custer
Re: [Repeater-Builder] Service Monitor (HP) calibration
James Delancy wrote: Does anyone know of a place relatively close to CT (or NYC metro area) that does service monitor calibrations? While not close to your area, here's a place that will do it right, and treat you right: http://www.amtronix.com/ Rick specializes in HP / Agilent as well as others. Kevin Custer
Re: [Repeater-Builder] Low Band Micor mobile not making power
Kris Kirby wrote: IIRC Motorola usually used about 1W at the exciter to drive the PA to full power. -- Kris Kirby, KE4AHR Disinformation Analyst Not on the MICOR line. All are 400 mW out of the exciter regardless of band. Low Band exciters usually make 600 mW, but their spec is 400 mW. UHF Stations takes the 400 mW at the VHF exciter and makes 1 to 2 watts for the PA as a function of the tripler. The UHF MICOR mobile is similar, but different. Kevin
Re: [Repeater-Builder] Low Band Micor mobile not making power
tahrens301 wrote: Hi all, Working on a micor mobile to be used as a repeater (only using the exciter/control board/PA). Was going through it, and am only able to get about 75 watts out of it with the exciter on 53.7. The exciter is putting out 0.3 watts... a bit more than most exciters I've seen, but they were high band. I'd expect to only see 75 watts out of a 110 watt PA if you only have 300 mW of drive. Low Band exciters usually have about 600 mW leaving the exciter on frequencies within original specification, and it's common to see 150 watts out of a Low Band PA. Under drive can be a bad thing. I'd look at it with a spectrum analyzer and make sure it isn't spurious because of the 3 dB of under drive. It probably isn't, but I'd check it anyway... Kevin
[Repeater-Builder] Pion and Simon - the rest of the story....
As promised, here are two replies I received about 30 minutes after sending an email to Al and Elizabeth: Kevin, I received an e-mail from him just today. I sent him a reply within minutes. I just read his response. I hope the attached file explains everything, but if not, please feel free to inquire further. And by the way, thanks again for your site. Best regards, Al KK7XO And I was CC'd on his response to John, John, it's unfortunate that you put a complaint on the repeater builder site. I answered your e-mail inquiry within minutes of reading it, as I do with virtually every e-mail I receive. Your check should clear as early as tomorrow according to the information I have. We have no control over how the check is handled. Apparently it has to do with the fact that there is an international transfer of funds and the related monetary conversion from Canadian funds to US funds. I will mail your board as soon as we have confirmation. It usually takes 3 days or less for the package to arrive after we mail it. I hope this is satisfactory. I'm sorry you had difficulty purchasing our board. We will do everything we can to make sure your order goes out promptly as soon as we get confirmation of the transaction. 73 de Al KK7XO I have sent a message to Al and Elizabeth as well - asking for help here. Maybe your messages are getting caught in a SPAM filter or something. This is not their normal practice and I can only assume your messages are not getting delivered. I'll let you know when I get their reply. Kevin Custer List Owner
Re: [Repeater-Builder] Pion and Simon - the rest of the story....
Tedd Doda wrote: But John said he paid with Paypal? Not all PayPal transactions are instantaneous. John paid with an eCheck, which is subject to delays just like a check that clears the the bank. There are ways to transfer money to PayPal instantly, like instant transfers from checking and savings accounts. Kevin Custer
Re: [Repeater-Builder] Pion and Simon - the rest of the story....
Tedd Doda wrote: Kevin Custer wrote: John paid with an eCheck, which is subject to delays just like a check that clears the the bank. There are ways to transfer money to PayPal instantly, like instant transfers from checking and savings accounts. In all the years (since 1999) of selling on Ebay, I've never run into a e-cheque. Lucky me, I guess :) The link below will explain the differences, advantages, (and obviously in this case, disadvantages) of using an eCheck. https://www.paypal.com/helpcenter/main.jsp?t=solutionTabsolutionId=13054cmd=_help-ext John's delay won't be substantial, only a few days. He is wanting to receive his controller before the 20'th of this month. I see no reason why he won't get it by then. Kevin Custer
Re: [Repeater-Builder] Pion and Simon
John J. Riddell wrote: Thanks, James.but you'll recall that my question was for a phone number. I sent two E mails with no reply..to the address shown... I have sent a message to Al and Elizabeth as well - asking for help here. Maybe your messages are getting caught in a SPAM filter or something. This is not their normal practice and I can only assume your messages are not getting delivered. I'll let you know when I get their reply. Kevin Custer List Owner
Re: [Repeater-Builder] Writing Guidelines
Kris Kirby wrote: I see the guidelines for writing; what are the guidelines for scanning documents? PDF please. Make the file as small as possible, BUT, don't skimp terribly just to save server space. There are many methods in which to scan and save - trial and error will reveal what you like and what you don't. Kevin
Re: [Repeater-Builder] 200 watts on a repeater transmitter - was something else...
We have been over this many times. If a system is balanced with a receiver at -116 dBm running 50 watts of power, then it will be balanced with 200 watts and a properly deployed preamp adding 6 dB of gain. The added power level on the repeater transmitter helps with noise that is common in urban locations experienced by the mobile; noise that is not experienced by the repeater receiver. Most commercial vendors will tell you a system is balanced with 100 watts and a receiver at -116 dBm. That mentality would require 400 watts to remain balanced with a mere 6 dB (easy) preamp improvement. Why is it that folks think that if you are running more than 100 watts of power that AUTOMATICALLY it qualifies as an alligator? I have two repeaters that run in excess of 200 watts - neither of them have EVER been considered an alligator. In fact, both are nicely balanced with a rural run 50 watt Japanese mobile. Kevin Custer The question that pops into my mind concerns the proposed 200 watt power amplifier. I have to wonder where the notion to run an alligator system originated. I see four possible answers: 1. We have this 200 watt amplifier, so we are duty-bound to use it regardless of whether it is necessary or not. 2. We subscribe to the policy that more power is always better, and it always increases coverage. 3. We have performed a thorough analysis of coverage, and have determined that less power will result in insufficient coverage. 4. We know that 50 watts is enough, but a real powerhouse station will give us bragging rights. Once again, I must recall my favorite repeater-coverage dictum: Repeater coverage is determined by receiver performance, not by transmitter power. 73, Eric Lemmon WB6FLY
Re: [Repeater-Builder] Re: 200 watts on a repeater transmitter - was something else...
Kris Kirby wrote: I think that one would be better served by choosing an antenna appropriate to the purpose of the repeater. If you need urban coverage, choose an antenna with more null-fill, or less gain. If you have to pay for power (or make your own power!), you'll spend more time working on an antenna that will cover what you need so your transmitter can be ten watts or less. The antenna doesn't know if it's receiving or transmitting - so the antenna has absolutely nothing to do with transmit or receive balance - which is now the subject. Kevin Custer
Re: [Repeater-Builder] Re: 200 watts on a repeater transmitter - was something else...
Steve wrote: It seems logical that if a rptr tx is running 200w, and the mobile is running say 50w then it is going to be one way ie mobile hears rptr but rptr don't hear mobile too well Common misconception. Lets say the mobile radio has a receive sensitivity of -116 dBm and 50 watts of transmitter power. The repeater has a receive sensitivity of -122 dBm - how much power will it take to balance out the receive advantage of the repeater? If you said 6 dB, you are correct. 50 watts with a 6 dB improvement is 200 watts. I have seen several VHF and UHF repeater systems with -125 dBm actual sensitivity on air - connected to the antenna and duplexing. You do the math... 400 watts is the answer. The original poster mentioned an LDG voter and remote links. If the repeater has remote receivers that will increase the distance of operation from the transmitter, he'll need all of his 200 watts. Kevin Custer
Re: [Repeater-Builder] Re: Hamtronics versus Commercial (Kenwood) Repeater Selection
skipp025 wrote: The more famous surplus commercial radio 224 MHz conversions replace the PA with a Hybrid RF Amplifier Module... wonder if they also include SWR Protection? They don't - at lease not all do, but in the case of the MICOR mobile - the power set functionality (power level setting, power leveling, and SWR protection) is retained. This is because the VHF directional coupler works very well at 220 MHz, and if done right, can still drive a power transistor; which then controls the hybrid module. Scott Zimmerman/Repeater Builder builds a nice PC interface board that allows all of this to happen easily: http://www.repeater-builder.com/products/ampbd.html The picture on the right (MICOR mobile installation) shows the TO-220 pass transistor and you can see the little purple lead from the power set board coming through the PA wall and connecting to the base of the pass transistor. Because, in a MICOR, the power set control is done with circuitry that is separate from power amplifier board - this protection is not difficult to maintain. The interface board allows easy installation of the hybrid and even incorporates the reverse polarity diode that gets removed when you discard the original MICOR VHF PA. In the case of the GE MASTR II, power control is done with a simple pot, and all SWR protection, leveling, etc. is bypassed/eliminated - at least with this interface board. Maybe someone has hacked the MASTR II PA to allow for the incorporation of its protection in a 220 conversion - but I have never saw it if it has been done. Kevin Custer
Re: [Repeater-Builder] Micor Stock Power Supplies
You wrote: Switchers -as a class- are more efficient and reliable than linear supplies. As a Class... More efficient - yes, More reliable - that's debatable. In the two-way radio world, linear supplies are the rule, switchers are the exception. In 25 or 30 years, we'll see if switchers are 'really' as reliable. In my experience with switchers (as a class), they are hard on filter capacitors, with failures of them way before the normal 'dry out' time - many times in just a few years. There are a few tower management companies that I know of that won't let you install a switcher because of the possibility of interference. The same companies also do not let anyone install LMR coax onto the site. I'll be interested to see the results too, Bob. Kevin
Re: [Repeater-Builder] Micor Stock Power Supplies
Sorry, I cannot answer that question. My reference was more toward the replacement of an existing linear supply or new installations such as GMRS or Amateur Radio systems - repeater or otherwise. Whether or not their rule applies to newer Motorola or other commercial radio manufacturers - I'm not certain. I am told that Motorola offers alternative powering methods to systems that normally come with switching supplies. I'm not totally sure why... possibly there are companies that aren't totally sold on switcher technology? Unfortunately, like with so many things, price dictates quality. If you buy a JAN crystal, be prepared to have it drift all over the place. If you buy a cheap switcher, be prepared to have it throw garbage out all over the place. While the better switchers like Samlex and DuraComm are good performers, many of us will buy something cheap. With education, more of us will buy the better product, like International Crystals with temperature compensation performed by them. Kevin So, these tower management companies no longer allow the latest Motorola and Kenwood stations- which come with switching power supplies- to be installed at their sites? 73, Eric Lemmon WB6FLY snip There are a few tower management companies that I know of that won't let you install a switcher because of the possibility of interference. The same companies also do not let anyone install LMR coax onto the site. I'll be interested to see the results too, Bob.
Re: [Repeater-Builder] Re: Micor UHF Repeater Base 9.6 vdc current requirement?
DCFluX wrote: How about a 7809 regulator IC with a 1N4004 diode in the ground leg to raise the output voltage to 9.6V? There is nothing mysterious about 9.6 volts. It could be 9.00 volts 10.00 volts 11.00 12.00 volts or *anything* in between. The part that is critical is that it is stiffly regulated. Something less than 10.6 volts was chosen because that is the point where a lead acid battery is technically totally depleted. This means the critical circuitry (oscillators, multipliers, etc.) are always fed with stable power to the point where the battery is dead. In a station, the 9.6 volt circuitry *could* be run from 12 volts, as long as its regulated. I'm not suggesting someone does that, because the circuits were optimized for 9.6 volts, but I'm trying to make a point. If it were me, I'd just use a 9 or 10 volt three terminal regulator (7809 or 7810) and skip the whole LM-317 or diodes in the ground leg deal. It only serves to make the circuitry more involved , harder to mount, and for NO advantage whatsoever. Kevin Custer
Re: [Repeater-Builder] Re: Key Collection
skipp025 wrote: Oh yeah..? Got an Allen B. Dumont, (Fred) Link key in that collection? My father had a Link FM transmitter on VHF - used a pair of 2E26's in the final. It was paired with a receiver, but I don't recall what it was. The receiver would get so hot it would burn up the tube sockets. Both were in a small Link cabinet, but the door wasn't lockable, as I remember. We did have a small/unstable DuMont oscilloscope - it sure wasn't a Tektronix. Kevin
Re: [Repeater-Builder] Bend an ICOM a little further
Doug wrote: Jared; You need to warp 4khz not 400hz... If they were made up for 146.01 I would assume that they can do that. Jared wrote: I just need the crystal to go up a hair more (400 Hz on the crystal freq). In Jared's defense, he did say on the crystal frequency He needs to go 3600 cycles higher on the channel, which relates to 400 cycles at the crystal because the LO multiplier in a VHF MASTR II receiver is 9 400 cycles (400 more than the present netting excursion, that is...) at the crystal frequency is going to be difficult without breaking the oscillator - IMHO. Kevin
Re: [Repeater-Builder] 85VAC to 12 VDC?
AJ wrote: Gents - I completely spaced using existing CATV gear - I have a pallet of Motorola/GI minibridger housings with just the power modules in the lid. I'll see what I can do to test this out over the week and try to report back - Pretty sure I can fit an entire remote receiver in to a MB housing... AJ, Just make sure the model power pack you have will take 90 VAC. Most Jerrold/GI/Motorola MiniBridgers up to and including 750 MHz were 60 volts. If you are lucky, you have 60/90 units. Also, I'd be interested in a few MB housings if the inserts aren't stripped and were never water damaged. I have a few castings that aren't good enough to be put into the field, but have good looking guts. Thanks! Kevin
Re: [Repeater-Builder] 85VAC to 12 VDC?
AJ wrote: We've been given the opportunity to setup a remote receiver at the end of local local cable television provider's plant on the hill to help with coverage. Powering is the only issue we're running in to - currently the only power available within 6 pole spans is the 90 V AC plant power across the CATV coax. They've offered to cut in a power inserter at this location to feed up to 4 amps of 90 VAC to us (roughly 85 VAC at that point in the plant) - what is out there for a reasonable cost effective solution to convert this to 12 VDC? This stub of plant does not have RF across it, nor will it any time soon (RF removed when fiber backbone was overlashed on the same pole line). Our first concern was leakage but that shouldn't be an issue. Build new coax plant as close to the desired location as possible. Have the CATV company feed this coax with the power inserter. The power inserter will allow the extraction of power without upsetting the RF if it is ever re-activated. Have the lineman cut in an old CATV amplifier housing with a mating power pack at the end of the coax line. Use the power supply module (power pack) inside the amplifier to convert the available AC to 24 volts DC. Then, use a regulator to cut the 24 down to 12. Obtain a few spares of the power pack so when lightning does its thing, you can get it back up and going. Another option to continuing the coax plant is to have them cut in the power inserter and then run some kind of power line (duplex cable) and use this line to feed a CATV power pack housed in a weather proof box. You can make the AC go much farther then the DC. I had a ham remote receiver location work for many years using this principal. The power availability wasn't nearly as substantial as what you have. I was at the end of the line in a 60 volt plant. Nearest power supply was 2 miles away and it fed the microwave receive site on the same tower I was on. I had to be careful not to drag the AC down too far or the receive site would go out. Available AC was about 45 volts and I used it to supply a CATV amplifier switching power pack (24 VDC out). The 24 volts fed a home brew charging circuit to trickle charge a 12 volt SLA battery. Since the duty cycle was relatively low, there was plenty of time to recharge the battery after use. The charging circuit was limited so even if the battery was stone dead, it wouldn't load the line too much that it outened the CATV microwave site. Kevin
Re: [Repeater-Builder] 85VAC to 12 VDC?
Eric Lemmon wrote: AJ, The obvious solution is to connect a commercial switching power supply- definitely NOT a linear supply- across the AC source. Most Samlex, Astron, and DuraComm switchers can work wonders in such an environment, where conventional linear power supplies will surely fail. Don't use a larger (higher capacity) power supply than you really need; in this case, larger is not better! Be careful here... The output of a CATV power supply is not a sine wave. I'm not sure how these commercial switchers would react to the AC available from the CATV line. Certainly while switching supplies are used in the CATV industry to power the amplifiers, nodes, and telemetry, I don't know if they are made exactly like the ones fed from commercial AC. It would be much better if he uses a power supply intended to be connected to the CATV line. These can be scavenged from working surplus CATV equipment. Several of the ones I'm familiar with can supply an amp or two at 24 VDC, and that used to feed a regulator or charging circuit for 12 volts. Kevin
Re: [Repeater-Builder] Re: 11m Repeater - THREAD NOW CLOSED - W3KKC
RE: 11M Repeater This thread is now closed. Period. Kevin Custer List Owner
Re: [Repeater-Builder] Question for the Moderators
Off topic but curious—my Google Alert for myself picks up every entry I make on Repeater builders—I belong to a number of sigs on yahoo and yours is the only one that Google finds, wondering if there is a sig setting to prevent Google from finding the posts or if it is something you like to have happen? Andy, It might be that it's not YahooGroups but rather the archive we have running for this list. Kevin Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) * To change settings via email: repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[Repeater-Builder] MICOR VHF receiver conversion to 2 Meter band - W3KKC winter special
I have decided to run another winter special on the conversion from high-band 150.8 - 174 MHz to 2 Meters (142 - 150.8 MHz) for the Motorola MICOR VHF receiver. This special is offered two ways: 1 - Just the helical resonator rebuild. 2 - The complete receiver redo - (for high-side injection). I use new Silver Mica capacitors for the conversion. Go here for more information and current pricing: http://www.repeater-builder.com/rbtip/hs-coilinstructions.html This pricing offer is also available for the conversion of 150.8 - 174 MHz MICOR receivers to 222 - 225 MHz. http://www.repeater-builder.com/rbtip/222sensitronRX.html This deeply discounted pricing won't last forever. Email me (directly please) with any questions. Thanks, Kevin Custer kuggie [at] kuggie [dot] com
Re: [Repeater-Builder] Remote Receiver site
John Szwarc wrote: I'm looking for some advice on constructing a remote receiver site. Ideally I'd like to have everything contained in one neat package just like at the repeater site. We'd be receiving on VHF and transmitting the link signal on UHF back to the repeater site.Any thoughts? Here's one... GE MASTR II mobile - VHF Receiver, UHF FM Exciter (and PA if necessary). Modify the audio path for flat audio and use an AP-50 for modulating the exciter. If you want or need a controller, use one of the plug-in NHRC models. Makes a nice little package and the sound will be excellent so the voter can do it's job well. FM exciters on UHF in the MASTR II are a little scarce. Use the following article to change the common phase modulated UHF exciter to FM: http://www.repeater-builder.com/ge/mastrII/ap-50-fm-mastr2.html Kevin Custer
[Repeater-Builder] PLEASE READ - was dispatch centers run through the internet
Since we have veered off course with this discussion, and it seams that everyone that was interested gave an opinion, the THREAD IS NOW CLOSED. Let's move on - back to subjects that are more on topic. Thank you, Kevin Custer
[Repeater-Builder] - was dispatch centers run through the internet
Kevin Custer wrote: and it seams Geesh It seems that I got lost in the seams.
Re: [Repeater-Builder] Mastr II mods and parts
Michael Cox wrote: Ralph (and others) So is there a IDA equipped version the controller? If not, what does it mean that I have the IDA equiped version? The IDA version of the MASTR II station was (originally) controlled by a means other than the usual plug-in cards. What you bought is okay, but maybe not the preferred version for building a stand-alone repeater. Does that mean I need, for example, a different duplexer? No, it has nothing to do with the duplexer - or anything RF for that matter. When we build repeaters from surplus equipment, most of us rip out the original control circuitry and connect an after market repeater controller of some sort. Many have mentioned the Pion Simon units because they plug right in, but not to the model of station you bought from eBay. That being said, either of the NHRC GE controllers will plug-in to one you bought. The conversion you'll do to this station to make a repeater will likely more closely follow one written for a mobile - as you'll be using the Systems Board for controller interface if you choose a plug-in NHRC model. If you choose some other controller - it'll have to be wired in making it a bit more difficult. Kevin Custer
Re: [Repeater-Builder] Longshot - Duke Energy/Texas Eastern
Jeff DePolo wrote: Does anyone have any two-way or microwave engineering contacts at Duke Energy or Texas Eastern (pipeline)? (If my memory isn't failing me As I remember) N3LIF Roy Ed Kern worked for Texas Eastern as a radio/microwave technician. He is likely retired now. Ed's in Green County - a repeater owner, and a nice guy. I don't have any contact information other than the usual QRZ database. Along the same lines, does anyone know if they maintain their own microwave network or if they subcontract the maintenance out? As of 10 or 12 years ago - they utilized mostly in-house maintenance. That may have changed. If you can get a hold of Ed, he might be able to put you in contact with the folks in engineering. KR3P might have Ed's email address he can relay via private message? Kevin
Re: [Repeater-Builder] Mastr II mods and parts
Michael Cox wrote: Will this Duplexer work with the Mastr II repeater? http://cgi.ebay.com/UHF-50W-6-CAVITY-DUPLEXER-FOR-REPEATER-FREE-TUNING http://cgi.ebay.com/UHF-50W-6-CAVITY-DUPLEXER-FOR-REPEATER-FREE-TUNING_W0QQitemZ350300447727QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518f88a3ef Sure, it would work. It's a six cavity unit capable of providing enough isolation for desense free operation with a receiver of -116 dBm and a 50 watt transmitter at a 5 MHz TX to RX spacing - as long as you aren't in a crowded RF environment. Would I recommend it? - absolutely not. As I and others have mentioned, a BpBr design, (like the WP-678 I referenced in an earlier mailing) would be a much better choice. Why? You'll likely buy a 100 watt PA to go along with your recent repeater purchase, and likely some day you'll want to add a receiver preamp for hearing the real weak ones The duplexer must provide enough RF isolation so the receiver can hear a very weak signal, while, at the same instant, putting out several watts from the transmitter so people can hear it. Look at it this way, let's say you are listening for a pin to drop on a cushioned floor while someone is shouting into your ear. The duplexer allows you to 'tune out' the person shouting - giving you the ability to hear the pin drop. This can only happen because the transmitter and receiver are on two distinctively separate frequencies and the duplexer is optimized for those exact frequencies. There are places to save money where building a repeater is concerned. The duplexer is not one of them. This doesn't mean you can't save money - you can. The $250.00 WP-678 I spoke of in an earlier mailing was about $800 to $1000 new. I'm recommending you buy $800.00 technology not $79.00 technology. Kevin Custer
Re: [Repeater-Builder] 73 Magazine Archivers
AA8K73 GMail wrote: Here is an attached scan, 2.59 MB. Wow, an IMSAI for development. That brings back memories. Mike - AA8K I remember reading it the first time around. It was the work which eventually evolved into the Advanced Computer Controls (ACC) RC-850. Fun reading... Thanks Mike. Kevin Custer
Re: [Repeater-Builder] dispatch centers run through the internet
The Internet is a shared medium. A private WAN/LAN commonly utilizes fiber optic cable or licensed wireless networking to accomplish connectivity. While private systems can deliver Internet, it is not (necessarily) THE Internet. Privately owned facilities like what many CATV, Phone, Internet, and combinations of them can have dark fiber or reserved virtual space that cannot get clogged with Internet overhead. The bottlenecking you might experience with facilities you cannot (do not) control can (will) be the downfall of such a system - unless a SLA can be gotten. A SLA is a service level agreement in which a company guarantees connectivity - to some degree. The more reliability the agreement extends - the higher the cost. Kevin Custer Jed Barton wrote: tell me about this system a little bit. You'll note that the manufacturer is not suggesting that you utilize the Internet for this device. It is marketed for use on a private LAN/WAN. Chuck WB2EDV
Re: [Repeater-Builder] Mastr II mods and parts
Michael Cox wrote: Thank you for your help. I appreciate it! I've put a couple of questions inline below. Well - you'll need a duplexer no mater the price... grin I was under the impression that if I had two antennas, I could get by without a duplexer. Thanks for the heads up. While two antennas will work, and you'd initially think there is a cost savings using two antennas, that isn't always the case. The determining factor usually ends up being the length and size of feed-line necessary to get from the repeater to the antenna. On UHF, unless the feed-line length is really short, you'll want to use some type of hard-line cable. The cost of this cable, depending on type and length, can be costly. It may be less costly to use one antenna and a duplexer then to install two antennas and have two runs of feed-line. In addition, you'll usually end up with a better balanced system using one antenna because using two can cause a disparity if both antennas don't have the exact same pattern - which could be difficult to achieve depending on the tower space available. In installations where you have to pay rent on tower space - it's usually by far cheaper to purchase a duplexer. RE: Power Amplifier Are these what I'm looking for? Generically - Yes. It looks like there is a UHF and a VHF version of the PA. Is that correct? Yes. Are they not compatible with each other? No. VHF and UHF are two totally different bands. You cannot use a UHF PA on a VHF repeater and vice-versa. The third one you listed is a Mobile PA - not something you'll want. You want a UHF Station PA like the second one you listed - but it isn't the exact one either. The one you want requires 200 mW of drive - not 20 watts - but, the correct one looks very similar to the one in your number two listing. I don't presently see a good candidate on eBay - but they show up all the time. Duplexer - used WACOM Products WP-678 (or similar), also available from eBay. I couldn't find any on eBay. Any guesses what I'd be paying for something like this? $250 plus shipping. Controller - I recommend a NHRC model that plugs into the Systems board, or, one of the Pion Simon models that plug into the card cage. http://www.nhrc.net/ge-stuff.php http://www.pionsimon.com/products.htm It looks like I can use the NHRC-4/M2 to make it a linked repeater. If I go with the Ham repeater, I'll most likely do that. That would require, if I understand correctly, another radio connected in, so that will have to be done later with future funds. :) Correct. If I decide to make it a GMRS repeater, I won't have to worry about that and will go with the PSE508-2, as its a little less expensive. Also a good choice. Kevin
Re: [Repeater-Builder] ACC RC-85 QUESTION.
W8YSU wrote: Did anyone have any problems after the new year? Our controller will not take any codes to set the time and the date. also some of the voice messages are not playing right. Here is your fix. Remember to set the date back in time (to 1982) so it matches the correct Day of the Week. http://www.repeater-builder.com/acc/acc-rc-85-96y2k.html Kevin Custer
Re: [Repeater-Builder] 220 repeater
Dan Blasberg wrote: All right folks, For those that run a 220 repeater, what are you running as far as the machine itself? MICOR VHF Mobile converted to 220 and duplexed to a repeater. A local group is looking to put a 220 MHz repeater on the air and would like some ideas. Here's how: http://www.repeater-builder.com/rbtip/micor-index.html#220 Kevin
Re: [Repeater-Builder] 220 repeater
Dan Blasberg wrote: So it look like the general recommendation is a converted GE or Micor. That is kind of the direction I was leaning for the group. As for conversions, what are folks using for final amps? Japanese Power Brick: http://www.repeater-builder.com/products/ampbd.html The Amp Board is a little circuit board that allows easy installation of a power module in a commercial band radio set. If you are into GE MASTR II radios instead of MICOR's, get yourself a PLL VHF MASTR II mobile and use this conversion kit. It's by far the simplest conversion to the 220 ham band. I prefer the MICOR, but there is absolutely nothing wrong with a MASTR II on 220. If you'd rather not do the conversion yourself, Scott Zimmerman will do the conversion (GE or Motorola) for you: http://www.repeater-builder.com/custombuilt/index.html Kevin Custer
Re: [Repeater-Builder] 220 repeater
Kevin Custer wrote: If you are into GE MASTR II radios instead of MICOR's, get yourself a PLL VHF MASTR II mobile and use this conversion kit. It's by far the simplest conversion to the 220 ham band. Forgot the dumb link http://www.repeater-builder.com/products/MIIconversionkit.html Kevin
Re: [Repeater-Builder] Mastr II mods and parts
Michael Cox wrote: I justed purchased a GE MAST II UHF repeater that has a 450-460 split (see it at http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=230415711221ssPageName=STRK:MEWNX:IT http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=230415711221ssPageName=STRK:MEWNX:IT) I need to get a power adapter, a CWID, You mean a Power Amplifier or simply called a PA. For a CWID, I recommend a real repeater controller. and, depening on the price, a duplexer. Well - you'll need a duplexer no mater the price... grin I'd like to modify this to use on either a GMRS repeater or a 40cm ham band. This will be my first repeater. I think you meant 70 cm ham band... Modification is easy, as no RF mods need made for either use. You just need to make it duplex. Information on www.mastr2.com will help you there. I'm assuming that I could get this http://www.repeater-builder.com/products/ampbd.html for the power adapter. You could, but I'd just buy the right PA. They are on eBay all the time. Do you have any recommendations for the duplexer and CWID? Duplexer - used WACOM Products WP-678 (or similar), also available from eBay. Controller - I recommend a NHRC model that plugs into the Systems board, or, one of the Pion Simon models that plug into the card cage. http://www.nhrc.net/ge-stuff.php http://www.pionsimon.com/products.htm Good luck, Kevin Custer
Re: [Repeater-Builder] Micor VHF 12W Amplifier??
tahrens301 wrote: .snip. I noticed that there is some silkscreen on the transmitter interconnect board (in the big hole to the right of the exciter) that says 12WPA. Didn't know whether Mot actually had put a low power amplifier into the space or not. Anybody know? Hi Tim, Yes, the 12 watt PA was used in UHF Stations in that location. On VHF, the amplifier was usually mounted externally - usually in the form of a mobile heat sink mounted into the rack above the Unified Chassis. The VHF 12 watt PA was commonly used to driver higher level tube-type PA's. The MICOR series is not known for its efficiency, especially when commercial frequency range gear is tuned into the ham band without being properly converted. That being said, there are several things that you can do to improve the power efficiency. I don't believe the exciter itself is terribly inefficient, as it uses an unheated channel element. The tuning of the exciter into the ham band usually results in factory specification performance without modification, the exciter filter and PA are another story. Modification of the exciter filter is usually not difficult, but the PA conversion can be. So, since you only want a small amount of transmitter power, you might want to look into using a Japanese Power Brick for the PA; as they are usually very power efficient. Repeater Builder makes a little circuit board to aide in the use of such a module for this type of purpose. http://www.repeater-builder.com/products/ The receiver can be made to have better power efficiency by removing the B+ from the audio power amplifier. Since these circuits are Class A/B, they draw current all the time. In solar applications I usually place a SPST switch in the B+ lead to the audio power amp so the current can be cut off when it's not in use. There is a bunch of other circuitry that you might also consider eliminating, like any cards that may no longer serve any useful purpose. Most repeaters can be built to deliver the necessities to a controller and the rest of the support circuitry can be gotten rid of. The NHRC Micro is a really good controller choice where power consumption is concerned. The Micro installed in a MICOR allows solid RF technology to be interfaced with a modern controller. http://www.nhrc.net Good luck with the project, Kevin Custer
Re: [Repeater-Builder] Dead GLB 2 Meter Preselector
Joe wrote: We were just talking about the GLB preselectors recently. Now I have a dead one. I got a call that one of the local ham repeaters went stone deaf after a lightning storm a couple of weeks ago. I got time today to stop by and found that the GLB preselector bit the dust. I have used several of these GLB preselectors and the ones that I have had apart use a Motorola MRF901 transistor. This one looks like it is using a different device but there are no markings except for a UF on one side. There looks like there are a couple of extra resistors on this one too. This is a very early version of the GLB unit. Any ideas? My guess is it has a GaAs FET transistor as the active device. Kevin
Re: [Repeater-Builder] MSTR II Mobile @ 100W
tahrens301 wrote: Hi Folks, snip--- Since I'm looking at using it as a solar pwr'd repeater, what is the best way to turn the power down (without making a bunch of spurs along with it)? Remove parts of the PA back to the desired output. Match that output correctly to the LPF. Here is a similar conversion where I took a 100 watt MICOR PA and sawed it in half - wound a custom output transformer - and coupled it to the LPF (low pass filter): Scroll down in the page to see the picture and read the caption above: http://www.kuggie.com/ahra/hmftinfo.html OR Use the exciter to drive a Japanese power brick. Easily done with one of these: http://www.repeater-builder.com/products/ampbd.html Tastes great - less filling (cheap and spur free) Remove the audio amplifier or put a switch in line with the B+ to it. Kevin
Re: [Repeater-Builder] Re: The GLB Preselector- Preamplifier
FWIW the BF981 is a dual-gate MOSFET, not a GaAsFET. I assume Aria switched to a GaAsFET for the current-production unit? Bob NO6B I bought several of these when they were first on the market. When this unit was first in production from Gil, he made it available like this: Under 200 MHz was Bi Polar, over was GaAs FET - HOWEVER, you could custom order under 200 MHz the GaAs option. The Bi Polar device was MRF-901 Motorola. I don't know what the FET was... I only ever owned one GLB Preselector/Preamp above 200 MHz (it was custom built for 222 MHz) and it had a MRF-901 in it -- go figure. GLB stand for Gilbert L. Boelke W2EUP inventor of the Hybrid Ring Duplexer - a design sold to Sinclair Radio Labs in Tonawonda NY Kevin Custer
Re: [Repeater-Builder] Re: The GLB Preselector- Preamplifier
skipp025 wrote: Smart guy... cumbersome type of duplexer that worked fairly well. I survived living near Tonawanda NY in Cheektowaga where snow is no fun. Yes, Gil was a very smart guy - somewhat ahead of his time. Here is the only information I can find (that is still available) about his untimely passing: http://barra.hamgate.net/links/jun2001.pdf Snow? Oh yes, about 6 inches here is Friedens PA today - it was 50 degrees yesterday. Kevin
[Repeater-Builder] Re: [GE Mastr II] MASTER II TO RC-210
W8YSU wrote: Does anyone on this list have pictures or scematic of a VHF Master II hooked up to an ARCOM RC-210? We are starting to work on one for our Club Repeater and I am looking for some examples for reference. Dean, Station or converted mobile? Did you look here? www.mastr2.com Kevin
Re: [Repeater-Builder] Simulcasting of Repeaters
Hi Folks, I know it's been done a lot, but I have no experience in having two repeaters simulcasting. Here's the info: There is an existing repeater that has some coverage issues in a neighboring area. The folks in that area, while still wanting to be on the same output frequency, will put a 2nd repeater (with a different rx PL tone) up on a hill. What kinds of issues will we see (from a user's perspective)? The dispatcher will probably key up both repeaters at the same time for tone-out purposes. What kind of frequency tolerance is acceptable to make sure there isn't any hetrodyning? (especially with PL tones tone-out tones). Here is a good tutorial written by a good friend of mine, Pete Policani K7PP Hope this helps... Kevin Custer Properly simulcast transmitters coupled with voted receivers really make a nice system; where the user is concerned *SIMULCASTING* By Peter Policani, K7PP So, what's all this simulcasting that we are hearing about? What's it mean and how does it work? Does it really help? These questions and many more have been asked since we started simulcasting on the K7PP repeater system. Well, let's talk about something you have heard. Have you ever heard two stations on two meters doubling with each other. It happens all the time and all that is heard is chaos. What would happen if two signals were transmitted on the same frequency at the same time? Would there still be the noise and chaos? Why? You might think of a time when you were operating CW. You switch to calibrate mode and check the band edges. You zero beat the calibrator. What do you hear when you are zero beat? If you said nothing, you are right. But the fact is, there are two signals occupying the same rf frequency at the same time. When they zero beat, the beat note is zero and no tone is heard. The same is true in simulcasting. In the K7PP repeater system, we have four transmitters on the same frequency. We zero beat all of the transmitters so that areas in between hear little or no zero beat tone. This is tough to do, so we use hi stability oscillators that don't drift much. If they do it's only a couple of hertz. The beat note from a couple of hertz is almost inaudible. Most radios don't like to pass audio that's under 300 hz and as a matter of fact the speakers themselves don't like to reproduce audio at that frequency either. The one remaining thing is the phase of the audio. If we transmit the same audio from the same source but the transmitters in the system are located different distances from the audio source, the audio arriving at the closest transmitter gets there sooner than the audio from the farthest. If we could just slow the audio down a little or delay it's arrival time at the closest transmitter a little, the audio would then be in phase. There are several manufacturers that make audio phase delay panels that are programmable. You just crank in the amount of delay you want. You might ask, how do you know how much delay is needed? The fact is, that radio signals travel at the speed of light. That works out to be about 5.4 microseconds per statute mile. Let's say that your two simulcasting transmitters are located with the first one at 20 miles from the audio source and the other at say, five miles from the source, you would have a difference of 15 miles between your first and second simulcast transmitter. If you take 15 miles times 5.4 microseconds, you come up with 81 microseconds. Now all you have to do is delay the audio to your closest transmitter 81 microseconds and then your source audio arrives at the same instant at both simulcast transmitters. With both signals zero beat and in phase, you have what amounts to one big transmitter. I know of one paging system in Puget sound that has 47 transmitters on the same frequency. This means that you could grow your existing system into coverage areas that you didn't have before. Many repeaters have gaps between them and their closest neighbors. Now you can move your coverage area out to your neighbors border where before nothing could be in operation because it was to close to either repeater. Since you won't be interfering with your self, you can pick and choose the right site to allow you to accomplish this. The other big advantage is that you don't have to run high power or for that matter operate from a tall mountain to get the coverage you and your group want. If it turns out to be too much, you could contact another
Re: [Repeater-Builder] Automated spam.
Facility 406 DM09 wrote: Well, you see, it's like this... You don't have a clue. You have been a member for 10 days, so, stick around and see how spam-less this list really works, or join one that explains the working of the lists here on Yahoo. This and every other off topic post is now over - back to our regularly scheduled programming. Kevin Custer List Owner
[Repeater-Builder] Off Topic (religious or other) posts - please read.
I asked once already for everyone to stop the threads where OT posts are concerned - many didn't listen. I'll ask once more - please do NOT post about this OT subject again. If I cannot gain the respect of those continuing to post, I WILL SHUT THE LIST OFF for a few awhile and we'll have a nice vacation. Those continuing with the OT posts will be promptly banned - period. Thank you for your consideration, Kevin Custer List Owner
Re: [Repeater-Builder] Re: Building Low Band Loop Antennas (DB-212)
Chuck Kelsey wrote: First, don't expect to land exactly where you expect simply by adjusting the lengths to a specific dimension. You really need to place the antenna on a tower to adjust properly and use an antenna analyzer. grin Reminds me of my first experience with a Cushcraft AFM-4DA (4 bay exposed dipole array for 2M) about 30 years ago. I put it on a nice galvanized mast and mounted it to a tall building free and clear of anything. While the antenna worked - it really didn't perform any better than a 5/8 wave ground plane. I realized that optimum gain was not being achieved because the dipoles were spaced around the galvanized support and weren't really in phase to help each other out. OK, no problem, I'll put them in a line all above one another. WOW, the gain in the direction where the dipoles were facing was fantastic - so, I fixed the gain problem - BUT I created another problem. The null in the opposite direction was so deep that the system didn't work where I needed it to (I really needed omni coverage - I couldn't suffer with a null anywhere). OK, no problem, I'll put the elements on a FIBERGLASS pole. I bought a hefty fiberglass pipe and carefully mounted the Cushcraft array to it - mounting all of the dipoles above one another will retain the gain, and the fiberglass pipe won't create a null - problem solved right? NOPE - a rubber duck would have performed better! What happened? This type of array REQUIRES the element to be in the presence of a metallic mast - otherwise the impedance of the element isn't close to 50 ohms. I didn't have the ability then to measure return loss or actual impedance of the individual dipoles, but I can guarantee you it wasn't close to 50 ohms. The antenna didn't work and the reflected power was awful. I used a Bird and hand-held to feed one dipole - while moving the distance between the dipole and the metal mast pipe - sure enough, when you got to the distance the mount was designed to give, the reflected was at a minimum. SO The distance between the antenna and the support varies the port impedance. Bought a Sinclair SRL-229 (super stationmaster type) and life went on Certainly on low band the concern of the elements exactly above on another is of a lesser concern because the difference in phase angle is likely less - so obtaining good low angle gain in an omni directional pattern is doable. Kevin Custer
