Re: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
In Texas the JCAH (Joint Commission on Accreditation of Hospitals) guidelines forbids installation and operation of radio transmitting equipment in hospital elevator equipment rooms. Both Scott and White and Kings Daughters Hospitals had us re-locate all of their radio equipment in the early 90s.. Coaxial cables still run through the elevator rooms, but there is no radio equipment installed therin. As earlier stated graphite from the motor brushes along with noise from relay contactors and now SCR/Triac control is not nice to say nothing of the ambient noise in the rooms - had to wear headphones to hear a receiver, make such installations unpleasant at best. I believe the reasoning was RF emissions possibly affecting elevator controls. Steve NU5D Nate Duehr wrote: On Oct 31, 2007, at 10:29 PM, Eric Lemmon wrote: to go. If I remember correctly, the issue was resolved by erecting a fireproof (cinder block) wall to separate the radio equipment from the elevator machine room, in essence creating a new room with a separate
Re: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
I remember one such room back in the mid to late 1970s; actually it was almost a floor in itself, as opposed to a room. Four huge Westinghouse traction motors, each with its own rotary converter, handled 11 floors. Racks with hundreds of microswitches and a moving panel followed the cab's progress and controlled the movement. A relay wall continuously clacked and sparked as buttons were pressed. We always wanted to figure out which relay to kick closed as we were leaving, to call one cab to the top floor so it would meet us there. There were several other pieces of radio equipment in the same area, including some government stuff, although theirs was located in a corner by the stairway and nowhere near the actual elevator stuff. Other than the constant clicking and whir of the MG sets, the noise wasn't that bad. I have more annoying noise from the fans in a 20kw FM transmitter at my UHF repeater site than was present in that old elevator room. Hearing protection? What's that? I doubt that the RF would have had any effect on the 120/240V DC relays used by the old Westinghouse system, but I can see how today's solid-state logic could be bothered by enough nearby RF. Maybe the NEC regs changed in the last 30 years. I think all the radio stuff eventually got moved to another building. Bob M. == --- Steve S. Bosshard (NU5D) [EMAIL PROTECTED] wrote: In Texas the JCAH (Joint Commission on Accreditation of Hospitals) guidelines forbids installation and operation of radio transmitting equipment in hospital elevator equipment rooms. Both Scott and White and Kings Daughters Hospitals had us re-locate all of their radio equipment in the early 90s.. Coaxial cables still run through the elevator rooms, but there is no radio equipment installed therin. As earlier stated graphite from the motor brushes along with noise from relay contactors and now SCR/Triac control is not nice to say nothing of the ambient noise in the rooms - had to wear headphones to hear a receiver, make such installations unpleasant at best. I believe the reasoning was RF emissions possibly affecting elevator controls. Steve NU5D __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [Repeater-Builder] Heliax
Any suggestions on what to use for a jumper between the Heliax and the antenna for the last few feet to provide flexability and make it easier to get the cable into the antenna mount? Thanks, Vern
Re: [Repeater-Builder] Heliax
[EMAIL PROTECTED] wrote: Any suggestions on what to use for a jumper between the Heliax and the antenna for the last few feet to provide flexability and make it easier to get the cable into the antenna mount? RG-214 Dex
Re: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
Code is one thing. At the end of the code it states Or as local authority dictates Which translates to what ever the local inspector (aka, self proclaimed god) believes to be the correct interpretation of the code. A few years ago at the Ford World Head Quarters building in Dearborn Michigan, The Glass House, an older building, there were multiple hard lines going through the elevator equipment room for years. No equipment in the room, just passing through. The inspector came in and said move them out. For one reason or another that got delayed. He came back, said Remove them immediately or I will be back with an ax. They got moved immediately So moral of the story, you run the risk of liability. So just don't do it. I know we all want the shortest run but those are the rules. Run it outside the room to another area or you may pay. Heck, it might be you in the elevator leaving when you test the repeater on the way down, one last time and you drop like lead 39 floors to go SPLAT. Now that would be ironic... 73 Shanon
Re: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
Hmmm...Sounds like we need to get the elevator buyers to make the bid specs include a VHF radio in each elevator car! 73 - Paul AE4KR - Original Message - From: Eric Lemmon To: Repeater-Builder@yahoogroups.com Sent: Wednesday, October 31, 2007 7:52 PM Subject: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways Actually, it is addressed in NFPA 70- the National Electrical Code- which is ratified by each State's legislature as law in that State. I quote NFPA 70-2005 Article 620.37, Wiring in Hoistways, Machine Rooms, Control Rooms, Machinery Spaces, and Control Spaces in its entirety: (A) Uses Permitted. Only such electric wiring, raceways, and cables used directly in connection with the elevator or dumbwaiter, including wiring for signals, for communication with the car, for lighting, heating, air conditioning, and ventilating the elevator car, for fire detecting systems, for pit sump pumps, and for heating, lighting, and ventilating the hoistway, shall be permitted inside the hoistway, machine rooms, control rooms, machinery spaces, and control spaces. If it wasn't required by the elevator manufacturer, it can't be installed in the hoistway or the machine room. Period. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n3dab Sent: Wednesday, October 31, 2007 6:54 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: KENWOOD TKR 750 Installation and problems-HELP!! I believe it is called The National Elevator Code which supplements the N.E.C. and it doesn't permit anything other than elevator equipment,wiring and controls in either ther shaft or equipment rooms. N3DAB --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Nate Duehr [EMAIL PROTECTED] wrote: On Oct 30, 2007, at 3:09 AM, skipp025 wrote: ... which is a big Non-Code no-no. If anything ever happens in those buildings and it's traced back toward pretty much any non- code installed wire or equipment within the elevator shaft... you will need multi million dollar liability insurance. It happened to at least one very large Company I know about... now long out of business. s. What's non-code or dangerous about it? Last I looked, there's very little in the NEC about RF cabling. It's considered low-voltage and thus, almost unimportant in most States. Of course, the nannies keep passing laws against just about anything, so maybe I missed it. Genuinely curious (how stupid are our codes now?), -- Nate Duehr, WY0X [EMAIL PROTECTED]
[Repeater-Builder] Re: Calculating required T/R isolation
Guys, thanks for the suggestions. The duplexer manufacturer websites have scant info. TX-RX Systems has two graphs, one for VHF high band, one for UHF, but no info on the assumptions behind the math. I'm skeptical about the usefulness of receiver adjacent-channel rejection specs, for two reasons: (1) They include IF filtering, and desense happens due to compression in mixer stages ahead of the IF, and (2) some filters have poorer rejection out a couple hundred kHz than they do on the adjacent channels. I think what I'd need for a generic formula would be a way to account for the dynamic range of the receiver front end, which is often spec'd as the range limited by 1 dB compression in the first mixer, and I'd need accurate sideband noise numbers for the transmitter. I don't know what receiver or transmitter I'd use at this point. My former repeater was a converted Mastr II mobile on UHF, with a TX-RX Systems 4-can, and appeared to have plenty of reserve at -96+ dB on each side, 5 MHz spacing, and dialed back to 18 watts out (just above where it started getting dirty at QRP.) What I'm working on now is an antenna designed with minimum tower coupling as its first priority, preserving the deep null which naturally occurs between vertical colinear arrays sharing a common vertical axis. I've been bugged for decades by that ARRL graph showing dB isolation at given vertical separations. Like the TX-RX website graphs, there's no explanation of how it was derived. It assumes half-wave dipoles for both antennas, but indicates no correction factor is required for gain antennas, and that makes no sense. Now that we have software which can accurately model antennas on towers, I'm going to actually model my antenna idea on a virtual tower, and see what happens. The goal is to potentially allow 6M or even 10M single-site repeaters using separate antennas for transmit and receive. (I know, I know...the holy grail.) It's going to be lots of work to model and test it, so I'm trying to do calculations applicable to a number of end-user configurations, not just one specific TX / RX set I might personally use. I'd love to set up a spreadsheet that accounted for all the necessary factors, and contribute it to the web site. If I actually build the repeater itself, I have two 100-watt-class Johnson mobiles on low band / low split, retired from service in the broadcast RPU band. (They're crystalled and tuned for 26-point-something, where radio stations did linking for remote broadcasts before CB-ers discovered VFOs.) They're nice, clean old rockbound rigs. I also have some monster surplus heatsinks, a clean Astron RS35RM, and I still have the 7K. I may yet talk myself into building another repeater. For all the hassles, it sure was educational and fun! 73, Paul AE4KR - Original Message - From: Nate Duehr To: Repeater-Builder@yahoogroups.com Sent: Wednesday, October 31, 2007 4:22 PM Subject: Re: [Repeater-Builder] Calculating required T/R isolation Paul Plack wrote: Guys, sorry for this repeat - my first attempt at a post to the list went out with an off-topic subject line related to Kenwood repeaters. Can anyone direct me to a good tutorial on how to calculate required isolation in a duplexer or separate-antenna setup? I can convert receiver sensitivity in uV and transmitter power in watts to dBm, and insert things like transmitter sideband noise specs, but I keep coming up with numbers like 150 dB to avoid desense. Since my last UHF repeater worked great with 96 dB measured isolation thru the duplexer, I know I'm missing a step somewhere. Thanks! - 73, Paul AE4KR Did you see K5BP Bernie's reply under the original topic? He had it right -- you likely forgot to subtract out your particular receiver's off-channel selectivity numbers. How much does the receiver you're planning to use reject off-frequency signals by design? Subtract that from your duplexer numbers. You'll also probably want to factor in how a receive pre-amp and possibly additional receive-side bandpass filtering figure into the equation if you're using a highly selective/non-sensitive receiver if and if you're going for maximum receive performance. Nate WY0X
[Repeater-Builder] Ledex control Model 2204
Anyone have a manual for the DTMF controller? Thanks, Jim
[Repeater-Builder] Re: Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
Eric Lemmon [EMAIL PROTECTED] wrote: I won't presume to know what prompts some people to ignore the law and/or common sense in these cases. Simple, pressure from the gobal economy and what I term the Wal Mart effect. s.
RE: [Repeater-Builder] Re: Calculating required T/R isolation
There is no magic formula. The curves given by the duplexer manufacturers are typical for radios like Motorola and GE. Duplexer isolation requirements have little if anything to do with adjacent channel receiver selectivity. That number only tells you how strong the neighboring frequency can be and not affect the one you want to hear. You are correct that receiver desense happens in the front end of the receiver and not in the IF stage. Receiver desense is a function of how much overload the first mixer can handle. In off frequency operation as in a duplex situation it is affected by the mixer capability itself, front end filter rejection capability and the preamp if one is used. Broadband noise is a function of how clean the transmitter is. Both of these specs are provided by the radio manufacturers of better radios. They will give that info at certain frequency separations. You can measure how much the receiver is affected by watching the limiter current in the receiver. Inject a low level signal which will produce a small amount of limiter current. If the current goes down when the transmitter is turned on it is the transmitter carrier causing desense in the front end. If the limiter current increases it is broad band noise causing the problem. Of course you could have both things going on at the same time. Each has to be sorted out separately by adding filters to either the transmitter or receiver. I see lots of guys worrying about turning down the transmitter power on a repeater to avoid desense. That should make little if any difference if things are set up right. Going from 100 watts to 25 watts is only 6 db of difference. Rarely are you that close with duplexer rejection capabilities. Transmitter noise may change when drive is reduced or it may not. Depending on how the power is controlled. Also many people think that the more duplexer isolation you have the better. In fact any more than enough is a waste as it does nothing for you but drain your wallet. The charts that show antenna isolation with vertical separation are for antennas exactly in line with each other. Substituting a gain antenna for a dipole usually won't degrade isolation. A gain antenna will have a deeper null in the vertical direction in most cases. Isolation figures can vary with types of installation from stray coupling. Low band is a problem as it takes more separation to get the same isolation as vhf gives you. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Paul Plack Sent: Wednesday, October 31, 2007 10:31 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Calculating required T/R isolation Guys, thanks for the suggestions. The duplexer manufacturer websites have scant info. TX-RX Systems has two graphs, one for VHF high band, one for UHF, but no info on the assumptions behind the math. I'm skeptical about the usefulness of receiver adjacent-channel rejection specs, for two reasons: (1) They include IF filtering, and desense happens due to compression in mixer stages ahead of the IF, and (2) some filters have poorer rejection out a couple hundred kHz than they do on the adjacent channels. I think what I'd need for a generic formula would be a way to account for the dynamic range of the receiver front end, which is often spec'd as the range limited by 1 dB compression in the first mixer, and I'd need accurate sideband noise numbers for the transmitter. I don't know what receiver or transmitter I'd use at this point. My former repeater was a converted Mastr II mobile on UHF, with a TX-RX Systems 4-can, and appeared to have plenty of reserve at -96+ dB on each side, 5 MHz spacing, and dialed back to 18 watts out (just above where it started getting dirty at QRP.) What I'm working on now is an antenna designed with minimum tower coupling as its first priority, preserving the deep null which naturally occurs between vertical colinear arrays sharing a common vertical axis. I've been bugged for decades by that ARRL graph showing dB isolation at given vertical separations. Like the TX-RX website graphs, there's no explanation of how it was derived. It assumes half-wave dipoles for both antennas, but indicates no correction factor is required for gain antennas, and that makes no sense. Now that we have software which can accurately model antennas on towers, I'm going to actually model my antenna idea on a virtual tower, and see what happens. The goal is to potentially allow 6M or even 10M single-site repeaters using separate antennas for transmit and receive. (I know, I know...the holy grail.) It's going to be lots of work to model and test it, so I'm trying to do calculations applicable to a number of end-user configurations, not just one specific TX / RX set I might personally use. I'd love to set up a spreadsheet that accounted for all the necessary factors, and
[Repeater-Builder] pc board duplexer article
Anyone got a scanned or photocopy of the famous PC-Board Duplexer QST Magazine Article from years past... they could/would share? This is the duplexer kit made sold by Circuit Board Specialists in Pueble CO. thanks in advance for your replies s.
RE: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
George, To my knowledge there was no grandfather period awarded. My 900 repeater is located in the penthouse of a 19-floor geriatrics housing building in Joliet, and they made us move all transmitters out of the elevator equipment room about 2 years ago, including the Sheriff, Joliet PD and FD, and all amateur equipment. I can't explain why it hasn't been address at the location you are questioning, but if I were you. I'd bring it to the attention of the building's management - before you ALL get cited. Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of George Henry Interesting... I wonder if existing equipment was grandfathered here in Illinois, or if the building where one of our machines is located is ignoring it. When accessing the roof thru the elevator machine room recently to do some maintenance on our antennas, I spotted 2 repeaters belonging to the site owner; one each for the Sheriff (labeled backup), local PD, and local FD, as well as another unmarked VHF (judging from the size of the attached cans) repeater in another corner. There's also network, PBX, and telco punchdown blocks galore up there. And the door to the other elevator machine room nearby has a cellular system warning sign on it... George, KA3HSW / WQGJ413
[Repeater-Builder] Re: Motorola Micor Unified Chassis
Hi Don, The quick answer is no yes no. The long answer is, On the low band Compa-Station the output power control Board samples the VSWR on the output and folds back, the gain of the pre-driver in the power amplifier when the VSWR gets too high compared to the current draw of the final transistors. On a low bay and mobile. The antenna matching board is used to adjust the VSWR on the output and there is a directional coupler that you can attach a test set meter to. But there is no feedback to the power amplifier. The power amplifier has a thermocouple which is located on the heatsink, that is connected to a relay that shorts out a winding in the coupling transformer between the driver and a final transistors. Thus reducing the drive to the final transistors when the heatsink gets too hot. The VHF Compa-Station and mobile radios use the same circuitry. Which is a directional coupler on a power control Board that samples VSWR on the output port and folds back the gain of the pre-driver in the power amplifier when the VSWR compared to the current draw of the final transistors gets to high. UHF Compa station and mobile radios use the same system, but wired a little differently. They sample the return of loss on the isolation port of the circulator and compare it to the current draw of the final transistors of power amplifier. If the return loss on the isolation port of the circulator gets too high compared to the current draw of the finals. The power control Board, folds back the gain on the predriver of the power amplifier chain. Gregory AC6VJ --- In Repeater-Builder@yahoogroups.com, Don [EMAIL PROTECTED] wrote: On the Motorola Micor Unified Chassis type repeater can anyone please tell me if the Power Control Module is the same thing I would also find in a Micor Mobile Radio? Thanks Don KA9QJG
RE: [Repeater-Builder] Installation of Radio Equipment in Elevator Machine Rooms and Hoistways
Actually, it is addressed in NFPA 70- the National Electrical Code- which is ratified by each State's legislature as law in that State. I quote NFPA 70-2005 Article 620.37, Wiring in Hoistways, Machine Rooms, Control Rooms, Machinery Spaces, and Control Spaces in its entirety: (A) Uses Permitted. Only such electric wiring, raceways, and cables used directly in connection with the elevator or dumbwaiter, including wiring for signals, for communication with the car, for lighting, heating, air conditioning, and ventilating the elevator car, for fire detecting systems, for pit sump pumps, and for heating, lighting, and ventilating the hoistway, shall be permitted inside the hoistway, machine rooms, control rooms, machinery spaces, and control spaces. If it wasn't required by the elevator manufacturer, it can't be installed in the hoistway or the machine room. Period. Well...close. Fire alarm and control systems vary for elevators and occupancies a bit. While mentioned above, they may not be 'required by the elevator manufacturer' but rather required via code by the AHJ. In my experience, the elevator inspector is God. I've seen entire jobs grind to a halt for a failed elevator inspection. NO ONE messes with the elevator inspector in my experience. You need them to sign off for occupancy, and if you fail your test it might be 3 weeks before he will come back and try again. I've had to change a couple things to pass: 1. One application specified two Cat5e drops to every phone jack, one for voice and one for data. In the elevator room we put the data jack on a faceplate, then ran the phone wire in conduit to the controller for connection to the car cable. Since the data jack wasn't integral, we were forced to pull the data wire back out and cover the box. 2. One installation the electricians had run metal conduit on one wall of the elevator mechanical room to a GFCI receptacle outside of the room, on an exterior wall. Since it was not a circuit for that room, they had to pull it out and re-route it. 3. One fire alarm installation we had a row of boxes on the wall with modules in them, basically the box takes an RS-485 data signal and addresses a relay to do a function. Six boxes, six modules, one of them actually for something not directly connected to the elevator circuitry and we had to pull it out and re-route everything. I'd never even consider placing radio equipment in there first due to the obvious code violation, second due to the life safety liability. 73 N7HQR
[Repeater-Builder] Re: Calculating required T/R isolation
Gary, I appreciate the comments, and agree with all but one. If transmitter sideband noise, filter skirts and dynamic range can all be represented by numbers, then they should be able to be distilled down to a formula. A complicated one, to be sure, but nothing magic. Those isolation-vs-separation charts date back almost a half-century and were probably created with a combination of direct measurement and sliderules. Today we have Excel and NEC. With an accurate enough model, even stray coupling can be approximated. Or, at least I'm gonna try! Most repeater antennas are chosen for gain and pattern and off-the-shelf availability, with an eye toward maxmizing gain at the horizon within budgets of money and tower space. All the rules of thumb are based in those priorities. My thought is that on low band, gain is limited by available tower space, so I'll shift my priority into reducing tower coupling first, optimizing gain and pattern second. If I can get 110 dB of isolation, 2 dBd gain at the horizon, a reasonable radiation pattern that's well-matched between transmit and receive, and a design that's both reproduceable and mechanically practical, it's a step forward. I'm quickly concluding that I'll need to model the antennas first, test to see if the model is accurate, then look for radios to fit. I'll let you know how I make out! 73, Paul AE4KR - Original Message - There is no magic formula. The curves given by the duplexer manufacturers are typical for radios like Motorola and GE... ...Receiver desense is a function of how much overload the first mixer can handle. In off frequency operation as in a duplex situation it is affected by the mixer capability itself, front end filter rejection capability and the preamp if one is used... ...Broadband noise is a function of how clean the transmitter is... ...Both of these specs are provided by the radio manufacturers of better radios. They will give that info at certain frequency separations. The charts that show antenna isolation with vertical separation are for antennas exactly in line with each other. Substituting a gain antenna for a dipole usually won't degrade isolation. A gain antenna will have a deeper null in the vertical direction in most cases. Isolation figures can vary with types of installation from stray coupling. Low band is a problem as it takes more separation to get the same isolation as vhf gives you. 73 Gary K4FMX
Re: [Repeater-Builder] pc board duplexer article
According to the ARRL web site QST index search, it was April 1979, page 11. I don't have that one, but do have a copy of the 1972 6-can duplexer construction article. Somebody out there must have the QST CD-ROM that covers 1979, though George, KA3HSW / WQGJ413 -Original Message- From: skipp025 [EMAIL PROTECTED] Sent: Nov 1, 2007 12:35 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] pc board duplexer article Anyone got a scanned or photocopy of the famous PC-Board Duplexer QST Magazine Article from years past... they could/would share? This is the duplexer kit made sold by Circuit Board Specialists in Pueble CO. thanks in advance for your replies s.
[Repeater-Builder] Motorola antenna adapter part number needed
Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ
RE: [Repeater-Builder] Re: Calculating required T/R isolation
Hi Paul, I meant that it was not complicated to figure out. For example if the receiver noise floor (sensitivity) is -120 dbm then the transmitter noise power must be known at the receive frequency (as supplied from the manufacturer or measured) and an amount of attenuation added at the transmitter via cavity filters to bring that noise power down below the -120 dbm receiver noise floor. If the transmitter generated -40 dbm of noise power on the receive frequency then you would need 80 db of attenuation in the transmitter line to limit the noise seen at the receiver to -120 dbm. That's all there is to it on that side. On the receiver side you must know at what level the receiver begins to go into compression and cause desense at the transmit frequency. You get that from the receiver manufacturer or you measure it. You then add attenuation in the receive line to attenuate the power of the transmitter carrier to a level below that point. For example, 100 watts of transmitter power is +50 dbm. If the receiver can handle only -30 dbm at the transmit frequency before desense starts then you need 80 db of filtering of the carrier in the receive line to reduce the carrier to -30 dbm at the receiver front end. Not complicated, you just need to know what the transmitter and receiver capabilities are. As a note, if you are measuring transmitter noise power with a spectrum analyzer you will probably need to place a notch filter at the input of the spectrum analyzer to reduce the transmitter carrier or the spectrum analyzer will overload and give a false reading. A 100 watt carrier is +50 dbm. If you are trying to look at noise at the -40 dbm level that is a 90 db range. Many analyzers do not have that kind of dynamic range and will overload from the carrier level. A notch filter that knocks the carrier down say 30 db then allows the analyzer to operate in a 60 db range. Some analyzers may not even be happy with that level especially those in service monitors so you will need more than 30 db of notch filtering for the carrier. Be careful with close spacing like at vhf (600 KHz) so that you don't also attenuate the noise power at the frequency you are trying to measure. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Paul Plack Sent: Thursday, November 01, 2007 1:31 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Calculating required T/R isolation Gary, I appreciate the comments, and agree with all but one. If transmitter sideband noise, filter skirts and dynamic range can all be represented by numbers, then they should be able to be distilled down to a formula. A complicated one, to be sure, but nothing magic. Those isolation-vs-separation charts date back almost a half-century and were probably created with a combination of direct measurement and sliderules. Today we have Excel and NEC. With an accurate enough model, even stray coupling can be approximated. Or, at least I'm gonna try! Most repeater antennas are chosen for gain and pattern and off-the-shelf availability, with an eye toward maxmizing gain at the horizon within budgets of money and tower space. All the rules of thumb are based in those priorities. My thought is that on low band, gain is limited by available tower space, so I'll shift my priority into reducing tower coupling first, optimizing gain and pattern second. If I can get 110 dB of isolation, 2 dBd gain at the horizon, a reasonable radiation pattern that's well-matched between transmit and receive, and a design that's both reproduceable and mechanically practical, it's a step forward. I'm quickly concluding that I'll need to model the antennas first, test to see if the model is accurate, then look for radios to fit. I'll let you know how I make out! 73, Paul AE4KR - Original Message - There is no magic formula. The curves given by the duplexer manufacturers are typical for radios like Motorola and GE... ...Receiver desense is a function of how much overload the first mixer can handle. In off frequency operation as in a duplex situation it is affected by the mixer capability itself, front end filter rejection capability and the preamp if one is used... ...Broadband noise is a function of how clean the transmitter is... ...Both of these specs are provided by the radio manufacturers of better radios. They will give that info at certain frequency separations. The charts that show antenna isolation with vertical separation are for antennas exactly in line with each other. Substituting a gain antenna for a dipole usually won't degrade isolation. A gain antenna will have a deeper null in the vertical direction in most cases. Isolation figures can vary with types of installation from stray coupling. Low band is a problem as it takes more separation to get the same isolation as vhf gives you. 73 Gary K4FMX
Re: [Repeater-Builder] Motorola antenna adapter part number needed
Is this what you're looking for: http://www.scannerworld.com/content/product/model/ANT38 Bob M. == --- Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: [Repeater-Builder] Motorola antenna adapter part number needed
If it will help any, I bought one at Radio Shack a few years ago. Johnny Mike Morris WA6ILQ wrote: Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ Yahoo! Groups Links
[Repeater-Builder] Donation Request - Repeater Builder Website - Please read.
Hello all, Reference RBTIP MASTR II websites: http://www.repeater-builder.com/ http://www.mastr2.com/ Everyone knows I hate asking for financial support, but it's the only way I can afford to keep the Repeater Builder site up and running reliably. I have been ask why don't you consider a cheap hosting site, and the answer is simple, speed and reliability. The cheap servers are so overloaded with traffic and customer support is terrible. I have had so much trouble with free/cheap hosting it isn't funny, and no one likes to look at advertisements from sites like Yahoo or GeoCities. I know I pay a premium for my hosting, but they are fast and have excellent customer support. Repeater Builder Dot Com is now approaching 5 Gigs in size as Mike Morris WA6ILQ, Scott Zimmerman N3XCC, Bob Meister WA1MIK, and I have added a _bunch_ more to it (especially service manuals) over the last year. With your donation, I'll be able to serve the site for another year. Remember, we don't charge for downloads of manuals for the GE MASTR II, IFR Service Monitors, Astron Power Supplies, and many others! This is a 'one time a year' request for financial support, so, if the Repeater-Builder or Mastr II websites have been of benefit to you, would you please consider a donation to help keep them going? I'll accept and appreciate any donation amount. Donations via regular mail or PayPal are welcomed. (see below) I would like to thank my webmasters Mike Morris, Scott Zimmerman, and Bob Meister, and the numerous other authors/suppliers of the information, and my _Email List Moderators_ for their continued support over the years. Donations can be made to my Pay-Pal account at: [EMAIL PROTECTED] ( kuggie at kuggie dot com ) Or by snail mail at: Kevin K. Custer 1143 Coleman Station Road Friedens PA 15541 Please don't reply to this message on the list(s). Personal comments or questions are always welcomed. Thank you in advance, Kevin W3KKC [EMAIL PROTECTED] ( kuggie at kuggie dot com )
Re: [Repeater-Builder] pc board duplexer article
At 01:32 PM 11/01/07, you wrote: According to the ARRL web site QST index search, it was April 1979, page 11. I don't have that one, but do have a copy of the 1972 6-can duplexer construction article. Somebody out there must have the QST CD-ROM that covers 1979, though George, KA3HSW / WQGJ413 Repeater-Builder has permission from the ARRL to have PDFs from QST on the web site. If anybody would send me the PDF of the 1972 article or the 1979 article I'll put it up. I'd also like to get a PDF of the introductory article on regulated power supplies that used the Astron schematic as a walkthrough from the December 2005 issue. Mike WA6ILQ
Re: [Repeater-Builder] Motorola antenna adapter part number needed
On Thu, 1 Nov 2007, Mike Morris WA6ILQ wrote: Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Why not just make a short adapter cable with a male Motorola connector on it and a male BNC at the other end? Crimp-ons are easy to use. -- Kris Kirby, KE4AHR [EMAIL PROTECTED] But remember, with no superpowers comes no responsibility. --rly
RE: [Repeater-Builder] Motorola antenna adapter part number needed
last ones I got from radio shack. They may still have some if you can get the salesman to stop trying to sell you a cell phone long enough! Mike KA2NDW -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Mike Morris WA6ILQ Sent: Thursday, November 01, 2007 5:42 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Motorola antenna adapter part number needed Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ
Re: [Repeater-Builder] Motorola antenna adapter part number needed
EXACTLY !!! They are closed now, I'll call them tomorrow and get two into the mail... Thanks! Mike WA6ILQ At 03:08 PM 11/01/07, you wrote: Is this what you're looking for: http://www.scannerworld.com/content/product/model/ANT38 Bob M. == --- Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links
Re: [Repeater-Builder] Heliax
I have 65w out of the duplexer on 2m. A friend has a rg214 jumper for me so I think I will use it. On Thu, 01 Nov 2007 13:14:00 -0700 Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: At 07:01 AM 11/01/07, you wrote: Any suggestions on what to use for a jumper between the Heliax and the antenna for the last few feet to provide flexability and make it easier to get the cable into the antenna mount? Thanks, Vern What's the power level? At 100w or less I use RG-400. At higher levels I use RG-393 (but it's not as easy to find as RG214). Yes, the 393 is 5db per 100 feet at UHF but we're talking short jumpers. See http://www.repeater-builder.com/antenna/double-shielded-coax.html and http://www.tessco.com/products/displayProductInfo.do?sku=57757eventPage=1 or http://www.cambridge-tec.com/wire/rg393.htm
Re: [Repeater-Builder] Heliax
At 07:01 AM 11/01/07, you wrote: Any suggestions on what to use for a jumper between the Heliax and the antenna for the last few feet to provide flexability and make it easier to get the cable into the antenna mount? Thanks, Vern What's the power level? At 100w or less I use RG-400. At higher levels I use RG-393 (but it's not as easy to find as RG214). Yes, the 393 is 5db per 100 feet at UHF but we're talking short jumpers. See http://www.repeater-builder.com/antenna/double-shielded-coax.html and http://www.tessco.com/products/displayProductInfo.do?sku=57757eventPage=1 or http://www.cambridge-tec.com/wire/rg393.htm
RE: [Repeater-Builder] Motorola antenna adapter part number needed
Mike, Go to your neighborhood Radio Shack emporium and ask for a #278-208 UHF-to-Motorola-Type Scanner Adapter. It'll set you back $3.49- if it is in stock. It is a male Motorola antenna plug on one end, and a SO-239 jack on the other. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mike Morris WA6ILQ Sent: Thursday, November 01, 2007 2:42 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Motorola antenna adapter part number needed Years ago the standard scanner radio antenna connector was the so-called Motorola car radio connector. It was a metal cylinder maybe 1/4 in diameter with a protruding center pin. Does anybody know of a commercial source of a male Motorola connector to BNC female adapter? Alternatively an SO239 female? I'm trying to put a couple of older scanners back into service - one is going to a new ham, one is going to a friend's repeater as a NOAA weather channel receiver. Both need to have external antennas added to them. Yes, I could butcher the radio and install a BNC female, but I thought I'd see if I could buy a couple first. Mike WA6ILQ
RE: [Repeater-Builder] Re: Calculating required T/R isolation
Paul, General Electric published several Datafile Bulletins which will help you. Here's one: www.repeater-builder.com/ge/datafile-bulletin/df-10003-01.pdf Since you already have experience with Mastr II radios, you'll appreciate that the Duplex Operation Curves are available on the GE Master Index site. Although I have ComStudy and similar high-end software that seems to take everything into account for coverage calculations, I have learned to take its conclusions with some confidence- but I don't stake my reputation on it! There are just too many variables to draw meaningful conclusions when many assumptions are made. Moreover, the assumptions can skew your calculations enough to make them unreliable. In any case, your pursuit of accurate formulae will increase the body of knowledge on the subject, and I applaud your efforts. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Paul Plack Sent: Wednesday, October 31, 2007 8:31 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Calculating required T/R isolation Guys, thanks for the suggestions. The duplexer manufacturer websites have scant info. TX-RX Systems has two graphs, one for VHF high band, one for UHF, but no info on the assumptions behind the math. I'm skeptical about the usefulness of receiver adjacent-channel rejection specs, for two reasons: (1) They include IF filtering, and desense happens due to compression in mixer stages ahead of the IF, and (2) some filters have poorer rejection out a couple hundred kHz than they do on the adjacent channels. I think what I'd need for a generic formula would be a way to account for the dynamic range of the receiver front end, which is often spec'd as the range limited by 1 dB compression in the first mixer, and I'd need accurate sideband noise numbers for the transmitter. I don't know what receiver or transmitter I'd use at this point. My former repeater was a converted Mastr II mobile on UHF, with a TX-RX Systems 4-can, and appeared to have plenty of reserve at -96+ dB on each side, 5 MHz spacing, and dialed back to 18 watts out (just above where it started getting dirty at QRP.) What I'm working on now is an antenna designed with minimum tower coupling as its first priority, preserving the deep null which naturally occurs between vertical colinear arrays sharing a common vertical axis. I've been bugged for decades by that ARRL graph showing dB isolation at given vertical separations. Like the TX-RX website graphs, there's no explanation of how it was derived. It assumes half-wave dipoles for both antennas, but indicates no correction factor is required for gain antennas, and that makes no sense. Now that we have software which can accurately model antennas on towers, I'm going to actually model my antenna idea on a virtual tower, and see what happens. The goal is to potentially allow 6M or even 10M single-site repeaters using separate antennas for transmit and receive. (I know, I know...the holy grail.) It's going to be lots of work to model and test it, so I'm trying to do calculations applicable to a number of end-user configurations, not just one specific TX / RX set I might personally use. I'd love to set up a spreadsheet that accounted for all the necessary factors, and contribute it to the web site. If I actually build the repeater itself, I have two 100-watt-class Johnson mobiles on low band / low split, retired from service in the broadcast RPU band. (They're crystalled and tuned for 26-point-something, where radio stations did linking for remote broadcasts before CB-ers discovered VFOs.) They're nice, clean old rockbound rigs. I also have some monster surplus heatsinks, a clean Astron RS35RM, and I still have the 7K. I may yet talk myself into building another repeater. For all the hassles, it sure was educational and fun! 73, Paul AE4KR - Original Message - From: Nate Duehr mailto:[EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Wednesday, October 31, 2007 4:22 PM Subject: Re: [Repeater-Builder] Calculating required T/R isolation Paul Plack wrote: Guys, sorry for this repeat - my first attempt at a post to the list went out with an off-topic subject line related to Kenwood repeaters. Can anyone direct me to a good tutorial on how to calculate required isolation in a duplexer or separate-antenna setup? I can convert receiver sensitivity in uV and transmitter power in watts to dBm, and insert things like transmitter sideband noise specs, but I keep coming up with numbers like 150 dB to avoid desense. Since my last UHF repeater worked great with 96 dB measured isolation thru the duplexer, I know I'm missing a step somewhere.
Re: [Repeater-Builder] Ledex control Model 2204
Jim, Have you had the cover off of it? I think I had one of those. There was basic jumper programming for touch tones and connection info on the inside of the top cover. 73, Gerald Pelnar WD0FYF McPherson, Ks - Original Message - From: K7OET [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 01, 2007 12:25 AM Subject: [Repeater-Builder] Ledex control Model 2204 Anyone have a manual for the DTMF controller? Thanks, Jim Yahoo! Groups Links
Re: [Repeater-Builder] pc board duplexer article
I'll scan the Dec. 2005 article tomorrow and send you both. George - Original Message - From: Mike Morris WA6ILQ [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Thursday, November 01, 2007 4:24 PM Subject: Re: [Repeater-Builder] pc board duplexer article At 01:32 PM 11/01/07, you wrote: According to the ARRL web site QST index search, it was April 1979, page 11. I don't have that one, but do have a copy of the 1972 6-can duplexer construction article. Somebody out there must have the QST CD-ROM that covers 1979, though George, KA3HSW / WQGJ413 Repeater-Builder has permission from the ARRL to have PDFs from QST on the web site. If anybody would send me the PDF of the 1972 article or the 1979 article I'll put it up. I'd also like to get a PDF of the introductory article on regulated power supplies that used the Astron schematic as a walkthrough from the December 2005 issue. Mike WA6ILQ Yahoo! Groups Links
RE: [Repeater-Builder] pc board duplexer article
Dump a copy of the duplexer article this way if you would. I need something better than the 4-6 cans I currently have. _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of George Henry Sent: Thursday, November 01, 2007 11:11 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] pc board duplexer article I'll scan the Dec. 2005 article tomorrow and send you both. George - Original Message - From: Mike Morris WA6ILQ [EMAIL PROTECTED] mailto:wa6ilq%40arrl.net net To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Sent: Thursday, November 01, 2007 4:24 PM Subject: Re: [Repeater-Builder] pc board duplexer article At 01:32 PM 11/01/07, you wrote: According to the ARRL web site QST index search, it was April 1979, page 11. I don't have that one, but do have a copy of the 1972 6-can duplexer construction article. Somebody out there must have the QST CD-ROM that covers 1979, though George, KA3HSW / WQGJ413 Repeater-Builder has permission from the ARRL to have PDFs from QST on the web site. If anybody would send me the PDF of the 1972 article or the 1979 article I'll put it up. I'd also like to get a PDF of the introductory article on regulated power supplies that used the Astron schematic as a walkthrough from the December 2005 issue. Mike WA6ILQ Yahoo! Groups Links
[Repeater-Builder] UHF Radio recommendations ??
The major problem I was having is resolved. I've finally got a UHF backyard pair for my portable repeater :-) No more hassling with trying to pack 4 radios into 1mhz of VHF bandwidth :-) Since there isn't a way to look at receiver specs and figure how much isolation is really needed, here I am asking - what is my best bet for radios to build a UHF repeater? I'm currently looking at a Hamtronics receiver/exciter pair with separate PA, but I'm pretty much open to anything I can get at a reasonable price (300-400 for both RX and TX, PA extra if needed). The repeater controller I will be using has PL built in, so the radios don't need it. I would prefer 50 watts or better output, 100w max. Size is important. I've only got about 16 of depth to mount this in, though there is a way I can get bigger than that if absolutely necessary. If the equipment recommended has any front panel controls, it needs to be 16 or less front to back. If no controls, then I have a lot more freedom in mounting.
Re: [Repeater-Builder] UHF Radio recommendations ??
On Nov 1, 2007, at 10:16 PM, John Barrett wrote: Since there isn’t a way to look at receiver specs and figure how much isolation is really needed, here I am asking – what is my best bet for radios to build a UHF repeater? I’m currently looking at a Hamtronics receiver/exciter pair with separate PA, but I’m pretty much open to anything I can get at a reasonable price (300-400 for both RX and TX, PA extra if needed). The repeater controller I will be using has PL built in, so the radios don’t need it. I would prefer 50 watts or better output, 100w max. You might consider talking to the sponsors of this mailing list, of course... Repeater Builder, the company. Scott and Kevin make a fine repeater from both Micor and MASTR II mobiles that would easily fit in your space, probably. It'd probably be below your budgeted price for the radios, and would perform as good as anything modern on the market. You could also take a dip into the RB knowledge base online and do a conversion/re-tune yourself -- the RB the Company guys might even have parts they would sell you that are known tested/working -- saving you some hassles in going up the learning curve of what to look for from the likes of eBay, etc... -- Nate Duehr, WY0X [EMAIL PROTECTED] 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:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
