Re: [Repeater-Builder] Can't get Vertex VXR5000 to program
Read the repeater first NIMS: 100 200 300 400 700 800 Arrl Extra Class VE HAZ MAT- A O sent from my blackberry mobile device -Original Message- From: wspx472 wpxs...@gmail.com Sender: Repeater-Builder@yahoogroups.com Date: Wed, 08 Sep 2010 19:24:15 To: Repeater-Builder@yahoogroups.com Reply-To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Can't get Vertex VXR5000 to program I got this to work before but now, no joy. I am using CE8 software, have the correct cable, and an older DOS PC. I get either a box saying there was communication problems or it quickly flashes Done! but hasn't actually read the repeater. Is there some special trick I have forgotten?
Re: [Repeater-Builder] Re: Can't get Vertex VXR5000 to program
That has happened to me twice and I read it then it would program. Sorry it didn't help you. NIMS: 100 200 300 400 700 800 Arrl Extra Class VE HAZ MAT- A O sent from my blackberry mobile device -Original Message- From: wspx472 wpxs...@gmail.com Sender: Repeater-Builder@yahoogroups.com Date: Wed, 08 Sep 2010 20:32:58 To: Repeater-Builder@yahoogroups.com Reply-To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Can't get Vertex VXR5000 to program That's what I was trying to do. --- In Repeater-Builder@yahoogroups.com, Gary W. Gibbs ke5...@... wrote: Read the repeater first NIMS: 100 200 300 400 700 800 Arrl Extra Class VE HAZ MAT- A O sent from my blackberry mobile device -Original Message- From: wspx472 wpxs...@... Sender: Repeater-Builder@yahoogroups.com Date: Wed, 08 Sep 2010 19:24:15 To: Repeater-Builder@yahoogroups.com Reply-To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Can't get Vertex VXR5000 to program I got this to work before but now, no joy. I am using CE8 software, have the correct cable, and an older DOS PC. I get either a box saying there was communication problems or it quickly flashes Done! but hasn't actually read the repeater. Is there some special trick I have forgotten?
[Repeater-Builder] Re: Circular polarization for VHF repeaters?
Thanks to all that replied. I appreciate your input. I'm still looking for answers, but may be onto something. I have emailed Bill Pasternak, the author of that Cushcraft 4-pole conversion article. I re-read his original article and may have figured out what I must do. That, plus any additional input from Bill, should hopefully help me to complete the project. I will post again later if I have any success. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net --- In Repeater-Builder@yahoogroups.com, Gary - K7EK gary.k...@... wrote: Greetings, I am in a particularly sticky situation with one of my two meter repeaters in Lakewood, WA (Tacoma). I have generally great coverage, however there is a very annoying problem with multipath and raspy signals in a large portion of my coverage area. Since the Puget Sound area of Western Washington is very hilly and mountainous, multipath is very damaging to all forms of VHF communication. Over the years I have read about folks employing circular polarization to overcome fading, nulls, multipath, etc. There is so very little written about this topic in amateur circles so I thought I'd bring it up here and see what I could come up with. In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. Best regards, Gary, K7EK
[Repeater-Builder] Circular polarization for VHF repeaters?
Greetings, I am in a particularly sticky situation with one of my two meter repeaters in Lakewood, WA (Tacoma). I have generally great coverage, however there is a very annoying problem with multipath and raspy signals in a large portion of my coverage area. Since the Puget Sound area of Western Washington is very hilly and mountainous, multipath is very damaging to all forms of VHF communication. Over the years I have read about folks employing circular polarization to overcome fading, nulls, multipath, etc. There is so very little written about this topic in amateur circles so I thought I'd bring it up here and see what I could come up with. In the 80's there was a amateur radio repeater book by a fellow, Pasternak I believe, that took two gamma match style Cuschcraft Four Pole antennas, combined them, and did some magic with phasing lines to end up with a four bay circularly polarized repeater antenna. Unfortunately the description leaves much to be desired, at least for me, so I never built one. If he would have included specifics on phasing line lengths, cable types, etc, the job would have been a whole lot easier. Has anyone actually gone circular with Cushcraft Four Poles, and if so, could you please share it with me and/or this group? I have done some inquiring to commercial companies about a custom built two meter four bay circularly polarized array, but that is entirely out of the question. They want thousands of dollars. There must be an easier (and cheaper) way. Similarly, is anyone in this group running circular polarization on your amateur repeater(s), and if so, could you please share the details in a manner that could be duplicated without a lot of guess work? I know that I could easily solve my multipath problem by installing one or more remote receivers, however I would like to keep that as a last resort and shoot for a circularly polarized antenna system at the main repeater site. I do understand that there is approximately 3 db of loss as a result of this, but that is quite acceptable. The dividends would greatly outweigh the down side. Thanks for any constructive ideas, suggestions, links, etc, that you might be willing to share concerning this situation. Best regards, Gary, K7EK Personal Web Page: www.k7ek.net
RE: [Repeater-Builder] Adding capacitors to lower electric bill
The guy did ok on the first part explaining how power factor works but fell down when it comes to the save money part. The utilities do not charge you extra or give you a break if you do or don't have any power factor correction. Unless you are an industrial customer. I have seen demonstrations at shows where the guy trying to sell consumers power factor correction devices had a motor and an ammeter showing current draw. He then switches in a capacitor and shows you how the current drops and shows you how volts times amps reduces the wattage used. Only problem is the electric meter doesn't care what the power factor is! So the utility will bill you the same amount if you use power factor correction or not in your home. The other thing involved if you are going to do power factor correction is that it needs to be done on EACH motor or inductive device. If you just hang a capacitor across the main power line of the proper size when all motors are running it will correct that. But when a motor or other inductive device is shut down and the capacitor is still across the line, now it will have a capacitive load rather than an inductive load. Same problem; capacitive current that is out of phase. You can hook a large AC capacitor across your power line and measure the current thru it. It may look like you are drawing a lot of power thru it but the meter will not see it. Yes it cost the utility more to generate that extra current whether it be capacitive or inductive but you don't pay for it. If the utility was really worried about it they would give incentives for high power factor equipment or they would bill you like they do in industry. We are small potatoes to them. Trying to sell power factor correction to home owners and small business' is a scam. You save nothing on your bill! 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bon Hal Sent: Saturday, August 21, 2010 2:39 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Adding capacitors to lower electric bill This is a reply to the power issue from a friend of mine: Yes, it's true. Heavy industry uses this technique to reduce their electrical utility costs. Steel production is an example. Some utility companies require that customers with large inductive loads use and pay for capacitor banks to correct the plant's power factor. The issue arises when large inductive loads are connected to the electrical grid. For example, a large horsepower electric motor presents two loads to the grid. One load is the energy consumed or dissipated in work. The other load is inductive. The inductive load stores electrical energy, does not dissipate it, and it is returned to the grid. It can't be helped. It is built into the design of electric motors. This is understandable. We understand that practical electric motor armatures are turned by a strong magnetic field. That magnetic field is produced by large inductors. As an electrical circuit, you can visualize the motor as a resistor in series with an inductor driven by a sine wave 60 Hz alternating voltage source (AC). On the positive half cycle voltage swing (0-180 degrees), electrical energy is dissipated in the load, the resistor. In the resistor the energy is dissipated in heat. In a motor, the energy is dissipated in work done. The inductor stores electrical energy on the positive half cycle then returns the energy to the grid on the negative half cycle (180-360 degrees). The resistor again draws and dissipates energy on the negative half cycle. In the electrical circuit analogy, if the inductor was zero Henrys and the Resistor was non zero Ohms, the Power Factor (PF) is defined as 1.0, or unity. This is a purely dissipative load. If the inductor was non zero Henrys and the Resistor was zero Ohms, the PF is defined as 0.0. This is a purely inductive load. In a practical circuit with some inductance, L, and some resistance, R, PF therefore varies between 0.0 and 1.0. For given values of L and R, PF can be measured or computed. The utility company sells the energy dissipated in a load. If PF = 1.0, the utility company sells all the energy it supplies. As PF decreases due to inductance, the load increasingly stores and returns larger amounts of energy to the utility company. The utility has to generate the additional power needed to charge the connected inductive loads, even if the energy is returned to the grid. The utility needs significantly more capacity and therefore greater investment and operating capital. Worse yet, the increased current flow causes more dissipative energy loss in the line resistance. This inefficiency is a measurable loss of money to the utility. Adding capacitance across and close to the load helps a lot. Briefly and simply, it works like this. The utility initially charges
RE: [Repeater-Builder] Adding capacitors to lower electric bill
You won't see any difference. The electric meter reads true power not VA. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Friday, August 20, 2010 8:00 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Adding capacitors to lower electric bill A while back, maybe a year or two ago, there was a discussion on here where a list member had success adding a capacitor to his electric service which reduced his bill. It was debated for a while. Anyway, I am wondering if the utility company ever came and replaced the spinning disk meters with electronic versions, and if so, what the outcome was. Could the original poster respond either here or privately? I just today had a similar discussion with another ham who tried essentially the same thing with no success - only his was a commercial model, so it cost him considerably more. Chuck WB2EDV Yahoo! Groups Links
RE: [Repeater-Builder] Adding capacitors to lower electric bill
True power (W or KW) is increased by poor PF and high apparent power (VA or KVA). The resulting increase in current demand raises the true power but the extra current is usually lost as heat instead of performing work. The bigger problem (bigger than an inflated utility bill) is the potential for fire from drawing too much current through a branch circuit that can't handle the highly reactive load that's been connected to it. Also beware of cyclical reactive loads on panels that also feed electronics. I recently troubleshot a commercial 3 phase panelboard feeding both UPS's and across-the-line HVAC gear (a bad combination). The UPS's were failing and the owner didn't know why. A quick power quality analysis showed it was due to excessive UPS transfers caused by the HVAC cycling during the daytime and causing the UPS's to see voltage dips. Average PF was .67 when we started, .91 when we moved the HVAC away from the panel and did some load balancing. Gary N6LRV -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Friday, August 20, 2010 6:14 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Adding capacitors to lower electric bill That's my take, but someone on here insisted otherwise based on testing he had done. I spoke with an electrical engineer who said the same thing, but then he wondered out loud if it could be possible if the power factor was shifted to an extreme with a spinning disk meter. He opined that an electronic meter wouldn't be fooled. Of course shifting the PF to an extreme would be a basis for utility company action. Chuck WB2EDV - Original Message - From: Gary Schafer gascha...@comcast.net To: Repeater-Builder@yahoogroups.com Sent: Friday, August 20, 2010 9:06 PM Subject: RE: [Repeater-Builder] Adding capacitors to lower electric bill You won't see any difference. The electric meter reads true power not VA. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Friday, August 20, 2010 8:00 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Adding capacitors to lower electric bill A while back, maybe a year or two ago, there was a discussion on here where a list member had success adding a capacitor to his electric service which reduced his bill. It was debated for a while. Anyway, I am wondering if the utility company ever came and replaced the spinning disk meters with electronic versions, and if so, what the outcome was. Could the original poster respond either here or privately? I just today had a similar discussion with another ham who tried essentially the same thing with no success - only his was a commercial model, so it cost him considerably more. Chuck WB2EDV Yahoo! Groups Links Yahoo! Groups Links No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3084 - Release Date: 08/20/10 14:35:00 Yahoo! Groups Links
RE: [Repeater-Builder] Polyphaser Question
Here is a little primer on lightning: Having your antenna grounded does not drain off any charge that helps prevent a strike. As a matter of fact grounding the antenna makes it slightly more prone to a strike but not grounding it is much worse as you have no control over what path the energy will take if not grounded. When a storm cloud moves over the area charge builds on objects on the ground. The ground items, towers etc start to emit streamers. When a strike is imminent step leaders come down from the charged cloud and move in approximately 150 foot steps. Changing directions with each step. When a step leader gets close enough to a streamer a connection is made. What follows is a plasma trail which is a very low impedance path that the lightning charge follows. Lightning can be thought of as a current source. In other words if there is a 10 KA strike it is going to develop that much current into whatever it strikes. If for example it hits your tower and the total impedance to ground is quite low then the voltage developed across the tower will be relatively low. But if the ground system is not a good one then the voltage will rise higher. It will still develop the 10 KA current. Bonding all equipment to a common point is one of the first steps to take. Just adding a polyphaser coax protector to the coax line will only equalize the current between center conductor and shield. If power is not protected and everything bonded together the coax protector will do little good. Even without a coax protector, just bonding everything is a great first step. The whole idea is to keep everything at the same voltage level when a strike occurs. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tony KT9AC Sent: Wednesday, August 18, 2010 9:25 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Polyphaser Question Remember the objective is not to take the brunt of a lightning strike, but to drain off any static that would attract that strike. Lightning is just a spark looking to close the gap, and if your antenna is closer to DC ground, it will find something closer to its potential (i.e. static charged) to hit. Any protection is better than nothing, and don't scrimp on buying the cheapest used protector. Its your equipment your protecting and potentially avoiding liability. I buy new Polyphasers for our site and sleep just fine. On 08/18/2010 08:56 AM, wd8chl wrote: On 8/17/2010 11:55 PM, Ray Brown wrote: What do you do when you want to install a small UHF linking repeater on a 4-story building that has no lightning protection on its' roof? (this is to link an ambulance at a hospital to its' base repeater 40 miles away) From what I've heard, it may not be a good idea to hook it to the HVAC, either. (sigh) Ray, KB0STN No. I would find the nearest copper pipe from either the in-house water system or the sprinkler system, and clamp to that (making sure you don't crimp the pipe!!!) using #6 or maybe #8 wire if it's REALLY close (less then 5') Again, not as good as a dedicated system, but MUCH better then nothing.
RE: [Repeater-Builder] Coax length, etc.
Russ, Of course the Bird 43 does not measure power directly. But it does sample voltage AND current on the line in amounts that are combined to indicate power. It is a directional coupler. The only time you will have a problem with it deviating from its accuracy is when the directivity becomes too low such as when the line impedance is way off from its design 50 ohms. As I said before it will read power accurately even if the transmission line is no a 50 ohm line. The manual even tells you that you can use it to measure line loss with an open at the far end of the line. Please read chapter 2 theory of operation of the Bird manual that you show the reference to. Then read it again! 73 Gary K4FMX Another chance? Which part, erroneous readings, don't directly measure power, or the voltmeter part? Sure, what the heck. ;-) I've had Bird 43's, and calibrated line sections with matched elements for that matter, give erroneous reflected power readings depending upon what was going on with the transmission line. By erroneous, I mean it was usually a reading that was, for example, excessively high versus what we knew was going on, such as a straight piece of rigid line or coax terminated into a known good load. On rare occasion, we found we slipped a bullet or had a bad connector. More often, relocating the instrument somewhere else along the line resolved those bad readings. RF calorimeters can measure power directly. But unless they've one hidden in them somewhere, ThruLine meters can not. Just because the Commission might accept wattmeter readings, or Bird says so, doesn't make it so. As for the voltmeter part, check out page 6 of the Bird 43 manual (page 18 of the PDF), a copy of which you'll recall is here: http://www.repeater-builder.com/bird/pdf/bird-43-wattmeter-2004.pdf I respectfully submit what is shown is a schematic/diagram of a directional coupler attached to a voltmeter as an indicator. An induced RF voltage sample is rectified, filtered and applied through a dropping resistor to a shunt-connected ammeter. By definition, a voltmeter is the shunt-connected ammeter with series resistor part. But don't take my word for it. Take a peek at Chapter 25 in any recent ARRL Handbook (this works for my 2007 copy anyway). Is it less a voltmeter because the induced voltage tracks current on the line? Want to call it an ammeter or current meter then, after all that's what the actual meter movement is? I submit this particular voltmeter happens to be calibrated to read average power at 50 ohms impedance, and it does this quite well within its limitations. I now await your thrashing. Please be gentle. ;-) Like the manual says, the Bird 43 is fast, convenient and accurate. I agree it's fast and convenient. I'll agree it's accurate with the caveats expressed. It beats lugging a slotted line around, and it beats every other meter like it, IMHO, including my old Daiwa dual-metered POS wattmeter. ;-) Oh, BTW, the emperor has no clothes either. :-P 73, Russ WB8ZCC
RE: [Repeater-Builder] Coax length, etc.
Hi again Russ, _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO, it's really messy. It can't tell the difference between a 1:1 VSWR and a 2:1 VSWR (both will calculate out to 1.4:1) on a 70 ohm line. That's not accuracy, that's nearly useless. Yes it gets a little tricky to find VSWR with a non 50 ohm line. But most of the time we really don't care what it is. I say we don't care because it is rare that the 50 ohm Bird meter gets used in a non 50 ohm transmission line. With a 50 ohm line things work out nicely to find power and VSWR no matter what kind of reflection the load presents. BTW, my POS Daiwa can show me a 100% reflected condition, just like the Bird. And just like the Bird, it doesn't indicate if that's an open or a short. So what? If you need to know that then you are using the wrong instrument. I believe Bird wants us to believe that their meter is faster and more convenient (it is) yet as accurate as a slotted line and calorimeter (sorry, nope). It's a calibrated voltmeter, not a network analyzer. Try doing the same thing with a voltmeter. :) No one claims it to be anything other than a simple wattmeter. It is not a super accurate at measuring power either. It is claimed to be 5% of full scale reading. That means with a 100 watt slug the best accuracy that you can depend on is +- 5 watts anywhere on the scale. So at 25 watts on the meter scale it could be as low as 20 watts or as much as 30 watts. But for what it is it works very well. For most everyday, mundane RF chores, it's just dandy as we don't really need high accuracy. And as long as line impedances stay reasonably close to 50 ohms, it turns out accuracy is pretty good, too. Again, line impedance doesn't matter for power measurement. 73 Gary K4FMX Certainly not bad for a portable instrument, and that's the point. If we remember what its limitations are, we should be good to go. That's why I own one and want more. Okay, I'm done picking
RE: [Repeater-Builder] Coax length, etc.
I don't know if you really don't get it or you are just trying to be controversial. I tend to think a little of both. Either way, I give up. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 7:37 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. Last round. Hi again, Gary. ;-) On 8/15/2010 7:09 PM, Gary Schafer wrote: Hi again Russ, _ From: mailto:Repeater-Builder@yahoogroups.com Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Sunday, August 15, 2010 4:54 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc. I see some folks are heading for the Advil. My apologies. Thanks, Gary, for admitting the 43 doesn't measure power directly. One myth down. Of course, it is a directional coupler, no argument. That makes it a reflectometer, it enables the instrument to isolate forward/reflected samples to some degree of reliability. What's the rest of the circuit? ;-) IMHO, what makes the 43 better than most (if not all) meters of its type, is the directional coupler is a true transmission line coupler, not a ferrite transformer, directly connected capacitor, etc. But it works the same way. Yeah, and? The Bird does it better. As far as rereading the manual, I have been. Bird's explanation requires the reader to suspend a standing wave viewpoint of transmission line theory, and buy into their traveling wave viewpoint. Uh, okay. But that kind of thing sends up red flags for me. I shouldn't have to suspend accepted transmission line theory to understand how their meter works. There are no standing waves that you can measure directly with the Bird meter. In order to truly measure standing waves you need to have a line length greater than a half wave length and measure where the nulls are along the line. Swr is calculated from forward and reflected power at one point on the line with a Bird type of meter. That's correct. As I said, the 43 isn't a slotted line. Regarding VSWR, all in-line meters make an attempt at this, some have fancy cross-needle indicators where VSWR is represented at the intersection of the needles. How else would you do determine VSWR with such a device? That was a rhetorical question. ;-) As it turns out, I don't. When line impedances get away from 50 ohms, accuracy falls and the meter behaves like you'd expect. It tracks whatever current is on the line at that (the meter's) point in the line without regard for impedance. Since it's just not calibrated for whatever that impedance might be, how can it be accurate? The Bird is set up so that the ratio of voltage and current that are detected work out to the power at 50 ohms. When the line is not 50 ohms that voltage/current ratio change that the meter detects. So you can no longer simply look at the scale on the meter and directly read power. For ANY reflected power reading you must subtract the reflected power shown from the forward power shown to find the true power delivered to the load. This holds true no matter what the impedance of the line is. Thanks, Gary, that's right. The meter is calibrated at 50 ohms impedance. When the line impedance isn't 50 ohms, you can't just look at the meter, the meter scale is no longer accurate, is it? Subtracting reflected from forward is a given, and never at issue here. Well, impedance does matter. At the characteristic impedance of the meter, line, load, etc., seems a waste of time to subtract nothing, you'll see right away there's no reflected power. ;-) If the meter did as you suggest, then it would show what the voltage and current are at any point in the line, and therefore be able to tell you what the impedance is at that point, all with some level of accuracy. It simply can't do all that. With the Bird meter you don't care what the impedance is because it measures voltage (by way of capacitive coupling) and current (by way of inductive coupling). Both create voltages that add together in the proper ratio to give the meter reading that represents power level for that combination of voltage and current. Gary, you seem to be contradicting yourself. A paragraph ago you said the ratio of voltage and current work out to the power at 50 ohms. Now we don't care what the impedance is? We either do or don't. As for me, I choose to care 'cuz that's the kind of guy I am. ;-) I understand the coupling, both are present, agreed. But if impedance didn't matter, then the meter would indicate power accurately regardless of line impedance. That's simply not so. The Bird manual even says it's not so. It's limited by its own line section. Yes, Bird describes what happens when using 70 ohm lines with the meter under less-than-perfect conditions. IMHO
RE: [Repeater-Builder] Coax length, etc.
One correction here; the Bird power meter is not just a voltage measuring meter. It does in fact measure voltage and current to calculate power. It will give true power even if used in a non 50 ohm circuit. But you must always subtract reflected power from indicated forward power to find true power delivered to the load. When measuring SWR you must always calculate it (or use the chart) and compare reflected to forward indicated on the meter. It is easy to be fooled as indicated forward power also drops as reflected power drops. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Russ Hines Sent: Saturday, August 14, 2010 4:30 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Coax length, etc.73 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. IMHO, we're making the same mistake I made in a post the other day, saying VSWR when what we really mean is reflected power as indicated on a meter. Jeff is correct, VSWR along a transmission line doesn't change if source, load and line impedances are stable, the ratio remains the same. What does change, and what is affected by line length, are actual impedances along the line under not-so-perfect-or-stable conditions; the actual impedances along the line change but the ratio does not. For example, 100+j0, 25+j0, 40+j30, and 40-j30, are different impedances yet all exhibit a VSWR of 2:1 in a 50-ohm impedance system. Voltage is proportional to impedance. We can't really have a voltage standing wave ratio greater than 1:1 without a voltage differential, and that really can't happen if impedances along the line remain the same. Our friends at Agilent have put together a Java applet demonstrating what happens along a transmission line. Maybe you're aware of it, it's really kind of cool. The applet allows you to change the load impedance of the model and see the changes, so have fun with it. http://education.tm.agilent.com/index.cgi?CONTENT_ID=6 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. With most transmitters I'm familiar with, a high VSWR condition is detected from a reflected RF sample from a directional coupler at the transmitter's output, so it's not a real VSWR measurement per se, it's a voltage measurement. Worse, these couplers tend not to be very selective, so out-of-channel and even out-of-band energy can cause high VSWR trips even when our measurements indicate all is well on our frequency of interest. Great discussion, keep it going. If I repeated what was already mentioned, my apologies. 73, Russ WB8ZCC _._,___
RE: [Repeater-Builder] Coax length, etc.
the cable at least that length.
And if the transmitter balks,, you place an isolator on it. :)
73
Gary K4FMX
The cable length between multiple cavities is predictable. As
an example between two notch cavities; the first notch
presents a very low impedance. With a quarter wave line to
the next cavity that low impedance is transformed to a high
impedance at the input to the next cavity. That high
impedance is then presented with a very low impedance of the
second cavity. This critical length cable increases the
ultimate notch depth because the high impedance that the
cable presents and the low impedance of the cavity form a
voltage divider. The greater the ratio the better the rejection.
'zactly. When done right, you can pick up close to 6 dB additional net
notch depth when cascading notch (or pass/notch) cavities when the
intra-cavity cables are cut this way.
Jeff WN3A
Yahoo! Groups Links
RE: [Repeater-Builder] Re: Coax length, etc.
Hi Allan, Do we really care what the output impedance of the transmitter is? Most transmitters do not present a pure 50 ohm output but are tuned to transfer maximum power into a 50 ohm load. This often comes out to something way different than a 50 ohm source impedance. As the source impedance does not affect SWR the system doesn't care what it is as long as the transmitter can transfer maximum power into 50 ohms. What the transmitter does sometimes care about is the reflected impedance from the first cavity (being hi Q) that is not on frequency. This presents a highly reactive load to the transmitter that can sometimes cause the transmitter to overheat or reduce output. Placing a cable of a different length between output and the first cavity can sometimes change the unwanted off frequency load seen by the transmitter. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of allan crites Sent: Friday, August 13, 2010 12:56 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Coax length, etc. Nate, I have both the 12th and 14th edition of the ARRL Antenna books, the 12th I acquired in 1974 and have read and re-read the section on transmission lines and impedance matching probabily more than anyone else has. I sometimes learn new things with each re-reading, as there is much to be learned. In my discussions with Kevin Custer about the length of the transmission line connecting the xmtr output and the input to the duplexer, he suggested and I accepted, to colaborate on an article explaining the problems associated with matching the output impedance of a solid state transmitter of somewhat different than the normal 50 Ohms, and the attempts made by a manufacturer of duplexers to adapt (read match) the xmtr output via certain lengths of transmission line and readjustment of the tuning of the cavity closest to the xmtr output to effect this matching, ignoring the possible degradation resulting to the pass and notch characteristics. The transmitter in our discussions was the HB GE Mastr 2 which, in the information available to me, appears to be having an output source impedance of 35+ or - (some unknown) reactance Ohms. Kevin commented that it appears that many hams are unaware of, or understand the methods needed, to do an appropriate job of impedance matching. Therefor we will be making this article for the benefit of those who don't understand the impedance matching necessary for optimum power transfer with a simple to understand way of impedance matching without the use of the infamous Smith Chart (which I have utilized for the past 50 yrs in all my impedance matching solutions and cannot be without). I agree that much information for impedance matching is contained in the ARRL Antenna Book but in my experience, real life adaptation of this information is and can be difficult to many hams. There is also another book I rely on and recommend, which is Electronic Applications of the Smith Chart by Philip Smith. Now, if you would like to contribute to our efforts I would gladly accept your contributions. Thanks for your input. Allan Crites wa9zzu _ From: Sid purvis...@yahoo.com To: Repeater-Builder@yahoogroups.com Sent: Fri, August 13, 2010 10:38:25 AM Subject: [Repeater-Builder] Re: Coax length, etc. I have a note in my file that I do not recall where it came from relative to cable length between the duplexer and the TX or between the duplexer and additional filter. Length = (30)(32.785)(vf/freq). 30 is for 30 degrees, vf is velocity factor, freq is the average of the pass and reject frequencies. If too short add 180 degrees. Don't know if this is good info or not. The article would be appreciated. Sid. --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Nate Duehr n...@... wrote: On Aug 5, 2010, at 11:20 AM, Kevin Custer wrote: 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. There's already a great book on that topic, it's called the ARRL Antenna Handbook, and the chapter on transmission lines covers it in more detail than anyone will ever need to know in the real-world, who's not a practicing RF Engineer. That book if read cover-to-cover, is also damn good for insomnia. Or at least it'll keep you distracted while you can't sleep! :-) -- Nate Duehr n...@... facebook.com/denverpilot twitter.com/denverpilot
Re: [Repeater-Builder] Hygain in Starkville MS
I'm almost positive Mfj bought them. When I placed a catalog order hygain was one of the catalogs I received. NIMS: 100 200 300 400 700 800 Arrl Extra Class VE HAZ MAT- A O sent from my blackberry mobile device -Original Message- From: Tim tahr...@swtexas.net Sender: Repeater-Builder@yahoogroups.com Date: Wed, 04 Aug 2010 08:02:45 To: Repeater-Builder@yahoogroups.com Reply-To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Hygain in Starkville MS Didn't MFJ buy them? Seems when I was working on my Ham IV, they were one of the places I could order parts from. Tim
Re: [Repeater-Builder] Re: Icom OPC-617 Cable
What model radio is this ? NIMS: 100 200 300 400 700 800 Arrl Extra Class VE HAZ MAT- A O sent from my blackberry mobile device -Original Message- From: Duane Hall du...@dheco.com Sender: Repeater-Builder@yahoogroups.com Date: Thu, 22 Jul 2010 11:18:04 To: Repeater-Builder@yahoogroups.com Reply-To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Icom OPC-617 Cable The solder jumpers D Data and F Flat only affect the freq response of the transmitted audio. A wrong setting wouldn't interfere with PTT. I think there was a drawing in the manual linked below, illustrating the locations. Are you grounding the PTT line and have reprogrammed the radio to allow external PTT? Regarding the speaker, are you getting the audio you need from the connector, but you want to disable the internal speaker? Maybe inserting a 3.5mm plug in the speaker connector on the back will mute the internal speaker. You could put a resistor inside the plug to provide a load. Duane AB8QU On 7/21/2010 9:13 PM, ryan_151 wrote: I connected the OPC-617 as you said but i didnt solder the D or F bead and is probly why it didnt work. when i recieve audio it comes out the little speaker inside the radio and the PTT wont work to let me transmit. Im not using any data so i guess i need to solder the D bead, is this Correct?? is the D bead the jumper on the left side of the radio when the display is pointing at you?? THANKS FOR YOUR HELP!!!
RE: [Repeater-Builder] Ruggedised panel antennas
Gareth, If it's of any help I have two new/old stock heavy duty Scala yagis available in the 460-470Mhz range. These are in the factory radomes as well. I'm looking to get rid of them because I don't think I'll ever use them. Reply directly to me if interested. Gary R. California _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gareth Bennett Sent: Tuesday, July 06, 2010 10:25 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Ruggedised panel antennas Hi Group, I'm just wondering if anybody has an alternative to Katherin-Scala for heavy duty radomed panel antennas in the 450-500 MHz band at around 10dBi gain that will stand up to the abuse of an alpine site (2Km ASL) Just after feedback and opinions Cheers Gareth Bennett RadioSystems Limited P.O. Box 5202 Dunedin 9024 New Zealand DDI: (03) 489 1101 FAX: (03) 489 1151 MOB: (0224) 588 377 gare...@radsys.co.nz - Original Message - From: Oz-in-DFW mailto:li...@ozindfw.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, July 07, 2010 10:07 AM Subject: Re: [Repeater-Builder] Proto boards Or: http://www.wa5vjb.com/products4.html 6.5 by 4.25 Large Proto Board $5 3.75 by 2.75 Small Proto Board $3 Kent is also a source of economical built-to-spec preamps. -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport)
RE: [Repeater-Builder] Heavy Duty Antenna question....
Talk to Scala in Medford, OR. I'm sure you've heard of them. They'll make a super heavy duty gain omni if you're willing to pay. They're website is http://www.kathrein-scala.com http://www.kathrein-scala.com/ . I got one NOS some time back second hand and I'm pretty sure meteors, ICBM's, and the like will bounce right off of it. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of batwing411 Sent: Monday, May 31, 2010 10:07 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Heavy Duty Antenna question well, i tried to search, but.. alas, sorting thru 1400+ posts just isn't going to work. i need actual use facts on high altitude (11k feet), severe duty antenna selection... i've always been a stationmaster (fiberglass) antenna guy - and never had a problem... but...i've never put an antenna up at this height. i am going to need something good for 150+ MPH winds, ICE, etc. Open to ideas. Yahoo! Groups Links http://groups.yahoo.com/group/Repeater-Builder/ Individual Email | Traditional http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) repeater-builder-dig...@yahoogroups.com repeater-builder-fullfeatu...@yahoogroups.com repeater-builder-unsubscr...@yahoogroups.com http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] HT-1000
Douglas, Your range information is a bit off target. The 'R' range typically operate in the 403-470Mhz range while the 'S' range radios typically operate in the 450-520Mhz range. These radios do not take well to any sort of retuning as you put it but the 'S' range radios can usually be easily programmed into the 440Mhz range without much effort. Read all the info on both the RB website and the Batlabs website to learn more. Oh, and the 'R' range radios are readily available but they're more popular for obvious reasons. These radios are part of a family commonly known as Jedi (Motorola's production 'pet name', all models have one) which includes the MT2000's, MTS2000's, JT1000's, and MTX8000's and 9000's. There are slight differences between all and they don't all share the same software but they do share the same accessories and are built on the same platform. Needless to say there's a lot yet to learn about them. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Douglas Sent: Tuesday, May 25, 2010 8:49 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] HT-1000 I have a question, maybe two on the Motorola HT-1000 portable radio. On the Repeater-Builder's information webpage that talks about how to decipher the model number example: H01SDC9AA3BN The forth digit/letter defines the working spectrum example S for the range 470-520mhz, R 438-482mhz, etc. I am talking obviously about the UHF model HT-1000 Jedi series radio here. My question is,are there model R out there and secondly, how easy or difficult to retune the S model if the range is outside the Amateur Radio arena? Many thanks guys. Yahoo! Groups Links
RE: [Repeater-Builder] HT-1000
Eric, Manual 6881200C75 was updated in manual revision FMR-1686-1 to show the splits we've all come to know as 403-470 and 450-520 beginning with radio version B. The 'S' split radios usually take nicely to the 70cm band in my experience using the SHIFT key method in fact, I have two here working this way right now. Subsequent versions of that manual as well as 6881200C40 show the actual splits by model family. 73, Gary N6LRV -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Tuesday, May 25, 2010 7:46 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] HT-1000 Douglas, According to the HT1000 Service Manual, the model number H01SDC9AA3BN breaks down as follows: H - Handheld Portable 01 - HT1000 Model S - 470-520 MHz D - 4.0 - 5.0 Watts RF Power C - Standard Controls, No Display 9 - Channel Spacing is Variable/Programmable A - Primary Operation is Conventional/Simplex A - Primary System Type is Conventional 3 - Feature Level is Limited Plus B - Version Letter is B N - Unique Model Variation is Standard Package Needless to say, your radio is not a good candidate for use at 70 cm. While it is possible to hack the RSS so that you can get the radio to accept 70 cm frequencies, it is quite another thing for the radio to function in the Amateur band with acceptable power and sensitivity, and without burning up the final. Moreover, there is nothing to tune inside the radio; there are significant differences within the radios for each band. Perhaps your best course of action is to sell your radio to someone who needs the S split, and buy an R split radio. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Douglas Sent: Tuesday, May 25, 2010 8:49 AM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] HT-1000 I have a question, maybe two on the Motorola HT-1000 portable radio. On the Repeater-Builder's information webpage that talks about how to decipher the model number example: H01SDC9AA3BN The forth digit/letter defines the working spectrum example S for the range 470-520mhz, R 438-482mhz, etc. I am talking obviously about the UHF model HT-1000 Jedi series radio here. My question is,are there model R out there and secondly, how easy or difficult to retune the S model if the range is outside the Amateur Radio arena? Many thanks guys. Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Re: how far
It sounds like you have a linear amplifier. Linear amplifiers are used when multiple low power transmitters are to be amplified by one amplifier. The peak power (actually peak envelope power) capability of the amplifier must be quite high in order to handle the multiple signals without generating intermodultion distortion. The peak envelope power increases by the square of the number of signals going into the amp. N^2 * power Example: two 5 watt signals into the amplifier have a peak envelope power of 20 watts. Three have a PEP of 45 watts. Ten 5 watt signals works out to a PEP of 500 watts. (10^2 = 100*5 watts = 500 watts pep) So if you have ten 5 watt transmitters fed into the amplifier the amplifier must be capable of 500 watts PEP. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of George Sent: Sunday, April 25, 2010 4:08 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: how far well this amplifier is rated 90 watts you can see it on e-bay just type powerwave in the search. it has error eliminating computer inside and no distortion what so ever. i have it modified and use it at 450 watts and i pushed it with two power supplys that can put more than 120 ampers at 24 volts. the antenna is rated at 500 watts... i wonder why woud they do that...just to put out 5 watts? --- In Repeater-Builder@yahoogroups.com, Joe k1ike_m...@... wrote: The typical cell site is probably running a 10 watt amplifier with an ERP of about 100 watts. City sites probably a lot less power. Your in the high power paging transmitter class. Physical damage can be done in the nearby horizontal field of the antenna using this much power and antenna gain. Joe On 4/25/2010 3:13 PM, George wrote: what do you mean...a cell site in the city radiates much more times than my antenna, its on the same level and shoots directly in peoples houses... Yahoo! Groups Links
RE: [Repeater-Builder] Re: how far
I am not saying that you are misleading anyone. I am just pointing out to all that the amplifier, if intended for multiple low power transmitter amplification, is indeed capable of rather high power output. 500 watts PEP output with multiple transmitters fed to it is certainly capable of 500 watts carrier output with a single transmitter. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of George Sent: Sunday, April 25, 2010 7:19 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: how far i am using BIRD watt meater with 1000 watt slug and i am not misdirectioning anybody --- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: It sounds like you have a linear amplifier. Linear amplifiers are used when multiple low power transmitters are to be amplified by one amplifier. The peak power (actually peak envelope power) capability of the amplifier must be quite high in order to handle the multiple signals without generating intermodultion distortion. The peak envelope power increases by the square of the number of signals going into the amp. N^2 * power Example: two 5 watt signals into the amplifier have a peak envelope power of 20 watts. Three have a PEP of 45 watts. Ten 5 watt signals works out to a PEP of 500 watts. (10^2 = 100*5 watts = 500 watts pep) So if you have ten 5 watt transmitters fed into the amplifier the amplifier must be capable of 500 watts PEP. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of George Sent: Sunday, April 25, 2010 4:08 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: how far well this amplifier is rated 90 watts you can see it on e-bay just type powerwave in the search. it has error eliminating computer inside and no distortion what so ever. i have it modified and use it at 450 watts and i pushed it with two power supplys that can put more than 120 ampers at 24 volts. the antenna is rated at 500 watts... i wonder why woud they do that...just to put out 5 watts? --- In Repeater-Builder@yahoogroups.com, Joe k1ike_mail@ wrote: The typical cell site is probably running a 10 watt amplifier with an ERP of about 100 watts. City sites probably a lot less power. Your in the high power paging transmitter class. Physical damage can be done in the nearby horizontal field of the antenna using this much power and antenna gain. Joe On 4/25/2010 3:13 PM, George wrote: what do you mean...a cell site in the city radiates much more times than my antenna, its on the same level and shoots directly in peoples houses... Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Re: Pager Interference Revisited
Just for grins, find a place (house) to hook your spectrum analyzer up to the local cable system and see if it is on there. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mike Besemer (WM4B) Sent: Saturday, April 24, 2010 6:15 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Pager Interference Revisited Problem is Milt, the darn signal level varies like crazy from day to day and location to location. I can be in a certain spot and receive the signal very well, drive until it disappears, and then have it reappear at a high level as I continue on. Obviously elevation and blockage has a lot to do with that, but it actually does that to the point of being ridiculous. almost like it moves. I have been wondering if one of the pole-mounted CATV amps is going crazy and the stuff is squirting out of the CATV system every place it leaks. Sure wish we'd get a trace of audio (besides the pager) on the darn thing. This is gonna drive us nuts before we're done. I'm hearing the stupid thing in my sleep! 73, Mike WM4B From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Milt Sent: Saturday, April 24, 2010 5:27 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Pager Interference Revisited OK, this is probably not going to be an easy one. I have seen several instances of mast-mounted TV preamps oscillating and acting as miniature transmitters capable of sweeping over wide swaths of spectrum as the temperature changes. They usually exhibit a raw AC buzz on the signal. They are almost never active when the weather is cold, only coming active as the ambient temperature rises. Usually were fed with twin lead. Your description of the audio seems to put that possibility pretty far down the list. At this point I would probably want to look at the incoming signals on the repeater with a spectrum analyser and see if you can quantify the level of the incoming interference signals. If the interference level is high enough you should be able to hear it and maybe track it with a service monitor that can be run off of 12v in a mobile. Since you can call a number on one of the transmitters you can control things a bit. Good luck hunting. Milt - Original Message - From: Mike Besemer (WM4B) mailto:mwbese...@cox.net To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 24, 2010 4:42 PM Subject: RE: [Repeater-Builder] Re: Pager Interference Revisited Milt, Not sure what you mean by 'come and go'. It's there when the pager transmitter is up, gone when it's not. It also comes and goes with heat and sun. we may have days with no interference if it's cool and cloudy or just plain cold. Rain makes no difference. Nothing remarkable about the audio. sounds like clean, clear paging tones. Never heard anything els There is an abundance of TV stations, DTV, translators, AM, FM. you name it. The paging signals are both, depending on which site it's coming from. I can get my hands on pretty much anything I need. Spectrum analyzer is no problem. I have a good 'connection'. Did some hunting with a spectrum analyzer last year to no avail, but now that I have the ability to call the system and have it send out a page we have a little better advantage. I'd call the area 'populated', but not 'urban'. Mostly housing around the site, but plenty of industry (and towers) visible from the top of the water tank. (We are, by the way, the only user on the tank.) From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Milt Sent: Saturday, April 24, 2010 4:19 PM To: Repeater-Builder@yahoogroups.com Subject: e: [Repeater-Builder] Re: Pager Interference Revisited Mike, Does the interfering signal come and go or is it constant? Does it have any AC component; ie buzz or hum at 60Hz, 120Hz, etc., or any raw buzzing noise? Are there any broiadcast TV stations in the area, DTV or LP translators? Is the UHF pager signal analog, digital or both? What test equipmet do you ahve available? Is the repeater in a poplulated area or remote? Milt N3LTQ - Original Message - From: Mike Besemer (WM4B) mailto:mwbese...@cox.net To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 24, 2010 3:36 PM Subject: RE: [Repeater-Builder] Re: Pager Interference Revisited I don't think so, Chuck. I work on Robins and traverse it pretty much from end-to-end daily. I also have to traverse it quite a ways just to get off of it to go foxhunt this beast. Generally the signals on-base are weak to non-existent. It's bloody amazing how much RF crap is in the air. Using a Google Earth application I can see zillions of sites within earshot. The mixing possibilities are endless! I'm
Re: [Repeater-Builder] Re: Duplexer parts
Sorry Skipp, never got that request, sometimes I think not all the emails to this group end up getting forwarded to me. If you've followed the thread you know I did order one that is not quite exact but should work. Thanks again everyone for your help. Gary - K7NEY On 4/17/2010 5:52 PM, skipp025 wrote: Joe k1ike_m...@... wrote: I don't know if this was suggested, but you can buy a cap of larger value that physically fits the area and then remove a plate/stator or two to get the proper value. Removing a plate and/or stator is a trick from way back in ham time when people scrounged parts and made them work. 73, Joe, K1ike I suggested the guy Email me a few well lighted pictures of the bad cap and I would have probably sent him one or told him of places I know where he could still buy them. Oh well... times up. s. ps: Seems most Amateur Photographers suffer from lack of decent lighting disease in their pictures so I always ask folks to kick the photon level up a bit when taking and submitting images.
Re: [Repeater-Builder] Re: Duplexer parts
Thanks, I sent them an email and they said they haven't sold that capacitor in 25 years and all spec sheets, etc are all gone. Was worth a try though. I'll keep looking Gary On 4/15/2010 4:28 PM, ac6vj wrote: Gary, Try Viking Technologies LTD. at www.cardwellcondenser.com they have a very large selection of Johnson, series 167 capacitors and will be able to give you the exact specifications on the broken one that you have. Gregory AC6VJ --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com, Gary Hoff k7ney...@... wrote: I already found that one, thanks anyway, the 167-205 is close but not enough plates, mine has 6 rotor and 6 stator. Physical size is right though, maybe this cap was made by Johnson also since the numbers are close. Gary On 4/15/2010 1:59 PM, DCFluX wrote: http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html (CAV) 167-205-71 sounds close to it. On Thu, Apr 15, 2010 at 11:59 AM, Gary Hoff k7ney...@... mailto:k7ney123%40q.com wrote: I have an old Phelps Dodge VHF Duplexer that has a frozen air variable. The Duplexer is a part# 499-509 and covers 144-174. The air variable in question is stamped 167-202 and is split stator about 1 3/8 square. Anybody know where I might find a suitable replacement, I haven't had any luck where I've been looking. Gary K7NEY Yahoo! Groups Links
Re: [Repeater-Builder] Re: Duplexer parts
I don't think I could make one. I've seen rotors and stators available you can assemble yourself but they are quite a bit larger and wouldn't fit in the box. I think I've found one that I can make work and ordered it. It's not exact, but it'll fit in the spot and should function OK. Thanks to all who responded to my query. There were a lot of good ideas and they are all appreciated. Gary - K7ney On 4/16/2010 9:58 PM, Barry wrote: If all else fails it should be simple to work out the requirements and make one requires some manual skill and patience though To: Repeater-Builder@yahoogroups.com From: k7ney...@q.com Date: Fri, 16 Apr 2010 06:49:25 -0600 Subject: Re: [Repeater-Builder] Re: Duplexer parts Thanks, I sent them an email and they said they haven't sold that capacitor in 25 years and all spec sheets, etc are all gone. Was worth a try though. I'll keep looking Gary On 4/15/2010 4:28 PM, ac6vj wrote: Gary, Try Viking Technologies LTD. at www.cardwellcondens http://www.cardwellcondenser.com they have a very large selection of Johnson, series 167 capacitors and will be able to give you the exact specifications on the broken one that you have. Gregory AC6VJ --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com, Gary Hoff k7ney...@... wrote: I already found that one, thanks anyway, the 167-205 is close but not enough plates, mine has 6 rotor and 6 stator. Physical size is right though, maybe this cap was made by Johnson also since the numbers are close. Gary On 4/15/2010 1:59 PM, DCFluX wrote: http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html (CAV) 167-205-71 sounds close to it. On Thu, Apr 15, 2010 at 11:59 AM, Gary Hoff k7ney...@... mailto:k7ney123%40q.com wrote: I have an old Phelps Dodge VHF Duplexer that has a frozen air variable. The Duplexer is a part# 499-509 and covers 144-174. The air variable in question is stamped 167-202 and is split stator about 1 3/8 square. Anybody know where I might find a suitable replacement, I haven't had any luck where I've been looking. Gary K7NEY Yahoo! Groups Links Looking for a hot date? View photos of singles in your area! http://clk.atdmt.com/NMN/go/150855801/direct/01/
[Repeater-Builder] Duplexer parts
I have an old Phelps Dodge VHF Duplexer that has a frozen air variable. The Duplexer is a part# 499-509 and covers 144-174. The air variable in question is stamped 167-202 and is split stator about 1 3/8 square. Anybody know where I might find a suitable replacement, I haven't had any luck where I've been looking. Gary K7NEY
Re: [Repeater-Builder] Duplexer parts
I already found that one, thanks anyway, the 167-205 is close but not enough plates, mine has 6 rotor and 6 stator. Physical size is right though, maybe this cap was made by Johnson also since the numbers are close. Gary On 4/15/2010 1:59 PM, DCFluX wrote: http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html http://www.surplussales.com/Variables/ButterflyCapacitors/ButCap1.html (CAV) 167-205-71 sounds close to it. On Thu, Apr 15, 2010 at 11:59 AM, Gary Hoff k7ney...@q.com mailto:k7ney123%40q.com wrote: I have an old Phelps Dodge VHF Duplexer that has a frozen air variable. The Duplexer is a part# 499-509 and covers 144-174. The air variable in question is stamped 167-202 and is split stator about 1 3/8 square. Anybody know where I might find a suitable replacement, I haven't had any luck where I've been looking. Gary K7NEY Yahoo! Groups Links
RE: [Repeater-Builder] Sineman/Gary Schafer
Yes I got it, thanks. I never saw one of those that was after my time with helper. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Dawn Sent: Saturday, March 27, 2010 5:45 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Sineman/Gary Schafer Did you get the e-mail of the Sineman brochure or do I have a wrong e- mail addy?
RE: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502)
Gary: The guy that marketed that 40 db power pad was actually a rep, a real character. I still have the data sheet and picture somewhere here in my library. He used to tell me his real money came from making and selling waders. BTW I do have the schematic and JPEG of the Cushman 40 db pad with the fuse inside. Should I send it to someone? Ciao, Tony, K3WX 73 Gary K4FMX Hi Tony, That was Don Simons. I think that he is still a rep but last I heard from him he was in Loveland, Co. He even left the rep business for a few years selling his waders. :) 73 Gary K4FMX
RE: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502)
The idea of the dual meter unit was to be able to quickly go thru a circuit without having to touch the meter to change ranges or change to AC or DC. If you stuck it on a DC circuit it would read that right. If you stuck it on an AC circuit it would read that. Also you could read an AC voltage riding on top of a DC voltage. One meter would display the DC and the other the AC value. Kind of handy sometimes. I may have a catalog sheet of it somewhere around here but I haven't run across it in some time, Yes the mod box was ok but didn't sell to well. The other item I assume that you meant lineman. That was a very slick box and sold well. It was a line level meter with tone generator and audio amp/speaker and mike. It had the commonly used tone remote tones built in so you could check the line level at those frequencies. Usually people bought two of them, one to use on each end of a line being tested. You could talk back and forth to the guy on the other end and send each other tones and measure levels each way. 73 Gary K4FMX There were very few combination analog/DVM's at service instrument prices and the DMM's that had bar graphs didn't have the resoloution for trends at the time. I can only think of a few off hand such as the Keithly,Simpson had an early one in a 260 type case with Nixies,Ballentine $, and Fluke . I think Heath had one for a short time too. I'd love to see a picture of this meter. I'm still trying to grasp what was so special about two separate meters for AC and DC. There had to be some of Bill's magic either comparator presets, audible alarm or some neat thing that would make service easier. While the subject is odd Helper stuff, remember the Mod Box or the Sineman?
RE: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502)
Ok, I never saw that one. That was after my time with them. There was another small company in Indiana that was started by a couple of ex wavetek guys that build a line test box too. It would fully simulate DC and tone remotes, measure line levels etc. Was a pretty nice box but pricey. I can't remember the name of it now. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Dawn Sent: Friday, March 26, 2010 4:29 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502) No Gary. I meant Sineman. I'm fully aware of the lineman. That was a bit overpriced for what it did. We had two Nortel units that we bought ex- telco that did the same thing elegantly. The Sineman was a unit that we received a mailed brochure. I'm looking at it now. The description: Microprocessor controlled test set features: AC voltmeter,Sineadder,Line Level meter,Single and DTMF tone decoding and portable battery operation $550 for a short time. The drawing of the unit shows a square box with a large meter and 16 digit keypad on the right. Bridge and terminate switch. 4 controls labeled Mode, Scale,Vol., Level. This doesn't have the typical appearance of Helper products. It looks like a keypad entry version of the Toner 3,Lineman,Sinadder 3 with DTMF decode added. This arrived after Susan took control of the company. I can scan this and upload it if anyone is interested. --- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: The idea of the dual meter unit was to be able to quickly go thru a circuit without having to touch the meter to change ranges or change to AC or DC. If you stuck it on a DC circuit it would read that right. If you stuck it on an AC circuit it would read that. Also you could read an AC voltage riding on top of a DC voltage. One meter would display the DC and the other the AC value. Kind of handy sometimes. I may have a catalog sheet of it somewhere around here but I haven't run across it in some time, Yes the mod box was ok but didn't sell to well. The other item I assume that you meant lineman. That was a very slick box and sold well. It was a line level meter with tone generator and audio amp/speaker and mike. It had the commonly used tone remote tones built in so you could check the line level at those frequencies. Usually people bought two of them, one to use on each end of a line being tested. You could talk back and forth to the guy on the other end and send each other tones and measure levels each way. 73 Gary K4FMX There were very few combination analog/DVM's at service instrument prices and the DMM's that had bar graphs didn't have the resoloution for trends at the time. I can only think of a few off hand such as the Keithly,Simpson had an early one in a 260 type case with Nixies,Ballentine $, and Fluke . I think Heath had one for a short time too. I'd love to see a picture of this meter. I'm still trying to grasp what was so special about two separate meters for AC and DC. There had to be some of Bill's magic either comparator presets, audible alarm or some neat thing that would make service easier. While the subject is odd Helper stuff, remember the Mod Box or the Sineman? Yahoo! Groups Links
[Repeater-Builder] Motorola L1884 For Sale
New/old stock Motorola L1884 rack mount reverting battery charger for high power MTR2000 repeaters. Made by Argus Technologies and includes manual and cables. Surplus to me and I need the storage space back. Cost a bunch new but will take $500 with free shipping in the continental U.S. Reply directly to me (off of this email group) if interested. Gary
RE: [Repeater-Builder] Motorola L1884 For Sale
The charger is spoken for. Thanks all. Gary _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gary Sent: Thursday, March 25, 2010 6:39 PM To: Repeater-Builder@yahoogroups.com; 2wayradios4s...@yahoogroups.com; radios4s...@yahoogroups.com Subject: [Repeater-Builder] Motorola L1884 For Sale New/old stock Motorola L1884 rack mount reverting battery charger for high power MTR2000 repeaters. Made by Argus Technologies and includes manual and cables. Surplus to me and I need the storage space back. Cost a bunch new but will take $500 with free shipping in the continental U.S. Reply directly to me (off of this email group) if interested. Gary
[Repeater-Builder] NOS GE Phoenix For Sale
New/old stock GE VHF Phoenix PSX-200 synthesized mobile for sale. Model N5HH2w40CB with mic, bracket, original order card, and some wiring. Absolutely new in the box. I think it's all there but not sure so offered as is. I need the storage space back so will take $50 with free shipping in the continental U.S. Reply directly to me (off this email group) if interested. Thanks. Gary
[Repeater-Builder] RE: Helper Instruments (Voltadder VA 502)
That was an auto ranging voltmeter. They were rather expensive at the time, compared to nowadays. As I remember it you could select auto range, or lock it in a particular range. 73 Gary K4FMX -Original Message- From: Alicia Mehrdad [mailto:abcza...@gmail.com] Sent: Wednesday, March 24, 2010 3:26 PM To: gascha...@comcast.net; skipp...@yahoo.com; Repeater- buil...@yahoogroups.com Subject: Helper Instruments (Voltadder VA 502) Hello gentlemen, I found your e-mails on line and I was wondering if you could help me figure out what type of equipment is this, I have a Voltadder Part No. VA 502 from Helper Instruments, it has two windows with a needle meter type and in between the windows it has some lights and number going down. please see example below. -DC + Volts db AC, 500+ 50 150+ 40 50 +30 15 +20 5 +10 1.5 0 db .5-10 .15 -20 . Your help would be greatly appreciated. thank you.
RE: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502)
Yes he did build some for a few years. They were never a big seller as the price was pretty high. They did work pretty well. It did not have a digital display, only analog meters. There were lights that showed what range it was on. You could read AC on one meter and DC on the other. Handy for some things. I kind of remember him playing around with an attenuator pad to go ahead of a service monitor. I don't remember the wattmeter part though. There was a guy in California making a 40 db power pad to use ahead of a service monitor. It was made during the Singer monitor era to go in front of it. It had a port for the transceiver and one for the signal generator and another for the receive input on the monitor. It worked pretty well. There may be a few floating around yet. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Dawn Sent: Wednesday, March 24, 2010 4:37 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Helper Instruments (Voltadder VA 502) Whoa! Bill actually went through with this? I never seen this as a production item although the idea of a service bench Analog/Digital voltmeter was something he was interested in doing. The DMM's A/D section was to go to an integrator and drive a meter for peaking or nulling. My understanding was this was going to be a service grade instrument with a 3 1/2 autoranging digit DMM basic. Was this a protoype? Are there any pics? While we're at it, what ever happened to the watt meter that fed a power pad like a termaline with an attenuated output? Was that talk, or did they ever do anything with that? --- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: That was an auto ranging voltmeter. They were rather expensive at the time, compared to nowadays. As I remember it you could select auto range, or lock it in a particular range. 73 Gary K4FMX -Original Message- From: Alicia Mehrdad [mailto:abcza...@...] Sent: Wednesday, March 24, 2010 3:26 PM To: gascha...@...; skipp...@...; Repeater- buil...@yahoogroups.com Subject: Helper Instruments (Voltadder VA 502) Hello gentlemen, I found your e-mails on line and I was wondering if you could help me figure out what type of equipment is this, I have a Voltadder Part No. VA 502 from Helper Instruments, it has two windows with a needle meter type and in between the windows it has some lights and number going down. please see example below. -DC + Volts db AC, 500+ 50 150+ 40 50 +30 15 +20 5 +10 1.5 0 db .5-10 .15 -20 . Your help would be greatly appreciated. thank you. Yahoo! Groups Links
RE: [Repeater-Builder] GAW/Motorola Test equipment
Hi Tony, Yes I remember them! They had some similar products to what Helper Instruments built and Automated Industrial electronics (AIE) run by Tony Crady in North Carolina. AIE later bought out the remains of the Measurements Corp. As I remember GAW did private label some products for Motorola for awhile and may have had their name on them in the Motorola catalog for awhile. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Tony Faiola Sent: Tuesday, March 23, 2010 5:11 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] GAW/Motorola Test equipment From what I remember, Norman Gaw was an ex engineer of the Measurement Corp, Boonton, NJ or one of the other Boonton companies. I still might have some product info in my library (hello Gary Shafer remember them?). Do you need more light? Ciao, Tony, K3WX On Mar 23, 2010, at 4:10 PM, Dawn wrote: Does anyone know what the background of GAW was? There wasn't a shop that I worked in that didn't have one of the Sinad/Distortion analyzers or the two tone generator that also was sold under the Motorola name. IIRC, there was also a small power supply with a hair trigger current trip/disconnect for pagers and handhelds that also was rebadged as a Motorola TEK product. I've heard two stories. One was the Galvin family owned the product line and another was that it was a private venture by an employee and distributed through the Moto network. Can anyone shed any light on this and what other products they made? I don't believe that I've ever seen any of these units sold on E-bay or through private sales although they were pretty ubiquitous. From what I remember, the construction quality was similar to kit grade rather then a professionally assembled product. dwt Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Re: GAW/Motorola Test equipment
I said North Carolina before but it should have been South Carolina where AIE was located. Yes Batesburg was the city. I think that he worked on a service monitor of his own that never really got off the ground. I don't know if he sold any or not. He later bought out the Singer Instruments service monitor, I think it was an FM100. That didn't go very far either as it was too expensive to build. Same reason Singer abandoned it. Motorola did have a bunch of the GAW two tone generators in their paging plant in Ft.Lauderdale. They also bought a pot load of the AIE two tone generators from me around 1984. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Dawn Sent: Tuesday, March 23, 2010 6:08 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: GAW/Motorola Test equipment Just about the time Detwiller came out with that service monitor (SM- 512) based on a Bearcat BC-210xlt, AIE sent us a flyer introducing a similar product under the Measurements name. From what I remember, it was a rectangular box like a CE-50 and based on a mobile scanner using LED bar graph displays instead of meters. Batesburg, Va. Wasn't it? Never heard anything about them after that. --- In Repeater-Builder@yahoogroups.com, Gary Schafer gascha...@... wrote: Hi Tony, Yes I remember them! They had some similar products to what Helper Instruments built and Automated Industrial electronics (AIE) run by Tony Crady in North Carolina. AIE later bought out the remains of the Measurements Corp. As I remember GAW did private label some products for Motorola for awhile and may have had their name on them in the Motorola catalog for awhile. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Tony Faiola Sent: Tuesday, March 23, 2010 5:11 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] GAW/Motorola Test equipment From what I remember, Norman Gaw was an ex engineer of the Measurement Corp, Boonton, NJ or one of the other Boonton companies. I still might have some product info in my library (hello Gary Shafer remember them?). Do you need more light? Ciao, Tony, K3WX On Mar 23, 2010, at 4:10 PM, Dawn wrote: Does anyone know what the background of GAW was? There wasn't a shop that I worked in that didn't have one of the Sinad/Distortion analyzers or the two tone generator that also was sold under the Motorola name. IIRC, there was also a small power supply with a hair trigger current trip/disconnect for pagers and handhelds that also was rebadged as a Motorola TEK product. I've heard two stories. One was the Galvin family owned the product line and another was that it was a private venture by an employee and distributed through the Moto network. Can anyone shed any light on this and what other products they made? I don't believe that I've ever seen any of these units sold on E-bay or through private sales although they were pretty ubiquitous. From what I remember, the construction quality was similar to kit grade rather then a professionally assembled product. dwt Yahoo! Groups Links Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Antenna Paint
Marine epoxy paint. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Tim - WD6AWP Sent: Wednesday, March 17, 2010 11:38 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna Paint I picked up a used Telewave antenna ANT150F6-2. It has a minor case of the fiberglass fuzzies and most of the blue paint is gone as it has been in the elements for 15 years. Should I paint it, apply a cote of resin, or just leave it alone? -- Tim, WD6AWP Yahoo! Groups Links
RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire
_ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jack Davis Sent: Wednesday, March 17, 2010 1:15 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire http://groups.yahoo.com/group/Repeater-Builder/message/98899;_ylc=X3oDMTJxM XBnc3YwBF9TAzk3MzU5NzE1BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEbXNnSWQDO Tg4OTkEc2VjA2Rtc2cEc2xrA3Ztc2cEc3RpbWUDMTI2ODgwMDcyMw-- Re: Copper pipe rather than 2/0 copper wire Posted by: Eric Lemmon mailto:wb6...@verizon.net?subject=%20re%3a%20copper%20pipe%20rather%20than% 202%2F0%20copper%20wire wb6...@verizon.net http://profiles.yahoo.com/wb6fly wb6fly Tue Mar 16, 2010 5:55 pm (PDT) Jesse, Not a good idea. Both NFPA 70 (the National Electrical Code) and NFPA 780 (the Lightning Protection Code) have strict requirements for wire sizes and connection methods. Neither grounding systems nor lightning protection systems may use a soldered connection in the circuit. Perhaps your best course of action is to understand the Code requirements, and construct your system accordingly. Keep in mind the fact that your insurance underwriter may deny any and all claims for damages due to lightning, if your system was constructed in a manner inconsistent with the applicable codes. 73, Eric Lemmon WB6FLY You dont need any solder joints with type K or L soft copper. The material comes is 60 or 100 foot rolls and you just flatten the ends and drill holes for mounting bolts and star washers. ½ inch soft copper is actually 5/8 inch OD and makes a great conductor. The material comes in size up to 2 inch but that gets pretty expensive. This pipe is designed to be buried in the ground so you can be assured it will stand up just fine outdoors. One caution is to anchor it down, swinging in the wind will cause it to break due to repeated flexing. All the normal bend radius for electrical conductors should be observed as lightning does not like to make sharp corners. Jack K6YC 5/8 OD gives you 1.96 inches (5/8 x 3.14) of surface area. 1 inch copper strap gives 2 inches of surface area. 2 inch copper strap gives you 4 inches surface area. Copper strap should be less expensive than copper tubing.__,_._,__ Why would you use copper tubing? 73 Gary K4FMX
RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Wednesday, March 17, 2010 1:36 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire On 3/17/2010 12:11 PM, Gary Schafer wrote: 5/8 OD gives you 1.96 inches (5/8 x 3.14) of surface area. 1 inch copper strap gives 2 inches of surface area. 2 inch copper strap gives you 4 inches surface area. Copper strap should be less expensive than copper tubing.__,_._,__ Why would you use copper tubing? Because it's cheaper and a lot easier to find. Many people probably already have some laying around scrap. Hardware stores don't carry copper strap. I know I would have to order it from someone like Tessco or someone else that sells tower site supplies. A quick google search turns up this: http://www.dxengineering.com/Products.asp?ID=102SecID=51DeptID=19 2 inch strap for $1.83 per foot. Someone earlier said that 1/2 inch copper pipe cost around $2.20 per foot. If 1/2 inch pipe is really 5/8 inch outside diameter that would give you a surface area, as I said before, of 1.96 inches. 2 inch copper strap would give you a surface area of 4 inches. Better than twice the surface area of the pipe and less money. To get the same surface area with pipe as with copper strap you would have to pay about $4.50 per foot for pipe verses $1.96 for strap. Doesn't look cheaper to me. 73 Gary K4FMX
RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire
Here is another place to get copper strap even cheaper: http://www.gacopper.com/ $1.05 per foot for 2 inch strap. (.012 thickness) $1.70 per foot for 2 inch strap. (.022 thickness) 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Gary Schafer Sent: Wednesday, March 17, 2010 3:39 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Wednesday, March 17, 2010 1:36 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire On 3/17/2010 12:11 PM, Gary Schafer wrote: 5/8 OD gives you 1.96 inches (5/8 x 3.14) of surface area. 1 inch copper strap gives 2 inches of surface area. 2 inch copper strap gives you 4 inches surface area. Copper strap should be less expensive than copper tubing.__,_._,__ Why would you use copper tubing? Because it's cheaper and a lot easier to find. Many people probably already have some laying around scrap. Hardware stores don't carry copper strap. I know I would have to order it from someone like Tessco or someone else that sells tower site supplies. A quick google search turns up this: http://www.dxengineering.com/Products.asp?ID=102SecID=51DeptID=19 2 inch strap for $1.83 per foot. Someone earlier said that 1/2 inch copper pipe cost around $2.20 per foot. If 1/2 inch pipe is really 5/8 inch outside diameter that would give you a surface area, as I said before, of 1.96 inches. 2 inch copper strap would give you a surface area of 4 inches. Better than twice the surface area of the pipe and less money. To get the same surface area with pipe as with copper strap you would have to pay about $4.50 per foot for pipe verses $1.96 for strap. Doesn't look cheaper to me. 73 Gary K4FMX Yahoo! Groups Links
RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire
The math is right. RF will not flow on the inside of a tube. It acts as a waveguide beyond cutoff. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Kirk Mefford Sent: Wednesday, March 17, 2010 4:49 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire Not that I think copper pipe is a good alternative to strap, but Gary's math is slightly off. If you are saying 2 inch strap has 4 inches of surface area by counting both sides of the strap, then you need to count both sides of the pipe. Inside and outside surfaces of a pipe equal to 5/8OD would be very close to the same surface area of a 2 inch strap of the same thickness. Might be ok for grounding a temporary setup or for ground radials on an HF antenna but I wouldn't want to gamble on insurance covering a station using flattened copper pipe as a grounding solution. - Original Message - From: Gary Schafer mailto:gascha...@comcast.net To: Repeater-Builder@yahoogroups.com Sent: Wednesday, March 17, 2010 11:11 AM Subject: RE: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Jack Davis Sent: Wednesday, March 17, 2010 1:15 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Copper pipe rather than 2/0 copper wire http://groups.yahoo.com/group/Repeater-Builder/message/98899;_ylc=X3oDMTJxM XBnc3YwBF9TAzk3MzU5NzE1BGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEbXNnSWQDO Tg4OTkEc2VjA2Rtc2cEc2xrA3Ztc2cEc3RpbWUDMTI2ODgwMDcyMw-- Re: Copper pipe rather than 2/0 copper wire Posted by: Eric Lemmon mailto:wb6...@verizon.net%20 wb6...@verizon.net http://profiles.yahoo.com/wb6fly wb6fly Tue Mar 16, 2010 5:55 pm (PDT) Jesse, Not a good idea. Both NFPA 70 (the National Electrical Code) and NFPA 780 (the Lightning Protection Code) have strict requirements for wire sizes and connection methods. Neither grounding systems nor lightning protection systems may use a soldered connection in the circuit. Perhaps your best course of action is to understand the Code requirements, and construct your system accordingly. Keep in mind the fact that your insurance underwriter may deny any and all claims for damages due to lightning, if your system was constructed in a manner inconsistent with the applicable codes. 73, Eric Lemmon WB6FLY You dont need any solder joints with type K or L soft copper. The material comes is 60 or 100 foot rolls and you just flatten the ends and drill holes for mounting bolts and star washers. ½ inch soft copper is actually 5/8 inch OD and makes a great conductor. The material comes in size up to 2 inch but that gets pretty expensive. This pipe is designed to be buried in the ground so you can be assured it will stand up just fine outdoors. One caution is to anchor it down, swinging in the wind will cause it to break due to repeated flexing. All the normal bend radius for electrical conductors should be observed as lightning does not like to make sharp corners. Jack K6YC
RE: [Repeater-Builder] Copper pipe rather than 2/0 copper wire
Copper strap is better as you get the benefit of both sides of the copper. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Jesse Lloyd Sent: Tuesday, March 16, 2010 11:42 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Copper pipe rather than 2/0 copper wire Hey All, I am thinking about lightening protection for a site and using 1/2 copper pipe runs rather than a heavy guage wire like 2/0. 1/2 copper is about $2.20 a ft, while 2/0 is about $3/foot... and 2/0's diameter is about 0.36 inches so bang for the buck 1/2 copper pipe seems the way to go. I know skin effect plays a big role in lightening since its mainly RF, what do you think about the idea? Cheers, Jesse Yahoo! Groups Links
RE: [Repeater-Builder] Copper pipe rather than 2/0 copper wire
3 wide copper strap gives you 6 of surface area. ½ pipe gives you 1.57 surface area. So even 1 strap provides more surface area than ½ pipe. I think that you will find it less expensive than pipe and with the added benefit of not having to splice it every 10 feet. ¾ pipe gives you 2.355 surface area. The inside area of pipe does not count. RF will not flow on the inside of a tube/pipe. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of David Jordan Sent: Tuesday, March 16, 2010 12:18 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Copper pipe rather than 2/0 copper wire Strap meaning solid copper, not copper or silver tinned braid. However, one might argue that the copper tubing has an equal amount of surface area and is more robust than the thin copper strap being sold.. if you fold 3 wide copper strap into a piece of tubing you get a ¾ OD tube. So, does the inside surface count? If not then the strap is the clear winner with double the surface area. What a hoot, Dave Wa3gin _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gary Schafer Sent: Tuesday, March 16, 2010 11:59 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Copper pipe rather than 2/0 copper wire Copper strap is better as you get the benefit of both sides of the copper. 73 Gary K4FMX
RE: [Repeater-Builder] Re: Dual receivers on one antenna for RX only site
with the same kind of loss that you get on a transmitter due to high vswr. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Nate Duehr Sent: Wednesday, March 10, 2010 5:42 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Dual receivers on one antenna for RX only site On Mar 9, 2010, at 8:37 PM, n...@no6b.com wrote: t most certainly does. Try random length cables from the cavities to the T instead of 1/4 wavelength (like one local did several years ago) watch your sensitivity drop by over 20 dB if you're unlucky (as he was). That mistake literally killed off a local radio club, as few of the members were able to use the repeater following the addition of the T wrong cables. Thanks both Bob and Skipp for explaining that one odd-ball configuration that would crush the receivers with random cable lengths that just happen to hit the right sweet spot to do this. I suspect, that if someone saw a 20 dB loss while installing this setup, they'd at least STOP and start asking questions -- maybe they wouldn't get it that they'd hit this perfect storm combination -- maybe they'd think they had some kind of receiver failure when it suddenly was really deaf -- but I also doubt that *most* people would hit the problem. Would you agree with that assessment? (Skipp's comment that if there's a train wreck to be found, he'll be there... I know that feeling.) I guess what I'm saying here in a round-about way is... random cable lengths really shouldn't be that much of an issue in a setup like this, but yeah... agreed... once in a while it'll bite you like an alligator (had to get that elephant/alligator theme in here, just one more time! GRIN!)... I've seen lots of people get away with it. As far as the 3dB lost in a true broadband splitter -- also true, of course, Bob -- at most of the sites where we have to share a receive antenna with multiple rigs, the site measured noise-floor is so high the 3dB doesn't have much of an impact... just keeping the local crud out of the receivers is difficult enough -- sometimes that 3dB loss helps, instead of hinders, so to speak. :-) I guess we should all probably also mention the evils of not terminating all the unused ports on a multi-splitter with 50 Ohm loads, too... if we're going to get this picky, right? ;-) -- Nate Duehr, WY0X n...@natetech.com facebook.com/denverpilot twitter.com/denverpilot
RE: [Repeater-Builder] Dual receivers on one antenna for RX only site
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of wd8chl Sent: Tuesday, March 09, 2010 11:07 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Dual receivers on one antenna for RX only site It you are not combining the UHF and VHF signals with cavities then a signal splitter should be used. Even a TV cable type splitter will work ok for this. Don't worry about it being 75 ohms rather than 50 ohms. Without a splitter one receiver can load the input of the other considerably (depending on the luck of cable lengths) if just a simple T is used to connect the antenna to the two receivers. I know of a system that has 2 VHF receivers tied to one antenna with a 'T' connector and random coax-deliberately. At the T junction, the receivers need *many* uV of signal...plus the squelch is all the way tight. Too many problems with out-of-town junk on the input. So it has many rx's and a big voter. It proves your point-if you just use a 'T' connector, it'll be deaf as a doorknob. In this case the receivers would benefit from a splitter. That would make everything see 50 ohms regardless of cable lengths. Also the splitter 3 db loss per side will probably be less that what it is now as each receiver takes half the power to start with no matter if you have a splitter or not. 73 Gary K4FMX
RE: [Repeater-Builder] Antenna Phasing Question
As far as phasing the antennas around the tower, it can't be done. Well it can but you will end up with more nulls and a worse pattern than you started with. The problem is that most signals will arrive at more than one antenna. Because they are different distances apart to the mobile there will be a time difference between the two. So you say ok, I will just make the phasing harness that same length as the antennas are apart. That would work great for one specific direction. But what happens when that mobile moves to a new azimuth location? Then there will not be the same distance to him between the two antennas as there was when you made the phasing harness. Now you have a new time difference between arriving signals but you have the same length phasing lines. The result is that the combined signals are no longer in phase so you have less gain. If the two signals fall out of phase then they will cancel. You have a big null in the pattern there. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of afa5tp Sent: Wednesday, March 10, 2010 12:31 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Antenna Phasing Question Hello Folks I have three (3) Antel [BCD 80010] 806-900 mHz vertical antennae that I would like to mount on the three legs of my tower for omni pattern (Rec. only). Several questions come to mind. 1.) At the rated frequency, how many inches should the side arm place the ant. from the tower? 2.)What would be the best way to phase the antennae? I have a Andrews three port Splitter, and will use LDF4-50A for feedline. I would suspect the length of the pigtail from each antenna to splitter is going to be critical...or not, for receive only? BTW..How good of an antenna is the Antel BCD 80010? Many thanks for any guidance and wisdom. Tim Hardy W7TRH/AFA0TP Vashon Is. Wa. Yahoo! Groups Links
RE: [Repeater-Builder] Re: Dual receivers on one antenna for RX only site
Well yes the T is sort of a magical device that makes the OTHER SIDE of the T disappear electrically. Actually it is not the T itself that does the job (that is just where IT happens) but it is the quarter wave length cables that perform the magic! Without the quarter wave length cables between the T and each set of cavities the duplexer would not work! That is what provides the 50 ohm isolation between tx and rx cans so the feed line still sees 50 ohms. The quarter wave cable effectively disconnects the transmitter from the feed line at the T (at the receive frequency). The quarter wave cable on the receive side of the T effectively disconnects the receive side from the feed line (at the transmit frequency). Without doing this each would load the other down and there would not be 50 ohms at the antenna port of the T. Once you are on the other side of the T (the antenna port) the feed line length has no effect on the duplexer operation. All that the quarter wave lines do on the duplexer side of the T are to give isolation to the opposite side (tx-rx) so each does not short out the feed line. A similar thing happens between can cables in a duplexer but rather than using them for isolation they are used to enhance the notch of each can by presenting a high impedance at each cans T from the previous cavity. Working with a high impedance is easier to notch out than a low impedance. The notch in the first cavity presents a short (low impedance) at the unwanted frequency and 50 ohms at the wanted frequency. By coupling the next cavity with a quarter wave length cable (at the unwanted frequency) that short is transformed to a quite high impedance at the next cavity while at the same time the wanted signal being at 50 ohms is passed to the next cavity where it sees 50 ohms and goes on its way unatenuated. But we are left with the high impedance at the unwanted frequency that was transformed by the quarter wave cable. The second cavity notch is also tuned to the unwanted frequency which it pulls down to a short (low impedance) to give further attenuation. When I say the notch presents a short it is not really a short but a very low impedance of say a few ohms. But by having the unwanted source impedance high rather than at 50 ohms it is much easier to pull the high impedance down with the few ohms short circuit than it would be if we were working at 50 ohms for the unwanted. It works like a voltage divider between the two impedances. The higher the source is (from previous cavity) to the short the more loss there will be which is just what we are looking for. In the case of the quarter wave cable to the T on the output of the duplexer we want to transform the low impedance up to a very high impedance at the T so that it does not load the circuit at that point on that frequency. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dan Hancock Sent: Wednesday, March 10, 2010 12:50 PM To: repeater builders Subject: [Repeater-Builder] Re: Dual receivers on one antenna for RX only site One thing was missed regarding cable lengths. The loops in the cans are part of the equation for figuring the 1/4 wave length. I've seen that discussed here many times in postings related to inter-cable lengths on duplexers. But the 1/4 wave length issue only applies to the inter-cabling between the cans. It is my understanding that the antenna to duplexer lengths are irrelevant since the T connector and the rest of the feedline are all part of the equation. It's not like the T is some magical device that makes the rest of the feedline disappear electrically. The only time length might be a problem is if the entire feedline happens to be a resonant length. If by some chance that happens, then changing the jumper a couple of inches will clear that. Dan N8DJP Posted by: n...@no6b.com http://us.mc1104.mail.yahoo.com/mc/compose?to=n...@no6b.com n...@no6b.com http://us.mc1104.mail.yahoo.com/mc/compose?to=n...@no6b.com no6b Date: Tue Mar 9, 2010 8:29 pm ((PST)) At 3/9/2010 20:12, you wrote: OK, question... If you put a cable which is 1/4-wavelength at VHF between the T and the UHF cavity, it's 3/4-wavelength at UHF. Since any odd multiple of a quarter wavelength will invert the impedance, what will this really accomplish on the UHF cavity side? Doesn't matter at UHF, since the cavity looks like (hopefully something close to) 50 + j0 ohms @ UHF, so the cable length has no effect (other than plain ol' cable loss) @ UHF. At VHF, the short at the UHF cavity connector (I'll take Gary's word that it looks like a short off-resonance, though to be sure you'd want to put the can on a VNA to get the actual phase angle at the connector) needs to be transformed to an open at the T so it has no effect VHF. The short-to-open transformation @ VHF is accomplished with a 1/4 wavelength of coax @ VHF. The dual
RE: [Repeater-Builder] Dual receivers on one antenna for RX only site
Quarter wave length cables are the thing to use to couple the cavities together at the antenna connection side of them. The uhf cavity gets a cable that is a quarter wave length at the VHF frequency and the VHF cavity gets a cable that is a quarter wave length at the UHF frequency. These connect to a T connector at the antenna line. This is the same way that you connect TX and RX cavities of a duplexer to an antenna. The UHF cavity loop provides a short circuit at the VHF frequency but the quarter wave cable from it transforms the short to an open (high impedance) at the T connection so you get no attenuation of the VHF signal there. The VHF signal then passes to the VHF cavity as if the UHF cavity was not there. The same thing happens to the UHF signal going to the other cavity. Without the proper length cables between the cavities and the antenna T connector both UHF and VHF signals will be attenuated depending on the luck of the cable length. The quarter wave length cable is the electrical length. It you are not combining the UHF and VHF signals with cavities then a signal splitter should be used. Even a TV cable type splitter will work ok for this. Don't worry about it being 75 ohms rather than 50 ohms. Without a splitter one receiver can load the input of the other considerably (depending on the luck of cable lengths) if just a simple T is used to connect the antenna to the two receivers. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Nate Duehr Sent: Tuesday, March 09, 2010 5:11 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Dual receivers on one antenna for RX only site Answers below On 3/9/2010 8:29 AM, Ross Johnson wrote: Can a dualband antenna VHF/UHF for RX ONLY be fed to two receivers one VHF, one UHF, without a quote duplexer using a T instead? Yes. Typically performance is better with mono-band antennas, since all multiband antennas are a trade off in their design, but a T, or even splitting multiple times is certainly an option for any receive-only antenna system, with the caveat that there's loss at each split. Pre-amplifiers can help a bit, but once an RF signal is lost, there's no getting it back by amplification. Here's the idea. This is a remote RX site. The idea is to run something like a beefed up X500 dualbander at tower top, then 7/8 hardline 100 feet down to the receivers. So far fine. Both receivers will have one or two bandpass cavities inline before the T. I assume when you say before the T you mean antenna - split - bandpass - receiver. Yes, this is probably a good idea to keep the receiver from being hammered by other signals that are out-of-band, but not 100% necessary if this receive antenna is out in the middle of nowhere with no high-power transmitters nearby. The bandpass filtering is lossy too, of course. The higher the Q of the bandpass filter, the less the loss. (High Q bandpass cavities are typically MUCH larger than BpBr duplexer cans. At VHF they're enormous and take up a lot of space. Ceiling mounts are common.) remember also that you're really only adding the bandpass to design for what the receivers NEED to have filtered to perform at their best. If the receivers are something like the GE MASTR II or similar with a cavity helical filter front-end (bandpass filter) built-in, you don't NECESSARILY need more filtering in front of them. Just sayin'. Design your filters specifically for your receiver's ability to handle out-of-band or nearby signals and the signals that you expect to be present at the site. The filtering has nothing to do with the multi-bandedness of the antenna, etc. UNLESS your chosen receiver is particularly bad when say, a 1/4 KW 900 MHz transmitter is 2 feet away from the receive antenna, and your particular radio doesn't like that. (An example I saw once... even WITH filtering the amount of 900 MHz energy coming through the filters was enough to piss off a UHF receiver, being it was a 2x multiple of the UHF's front end and passed through without much loss. Would a duplexer be necessary in this case. Or could it be done with proper cable lengths and a T? A duplexer is a set of filters designed to pass a transmit frequency and filter it out of a receiver on a nearby frequency. Did you mean diplexer? I think that's what you're really meaning to ask. And the answer is no... you don't truly need a diplexer. ESPECIALLY if you're running separate bandpass filters on each receiver. Think about what a diplexer does... it passes lower frequencies to one port, and higher frequencies to another port... if you're already going to bandpass filter there's no need for it. As far as cable lengths go, I have no idea what you're asking. Cable lengths should have no effect on this system at all. Thanks for your time and for the probably obvious answer I'm not sure
RE: [Repeater-Builder] Dual receivers on one antenna for RX only site
_ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Nate Duehr Sent: Tuesday, March 09, 2010 7:24 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Dual receivers on one antenna for RX only site On 3/9/2010 4:53 PM, Gary Schafer wrote: Without the proper length cables between the cavities and the antenna T connector both UHF and VHF signals will be attenuated depending on the luck of the cable length. What technical reason causes this? Nate Hi Nate, A UHF pass band cavity for example will pass only a UHF frequency that it is tuned for. On frequency signals coming into it will see 50 ohms. Off frequency signals will see a short circuit and will be greatly attenuated. The input loop of the cavity (as well as the output loop) looks like a short circuit at all but the tuned frequency. So anything that happens to be in parallel with the loop will also see the short circuit if the frequency is not that to which the cavity is tuned to. So if you had a half wave length cable between the cavity and your T connector, then the short circuit at the cavity (off frequency short) would also look like a short circuit at the T connector. No problem for the UHF signal as that frequency sees 50 ohms at the T. but any other frequency sees a short circuit at the T and would be attenuated there. Now if that cable was a quarter wave length instead of a half wave length, the short circuit (off frequency short) would be transformed to an open circuit at the T connector. That would allow all other frequencies to be present with no attenuation at the T. If you used a random length of cable here, you may be ok and you may not be depending on how far away from a quarter wave length the cable happened to be. This is exactly how a duplexer works. The cables between the T and each cavity set is a quarter wave length at the opposite frequency for which the cavity is tuned to. The quarter wave length cable connected to the T always wants to see a short at the other end at the frequency that it does not want to pass, as the quarter wave length transforms the short to a open which does not load down the other side of the circuit.. With close spaced duplexers sometimes the two cables may be very close in length or the same as the cable is not near as high a Q as the cavity is. 73 Gary K4FMX
RE: [Repeater-Builder] Motorola cabinet key wanted
Ok, thanks to all that replied. It looks like it is a 2553 that I need. Looking at the chart it looks like the CH751 is for the old outdoor cabinet and the 2553 is for the indoor cabinet. Also looks like the GE cabinet that I have is probably the desk mate and takes the LL201 key. Ted, K9MDM sent me an email saying that he has those keys for sale. I will probably get them from him. Thanks again to all Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bill Hudson Sent: Wednesday, February 24, 2010 1:51 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted This is what you saw - and this is what you are looking for: http://www.repeater-builder.com/keyspage/keyspage-index.html Bill Hudson W6CBS Ex-Motorola 1983 _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of ka9qjg Sent: Tuesday, February 23, 2010 10:35 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted Let Me tell You youngsters out here How bad Memory loss is , as Some of us get older I could swear that on this group or one I use Someone Posted a File about KEYS But for the life of Me I cannot find it , It listed Everything . And I have searched for 2 hours trying to help but did not find it. Oh well just wait Some of you will catch up soon , My favorite saying is that it's Great as We get Older to learn something New every day it is remembering it is the problem PS Please tell Me that I am not just making this up Happy Repeater Building Don KA9QJG
RE: [Repeater-Builder] Motorola cabinet key wanted
Hi Bill, Well now I am having second thoughts! The Motorola cabinets that I have are older than the Motrac era. I can't recall the model of the radios but the finals in one are 100TH tubes. That was before the motrac. The cabinets are at my farm in Wisconsin so I can't run out and look at them for a few months. They are not the black wrinkle paint finish. They have 3 or 4 simpson meters on the top outside. On the GE cabinet I am not sure what vintage that is. The key list that you referred to shows the LL201 being for some GE desk mates and also the BF10A for later ones I assume. Thanks! Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bill Hudson Sent: Wednesday, February 24, 2010 5:30 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted OK - you are getting closer. Yes, from your original description of the Motorola cabinet, the 2553 is correct. It is the Micor / Motrac era. Yes, the CH751 is the large beige upright cabinet with a handle on it. Motrac era. NO, if it is truly a GE DESKMATE cabinet, it will take a BF10a key. While the documentation I referred you to discusses LL201 for a deskmate cabinet, I have never seen an LL201 work on a deskmate cabinet. The deskmate was during the progress line era. LL201, is for what was known as pre progress line. Just for fun, I tried an LL201 in a GE DESKMATE cabinet, and it would not work. I'm sure there is an exception somewhere in the world. I have just about every key for all radios including EF Johnson. I hate getting locked out of radios and cabinets. Ha ha Bill Hudson W6CBS _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gary Schafer Sent: Wednesday, February 24, 2010 1:16 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted Ok, thanks to all that replied. It looks like it is a 2553 that I need. Looking at the chart it looks like the CH751 is for the old outdoor cabinet and the 2553 is for the indoor cabinet. Also looks like the GE cabinet that I have is probably the desk mate and takes the LL201 key. Ted, K9MDM sent me an email saying that he has those keys for sale. I will probably get them from him. Thanks again to all Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bill Hudson Sent: Wednesday, February 24, 2010 1:51 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted This is what you saw - and this is what you are looking for: http://www.repeater http://www.repeater-builder.com/keyspage/keyspage-index.html -builder.com/keyspage/keyspage-index.html Bill Hudson W6CBS Ex-Motorola 1983 _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of ka9qjg Sent: Tuesday, February 23, 2010 10:35 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted Let Me tell You youngsters out here How bad Memory loss is , as Some of us get older I could swear that on this group or one I use Someone Posted a File about KEYS But for the life of Me I cannot find it , It listed Everything . And I have searched for 2 hours trying to help but did not find it. Oh well just wait Some of you will catch up soon , My favorite saying is that it's Great as We get Older to learn something New every day it is remembering it is the problem PS Please tell Me that I am not just making this up Happy Repeater Building Don KA9QJG
RE: [Repeater-Builder] Re: Can the 4th harmonic of 1250 AM keep UHF repeaters locked up?
Don't be too sure about that. Once the am station signal gets into the receiver it can go anywhere and cause havoc. It could be getting into the IF or the mixer once picked up by cables. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of KT9AC Sent: Wednesday, February 24, 2010 4:42 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Can the 4th harmonic of 1250 AM keep UHF repeaters locked up? If it was just audio then there would be no feedback of the PL/DPL tones, keeping the repeater locked up. Good advice though. Jeff DePolo wrote: On 2/23/2010 3:11 PM, Jim WB5OXQ inb Waco, TX wrote: Is it possible the AM signal is getting into an audio stage instead of the receiver front end? I had that happen once. Same here. All audio inteconnects are now tiny coax cables at that site now, installed with shield grounded at ONE end... Nate WY0X At AM broadcast sites or studios co-located with the transmitter, hard-grounding the shield at one end and RF-coupling the shield at the other end to the equipment ground via caps (0.01 uF as a rule of thumb) is often the most effective technique in many situations. --- Jeff WN3A Yahoo! Groups Links
[Repeater-Builder] Motorola cabinet key wanted
I am in need of a cabinet key for an old Motorola base station cabinet. It is an old low band 1/4 kw rig. Had 100TH tubes in final. This is the 6 foot tall cabinet. Anyone know the key number for these? Have a key? Also have an old GE progress line base cabinet that needs a key. This cabinet is about 3 feet tall and longer than wide. Thanks! Gary K4FMX
RE: [Repeater-Builder] Motorola cabinet key wanted
Hi Bill, The key is like a 2135 and a 2135 will fit in the lock (I have a 2135) but it will not open it. I actually have two of these station cabinets and my 2135 key will not open either cabinet. I kind of remember that some of the cabinets had a different key from the mobiles way back when. Any other guesses? Thanks Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Bill Hudson Sent: Tuesday, February 23, 2010 10:37 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted Just because I gamble a little - I'm going to bet that the older Motorola cabinet is a CH751. This is a one sided key unlike a 2135. The Micor cabinets became a 2553. Cabinet Keys more prominent in the high power stations. I'll go along with the BF10a for the Prog Line - that's for sure. Bill Hudson W6CBS _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Andrew Seybold Sent: Tuesday, February 23, 2010 6:18 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Motorola cabinet key wanted The Motorola key should be a 2135 and the GE Key is probably a BF10A, they are hard to find but around-I can make you copies if you want to pay the key making price and postage. Andy W6AMS From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gary Schafer Sent: Tuesday, February 23, 2010 6:16 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Motorola cabinet key wanted I am in need of a cabinet key for an old Motorola base station cabinet. It is an old low band 1/4 kw rig. Had 100TH tubes in final. This is the 6 foot tall cabinet. Anyone know the key number for these? Have a key? Also have an old GE progress line base cabinet that needs a key. This cabinet is about 3 feet tall and longer than wide. Thanks! Gary K4FMX
RE: [Repeater-Builder] Re: DB-201 Measurements for 6 Meters?
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Kris Kirby Sent: Monday, February 22, 2010 5:03 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: DB-201 Measurements for 6 Meters? On Mon, 22 Feb 2010, Jeff DePolo wrote: On Mon, 22 Feb 2010, Jeff DePolo wrote: Kinda along the same lines as always make the cable from the connector on the transmitter to the connector on the duplexer an even half-wave. The reason for doing that is that if the duplexer presents a short-circuit, said short-circuit won't appear at antenna port. Uwhat? I was thinking quarter-waves. If you have a tee, connect the antenna at the center and a duplexer to either side using quarter-wave cables, the effect I noted should occur, minimizing losses. -- Kris Kirby, KE4AHR Disinformation Analyst Well, at the output side of the duplexer that is what is happening already. The cables are a quarter wave length. The one from the transmit cans (to the antenna port) is a quarter wave length at the receive frequency and the one from the receive can (to the antenna port) is a quarter wave length at the transmit frequency. Since the receive can is tuned to the receive frequency, its output loop presents a short circuit to the transmit frequency. And since the cable going from that loop to the antenna T is a quarter wave length at the transmit frequency that short at the loop is seen as a very high impedance to the transmit frequency at the antenna T. The same thing happens on the transmit side of the affair but on the other frequency. That's how you get separation between the transmitter and receiver at the T junction. However, what Jeff was talking about was the cable between the TRANSMITTER and the duplexer input. His comment was tongue in cheek to make his point about the antenna. That cable in most cases can be any random length. There are times when a selected length will help the transmitter with the load that it sees due to out of band impedances that get presented to it. But you can not say that a certain length will be called for. 73 Gary K4FMX
RE: [Repeater-Builder] HAM Mototrbo Systems
Here in Southern CA. (LA, Orange, and San Diego counties) we have at least 4 Mototrbo repeaters running AND IPSC linked on the amateur band. There are more than two dozen users known to have invested in Trbo radios with interest growing steadily. Given the behind-the-scenes Mototrbo activity that has been taking place over the past two years in amateur radio it's become increasingly clear that the system works well and that Motorola is continuing to improve or release features and tools all the time. They really hope APCO adopts their TDMA format as the next generation of P25 but that is yet to be seen meanwhile Motorola is clearly focused on developing the Mototrbo platform. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Dan Blasberg Sent: Sunday, February 14, 2010 10:12 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] HAM Mototrbo Systems Mike, In the DC area there is currently one UHF machine and about 5-10 amateurs playing with MOTOTRBO. I would be interested to know what other areas are using for setting or are they leaving everything in the default setting? Dan KA8YPY
Re: [Repeater-Builder] DB-4072 duplexers
I tuned one at one time on 447.05/442.05 and it worked well. Don't remember the rejection numbers though. Gary - K7NEY On 2/5/2010 9:52 PM, James Adkins wrote: Wondering if anyone knows if the 6-cavity set of DB-4072's made for 450-470 MHz will go down to 444.425 MHz / 449.425 MHz? I know the specs say only down to 450, looking for anyone that's tuned these in the real world and how low you've tuned them. Thanks, -- James Adkins, KB0NHX
[Repeater-Builder] MSF 5000 Part TLE5834 Needed
Does anyone have or know someone that I can get the listed part above? Motorola doesn't make this part anymore.
RE: [Repeater-Builder] Was Repeater Battery Question
The site I maintain isn't solar powered but I did add battery backup two years ago and it's been working very well. Batteries are Interstate SRM29's charged by a Samlex SEC-2415 auto charger. The loads are powered thru a Samlex ST1500-124 pure sine wave inverter with a built in transfer switch. I find the switch to be bumpless and the inverter's output is quite sinusoidal. Batteries were $95 each delivered. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of rrath Sent: Friday, January 08, 2010 9:03 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Was Repeater Battery Question Well, I did not receive any replies to my question. So I will ask this question: For those of you that have solar operated repeater sites, what type of battery are you using? Are you satisfied with them? Thank you. Rod kc7vqr Yahoo! Groups Links
RE: [Repeater-Builder] Motorola R 2600 Service Monitor Comments/Price??
The R2600 is a fine service monitor for analog applications below 1000Mhz. If you're looking for a monitor that can be upgrade for digital audio applications then the R2600 is not for you. Only the R2670 offers such upgrades. Since you mentioned it's monochromatic I'll assume it's either an A, B, or C version. One bit of advice on these, If it's a R2600 CBS (cellular base station) and it's in otherwise good shape then I'd recommend getting it. CBS's came stock with the high stability oscillator, 100 watt capability, and tracking generator. The service center in Illinois can remove the cellular slice, upgrade the firmware, fix anything else and return you a R2600CHS. That's what I did and I'm very pleased with it. The R2600 is larger and heavier than most of the 8920 series HP's but I find it just as easy if not easier to use. Scheduling repair or calibration work can be a little tricky now that GD manages the product line and the service center is no longer run by Motorola but the same folks are still there and the service hasn't changed from what I understand. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of ab6li Sent: Wednesday, January 06, 2010 11:02 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Motorola R 2600 Service Monitor Comments/Price?? Hello to the group. I have an oppurtunity to purchase a Motorola R 2600 Service Monitor. It has the monochromatic screen, tracking gen, etc. It seems to be in working order, reminds me of the HP 8920a I had for a short time. Does anyone have any comments about this unit? Are they reliable in hilltop service? Any comments on what current pricing should be? My 1500S needs repair and I have a CE 6030a that isn't doing to well either. Both of then need a trip to the doctor and I don't even want to think about what that will run me. Any comments on service facilities for these units? Any comments would be appreciated. Thanks in advance. John AB6LI Yahoo! Groups Links
RE: [Repeater-Builder] Re: Programming Moto X9000 on a P1
Mike, MoSlo Deluxe for DOS takes care of CPU cache automatically and offers an option to turn the COM port controller's FIFO buffer OFF as well. While I still use these instructions when executing MoSlo I find my PC's all default to FIFO OFF anyway. Gary/N6LRV -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of w5jr.mike Sent: Saturday, December 26, 2009 12:11 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Programming Moto X9000 on a P1 Thanks Gary. I have not been using Deluxe but maybe that is the trick versus the Basic trial version. I also expect CPU cache is involved here somewhere. I do have the COM port FIFO turned OFF. -mike/w5jr --- In Repeater-Builder@yahoogroups.com, Gary n6...@... wrote: Yes. I'm running it fine on a PIII and can read and write with 100% reliability. The trick is to lauch MoSlo twice in a row. I'm using the latest version known as MoSlo Deluxe for DOS. If you are as well then try lauching MoSlo once then launch it a second time. You'll see an odd processor speed show up after the second execution of MoSlo but ignore it and move on to running the RSS. I've tried it on several PIII's with both DOS 6.22 and Win 98SE operating systems (Win 98SE booted to DOS of course) and every one works equally well. Gary/N6LRV -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mike/W5JR Sent: Friday, December 25, 2009 8:58 PM To: Repeater Builder Subject: [Repeater-Builder] Programming Moto X9000 on a P1 Oh, great wizards. I have an aging, fragile 386sx laptop that has faithfully programmed my X9000 radio for years. I also have a Compaq LTE P1 120 that I program all of my other Moto radios with successfully except for the X9000. On the Compaq, I have tried booting to real DOS6.22 from a floppy (Windows 98SE DOS gives same problem). Using moslo, the X9000 program launches just fine but I am unable to read the radio. I receive the dreaded Serial Bus Failure. Power Fault. message. I can only guess that the computer speed still hoses the serial port despite using moslo to dial back the computer. I have read through all of the repeater-builder and Blenderman sites on the issue. Has anyone made the X9000 program work on a P1? If not, I guess I'm going garage sale shopping. Thanks Mike/W5JR Yahoo! Groups Links
RE: [Repeater-Builder] Programming Moto X9000 on a P1
Yes. I'm running it fine on a PIII and can read and write with 100% reliability. The trick is to lauch MoSlo twice in a row. I'm using the latest version known as MoSlo Deluxe for DOS. If you are as well then try lauching MoSlo once then launch it a second time. You'll see an odd processor speed show up after the second execution of MoSlo but ignore it and move on to running the RSS. I've tried it on several PIII's with both DOS 6.22 and Win 98SE operating systems (Win 98SE booted to DOS of course) and every one works equally well. Gary/N6LRV -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Mike/W5JR Sent: Friday, December 25, 2009 8:58 PM To: Repeater Builder Subject: [Repeater-Builder] Programming Moto X9000 on a P1 Oh, great wizards. I have an aging, fragile 386sx laptop that has faithfully programmed my X9000 radio for years. I also have a Compaq LTE P1 120 that I program all of my other Moto radios with successfully except for the X9000. On the Compaq, I have tried booting to real DOS6.22 from a floppy (Windows 98SE DOS gives same problem). Using moslo, the X9000 program launches just fine but I am unable to read the radio. I receive the dreaded Serial Bus Failure. Power Fault. message. I can only guess that the computer speed still hoses the serial port despite using moslo to dial back the computer. I have read through all of the repeater-builder and Blenderman sites on the issue. Has anyone made the X9000 program work on a P1? If not, I guess I'm going garage sale shopping. Thanks Mike/W5JR Yahoo! Groups Links
RE: [Repeater-Builder] Re: battery
a battery charger before disconnecting the charger leads from the battery. I have seen a couple of batteries explode when someone disconnected the charger from the battery first. It is a bomb! That's more than most will want to know. 73 Gary K4FMX As another note . . . Please do not tie a back-up battery directly across the main output terminals of a power supply (which provides no current limiting to the battery while re-charging). I have found this actually done at a hill top site. What had happened was that AC power to a repeater had been off for three days or so. The repeater was running exclusively off the battery for 3 days and finally depleted it. Well, when AC power was restored, the battery started pulling an enormous amount of amperes from the power supply (since it was now depleted). I was there at the time the AC was restored, and within a matter of a minute of the power being restored, I smelled something burning. After sniffing out it's point of origin in the room, I found that the power supply tied to the battery was too hot to touch, and that the wires connecting it to the battery were just about melting the insulation off. What a fire hazard. I disconnected that battery right then and there and notified the owner of the repeater. So please don't burn down our repeater sites. It's hard enough trying to get into commercial sites as it is. Many radio sites will never again accept an Amateur Radio station due to previous experiences with hams. Please don't add to that. Have Fun ! Paul Metzger - K6EH DVARA
[Repeater-Builder] Midland 13-509
There was a time when the ol' Midland 13-509 mobiles made good radios from which to build a 220Mhz amateur repeater. I have a 13-509 for sale in excellent condition and in the original box. Included is the manual, mounting bracket, and mic. Has several pairs of crystals already installed. Asking $50 +s/h. If interested please email me direct (off the group). Gary N6LRV
RE: [Repeater-Builder] Midland 13-509
The Midland 13-509 is spoken for. Thanks all, Gary _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gary Sent: Friday, November 27, 2009 1:38 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Midland 13-509 There was a time when the ol' Midland 13-509 mobiles made good radios from which to build a 220Mhz amateur repeater. I have a 13-509 for sale in excellent condition and in the original box. Included is the manual, mounting bracket, and mic. Has several pairs of crystals already installed. Asking $50 +s/h. If interested please email me direct (off the group). Gary N6LRV
RE: [Repeater-Builder] Re: The GLB Preselector- Preamplifier
It comes down to where are the IM products really being generated. I think what Skipp is trying to say is that if the preamp generates spurious products from overload that fall outside of the center frequency, that filtering behind the preamp will help keep those products out of the receiver. While this may be true, keep in mind that any IM products that are generated by the preamp are going to be at fairly low levels because of the inefficiency of the mixing action in the preamp. A mixer is what it becomes when you get into the non linear range of the preamp. But as with any mixer its product amplitude is going to be way down from the signals that cause the mixing. The off frequency products generated by a non linear preamp are not the real problem. It is the on frequency products that get thru. They are going to be relatively weak also but because they are on frequency everything in the chain is going to amplify them. Filtering at the output of the preamp will do nothing to reduce any mixing action in the preamp as that is dependent on input level. Measuring 3rd order products is done at the output of the device so with filters at the output it is going to look like the filters are helping reduce these off frequency products but that is not how you measure IM performance of a device. They are usually referenced to on frequency levels. Also keep in mind when reading IM specs for an amplifier that some manufacturers reference to the input and some reference to the output of the amplifier. Referencing to the output makes the spec look better by the amount of gain that the amp has. Adding filters to the output of the device can help reduce the IM tendencies in the following receiver however by keeping off frequency signals out of the receiver. It is the total amount of power that reaches a device that causes overload. But any off frequency IM products that may be generated in the preamp will be much weaker than direct off frequency signals So the addition of filters after the preamp may seem like they help the preamp but they are really helping the receiver from generating IM in its first active stage. Remember that when you add a preamp you destroy the IM performance of the receiver by the amount of gain in the preamp. 73 Gary K4FMX Letting the preamp generate poop then filtering the off-channel garbage you've already generated in that preamp is a poor solution; Ah, now were getting close... now assume the preamplifier generates really bad unwanted products in extremely overloaded conditions that don't occur most of the time. When the buckshot flies for relatively modest times... the trailing internal/external filters (regardless of location) would help a good receiver better deal with the event. the in-band garbage generated in the preamp goes right on through. And now we ask how much F-center and close adjacent in band garbage actually gets to the receiver front-end and how well do the receiver(s) handle this event? With the right hardware layout a lot better than you might assume at first glance.
RE: [Repeater-Builder] Re: pre-amp placement
Most of the time you will want as much selectivity as you can get in front of the preamp. The only time that I can think of off hand where you might want a filter behind a preamp is if you are getting a receiver feed from a receiver multicoupler that has a preamp in it, giving a few megs wide signal out of the multicoupler. Overload of a preamp depends on the total amount of power that gets into it. The wider the window in front of it the more total power that has potential for getting in from many other transmitters. This can cause IM products to be generated in the preamp itself. Once that happens you have opened the barn door and there is not much you can do after the preamp to help the receiver. Sometimes if is good to use a preamp that doesn't necessarily have the best noise figure but maybe has a higher dynamic range (higher intercept point) if your site has lots of nearby transmitters and noise that could overload the preamp. Having a very low noise figure doesn't do you any good if the preamp causes IM to be generated. The second thing is not to run too much gain in the preamp so that the added gain overloads the front end of the receiver. For every Db of gain the preamp provides that reduces the receivers IM rejection ability by the same number of Db. So again if you have lots of strong adjacent signals at your site you don't want lots of preamp gain. Total receiver system noise figure is partially set by the preamp if its noise figure is lower than that of the receiver, which it usually is. Using a preamp with a .5 Db noise figure and a receiver with an 8 Db noise figure won't give you a total noise figure of .5 Db, but somewhere in-between. The more gain the preamp has the lower the overall noise figure will be in this case, unless you have enough gain to cause some of the other low noise figure stages in the receiver to go into compression as Mel eludes to. The stage that goes into compression in the receiver doesn't necessarily have to be the front end of the receiver. The first IF stages in most receivers have a pretty low noise figure and help establish the overall noise figure of the receiver as well as the front end of the receiver. So these stages can be overloaded with too much gain and cause a noise figure reduction. But the biggest problem with too much preamp gain is overloading the mixer in the receiver and causing it to generate IM products. By controlling the gain of the preamp (using attenuators after the preamp) or by other means you can usually find a happy medium of some gain to improve system noise figure (sensitivity) and not too much gain to destroy the IM performance of the receiver. One way to do that is to put in attenuation until the sensitivity just starts to degrade with the preamp in the circuit. That will give you good sensitivity and good IM performance. Any more gain and all you are doing is degrading the receiver IM performance. When shopping for preamps don't only look at gain figures and noise figures, also look at the intercept point to see how much signal it will handle before compression starts. That's where it will start generating IM products. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Mel Swanberg Sent: Thursday, November 26, 2009 12:40 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: pre-amp placement You might need to add a several DB attenuator between the pre amp and the receiver to keep from over driving the front end. Not if you use a good receiver, or not use a preamp with too much gain. Bob NO6B What defines too much gain can vary wildly. One trick I learned in building transverters for the microwave bands, and one I now apply to VHF/UHF preamps is to check the overall noise figure of the system as a whole. You'd be surprised at what just a few db too much gain can do, and it doesn't necessarily show up with a quick sensitivity check. A preamp can be placed in front of a receiver and, yeah, now the receiver is more sensitive. But if it's a .5 DB NF preamp, and you're not careful, your system noise figure can end up going from, say, 6 db for the barefoot receiver, to 4 db with the preamp - an improvement to be sure, but not nearly as good as the preamp may be capable of. If that preamp is driving the receiver front end even just a little bit into compression, you've lost a lot of potential. Even with a good receiver. Carefully balancing preamp gain with attenuation on the output can be extremely useful. Not everyone has a noise figure meter, though, and measuring NF on an FM receiver is a pain in the neck. A sinadder can be used to the same effect, even if the actual noise figure isn't known. It can be interesting to observe insertion of a few db of pad between the preamp and a receiver, and watch the sinad sensitivity of a receiver improve by a few
RE: [Repeater-Builder] Best coax for marine use
You certainly don't want just any old coax. You for sure don't want any type of hard line run up the mast as the flexing will break the center conductor or outer conductor. You want to have a stranded cable such as RG8 type. Also don't use any type of foam dielectric type cable on a boat as the center conductor will migrate to the shield and short the cable especially at places where the cable bends. Polyethylene center insulator is best for this application. Even though foam has slightly lower loss, the low loss doesn't do you any good if the cable fails. Inside a sailboat mast there is no way to secure the cable and it will flop around inside the mast. Lots of stress on the cable. As a side note, there should be NO solid conductor wires used on any boat. Only stranded wires due to the constant movement and related stress. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Vernon Densler Sent: Tuesday, November 24, 2009 11:18 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Best coax for marine use I have been in a big discussion with the guys on my boat list about the right coax for running up the mast for VHF marine radio. Keeping in mind that we are talking about a 70' or so run going up the center of an aluminum mast, in a salt water environment, and the radio is limited to 25 watts. Also keep in mind that when off shore this is a life line and the best possible send and receive is needed in an emergency situation. So given the criteria what is the best possible coax to use knowing that thickness matters and bend radiuses may be tight? Others on the list are saying just grab any old 8X type cable and you will be fine. I say use something with very low loss and suggested small heliax. Any suggestions? Vern s/v Nirvelli KI4ONW
RE: [Repeater-Builder] Has anyone measured out-of-band rejection for a duplexer?
You can make the measurement with a signal generator and a tunable receiver that has some kind of indicator for signal strength. It doesn't even need to be calibrated. Connect the signal generator to the antenna port and the receiver to the receiver port of the duplexer. Be sure to disable the transmitter. Find a reference level with the signal generator on the operate frequency. Then tune the signal generator to the interested rejection frequency and find it with the receiver. Then note the signal generator level and increase its output to match the receive strength that you noted at the start. The difference between the two levels is the amount of rejection the filters are giving you at the frequency of interest. With a pass/reject duplexer you won't have a lot of off frequency rejection as there is not much of a pass band on that type of duplexer. There will be good pass band rejection in the space between tx and rx frequencies due to the overlap of the filter skirts but outside of either it is not much. For an added receiver filter, your pass/notch filters again will not do too much for you as far as pass band rejection goes. If you use them to reject a specific frequency, each can should give you about 30 db of notch rejection but you may have some degradation of the wanted frequency if it is far removed. And you will probably not be able to move the notch far enough such as the broadcast band. You may be able to convert the cans to pass cavities by changing the coupling loops. Then you can do the same measurement as described above to see how much rejection you will get. Also look at some pass band curves in the catalogs and you will see about how much rejection a pass cavity will give you at a given distance away from where it is tuned. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Tony KT9AC Sent: Monday, November 23, 2009 1:36 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Has anyone measured out-of-band rejection for a duplexer? Hi Everyone, Without the benefit of a spectrum analyzer, I would like to find out how much rejection of out-of-band signals can be expected from a typical UHF duplexer. Have a MSF5000 on 452 that works fine with the T4084 duplexers (1500 style), but have a lot of VHF data and FM broadcast hash that is trying to make it in (the 45kW FM is about 400 yards away and the VHF data is almost 1/3 harmonic). Looking at the documentation, I can guess its about 20db per cavity (or can), but the graphs don't extend very far. So for a regular four-can duplexer I might be providing 40db of protection. I want to increase this, and plan on adding one or two more cans on the receive side, and a Sinclair preselector in-between the latter two to make up for the increased insertion loss. Just wondering if anyone ever tried/measured this, or had ideas about filtering out FM broadcast. Eric mentioned using a single 7 Sinclair cavity, but I'd like to see if I can use some spare 1500 bandpass/reject cavities first. I don't think a 1/4-wave stub will work with that much field strength prying open the MSF's front-end. Thanks, Tony Yahoo! Groups Links
RE: [Repeater-Builder] Re: 2 dB Error in DVM level readings
I don't have a 189 but have other fluke meters. Measuring in dBm, to measure an absolute value, you must first know what load you are measuring across. Then the meter must be set up to read zero dBm across that load impedance. One of the fluke meters that I have has several different settings of load resistance references so that it will read absolute dBm correctly. If you just want to read relative dB between two different levels then the load impedance is not important. Just stick the meter on the load with the signal applied and read the reference level in dBm (or offset the zero at that level) then change the level of the signal and read the dB difference between the two. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of skipp025 Sent: Friday, November 20, 2009 2:38 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: 2 dB Error in DVM level readings So we all (here) pulled out our meters for a comparison. First off... our one Fluke 189 does measure in dBm as did every meter and transmission test set in the shop. So all is not glitters that is written in technical forum stone (gold). s. skipp025 skipp...@... wrote: Pasted from another Technical Forum This comes up from time to timewell, it came up again. Check the display for the measurement unit. Fluke 189s measure in dBV (dB referenced to one Volt), not dBm (dB referenced to one milliWatt). 0dBm (.775 VAC) is a couple dB different in voltage from 1 Volt. A good clue is on the display of the 189 over to the right, it says dB and V. When the 189 is measuring a 0 dBm tone, it indicates -2.21 dB V and the small voltage display indicates .775. If you use the old 20 log (.775/1) formula, you come up with a difference of -2.21 dB. All of the DVMs are high impedance input, so they don't measure actual power. The 189s only know that 1VAC is displayed as 0dBV and the 287s know that .775 VAC is displayed as 0dBm when it is in the dBm mode. Those of you who have the new 287s get to read dBm directly and as an added bonus, get to change batteries very frequently. Those of you who have the 189s get to use your smarts more and don't have to change batteries so often. Check the specs on your individual DVM. It may be able to count CTCSS. The old wideband AC Voltmeters are failing rapidly. You will have to use your Transmission Test Set and possibly some functionality of your DVM to replace the greatness of the old wideband AC Voltmeter. Yahoo! Groups Links
RE: [Repeater-Builder] ACSSB
Agreed Rob. ACSSB is nothing more than regular old SSB with a few things added. The compandering is simply speech compression on the transmit end and an equivalent expansion on the receive end to restore the dynamic range of the voice. This gives some noise reduction in the circuit. As mentioned before the SEA radios placed the pilot tone in the middle of the band pass. The other guys just inserted some carrier (as I remember) for a pilot. This has been done for many years in the marine radio service on the SSB circuits. The carrier was run at 20 db down from peak power. The repeaters were licensed with a specific ERP and height above average terrain. So combiner loss, cable loss, antenna gain and height above average terrain were all factored in to determine the power output of the repeaters. The biggest problem was the cost of the equipment. They could not get the cost down to be competitive with FM. ACSB started out on the VHF bands with a few channels placed in-between FM two way channels. The problem there was too much interference from the FM side bands that clobbered the ACSSB receivers. Being amplitude based there is no capture or limiting like there is with FM so any little noise is heard. ACSSB can have much better range than FM with a clear channel (no noise) but it is hard to find such. SEA petitioned the FCC for a portion of the 220 band to get ACSSB only channels to get away from the problems with sharing with FM on the VHF channels. It was a good thought but the equipment had other problems, mostly manufacturing at reasonable cost. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Robert Pease Sent: Friday, November 13, 2009 8:01 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] ACSSB Interesting thing about part 97. It is written differently than any other part of the rules. In most of the rules they tell you what you can do and if it isn't specifically spelled out then you can't do it. In part 97 it is the other way around. For the most part they tell you what you can't do. So unless it specifically says you can't so it, it is assumed ok. This was done this way to promote experimentation with new modes and new ways to use old modes. I can't speak to this mode specifically but look at it technically as in bandwidth, modulation,... The tech specs that may exclude it from use, not the name or mode itself. JMO. YMMV. Rob Sent by Good Messaging (www.good.com) -Original Message- From: DCFluX [mailto:dcf...@gmail.com] Sent: Thursday, November 12, 2009 09:13 PM Eastern Standard Time To: Repeater-Builder@yahoogroups.com Subject:Re: [Repeater-Builder] ACSSB Could you please provide a rule number to back this up? Linear Modulation and ACSSB share 4K00J3E as the emission designator. On Thu, Nov 12, 2009 at 5:34 AM, n0fpe n0...@cox.net wrote: One thing to remember. Amatuers are NOT authorized to use ACSSB above 30mhz. Please check part 97 for the exact modes we are able to use. heck if we were there would be tons of ACSSB repeaters already modified into the ham band. (Yahoo! ID required) Change settings via email: Switch mailto:repeater-builder-dig...@yahoogroups.com?subject=email%20delivery:%20 Digest delivery to Daily Digest | Switch mailto:repeater-builder-fullfeatu...@yahoogroups.com?subject=change%20deliv ery%20Format:%20Fully%20Featured to Fully Featured Visit http://groups.yahoo.com/group/Repeater-Builder;_ylc=X3oDMTJjdGcyZDNmBF9TAzk 3NDc2NTkwBGdycElkAzEwNDE2OARncnBzcElkAzE3MDUwNjMxMDgEc2VjA2Z0cgRzbGsDaHBmBHN 0aW1lAzEyNTgxMTcyMjE- Your Group | Yahoo! Groups http://docs.yahoo.com/info/terms/ Terms of Use | Unsubscribe mailto:repeater-builder-unsubscr...@yahoogroups.com?subject=unsubscribe
RE: [Repeater-Builder] Icom F420 programming
Seems you radios are probably -9's (400-430Mhz). They can be retuned up to around 450Mhz. There's a procedure discussed on the mods.dk website. You'll have to program several channels throughout the amateur band then use the service mode of the software to access the soft tuning tools. Not too difficult once you learn the procedure. When you're done it should function fine from about 420 to 450Mhz. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wa0vus Sent: Monday, November 02, 2009 7:19 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Icom F420 programming Anyone here programmed these Icom F420 radios. I cannot seem to get them to play in the 440 area. I have all the software and cables but sure am missing a step somewhere. I program a high and low freq such as 440 and 470. I try to set the pll voltage using this and can only get 7.75 volts no matter what. The freq display is flashing so I knowit is out of lock. I can go back to the original 413 mhz channel and the pll drops to 3.85 and locks right up. I have the 300 programming software but cannot find the directions for programming anywhere. I downloaded the manual for the johnson rig and followed that instructions but still not happening. Any ideas? Got 4 nice radios I bought on here but just paper weights right now. Larry WA0VUS Yahoo! Groups Links
[Repeater-Builder] Kenwood KSG-4500 repeater to external controller
Hello, I am looking for the pin-out of the DB-15F connector on the back of this repeater. Any help would be appreciated very much. Thanks 73 Gary K2ACY
[Repeater-Builder] Re: Kenwood tk-370
Hello Ian, I happen to have both the connector ( NEW ) for the radio and several new in the bag KRA-17M Kenwood antennas. Send me your shipping address and I will get to you a price for parts and shipping. Gary --- In Repeater-Builder@yahoogroups.com, kerinvale kerin...@... wrote: Hi guys .Would anyone know where we can replacement antenna parts for the Kenwood tk-370. I am chasing the sma-f antenna socket in the top of the radio and also a antenna but seem to be having trouble finding a supplier or replacement parts  Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Ph 0749922449 or 0409159932 or 0749922574 www.kerinvalecomaudio.com.au
[Repeater-Builder] Re: Astron Power Supply Alert
Hello Eric, Would you kindly provide me with the Tech support email address you used for Astron. Ive been un able to get a good address. Thank you in advance! Gary
[Repeater-Builder] Commchek
Back around 1997 Motorola distributed a small utility program to assist in troubleshooting and configuring comm. ports used with RSS applications. The program was called COMMCHEK. Does anyone on the list happen to still have a copy of this? I have a current need for it and would appreciate a copy. If you're not sure what I'm referring to check SRN1201 or SRN1201A. Yes I checked with Motorola already. This was apparently long enough ago that current tech support staff haven't heard of it. Thanks all, Gary
RE: [Repeater-Builder] Narrow Banding and VHF Low Band
Don't know where you got the below 512Mhz comment from (except perhaps a sloppy comment in a recent article printed in Urgent Communications) but here's what the R O really says; Earlier in this proceeding, the Commission took the following actions in order to bring about a timely transition to narrowband technology: (1) set January 1, 2013, as the deadline for Industrial/Business and Public Safety Radio Pool licensees in the 150-174 MHz and 421-512 MHz bands to either migrate to 12.5 kHz technology, or utilize a technology that achieves equivalent efficiency; (2) prohibited any applications for new systems using 25 kHz channels, or modification applications that expand the authorized contour of an existing 25 kHz station, effective January 1, 2011; (3) prohibited the manufacture and importation of any 150-174 MHz or 421-512 MHz band equipment capable of operating with only one voice path per 25 kHz of spectrum, i.e., equipment that includes a 25 kHz mode, beginning January 1, 2011; and (4) prohibited the certification of any equipment that includes a 25 kHz mode beginning January 1, 2011.2 Keep in mind this applies to Part 90 services and not Part 95 or 97 radio services. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of wmhpowell Sent: Monday, August 31, 2009 9:49 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Narrow Banding and VHF Low Band Help! The FCC rules on narrow-banding seem to be contradictory when it comes to determining if VHF low band must be converted to narrow band. On one hand, the FCC states that All below 512 MHz which implies VHF low but on the other they specifically mention VHF high and UHF, specifically NOT mentioning VHF low band. I need to come up with a specific reference from FCC docs either requiring or exempting VHF low from narrow banding requirements. Urban legend and I heard won't get the funding if VHF low must be narrow-banded - only something form the FCC can make the $$ flow. And, yes, I looked but found nothing definitive. Thanks, Bill - WB1GOT Yahoo! Groups Links
Re: [Repeater-Builder] IFR 1600S
I have a 1600S, have had it now for about 3 years. No trouble at all. I Love it.. The operators manual is available on the net in a PDF, however I got mine from the company I purchased the Monitor from in printed form. It's several hundred pages. Gary - K7NEY shibukiau wrote: I have a chance to acquire an IFR 1600S and would like some users reports on their experience relative to the instruments performance and reliability to help me make my decision! Are manuals available somewhere for these units other than from IFR?? Thanks for your help!! Lloyd VE3ERQ
Re: [Repeater-Builder] Re: IFR 1600S
I sent it to Mike WA6ILQ for posting on the Repeater Builder Site, It's a really big file, youcan get it there when he gets it posted. I couldn't find it again on the internet but had a copy on my system. Gary shibukiau wrote: Thanks for the comments Gary -- much appreciated!! Could you send me the link for the operators manual?? I don't have any info on the unit so I'm sort of flying blind trying to run this unit!! Thanks again for your help!! Lloyd VE3ERQ --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com, Gary Hoff k7ney...@... wrote: I have a 1600S, have had it now for about 3 years. No trouble at all. I Love it.. The operators manual is available on the net in a PDF, however I got mine from the company I purchased the Monitor from in printed form. It's several hundred pages. Gary - K7NEY shibukiau wrote: I have a chance to acquire an IFR 1600S and would like some users reports on their experience relative to the instruments performance and reliability to help me make my decision! Are manuals available somewhere for these units other than from IFR?? Thanks for your help!! Lloyd VE3ERQ
RE: [Repeater-Builder] isolation
Absolutely you need some reserve. The same if you are designing a point to point path. You don't select equipment that will just do the job. You always need a certain amount of reserve for changes of equipment etc. the idea is that some think the repeater is going to work better with more isolation in the duplexer just because it has more isolation. Once you meet the isolation requirement and some reserve built in to cover things that drift etc., then more is not going to help you. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Chuck Kelsey Sent: Sunday, August 23, 2009 8:45 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] isolation I agree with Kevin. You need a little headroom built in for conditions that could change. Equipment ages and changes it's operating characteristics. Temperature swings cause the same issues. Does one need to go overboard? Probably not. But if you happen to be right on the edge under perfect conditions, you may be unhappy when something moves a bit out of tolerance. Chuck WB2EDV - Original Message - From: Kevin Custer mailto:kug...@kuggie.com To: Repeater-Builder@yahoogroups.com Sent: Sunday, August 23, 2009 9:30 AM Subject: Re: [Repeater-Builder] isolation Gary wrote: Dan Kagabine, the chief engineer at TX-RX systems use to always say that once you have enough isolation to overcome any desense, then any more is a waste of money as it does nothing for you. If you only need 70 db then a 100 db duplexer does nothing more for you than a 70 db duplexer. While I'll agree that more isolation, then what is needed to insure no desense is a waste; if this gentleman is suggesting that isolation in reserve is a waste, I strongly disagree. Why? Operating conditions can change - snow and especially ice on the repeater antenna can detune the system and isolation in reserve will allow the repeater to operate without desense until the reserve is used up. Kevin Custer
RE: Re: [Repeater-Builder] Diversity FM reception
The reason FM stations transmit circular polarization is to accommodate both horizontal and vertical receive antennas. Most fixed receivers are horizontal and most cars are vertical. You can not transmit both horizontal and vertical polarization at the same time. Feeding a horizontal antenna and a vertical in phase will give 45 degree polarization. For simultaneous vertical and horizontal the antennas must be fed as circular. They then contain both the horizontal and vertical component. They are not doing this for the sake of circular polarization but only so vertical and horizontal polarizations can be transmitted together. TV has no need to transmit anything other than horizontal polarization as most TV reception is done with a horizontal antenna. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of John Sehring Sent: Sunday, August 23, 2009 12:51 AM To: Repeater-Builder@yahoogroups.com Subject: Fw: Re: [Repeater-Builder] Diversity FM reception I turn out that use of CP in urban suburban areas results in somewhat more signal strength on linearly polarized antennas, e.g. vertical whips on cars straight rod aerials on portable FM radios. Due to preferential scattering of vertically polarized sigs from typical urban structures, there tends to be more of that available, esp. good for auto FM reception. The Germans for example are more concerned with signal quality than quantity so don't use CP. However, there is a drawback: there's more multipath. So the tradeoff was made--more signal strength but at lesser quality (due to multipath distortion). Well designed FM radios reduce separation intelligently in the presence of multipath: first they gradually blend the stereo channels into mono, high audio frequencies L-R info first, then all audio (L+R) is gradually lowpass filtered. This happens dynamically, on the fly. Works well IMO when done properly. TV broadcasters tried CP as well but couldn't live the extra multipath: it was easily visible as more ghosting. See for example: http://www.ham-radio.com/k6sti/ for more on this. --John --- On Fri, 8/21/09, larynl2 lar...@hotmail.com wrote: From: larynl2 lar...@hotmail.com Subject: Fw: Re: [Repeater-Builder] Diversity FM reception To: Repeater-Builder@yahoogroups.com Date: Friday, August 21, 2009, 9:08 PM In reference to below, what would be the real advantage to using CP antennas in addition to the V and H you'd have already? Any signal that arrives will excite a V and/or H antenna according to it's arriving polarization, and I don't see where CP would be a help. Most FM broadcasters use CP. Those that don't are licensed for only V or H or choose to use a less-expensive single-polarization antenna. And many of them look like rototillers, and other shapes. Laryn K8TVZ --- In Repeater-Builder@ yahoogroups.. com, John Sehring wb...@... wrote: There's more to be done with polarization as well: Circular, both RH LH. It is possibile to make omnidirectional CP antennas. FM broadcasters use a lot of them. They look like a bunch of arrows.
RE: [Repeater-Builder] isolation
Dan Kagabine, the chief engineer at TX-RX systems use to always say that once you have enough isolation to overcome any desense, then any more is a waste of money as it does nothing for you. If you only need 70 db then a 100 db duplexer does nothing more for you than a 70 db duplexer. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Kevin Custer Sent: Saturday, August 22, 2009 5:38 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] isolation Eric, You may have missed the point. While your program calculated a necessary isolation amount of 99.65 dB, using a GE M2 PLL exciter would dictate 77.65 dB of necessary isolation - which is easily obtainable with a quality 4 cavity (okay, 4 large cavity) duplexer. While I certainly wouldn't recommend a duplexer using four 5 cavities, a four cavity duplexer utilizing 8 inch cavities would provide more than adequate isolation (90+ dB of isolation) for this gentleman's arrangement. If he were using a multiplier exciter (which the 'program' assumed), then one can certainly understand your recommendation - but - he did say PLL exciter and M2 equipment. I'm not sure I understand your statement Nothing about duplexers is for certain. All of the duplexers I have ever tuned came out to factory specifications or better. If not, something was physically wrong - lightning damage - cabling problems - loop problems, etc. I don't believe that if this person were to utilize a quality four cavity duplexer that we'd be setting him up for failure. Engineering is on our side, and he can benefit from not needing to spend extra money for something that isn't really necessary. BTW: It is possible to duplex a PLL exciter (200 mW) and M2 receiver (no preamp) at 600 kHz with nothing more than a tee connector. You do have to skew the helical tuning a bit so the skirt is sharp on the side of the transmitter; which reduces receive sensitivity to less than factory specification. I won't say there will be zero desense, but you won't even get close with a multiplier exciter in the same test. It's fun - tastes great - less filling! Kevin Kevin, Nothing about duplexers is for certain. While I agree that a PLL exciter is inherently less noisy than its multiplier counterpart, I never assume that it's okay to plan ahead for less than optimum isolation. Some duplexer designs are known to have better performance than physically identical designs from other manufacturers- the silver-plated copper cans from Decibel Products are one example. I feel that it's better to have a duplexer that is perfectly tuned and has absolutely zero desense, than a lower-performance duplexer that has only a little desense. In an ideal world, KJ4SI should be able to buy a four-cavity BpBr duplexer and try it out for 30 days to see if it had zero desense- with the option to purchase two more cans and the appropriate jumpers at a discount for upgrading it to a six-cavity duplexer. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Kevin Custer Sent: Saturday, August 22, 2009 12:52 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] isolation Eric, Are you sure about your six-cavity recommendation? The MASTR II PLL exciter has 22 dB less side-band noise than a typical multiplier exciter - using 600 kHz TX to RX separation. Assuming his preamp isn't driven into a non-linear region (it shouldn't be), a good 4 cavity duplexer, like a WACOM WP-641, should give plenty of isolation... Kevin Custer My CommShop calculates 99.65 dB is required. I'd definitely be looking at a six-cavity BpBr duplexer for this station. 73, Eric Lemmon WB6FLY -- Hope someone may have a program,commshop? What I need to know is what amount of isolation with duplexers that is required for a GE m2 receiver with .1...@12db and a m2 pll exciter,100 watt PA on vhf,600kc split?1/2in helix,with 4pole db224 antenna at 70 ft. thanks kj4si
RE: [Repeater-Builder] Re: Motorola MTR2000 Question
The UHF repeater is likely mismarked or the frequency info you obtained for your school's license is inaccurate. The UHF repeater is likely the school's repeater. As mentioned earlier the MTR2000 is a multi-channel radio but can only repeat on the channel it is left on. Recommend you find a dealer or tech experienced with the MTR and who has the software necessary to configure it. Have them download its codeplug. Recommend you do the same with your school radios. A comparison of the data will likely answer a lot. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Christopher Hodgdon Sent: Thursday, August 13, 2009 4:29 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Motorola MTR2000 Question Here's the deal, I work for a local school district, I have been kind of thrust into a temp. communications specialist position while we obtain some new buses and working with the company that will be adding the new radios to them. Over the last few weeks, we have been trying to determine the location of our repeater. The place were it is listed on the FCC license paperwork does not exist. I know, I am pushing them to get it updated. But that is another story all together. I do have access to a radio house located at our high school football field and it has two MTR2000 in it, plus two different antennas. One connected to one radio and one connected to the other. One radio is marked with the description of KISD PD, which is our police department for the district and has the following frequency pair listed on it: VHF: RX 173.325 DPL 331 and TX 158.385 DPL 331 The other radio is marked the following: UHF: 451.725 / 456.725 There is no documentation with this equipment, the person incharge of them originally left the district some years ago and no one knows anything about them, expect where they are located, as far as these two boxes go and what frequencies that have listed. Which brings me back to our department, we can find out repeater located anywhere physcially. Our repeater pair is listed as: UHF: 451.750 / 456.750 That is according to FCC, repeater listing and other information I have been able to obtain and by listening to it on a UHF amateur radio to see which frequency they were on. That being said, it is possible that the MTR2000 that is marked with the one UHF frequency, might actually have both pairs programmed into it, but only one can run at a time, right? Is there a way to find out if there is more than one frequency is programmed into the unit and if so, how might we go about that? Another reason I am asking is that we might be upgrading our system in the very near future and I might be able to get my hands on these repeaters. Thanks in advance. --- In Repeater-Builder@yahoogroups.com, Brian Raker brian.ra...@... wrote: The radio can be programmed for multiple frequency pairs. That being said, it cannot operate more than one channel / programmed pair of frequencies at one time. -Brian / KF4ZWZ On Thu, Aug 13, 2009 at 3:23 PM, Christopher Hodgdonchris.hodg...@... wrote: This is a question I have been asked and don't have an answer for. This could be for either amateur operation or commercial operation, but it relates to the repeater itself. Can a Motorola MTR2000 setup on UHF be setup to function as a repeater on more than one pair of frequencies? I know looking at the brochure on the website, it says that the NO. of Frequencies are upto 32. Does that mean it can handle two different sets of repeater pairs at the same time in the same radio? These are commercial frequencies I am listed at commercial, but they are for example purposes: Can the following setup work with the MTR2000? Frequency Pair 1: 451.725/456.725 Frequency Pair 2: 451.750/456.750 Can one MTR2000 handle both of these at the same time? Thank in advance. Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] Re: Motorola MTR2000 Question
You didn't mention the maintenance dept. having their own channel. If buses are using your channel (45x.750) then the repeater is likely at a higher location so it can better cover the area. If you've exhausted all available records, can't contact the previous tech, and can't find a dealer that knows where your repeater is then I'd suggest a good ol' fashioned transmitter hunt. Do you have any amateurs in your area that are up to the task? Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Christopher Hodgdon Sent: Thursday, August 13, 2009 5:43 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Motorola MTR2000 Question I wish I had a picture of the repeater house. The frequency listed on the MTR2000 is that of the schools maint. department. The other MTR2000, hook to the other antenna, is the Schools PD. I know those for a fact. Now its time to locate the other repeater system. The only odd ball thing I do know is that every once in a while, when a bus is talking to another bus or dispatch, you get a high squeal walk on over them, but its most likely another drive not paying attention and trying to key their radio. But I wonder if it might be the maint. since their frequency is so close to ours.
RE: [Repeater-Builder] Isolator vs intermod panel?
Definitions: Circulator - ferrite device with 3 ports. Isolator - Circulator with a load on the 3rd port. Intermod panel - Isolator with a harmonic filter. The harmonic filter may consist of a 2nd harmonic notch filter or a low pass filter or a band pass cavity. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Paul Kelley N1BUG Sent: Monday, July 20, 2009 6:16 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Isolator vs intermod panel? I guess I was lucky in my first few years as a repeater owner. Lately I have nothing but grief in many forms. (Yeah I know, welcome to the real world!) Can someone tell me in basic terms what is the difference between an isolator and an intermod suppression panel which contains an isolator? If one has a high power tube PA on a repeater, I assume he would need to use a high power isolator or intermod panel after the PA? Or would it be sufficient to use a lower power one between the solid state exciter and tube PA? Thanks... Paul N1BUG Yahoo! Groups Links
Re: [Repeater-Builder] Re: wp-639 -- How far should I expect to move the invar rods?
Joe is correct, if you're going to try an tune it without the proper test equipment, you will not get it perfect. It may work, but not as well as it could. Early in my career, I was able to tune a duplexer with a couple HT's, one for xmit and one for receive, but I found I needed a step attenuator to keep from saturating the receiving HT. I was really proud of myself cause I could tune for the peak and the null by using this method. It worked, but later when I had access to the proper equipment, I checked the duplexer and found I missed the proper settings by 10 Db on one side and 15 on the other. I don't think there is anyway you'll be able to tune it by ear. Try and find someone with the proper gear, you'll be much happier in the end. Gary - K7NEY Joe wrote: Hopefully, you have only tried to tune on of the cans. If you still have a can that is tuned to the original frequency they were working (???) on, try to follow the procedure on repeater builders carefully. If you get that one working, you can try to set the rods to the same dimensions as the good one a try to tune the other ones. It is possible to get a duplexer working satisfactorily (but probably not optimally) without the proper test equipment (tracking generator, etc) but takes a lot of patience and time. I did it many years ago to a set of homebrew 220Mhz cans with an HT and an RF detector on an Oscilloscope. After several nights of tuning and graphing results I got them to work very well. If you start with a working set of cans, moving them to a new frequency is easier. It sounds like you need to hook up with someone that has a service monitor or a network analyzer. Where are you located? Maybe someone can give you a hand. 73, Joe, K1ike
Re: [Repeater-Builder] wp-639 rexolite
I have in face tuned a WP-639 and would guess for that freq swing from 146.97 to 146.88 it will be very little movement of the rod assuming the pass tuning is correct. Remember, the rexolite rod is tuning the notch and that notch is relative to the pass setting of the invar rod. It is extremely sharp and has to be moved only very slightly to find the deepest part of the notch. Tune your generator (HT) to the notch frequency (.28) and feed it through the hi-pass section of the duplexer and tune for the null. Be careful that you don't mistakenly tune the low-pass section of the duplexer to pass the high frequency because sometimes you can find a null but not the right one. I would tune it for you for nothing but I have no Idea where you are located and I'm sure there are others who would also if you would give a location so someone could respond. Gary - K7NEY hbbcara wrote: Hi again, In my first post I miswrote a thing or two and much confusion as to my question ensued. Hopefully I've written this more clearly. Thank you to all who responded to my earlier question and my apologies for wasting your time by having you answer the wrong question. I have a wp-639. I'm its at least third owner and don't know its previous history. It's got a factory sticker marked 146.97 / 37. I don't know anyone who currently has the correct equipment locally and I don't have the budget to take it to a radio shop so I've used alternate methods of tuning similar to mentioned on the repeater builder website. I've gotten it tuned to work OK with my repeater on 146.88 / 28 but I'm guessing it could be better. In tuning the pass adjustments, there was a definite sweet spot. Go a quarter or a third of a turn off of that and there was a definite difference. But I didn't find that sweet spot in tuning the reject and I wonder how wide of an adjustment it usually is. What I mean is, for example the pass tuning went from not very good to good to not as good within about one turn of the knob. In tuning the reject, should I be looking for that pattern while moving the rexolite over an inch of travel, a half-inch, two inches or ? So my question is not how to tune it but as I tune it, how much should I expect to have to move the rexolite rods to notice the not good – good – not good pattern? Or will it even be there? I suppose the question is only to those who have tuned a wp-639 for a standard 600kc split. Someone who hasn't tuned a `639 will be basing their answer on a comparison to something they have tuned, which may not be all that comparable. For the sake of brevity I won't post the method I used to tune it unless someone wants to know it. Again, thanks to those who answered earlier and thanks in advance any who answer this. rj 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: mailto:repeater-builder-dig...@yahoogroups.com mailto:repeater-builder-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: repeater-builder-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Re: DC Ground Lightning Protection / Concrete Electrode
Actually galvanized and copper plated ground rods should not be mixed in any ground system. Electrolysis will deplete the plating. All ground rods in any ground system are electrically connected to one another. 73 Gary k4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Glenn Little WB4UIV Sent: Tuesday, June 30, 2009 7:53 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: DC Ground Lightning Protection / Concrete Electrode Another way to pass a ground cable through concrete is via a PVC pipe. The last thing that you want to do is run a ground cable that can carry lightning fault current through concrete without isolating the cable from the concrete. The fault current will rapidly heat the ground cable, causing it to expand, at the same time vaporizing the water trapped in the concrete. The result is a violent steam explosion. The results could be the total fragmentation of the concrete. MIL HDBK 419 is available for download. This is a military manual that addresses grounding. Another very respected guide is Motorola R-56. Galvanized ground rods should only be used at the guy anchor points. Copper plated ground rods should be used around the tower base and the building with all bonded together by exothermic welds 18 inches below grade. Ground rods are to be placed no closer than twice the length of the rod. Any closer and you are wasting your funds. YMMV. 73 Glenn WB4UIV At 10:07 AM 6/30/2009, you wrote: I'm going to disagree with the following posting: If the tower is bolted to galvanized pipe that is embedded in concrete of which a significant amount is in contact with soil, you have a concrete-encased grounding electrode which is hard to improve upon. It is not likely that a ground rod would be worthwhile, since damp concrete (concrete in intimate contact with soil at grade level) is a fairly good conductor, and such a footing or foundation has hundreds of times the surface area of a ground rod. I have read Ericsson specs for cellular tower installation in that disagrees with the previous statement. Standard concrete without conductive enhancing materials can crack, pop or crumble if subjected to a direct lightning strike if ground rods are not properly installed. The water contained within the concrete will vaporize instantly causing the concrete to fail. There are types of conductive concrete mixes or additives that can be used, but the most common practice is to use a ground rod from each leg with a copper wire bonded to each tower leg. Our mfg building at work is made from steel I-Beams into concrete. I have noticed each I-Beam has its own ground connection. The strap is bolted to the beam about 1 above the concrete, then disappears into the concrete, and suspect there is a ground rod going into the soil beneath the concrete piling, but thats just a theory, as I dident see it before the mud was poured. Ed N3SDO
RE: [Repeater-Builder] DC Ground Lightning Protection on antenna????
Some lightning facts: There is no amount of grounding that will help protect an antenna from lightning damage. Grounding will not help an antenna or tower from being struck by lightning. However if a lightning rod is placed above the antenna or a wire sloping down from above and around the antenna it will intercept a lightning strike and prevent the antenna from being hit. It would be important to have the lightning rod/wire well bonded to the tower and the tower well grounded. A well grounded tower and antenna bonded well to the tower will help prevent damage to other equipment tied to the antenna. Also feedlines should be well bonded to the tower at top and bottom. Ground rod surface area is much less important than length. Extra surface area contributes little to rod effectiveness. Too long of a ground rod and the extra length becomes ineffective due to the high inductance of the long length. Several ground rods spaced approximately the sum of the length of two adjacent rods is most effective. A good lightning ground consist of a low impedance, low resistance and high capacitance coupling to earth. Lightning is composed of very low (DC) and high frequencies (peak at around 1 MHz). If many ground rods are used in a star configuration, it is not necessary to use large wire connecting all the rods as the lightning energy will be divided between all paths so less current flows on any individual wire. If ground rods are placed in a star configuration it does no good to add rings of wire connecting the rods together. The lightning energy travels in a straight line out away from the tower on each radial and each radial carries equal current. So there is no difference of potential between rods or radials. Copper strap for ground connections will reduce the inductance thus lowering the impedance of the path. A separate heavy copper wire or strap running down a tower tied to the antenna to ground is a waste of copper. The tower itself is a much lower inductance path than what a separate ground wire provides. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Eric Lemmon Sent: Monday, June 29, 2009 7:42 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] DC Ground Lightning Protection on antenna If the tower is bolted to galvanized pipe that is embedded in concrete of which a significant amount is in contact with soil, you have a concrete-encased grounding electrode which is hard to improve upon. It is not likely that a ground rod would be worthwhile, since damp concrete (concrete in intimate contact with soil at grade level) is a fairly good conductor, and such a footing or foundation has hundreds of times the surface area of a ground rod. Just be certain that your station equipment is solidly bonded to the tower and to the electrical service neutral with a #6 AWG or larger copper conductor. Specific guidance for the grounding and bonding of radio and television antennas, including Amateur Radio systems, is found in Article 810 of NFPA 70, the National Electrical Code. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of agrimm0034 Sent: Sunday, June 28, 2009 9:34 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DC Ground Lightning Protection on antenna I bought a nice looking RFS Celwave antenna to use on 462.600 Specs are DC ground for lightning protection but is there something I need to do to make sure it is protected? It sits on 3 legged tower 40 ft up and the tower is mounted on the side of a structure. It sets on 3 pieces of galvanized pipe that are set in concrete. Overall the tower is grounded just not as good as what I could make it be. If I ran a grounding rod into the ground and ran #8 or heavier wire to the tower would I just be wasting my time to protect the antenna or what should I do to make sure everything is protected ok. Thanks Yahoo! Groups Links
RE: [Repeater-Builder] Re: Desense on High Power Linear Repeater?
Receiver gain does not work the same as transmitter power increase. A 10 db increase in transmitter power is not the equivalent of adding a 10 db preamp on the receiver. It would be if your receiver was very noisy (internally)(very poor receiver) to start with and the 10 db preamp overcame the receiver noise by that amount. But that rarely is the case. With a good receiver to start with you may gain only a couple of db realization on the receiver when adding 10 db or more gain ahead of it. You may not realize any increase in signal recovery if there is a high noise level at the site. Also for every db of gain that you add in front of the receiver you decrease the intermod performance of the receiver by the same amount. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of Kris Kirby Sent: Wednesday, May 20, 2009 9:03 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Desense on High Power Linear Repeater? On Thu, 21 May 2009, atms169 wrote: Yes, 80 dB on the duplexers, 100 watts in, that's 10 dB and the preamp 18 dB, so I'm losing 8 dB ?? Assuming you're not experiencing front-end overload because of your pre-amp. The sensitivity I believe is 0.4 uV Dstar system. I live in Texas where it's flat. I'm adjusting my station to compensate for the height value. More power good receive. There is a 1000 foot commercial tower here which would have been perfect, but they want too much to let me use it. Yeah, they tend to charge quite a bit to get to the top of a 1kft tower. I had thought of adding two more cans and purchasing a new phasing harness but, someone told me to stop and just add more filters. So I'm not sure which direction to go. I would like to push more power if possible. Transmit power does not equal recieve capability. You have to think bi-directionally. If you have a 6dBd antenna, and a mobile has a 3dBd antenna (unlikely these days), then transmitting 5W is equivalent to the mobile transmitting 10W. However, reciever sensitivity plays an important part as well. If you can't hear a station who is running 50W into a 3dBd antenna, he likely is not in a position to hear your repeater at 25W into a 6dBd antenna. Again, take out the pre-amp, insert a silver-plated teflon barrell. -- Kris Kirby, KE4AHR Disinformation Analyst Yahoo! Groups Links
RE: [Repeater-Builder] Re: Isolator Loss
Do you have a low pass filter after the isolator? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- buil...@yahoogroups.com] On Behalf Of offtrack Sent: Saturday, May 16, 2009 11:19 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Isolator Loss Eric Thanks for the confirmation on this. Its an older one that was tuned for me its a T-2200 that was replaced by the T-1530 I think, if I read correctly at the telwave site. I notice that the TKR 750 is running fine with no intermod issues ect. I was not sure about adding that meter in line and only did a quick check. Thanks for the warning on that one. The Diamond is so far working ok. I soldered all the parts in the antenna and sealed up all the possible leak points with a compound call through the roof This stuff stays semi flexible and is clear. Its located at my home and has been in service for about 2 years for my Simplex Echolink node I replaced with the repeater. Works pretty good, but that said I would never put it on a remote site as your correct not at all heavy duty. the radome is egg shell thin, I worry about it at the house as I am on a hill and get hit with some good winds/icing. So the Isolator in line helps ease my mind a bit. Thanks KB7DZR Scott --- In Repeater-Builder@yahoogroups.com, Eric Lemmon wb6...@... wrote: Scott, I must assume that you purchased a Telewave T-1530 Isolator, and its specified insertion loss is 0.4 dB. The readings you took indicate that the isolator is working properly. However, it is not a good idea to insert a meter between the isolator and the dummy load. The correct operation of the isolator depends upon a stable 50 ohm impedance at the dummy load port. I think you made some good choices for the duplexer, feedline, and isolator. The Diamond F22 is perhaps not the most rugged antenna for 2m repeater use, but YMMV. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of offtrack Sent: Friday, May 15, 2009 7:27 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Isolator Loss Hi all, Thanks for the group it has helped me out a bunch. My system here is a Kenwood TRK K2 and Telewave TPRD-1556 6 can set. Feed line is Heliax LDF4-50A about 70 feet and the antenna is a Diamond F22 that has been worked over and sealed up better. The system is new and today I added a Telewave Isolator to the PA output before the duplexer TX input. With my meter I got about 28 watts out of antenna side of the duplexer set when connected to my antenna with out the isolator. With the Isolator I am getting about 26 watts out now. This seems good to me but I am new to an Isolator. Putting the meter between the isolator and the dummy load it is showing around 1.6 watts going to the dummy load. Just want to see if this is ok for this? KB7DZR Scott Yahoo! Groups Links
[Repeater-Builder] FS- Cable Entry Parts
Spring cleaning and found some new/old stock Microflect (Valmont) cable entry boots and inserts. Have the following available; 2 each B1346B 4 entry boots, one with a single ½ hole insert and one with a dual hole (3/4 1) insert 1 each B1346 bag of five (5) single hole split inserts, ½, with clamps 1 each B1374 bag of five (5) dual hole split inserts, 1 3/4, with clamps I think these sold for around $22/ per bag or boot but Ill offer all for $75 shipped anywhere in the continental U.S. Reply to me direct if you have interest in these entry boots inserts. Thanks, Gary R.
Re: [Repeater-Builder] Re: MASTR II PTT
Is this the serial port or the parallel port on the computer that you are using? The serial port I always thought met RS-232 standards which swung from positive to negative. I used to use a RS232 to TTL logic converter back in the good old days to convert the signals but it was a commercial computer, not a PC. Measure the voltage out of the computer and see what you really have. A half volt swing is not enough. Gary - K7NEY Chuck Kelsey wrote: Sounds like the transistor isn't biased on all the way. Could be the series resistor on the transistor base is too high a resistance value or the transistor choice was bad. A 2N3904 or 2N should work OK. If you really want a hard low, use a power mosfet instead of the transistor - like a 2N7000 or a VN10LP. In that case, the gate would correspond to the base connection, the Source goes to ground, and the Drain is your connection to the PTT on the radio. Chuck WB2EDV - Original Message - *From:* Vernon Densler mailto:m...@highwayusa.com *To:* Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com *Sent:* Saturday, April 18, 2009 6:05 PM *Subject:* RE: [Repeater-Builder] Re: MASTR II PTT With the simple echolink interace which has a NPN transistor doing the switching the voltage across the PTT line and ground is 7v when the com port is not active and 6.5v when it’s active. So I am only getting a ½ volt drop instead of a total short to ground. Is it because the transistor can’t pull it down far enough? Will a transistor with a higher power dissipation help? Thanks, Vern
Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone?
- Original Message - From: wd8chl To: Repeater-Builder@yahoogroups.com Sent: Tuesday, April 07, 2009 10:12 AM Subject: Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone? And M/A-Com is suing the state because they DID meet the original specs/requirements, and the state is just trying to back out of spending the money. Crooked gov't? naaahhh... must be Illinois...
Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone?
yes, remember the claims of 'extended dynamic range' ?? now, producers and 'artists' want every bit to be a '1' look at a current 'hit' with Adobe Audition it has all the 'dynamic range' of a concrete block Gary - Original Message - From: Paul Plack To: Repeater-Builder@yahoogroups.com Sent: Monday, April 06, 2009 1:09 PM Subject: Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone? Somehow, at some point, possibly about the time the compact disc was introduced, the world started defining audio quality solely as signal-to-noise ratio. Anyone with a new mobile device who mocks old analog bag phones has forgotten how great they sounded. 73, Paul, AE4KR
Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone?
not to worry it's 'DIGITAL' and that cures all ills. G - Original Message - From: AJ To: Repeater-Builder@yahoogroups.com Sent: Monday, April 06, 2009 1:23 PM Subject: Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone? It's amazing when talking to the techs deploying our regional 700 MHz P25 Mother /\/\ system about the requirements for SNR, they had absolutely no understanding of the concept of C/NR and how the existing analog UHF infrastructure already suffered from poor performance - simply replicating the exact same sites with 700 MHz digital equipment was simply engineering a doomed system. Too many times it seems the existing underlying issues of a system are overlooked or forgotten when deploying a new system directly on top of it. Oh well - my tax dollars at work... Again... On Mon, Apr 6, 2009 at 12:17 PM, Gary Glaenzer glaen...@verizon.net wrote: yes, remember the claims of 'extended dynamic range' ?? now, producers and 'artists' want every bit to be a '1' look at a current 'hit' with Adobe Audition it has all the 'dynamic range' of a concrete block Gary - Original Message - From: Paul Plack To: Repeater-Builder@yahoogroups.com Sent: Monday, April 06, 2009 1:09 PM Subject: Re: [Repeater-Builder] (OT) APCO P25 horror stories anyone? Somehow, at some point, possibly about the time the compact disc was introduced, the world started defining audio quality solely as signal-to-noise ratio. Anyone with a new mobile device who mocks old analog bag phones has forgotten how great they sounded. 73, Paul, AE4KR
Re: [Repeater-Builder] supply
the heat sink resembles the M-70 supplies, but they didn't have that many capacitors - Original Message - From: Bill Hudson To: Repeater-Builder@yahoogroups.com Sent: Thursday, March 26, 2009 6:17 PM Subject: RE: [Repeater-Builder] supply Find the TPN- Number on it. Then Google it. Looks like Mocom 70 era of Motorola Supplies Bill -- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Merrill Sent: Thursday, March 26, 2009 4:06 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] supply can anyone identify this supply thanks in advance Merrill KG4IDD -- Checked by AVG - www.avg.com Version: 8.0.238 / Virus Database: 270.11.30/2025 - Release Date: 03/26/09 20:05:00
