[Repeater-Builder] repeater equipment
hey this is dustin kd5ood im a ham and a oklahoma army mars member in comanche oklahoma i have been working on a repeater for mars and i was wondering if anybody hand any equpiment for sale or to donate thanks
Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Hi all! If a piece of coax is sitting at ground and you suddenly attach a battery (DC) across it, you're really talking about a step function change in voltage which carries a wide spectrum of high frequencies The 'change' propagates down the coax at near the speed of light as expected. True DC, on the other hand, means nothing is changing. Everything is constant forever. In this case speed of propagation is a moot point. Regarding the upper frequency rolloff its pretty easy to see how it comes about. Current flowing in a straight wire give rise to a magnetic field around it. Since it takes energy to create the field and whe the field collapses it returns the energy, we're talking about series inductance. Yes, the central conductor of a piece of coax exhibits a certain number of nH per inch. It also has parallel capacitance to the outer braid or cylinder in terms of pF per inch. As frequencies increase the series inductive impedance increases which tends to block the series flow. Simultaneously, as frequencies increase the parallel capacitive impedance decreases tending to shunt the flow to the shield. The combination of these two effects are what gives rise to the high frequency rolloff characteristics. Larger diameter coax has less capacitance per inch and so has less rolloff for a given frequency. There is one other effect that also causes rolloff at even higher frequencies, and that is increased dielectric loss. Hope this helps. - Original Message - From: Gary Schafer To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 01, 2007 6:58 PM Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers How do you know it is not 75 ohms at DC? How long do you think it will take for the DC signal to reach the other end of the coax if it is applied at one end? Will it be at the speed of light? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:02 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Jeff, The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. I would think you would agree one will not see RG59 being 75 Ohm at DC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 01:18:35 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. If what you say is true, can you tell me, using sound engineering and math, why you can carry DC on coax if it has a low-frequency cutoff? --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links -- No virus found in this incoming message. Checked by AVG. Version: 7.5.485 / Virus Database: 269.13.1/982 - Release Date: 8/31/2007 5:21 PM
Re: [Repeater-Builder] repeater equipment
Dustin, I don't have any equipment at the moment I can donate, sorry. One word of advice on the MARS repeater. Most often in the VHF range MARS uses 143/148 frequencies with 5+/- offsets for repeaters. We hams use 0.6 MHz offsets and we normally have to use large expensive duplexers, $800-1500 new/$400 used. However, with 5 MHz offset one can often use mobile duplexers commonly found in old mobile phones...you know the old large trunk mount phones with large handset up front. When you really had to know someone to get a mobile phone. So when considering your repeater needs might consider use of a mobile duplexer. These can be had for $20 used. You have to tune, but do pretty good job. They do limit power to about 50 watts. Just some info that might save you some money. However, don't skimp on the feedline and antenna. 73, ron, n9ee/r From: Dustin Stinson [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 10:51:59 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] repeater equipment hey this is dustin kd5ood im a ham and a oklahoma army mars member in comanche oklahoma i have been working on a repeater for mars and i was wondering if anybody hand any equpiment for sale or to donate thanks Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: [Repeater-Builder] Re: subaudibe tones..
Although I think most coordinating councils do a good job, they do here in Florida, I really do not want the council telling repeater builders what equipment to use. They come up with the most stupidest and crazy ideas every once in a while. The policies are decided in a board room, nice and air conditioned often with lots of certificates on the wall from 10 minute courses. As long as they follow tested coordinating procedures it makes it easy for them to decide good coordination. But when it comes to technical issues I don't trust them. 73, ron, n9ee/r From: George Henry [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 11:17:49 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: subaudibe tones.. - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 01, 2007 5:35 PM Subject: Re: [Repeater-Builder] Re: subaudibe tones.. [snip] You guys have control of the quality level of the equipment used when issuing coordinations? We have control of the technical operating parameters; see Part 97.3 (a)(22). CORRECTION: 97.3 (a)(22) says recommends, NOT establishes technical parameters...Deny a repeater owner coordination based solely on the equipment used to build the repeater, and you open yourselves up to a possible lawsuit. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Gary, Now I know you are kidding, hi. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 08:58:13 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers How do you know it is not 75 ohms at DC? How long do you think it will take for the DC signal to reach the other end of the coax if it is applied at one end? Will it be at the speed of light? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:02 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Jeff, The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. I would think you would agree one will not see RG59 being 75 Ohm at DC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 01:18:35 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. If what you say is true, can you tell me, using sound engineering and math, why you can carry DC on coax if it has a low-frequency cutoff? --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Gary, I don't know. Why don't you tell us. I don't know why gravity will pull me to the ground real fast if I jump off a bridge, but I have all the faith in the world it will. Einstin tried to explain it, but died before he got the results. Taking the word of good test equipment is a good engineering approach. Doing the math, I am sure I have here somewhere, and I am sure the defferential equations would take a while probably starting with Maxwell's, but as with gravity if you know it does what it does I use it. These discussions can at times go no where, hi. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 08:48:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ron, Maybe you could tell us why coax cable has a lower frequency limit? You claim that it does but have not explained why or how. Why does the impedance change significantly at lower frequencies? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:49 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, Yes the HP meter was spec'd to go below below 0.5 MHz, it went down to 100 kHz. I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. I know about low freq RF. Worked on a Navy program that used 18 kHz, a C130 aircraft with 30,000 ft of wire hung out the back as a platform to talk to surmerged submarines. Ran over 250 kW. It was called TACMO. Due to the weight the wings kept falling off...well they were continously inspected and replaced before they fell off, but the aircraft was deffinitly over loaded. Had generators on all 4 engines to get the power they needed. Now that was a repeater. However, AC power distribution is not trying to radiate power, but transfer it with widly varing loads. Totally different engineering. At low frequencies such as 1 kHz little radiation takes place. Far less at 60 Hz. The EMF returns to the radiator, wire, before the next cycle can force it out. This is a problem in some applications, but since most do not want radiation it is not. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/31 Fri PM 05:59:28 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Are you sure that the impedance meter you used was speced for operation below .5 MHz? Yes all capacitors have inductance. Lead length is particularly a problem. 15 KHz can be treated as RF or audio it all depends on what transducer you are using it to couple it with. Use a speaker and it is audio. Use an antenna it is RF. All RF propagates the same on a transmission line. 15 KHz or even 1 KHz propagates as RF just like any RF signal does through the air and even thru the ground as in the case of low frequencies. Read about what some of the VLF guys are doing. On a video cable remove the termination on the far end of the cable and look at the reflected energy. It has the same effect at those frequencies as it does at HF or VHF. Yes long runs of video cable can be a problem. Long runs of cable in the catv industry have the same problems of frequency roll off. They call it tilt and their amplifiers have compensation for cable attenuation in order to make the system flat. I have an HP signal level meter that measures RF from 10 Hz to 30 MHz. I can feed an audio oscillator set to 1 KHz or 1 MHz into the same input as I feed a 1 MHz RF generator into. The signal level meter handles it the same. Only difference is the output impedance of the audio oscillator is 600 ohms rather than 50 ohms. The instrument doesn't know or care if we want to call it audio or RF. As far as it is concerned it treats it as RF. I have an audio amplifier that has just about a flat response from around 5 Hz to 1 MHz. Is that an audio amplifier or an RF amplifier? :) 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Friday, August 31, 2007 7:12 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, To measure the impedance of the RG59 I used an HP impedence meter which displayed Z and phase. I use to use it to determine where caps became resonant as a demo for many caps look inductive above a given freq. Mica caps did pretty good, but still hard to find a cap at 1000 pf that was a cap above 25 MHz. These become issues in bypass caps and also for resonant circuits trying to get higher Qs where the C is large. In a
Re: [Repeater-Builder] Micor UHF RX IC needed M6707
Bill, The UHF Micor receivers are pretty much standard in all Micor radios. Probably cheapest and best place to look is for a mobile which can be had on e-bay for $10 plus $100 shipping. The receiver is a simple remove (it unplugs), insert in your repeater and tune. If you could talk the e-bay seller into removing the receiver and shipping it only he might reduce the shipping to $90 (shipping $10, handling $80). I am not sure if you are using a mobile converted to a repeater or a full real live Micor repeater. In the live one the TXs are radically different so the mobile TX parts will not do you much good unless you would like to go thru the pain of removing a PA, hi. 73, ron, n9ee/r From: William Delbert Ellis [EMAIL PROTECTED] Date: 2007/09/01 Sat AM 10:14:59 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor UHF RX IC needed M6707 Howdy fellow repeater builders. My Micor UHF ham band repeater has gone deaf. Basic troubleshooting reveals no discriminator output When I hang a scope on the input to the 2nd IF amplifier everything looks great. I can key up my FT-817 on the machine's input frequency and see a nice signal with deviation as I talk. Switching to another repeater frequency on the FT-817 I get nothing so I'm sure the Channel element, mixer all the doubler circuits and all the other IF stages and crystal filter stages are ok. The output of U102 the 2nd IF Amplifer M6707 IC has nothing. I pulled one end of C192 the end that goes to L137 from the output of the AMP. This is easy because it's mounted dead bug on the back of the PCB. Still no output from the AMP. I did this to make sure no other circuitry down the line was holding down the output of the AMP. So I think the four diodes in the discriminator are OK. When the machine is cold and been powered down for 30 minutes or so the amp seems to work for about 5- 8 seconds when first powered up then shuts down so I'm pretty sure this IC is bad. The questions are: A. Is this a common problem? B. Where can I find a replacement? C. Is there a new device that can be used in it's place? It's in a 9 pin round package. D. Shoud I look for an old mobile UHF Micor and remove the part? Thank You group and have a nice Labor Day weekend. Bill N5ZTW Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. You said coax has a low-frequency cutoff. I'm asking about that specifically. I didn't ask about about impedance. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. Under steady-state conditions, yes, you'd be right. At DC, I would think you would agree one will not see RG59 being 75 Ohm at DC. At steady-state DC, there's no such thing as impedance, there's only resistance. By definition, impedance is the opposition to a varying electric current, i.e. it only applies when we're talking about AC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. No, it can't. If you had a piece of cable long enough, it would behave the same way at 5 Hz as would a 100 foot piece of cable on 2m. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff
[Repeater-Builder] Re: DB224 Survival in Florida
I have an idea for everyone. I have not tried this yet...so if anyone has...and has had issues...LET US KNOW. I have a db420 that we are putting up on a 300ft tower here in metro ATL. This stuff is not only used on aircrafts, but look down at the very bottom of the page. When shooting Pirates of the Caribbean, they ran into corrosion issues. It's not cheap. I paid $30.50 for a 32oz bottle. However...a very thin film is used. Working on some duplexers now and will be coating them with this stuff. I need my db420 to be on the 20yr plan. Can't afford for this to go bad, espcially for what it will be used for. The gentleman who turned me on to this used this, used it on his private airplane. Said that it actually looks for that corrosin and gets under it. After reading these posts...I may use this stuff on the WHOLE antenna instead of just the connections. 73, Robert www.georgiaskywarn.com
[Repeater-Builder] Low-Frequency Cutoff (Was: Duplexers)
I think we're talking apples and oranges here. A hollow waveguide of a specific dimension does have a low-frequency cutoff point, below which a wave cannot propagate through its length. But, a coaxial cable is not a waveguide, and it does not have a low-frequency cutoff. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo Sent: Sunday, September 02, 2007 7:01 AM To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers major snip There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff
Re: [Repeater-Builder] Micor UHF RX IC needed M6707
Thanks Ron for the input. I will look for a used mobile UHF Micor. The ironic thing is that I work for Freescale Semiconductor, we used to be Motorola. I have been there 22 years. I most likely helped build the IC I need. Bill - Original Message Follows - From: Ron Wright [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor UHF RX IC needed M6707 Date: Sun, 02 Sep 2007 06:55:02 -0500 (CDT) Bill, The UHF Micor receivers are pretty much standard in all Micor radios. Probably cheapest and best place to look is for a mobile which can be had on e-bay for $10 plus $100 shipping. The receiver is a simple remove (it unplugs), insert in your repeater and tune. If you could talk the e-bay seller into removing the receiver and shipping it only he might reduce the shipping to $90 (shipping $10, handling $80). I am not sure if you are using a mobile converted to a repeater or a full real live Micor repeater. In the live one the TXs are radically different so the mobile TX parts will not do you much good unless you would like to go thru the pain of removing a PA, hi. 73, ron, n9ee/r From: William Delbert Ellis [EMAIL PROTECTED] Date: 2007/09/01 Sat AM 10:14:59 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Micor UHF RX IC needed M6707 Howdy fellow repeater builders. My Micor UHF ham band repeater has gone deaf. Basic troubleshooting reveals no discriminator output When I hang a scope on the input to the 2nd IF amplifier everything looks great. I can key up my FT-817 on the machine's input frequency and see a nice signal with deviation as I talk. Switching to another repeater frequency on the FT-817 I get nothing so I'm sure the Channel element, mixer all the doubler circuits and all the other IF stages and crystal filter stages are ok. The output of U102 the 2nd IF Amplifer M6707 IC has nothing. I pulled one end of C192 the end that goes to L137 from the output of the AMP. This is easy because it's mounted dead bug on the back of the PCB. Still no output from the AMP. I did this to make sure no other circuitry down the line was holding down the output of the AMP. So I think the four diodes in the discriminator are OK. When the machine is cold and been powered down for 30 minutes or so the amp seems to work for about 5- 8 seconds when first powered up then shuts down so I'm pretty sure this IC is bad. The questions are: A. Is this a common problem? B. Where can I find a replacement? C. Is there a new device that can be used in it's place? It's in a 9 pin round package. D. Shoud I look for an old mobile UHF Micor and remove the part? Thank You group and have a nice Labor Day weekend. Bill N5ZTW Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Cleaning of duplexers...pt 2
You just want to remove the tarnish, not dissolve the metal. Muriatic acid is probably way too strong, not to mention toxic, even when you know what you're doing while using it. Depending on how much elbow grease you want to expend (I'm all for soaking the can in some kind of solution) you could also try Noxon metal polish, available in a small green squeeze bottle (smaller than TarnX). You apply some of this with a wet sponge, let it sit a few minutes, then wipe the crud off. Rinse with a clean rag. Apply again if necessary. You may have to rub quite a lot, but at least you won't burn your fingers off. As usual, follow the directions on the container. It works great on most metals: brass, copper, etc. Bob M. == --- georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert Sick sense of humor? Visit Yahoo! TV's Comedy with an Edge to see what's on, when. http://tv.yahoo.com/collections/222
Re: [Repeater-Builder] Low-Frequency Cutoff (Was: Duplexers)
From: Eric Lemmon [EMAIL PROTECTED] Date: 2007/09/02 Sun AM 09:47:30 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Low-Frequency Cutoff (Was: Duplexers) I think we're talking apples and oranges here. A hollow waveguide of a specific dimension does have a low-frequency cutoff point, below which a wave cannot propagate through its length. But, a coaxial cable is not a waveguide, and it does not have a low-frequency cutoff. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jeff DePolo Sent: Sunday, September 02, 2007 7:01 AM To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers major snip There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
At 9/1/2007 16:45, you wrote: I really do not see a problem with D-Star repeaters existing with analog as long as D-Star follows the analog band plans set forth by the repeater councels. We've been trying to co-channel D-Star with analog systems it hasn't been working well. Kind of like trying to co-channel analog with packet. D-Star is narrow bandwidth and for this reason see they can put more repeaters in less space. A problem of say putting 2 D-Star repeaters on say one analog repeater channel space with each D-Star next to one another would cause ajacent interference for the 2 together would be wider. Correct. The only way to take advantage of D-Star's narrower bandwidth is to pack D-Star systems adjacent to each other. Bob NO6B
Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
At 9/1/2007 16:51, you wrote: [EMAIL PROTECTED] wrote: At 8/31/2007 11:18, Nate Duehr wrote: FYI. Cross-posting to IllinoisDigitalHam list and Repeater-Builder list from the [EMAIL PROTECTED] list. Thoughts folks? Thanks to Mark N5RFX for doing real testing. Thanks Nate. This is most informative. Now if you throw in the added benefit of DStar's error correction coding, I believe 10 kHz is the ideal channel spacing. Which is good for us here in SoCal because TASMA just voted to create 4 auxiliary link pairs for very narrow band digital systems at 145.585, 145.595, 145.605 145.615 outputs (inputs all -600 kHz). With the 10 kHz spacing, currently only DStar systems are compatible so they're essentially DStar pairs. I expect all 4 pairs to be assigned to 1 or more DStar systems at our next coordination meeting. Bob NO6B Bob, Does this mean TASMA has made the determination that DStar repeaters are not by definition a repeater (as part 97 would define a typical analog mode repeater) and can be operated outside the defined repeater sub bands as an auxiliary station while still performing the functional equivalent of an analog mode repeater? Ed Yoho WA6RQD We do not address the issue of whether D-Star systems are repeaters. We do claim that they fit the definition of an auxiliary station as defined in Part 97.3 (a)(7) therefore may be operated in the 145.50-145.80 MHz segment. Bob NO6B
Re: Re: Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
At 9/1/2007 17:01, you wrote: Bob, Part 97.201 reads: (b) An auxiliary station may transmit only on the 1.25 m and shorter wavelength bands, except the 219-220 MHz, 222.000-222.150 MHz, 431-433 MHz, and 435-438 MHz segments. This is outdated. However, this is from Part 97 dated Oct 2006. I know there were some changes in Dec 2007 about 2 meters although I did not think the repeater and aux bands changed. They did. Bob NO6B
Re: [Repeater-Builder] Re: subaudibe tones..
At 9/1/2007 21:17, you wrote: - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 01, 2007 5:35 PM Subject: Re: [Repeater-Builder] Re: subaudibe tones.. [snip] You guys have control of the quality level of the equipment used when issuing coordinations? We have control of the technical operating parameters; see Part 97.3 (a)(22). CORRECTION: 97.3 (a)(22) says recommends, NOT establishes technical parameters... ...and frequencies. That's what a coordination is: a recommendation. Technical parameters in the above context carries as much weight as the frequency coordination itself Bob NO6B
Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Jeff, Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Yes DC is steady state. Guess you can get the simple stuff. No a coax will not function the same at 5 Hz as it does at 2 meters. Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh well. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/02 Sun AM 09:01:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. You said coax has a low-frequency cutoff. I'm asking about that specifically. I didn't ask about about impedance. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. Under steady-state conditions, yes, you'd be right. At DC, I would think you would agree one will not see RG59 being 75 Ohm at DC. At steady-state DC, there's no such thing as impedance, there's only resistance. By definition, impedance is the opposition to a varying electric current, i.e. it only applies when we're talking about AC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. No, it can't. If you had a piece of cable long enough, it would behave the same way at 5 Hz as would a 100 foot piece of cable on 2m. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
[Repeater-Builder] Moto Service Monitor Scope
Hey Folks, Got a Moto S1327B service monitor whose scope is sick. Traced the problem to the IC... Problem is my book calls for a MC1357P chip. TV/FM Sound IC...but in my scope it is a different chip and different pin outs. My chip has number: FU6A7754394 which I suspect is a moto number. Below that number is 7043 Anyone know what this chip is? It is bad and I need to replace it. Thanks, ron
Re: Re: [Repeater-Builder] Re: subaudibe tones..
At 9/2/2007 04:38, you wrote: Although I think most coordinating councils do a good job, they do here in Florida, I really do not want the council telling repeater builders what equipment to use. We don't tell or even officially recommend (coordinate) specific types of repeater equipment. We do recommend (coordinate) technical operating parameters such as maximum power, deviation, self-desense, etc. If someone can make a pair of IC-2ATs work at a comm. site, we say congratulations. But if they work the way one would expect given the quality of the radio, then they'll likely have some problems getting coordinated. Bob NO6B
[Repeater-Builder] Re: Duplexers
Ah, I didn't think of tapering. Obviously a good idea in this application. Thanks for the details. I see we're off topic, so I'll stop now. Regards, Jeff W6JK --- In Repeater-Builder@yahoogroups.com, Jim Brown [EMAIL PROTECTED] wrote: On the E-4 aircraft we delivered to the Air Force, the wire was about 1/4 inch at the aircraft end and tapered down to around 1/8 inch at the drogue at the far end. (to keep the wire from whipping around in the slipstream). We could never deploy the wire over the US, but had to go down to the closed airspace south of Eglin AFB in the gulf to let the wire out. Can you imagine what would happen to the power distribution system over land if you had to cut the wire? The wire was spiral wrapped ribbon and I don't know what the core looked like. 73 - Jim W5ZIT Jeff Kincaid [EMAIL PROTECTED] wrote: What size wire does it take to be self supporting at that length? 'JK --- In Repeater-Builder@yahoogroups.com, Ron Wright mccrpt@ wrote: ... a C130 aircraft with 30,000 ft of wire hung out the back... - Luggage? GPS? Comic books? Check out fitting gifts for grads at Yahoo! Search.
RE: [Repeater-Builder] Moto Service Monitor Scope
Ron, Remove the F and you have a Fairchild part number- although it's probably obsolete. The 7043 is likely a date code. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of rwjohn49 Sent: Sunday, September 02, 2007 9:58 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Moto Service Monitor Scope Hey Folks, Got a Moto S1327B service monitor whose scope is sick. Traced the problem to the IC... Problem is my book calls for a MC1357P chip. TV/FM Sound IC...but in my scope it is a different chip and different pin outs. My chip has number: FU6A7754394 which I suspect is a moto number. Below that number is 7043 Anyone know what this chip is? It is bad and I need to replace it. Thanks, ron
RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Impedance is specific to AC. There's no such thing as impedance at DC, only resistance. Look up in the definition of impedance in any engineering text and you'll find that it only applies to AC. A cable's characteristic impedance is determined by the ratio of E to I when there are no reflections on the line. Reflections can only exist when the current being carried is varying, i.e. an AC waveform. A coaxial cable that has a 75 ohm characteristic impedance will conduct steady-state DC at any E to I ratio, and will do so without reflection. The cable does not perform any transformation regardless of the load, unlike the AC case. No a coax will not function the same at 5 Hz as it does at 2 meters. Why not? Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh, I think have... --- Jeff
Re: [Repeater-Builder] [Fwd: DStar Channel Spacing]
[EMAIL PROTECTED] wrote: At 9/1/2007 16:51, you wrote: [EMAIL PROTECTED] wrote: At 8/31/2007 11:18, Nate Duehr wrote: FYI. Cross-posting to IllinoisDigitalHam list and Repeater-Builder list from the [EMAIL PROTECTED] list. Thoughts folks? Thanks to Mark N5RFX for doing real testing. Thanks Nate. This is most informative. Now if you throw in the added benefit of DStar's error correction coding, I believe 10 kHz is the ideal channel spacing. Which is good for us here in SoCal because TASMA just voted to create 4 auxiliary link pairs for very narrow band digital systems at 145.585, 145.595, 145.605 145.615 outputs (inputs all -600 kHz). With the 10 kHz spacing, currently only DStar systems are compatible so they're essentially DStar pairs. I expect all 4 pairs to be assigned to 1 or more DStar systems at our next coordination meeting. Bob NO6B Bob, Does this mean TASMA has made the determination that DStar repeaters are not by definition a repeater (as part 97 would define a typical analog mode repeater) and can be operated outside the defined repeater sub bands as an auxiliary station while still performing the functional equivalent of an analog mode repeater? Ed Yoho WA6RQD We do not address the issue of whether D-Star systems are repeaters. We do claim that they fit the definition of an auxiliary station as defined in Part 97.3 (a)(7) therefore may be operated in the 145.50-145.80 MHz segment. Bob NO6B Interesting. Does TASMA consider other digital format (P25, etc.) systems to also be within the auxiliary class? If so and the FCC does not formally disagree, it would create quite a few additional pairs (although they would not be 600KHz splits) for digital audio retransmission as inputs could be below 144.5 MHz and outputs above 145.5 MHz. Ed Yoho WA6RQD
Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Ok. Coax doesn't have an impedance at DC it has a resistance. Coax impedance is found by: Zo = sqrt [ (R +j 2 pi f L ) / (G + j 2 pi f c) ] where: f is frequency L is inductance C is capacitance R is the resistance G is shunt conductance in mhos caused by the dielectric j is of course the imaginary number At extreamly low frequencies 2 pi f L and 2 pi F c are small compared to R and G, So you can now rewight as: Zo= sqrt (R/G) once f gets large enough, R and G can be neglected so the equation then is: Zo= sqrt [j 2pi f L / j 2pi f L) or Zo = sqrt (L/C) So as you can see the equation for transmission lines involves f, therefor f does have an effect on imedance... Ron's right. Jesse On 9/2/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Yes DC is steady state. Guess you can get the simple stuff. No a coax will not function the same at 5 Hz as it does at 2 meters. Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh well. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/02 Sun AM 09:01:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. You said coax has a low-frequency cutoff. I'm asking about that specifically. I didn't ask about about impedance. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. Under steady-state conditions, yes, you'd be right. At DC, I would think you would agree one will not see RG59 being 75 Ohm at DC. At steady-state DC, there's no such thing as impedance, there's only resistance. By definition, impedance is the opposition to a varying electric current, i.e. it only applies when we're talking about AC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. No, it can't. If you had a piece of cable long enough, it would behave the same way at 5 Hz as would a 100 foot piece of cable on 2m. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Micor UHF RX IC needed M6707
There are a couple of Micor receivers on E-Bay right now - Original Message - From: Ron Wright [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Sunday, September 02, 2007 6:55 AM Subject: Re: [Repeater-Builder] Micor UHF RX IC needed M6707 Bill, The UHF Micor receivers are pretty much standard in all Micor radios. Probably cheapest and best place to look is for a mobile which can be had on e-bay for $10 plus $100 shipping. The receiver is a simple remove (it unplugs), insert in your repeater and tune.
[Repeater-Builder] somewhat OT... More housecleaning / garage cleaning...
More garage and housecleaning... got to be out of the house in 20 days or so... Make offer... Two GE M2 mobiles - no cables or heads. Looks like 40w UHF. ARRL amateurs manuals from 1942, 1954, 1956, 1964, 1977, 1978 Callbooks from 1974, 1978, 1980. If they are of any use I will GIVE these to testing groups - as I understand it they can use them to verify old licenses. Just pay the postage. Free to a good home - a 286 desktop. Was last used as a voice mail system with a Brooktrout card (that I'm keeping to use on asterisk). But it would make a dandy RSS / programming computer... Pickup in the Los Angeles area or pay the shipping. I think I have a couple of brand new minitower AT cases / power supplies as I get down deeper in the garage... anybody interested in a small housing for a 386 motherboard? I -might- have a couple of those too One thing I did find, and will probably send to the paper recycle bin... 6 boxes of punch cards, 4 are unpunched virgin cards, one box has all my standard decks from the 1970s, the 6th has source deck for Adventure in the original fortran Memories of 026 and 029 keypunch machines and IBM 1401, 360/30, CDC 3100 and Burroughs 3500 mainframes... And I'm still looking for a buyer for this: 1) Original IBM 5150 PC... the floppy based one... with 5151 monitor and I think I have the original keyboard. 2) Altair Computer Altair dual 8 drive cabinet Lots of Altair manuals 3) Imasi computer two cabinets each with two 8 inch drives computer has a 2mb Semidisk board - makes the program compilations that take 30 minutes finish in 20-30 seconds. Lots of hardware, chip and CP/M system programming and application programming manuals Two spare Imsai front panels... with the red and blue toggles 4) Larry Niven's Altair (yes, THAT Larry Niven - the science fiction writer) I picked it up as potential spare parts for mine, then found the Imasi (which has a MUCH better design, and a much better power supply) Larry has offered to sign a certificate of authenticity but I can't find an interested buyer... 5) Original ST506 hard drive, still in the original styrofoam 5mb, 180-odd cylinders, a DC power hog. Even has the teletype-printed bad block table in the plastic pocket on the side of the drive.
Re: Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Jesse, You got it, well said. If you take a simple 100 ft piece of 1/4 superflex a typical value for its C=2400pf, L=6 uH and R=570 Ohm. At 5 Hz the Ls and Cs mean little compared to the R. At 10 MHz Ls and Cs mean a lot compared to the R. One can see there becomes a point where the coax will not look like coax at low frequencies or atleast have a characteristic impedance of something other than it normal value. I did this about 30 years ago for RG59, but cannot remember the numbers for some reason, hi. 73, ron, n9ee/r From: Jesse Lloyd [EMAIL PROTECTED] Date: 2007/09/02 Sun PM 12:38:28 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ok. Coax doesn't have an impedance at DC it has a resistance. Coax impedance is found by: Zo = sqrt [ (R +j 2 pi f L ) / (G + j 2 pi f c) ] where: f is frequency L is inductance C is capacitance R is the resistance G is shunt conductance in mhos caused by the dielectric j is of course the imaginary number At extreamly low frequencies 2 pi f L and 2 pi F c are small compared to R and G, So you can now rewight as: Zo= sqrt (R/G) once f gets large enough, R and G can be neglected so the equation then is: Zo= sqrt [j 2pi f L / j 2pi f L) or Zo = sqrt (L/C) So as you can see the equation for transmission lines involves f, therefor f does have an effect on imedance... Ron's right. Jesse On 9/2/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Yes DC is steady state. Guess you can get the simple stuff. No a coax will not function the same at 5 Hz as it does at 2 meters. Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh well. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/02 Sun AM 09:01:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. You said coax has a low-frequency cutoff. I'm asking about that specifically. I didn't ask about about impedance. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. Under steady-state conditions, yes, you'd be right. At DC, I would think you would agree one will not see RG59 being 75 Ohm at DC. At steady-state DC, there's no such thing as impedance, there's only resistance. By definition, impedance is the opposition to a varying electric current, i.e. it only applies when we're talking about AC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. No, it can't. If you had a piece of cable long enough, it would behave the same way at 5 Hz as would a 100 foot piece of cable on 2m. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
[Repeater-Builder] Re: Cleaning of duplexers...pt 2
Hi Bob, Well...I can dissolving the metal would not be good ;-) The thing that impressed me about the TarnX was that it really got in every nook and cranny...that you can barely get hands into. What about a very deluted solution? I am sure what acid that is TarnX is pretty deluted. Robert --- In Repeater-Builder@yahoogroups.com, Bob M. [EMAIL PROTECTED] wrote: You just want to remove the tarnish, not dissolve the metal. Muriatic acid is probably way too strong, not to mention toxic, even when you know what you're doing while using it. Depending on how much elbow grease you want to expend (I'm all for soaking the can in some kind of solution) you could also try Noxon metal polish, available in a small green squeeze bottle (smaller than TarnX). You apply some of this with a wet sponge, let it sit a few minutes, then wipe the crud off. Rinse with a clean rag. Apply again if necessary. You may have to rub quite a lot, but at least you won't burn your fingers off. As usual, follow the directions on the container. It works great on most metals: brass, copper, etc. Bob M. == --- georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert __ __ Sick sense of humor? Visit Yahoo! TV's Comedy with an Edge to see what's on, when. http://tv.yahoo.com/collections/222
Re: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Jeff, I have plenty of text books here, oh well. All refer to impedance as Z and Z=R+jX or Z = magnitude and phase angle. A 500 Ohm resistor has an impedance of 500 Ohms or 500+j0 or 500 0 deg phase. I think in Jesse's and my last posting you might see about the low and high freq differences in coax. Maybe not. Oh well. Good discussion. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/02 Sun PM 12:12:51 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Impedance is specific to AC. There's no such thing as impedance at DC, only resistance. Look up in the definition of impedance in any engineering text and you'll find that it only applies to AC. A cable's characteristic impedance is determined by the ratio of E to I when there are no reflections on the line. Reflections can only exist when the current being carried is varying, i.e. an AC waveform. A coaxial cable that has a 75 ohm characteristic impedance will conduct steady-state DC at any E to I ratio, and will do so without reflection. The cable does not perform any transformation regardless of the load, unlike the AC case. No a coax will not function the same at 5 Hz as it does at 2 meters. Why not? Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh, I think have... --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Re: Cleaning of duplexers...pt 2
From the smell, I always assumed that TarnX was a dilute sulfuric acid solution. The real key to using it was to QUICKLY flush the treated item with LOTS of water. (I would recommend distilled water if you are going to try and use it on a duplexer...) - Original Message - From: georgiaskywarn [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Sunday, September 02, 2007 1:47 PM Subject: [Repeater-Builder] Re: Cleaning of duplexers...pt 2 Hi Bob, Well...I can dissolving the metal would not be good ;-) The thing that impressed me about the TarnX was that it really got in every nook and cranny...that you can barely get hands into. What about a very deluted solution? I am sure what acid that is TarnX is pretty deluted. Robert
[Repeater-Builder] Re: Cleaning of duplexers...pt 2
--- In Repeater-Builder@yahoogroups.com, georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert Robert, Try rinsing metal polish away with plain water, then blast the clean surface with contact cleaner and watch the black grime sheet off. I've found that not all contact cleaners are created equal. I've been using WAXIE #410510 which has a high-velocity/high-volume spray. James K7ICU
[Repeater-Builder] Re: Cleaning of duplexers...pt 2
Why is everyone so crazy to clean the inside of Motorola T-1500 duplexer bottle body with cleaners? Unless there is some pitting on the plunger body... you need only blow out the dust, put a little tiny bit of lube (I use dry silicon, teflon, or Amsoil MP) on the threaded shaft and slowly spin the plunger up and down through its range a few times. The finger stock is set up by design to polish the plunger body as it goes up and down. Silly people use the wrong type of wire wheel to scratch and embed metal into the plunger body. I've never found a need to use sand paper... s. georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert
Re: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
So to plug some numbers in: Say you have a cable with the following specs (50 ohm cable) Capacitance of 100.3 pF/m Inducatance of 251 nH/m Resistane of 0.164 ohms/m Shunt conductance of 12.8 mS/m Zo = sqrt [ (R + j 2 pi f L ) / (G + j 2 pi f C ) ] at 100 Hz= 113 ohms at 1 Khz= 111 ohms at 10 Khz= 97 ohms at 100 Khz= 65 ohms at 1 Mhz= 52 ohms at 100 Mhz= 50 ohms at 1 Ghz= 50 ohms Proved.com Jesse On 9/2/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, I have plenty of text books here, oh well. All refer to impedance as Z and Z=R+jX or Z = magnitude and phase angle. A 500 Ohm resistor has an impedance of 500 Ohms or 500+j0 or 500 0 deg phase. I think in Jesse's and my last posting you might see about the low and high freq differences in coax. Maybe not. Oh well. Good discussion. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] jeff%40depolo.net Date: 2007/09/02 Sun PM 12:12:51 CDT To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Impedance is specific to AC. There's no such thing as impedance at DC, only resistance. Look up in the definition of impedance in any engineering text and you'll find that it only applies to AC. A cable's characteristic impedance is determined by the ratio of E to I when there are no reflections on the line. Reflections can only exist when the current being carried is varying, i.e. an AC waveform. A coaxial cable that has a 75 ohm characteristic impedance will conduct steady-state DC at any E to I ratio, and will do so without reflection. The cable does not perform any transformation regardless of the load, unlike the AC case. No a coax will not function the same at 5 Hz as it does at 2 meters. Why not? Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh, I think have... --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Re: Cleaning of duplexers...pt 2
I agree skipp, just lube it up and use it... unless it was buried in a pile of sand I cant see many benefits to cleaning it, other than getting familiar with the inside of a duplexer. Generally I don't ever open duplexers, a pain in the neck to take a part and way to easy to mess up putting them back together. The only time I had to do that was on a sinclair one when I dropped the rod into the can...oops. Jesse On 9/2/07, skipp025 [EMAIL PROTECTED] wrote: Why is everyone so crazy to clean the inside of Motorola T-1500 duplexer bottle body with cleaners? Unless there is some pitting on the plunger body... you need only blow out the dust, put a little tiny bit of lube (I use dry silicon, teflon, or Amsoil MP) on the threaded shaft and slowly spin the plunger up and down through its range a few times. The finger stock is set up by design to polish the plunger body as it goes up and down. Silly people use the wrong type of wire wheel to scratch and embed metal into the plunger body. I've never found a need to use sand paper... s. georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert
[Repeater-Builder] MSR 2000 R1 Audio Squelch
Hey Guys, The schematic on the website of this card doesn't have the Intercom switch/button on it. From what I've read there are 2 versions of this board, the one published on the site and the one I have. The boards appear very similar, mine just has a few extra parts on it for more features I assume. What does this botton do? Jesse
[Repeater-Builder] DB224 Survival in Florida
Ron and Eric, I emailed this out before, here goes again. I learned all I know about the DB antennas from two of the engineers that designed the antenna many years ago. My Boss at the time was a personnel friend of one and the other ended up at Wacom where I did a lot of business with him. I have a lot of respect for both. First, when you get a DB folded dipole antenna, disconnect all connections at the dipoles and tighten everything and put it back together. After that, put as many coats as you can of Scotchkote from 3M on every connection, especially if dissimilar metals are present. Coat every knot, terminal and joint on the antenna with Scotchkote that you can. Coat the whole thing if you can. That keeps the salt from getting to those parts. Do this and the antenna will last much longer and outlive the fiberglass antennas every time. I was Director of Field Engineering for a nationwide paging company, we had a office in Tampa Florida and all we used were the DB-224 antennas. I threatened to fire anyone that put an antenna in the air without tightening the connections and sealing it first. Never had to fire anyone over that, they knew how important it was to me. We still had a few problems mainly from the first batch of Phelps Dog (Dodge aka Celwave aka RF Industries or whatever they call themselves now) antennas we put up. The difference between the folded dipole antenna and fiberglass radome antennas in lightning was not worth the chance in a emergency system. Hope this helps, Paul -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Saturday, September 01, 2007 9:45 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB224 Survival in Florida Paul, Eleven years in a salt-air and lightning-prone environment is pretty darn good! I daresay the Super Stationmaster would not last that long. Fiberglass vertical antennas can be permanently damaged when struck by lightning, whereas the aluminum dipoles might shrug off such abuse. At least, that's been the experience at nearby Vandenberg AFB. It is not clear from your post if you have established beyond any doubt that it is the antenna causing your SWR problem. Have you determined that the feedline is not cracked or dented due to flexing, not worn through at some point, no water in the line, center pin(s) haven't pulled out due to elongation, no bullet holes, etc., etc.? 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 7:12 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry Paul, I have a DB224 at 1175 ft above ground 1/2 mile from the Gulf of Mexico here in FL. Put up in 1996 and it is having serious problems, 2:1 SWR on the ground. Think it is the salt air. The connections, on antenna and connectors, were coated and sealed before install. Other services with exposed dipoles have had the same problem here. We have same antennas about 5 miles from the Gulf that last for years although none past 20 years. Have seen about 5 of these replaced recently, most VHF. When I replace my DB224 I am going to a SuperStation Master fiber glass pole. It is obvious the exposed dipoles have a survival problem in this salt air. I know what you mean about the fiber poles and lightning due to the soldering connections. If top mounted would be reluctant, but have seen these last over 20 years and still had plenty of life in them in some harsh enviorments. I like the DB224 with it squeeing of the pattern, but exposed dipoles can have problems. Same with towers up north with ice falling off a tower. 73, ron, n9ee/r unrelated text deleted Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.0/980 - Release Date: 8/30/2007 6:05 PM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2 - Release Date: 9/1/2007 12:00 AM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2 - Release Date: 9/1/2007 12:00 AM 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/
Re: [Repeater-Builder] Re: Cleaning of duplexers...pt 2
We had a VHF 70mhz once have other frequencies coming through and on inspection we found a small area of corrosion in one tin at the base plate once cleaned all ok again . Thank You, Ian Wells, Kerinvale Comaudio, www.kerinvalecomaudio.com.au ---Original Message--- From: Jesse Lloyd Date: 3/09/2007 7:17:56 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Cleaning of duplexers...pt 2 I agree skipp, just lube it up and use it... unless it was buried in a pile of sand I cant see many benefits to cleaning it, other than getting familiar with the inside of a duplexer. Generally I don't ever open duplexers, a pain in the neck to take a part and way to easy to mess up putting them back together. The only time I had to do that was on a sinclair one when I dropped the rod into the can...oops. Jesse On 9/2/07, skipp025 [EMAIL PROTECTED] wrote: Why is everyone so crazy to clean the inside of Motorola T-1500 duplexer bottle body with cleaners? Unless there is some pitting on the plunger body... you need only blow out the dust, put a little tiny bit of lube (I use dry silicon, teflon, or Amsoil MP) on the threaded shaft and slowly spin the plunger up and down through its range a few times. The finger stock is set up by design to polish the plunger body as it goes up and down. Silly people use the wrong type of wire wheel to scratch and embed metal into the plunger body. I've never found a need to use sand paper... s. georgiaskywarn [EMAIL PROTECTED] wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert
RE: [Repeater-Builder] MSR 2000 R1 Audio Squelch
Jesse, What number is stamped in black ink on your card? I'll see if I can dig up the data. I see at least seven different AS cards used in the MSR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 2:36 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] MSR 2000 R1 Audio Squelch Hey Guys, The schematic on the website of this card doesn't have the Intercom switch/button on it. From what I've read there are 2 versions of this board, the one published on the site and the one I have. The boards appear very similar, mine just has a few extra parts on it for more features I assume. What does this botton do? Jesse
Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch
Its a TRN 9689 On 9/2/07, Eric Lemmon [EMAIL PROTECTED] wrote: Jesse, What number is stamped in black ink on your card? I'll see if I can dig up the data. I see at least seven different AS cards used in the MSR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 2:36 PM To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] MSR 2000 R1 Audio Squelch Hey Guys, The schematic on the website of this card doesn't have the Intercom switch/button on it. From what I've read there are 2 versions of this board, the one published on the site and the one I have. The boards appear very similar, mine just has a few extra parts on it for more features I assume. What does this botton do? Jesse
Re: [Repeater-Builder] DB224 Survival in Florida
Paul, Prior to putting up our DB224 we coated the connections with a commerical coating for antennas. It was from a local broadcast station who uses it. Not sure if same 3M product you mentioned. It was gold in color and really stands out on the antenna. This has been done on a number of exposed dipoles like the DB408s here and it last less than 10 years, some as short as 6 years. I like the DB224, but do not trust it for the salt air and will go with a RFS/Cel Wave 200 with both a bottom and top bracket. Another problem with these is with mounting only at the bottom and they do not like waving the wind. We had another UHF system install a new one and from the start static when windy. A top bracket solved the problem...this goes back about 4 years and it is still in service and is about 1/2 mile from the salt water. We did the same for the DB224 install. Thanks for the info. I am sure many here can use the experience and advice. 73, ron, n9ee/r From: Paul Finch [EMAIL PROTECTED] Date: 2007/09/02 Sun PM 04:55:00 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB224 Survival in Florida Ron and Eric, I emailed this out before, here goes again. I learned all I know about the DB antennas from two of the engineers that designed the antenna many years ago. My Boss at the time was a personnel friend of one and the other ended up at Wacom where I did a lot of business with him. I have a lot of respect for both. First, when you get a DB folded dipole antenna, disconnect all connections at the dipoles and tighten everything and put it back together. After that, put as many coats as you can of Scotchkote from 3M on every connection, especially if dissimilar metals are present. Coat every knot, terminal and joint on the antenna with Scotchkote that you can. Coat the whole thing if you can. That keeps the salt from getting to those parts. Do this and the antenna will last much longer and outlive the fiberglass antennas every time. I was Director of Field Engineering for a nationwide paging company, we had a office in Tampa Florida and all we used were the DB-224 antennas. I threatened to fire anyone that put an antenna in the air without tightening the connections and sealing it first. Never had to fire anyone over that, they knew how important it was to me. We still had a few problems mainly from the first batch of Phelps Dog (Dodge aka Celwave aka RF Industries or whatever they call themselves now) antennas we put up. The difference between the folded dipole antenna and fiberglass radome antennas in lightning was not worth the chance in a emergency system. Hope this helps, Paul Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch
Jesse, I have the info for that module, and I will scan it and send it to you directly. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 3:50 PM To: Repeater-Builder@yahoogroups.com Subject: [Norton AntiSpam] Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch Its a TRN 9689 On 9/2/07, Eric Lemmon [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] wrote: Jesse, What number is stamped in black ink on your card? I'll see if I can dig up the data. I see at least seven different AS cards used in the MSR2000 station. 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 Jesse Lloyd Sent: Sunday, September 02, 2007 2:36 PM To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] MSR 2000 R1 Audio Squelch Hey Guys, The schematic on the website of this card doesn't have the Intercom switch/button on it. From what I've read there are 2 versions of this board, the one published on the site and the one I have. The boards appear very similar, mine just has a few extra parts on it for more features I assume. What does this botton do? Jesse
Re: Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch
Sounds good, thanks! Jesse On 9/2/07, Eric Lemmon [EMAIL PROTECTED] wrote: Jesse, I have the info for that module, and I will scan it and send it to you directly. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 3:50 PM To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: [Norton AntiSpam] Re: [Repeater-Builder] MSR 2000 R1 Audio Squelch Its a TRN 9689 On 9/2/07, Eric Lemmon [EMAIL PROTECTED] wb6fly%40verizon.net mailto: [EMAIL PROTECTED] wb6fly%40verizon.net wrote: Jesse, What number is stamped in black ink on your card? I'll see if I can dig up the data. I see at least seven different AS cards used in the MSR2000 station. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com [mailto:Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com ] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 2:36 PM To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: [Repeater-Builder] MSR 2000 R1 Audio Squelch Hey Guys, The schematic on the website of this card doesn't have the Intercom switch/button on it. From what I've read there are 2 versions of this board, the one published on the site and the one I have. The boards appear very similar, mine just has a few extra parts on it for more features I assume. What does this botton do? Jesse
RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
But it is your statement. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Sunday, September 02, 2007 6:46 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, I don't know. Why don't you tell us. I don't know why gravity will pull me to the ground real fast if I jump off a bridge, but I have all the faith in the world it will. Einstin tried to explain it, but died before he got the results. Taking the word of good test equipment is a good engineering approach. Doing the math, I am sure I have here somewhere, and I am sure the defferential equations would take a while probably starting with Maxwell's, but as with gravity if you know it does what it does I use it. These discussions can at times go no where, hi. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 08:48:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ron, Maybe you could tell us why coax cable has a lower frequency limit? You claim that it does but have not explained why or how. Why does the impedance change significantly at lower frequencies? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:49 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, Yes the HP meter was spec'd to go below below 0.5 MHz, it went down to 100 kHz. I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. I know about low freq RF. Worked on a Navy program that used 18 kHz, a C130 aircraft with 30,000 ft of wire hung out the back as a platform to talk to surmerged submarines. Ran over 250 kW. It was called TACMO. Due to the weight the wings kept falling off...well they were continously inspected and replaced before they fell off, but the aircraft was deffinitly over loaded. Had generators on all 4 engines to get the power they needed. Now that was a repeater. However, AC power distribution is not trying to radiate power, but transfer it with widly varing loads. Totally different engineering. At low frequencies such as 1 kHz little radiation takes place. Far less at 60 Hz. The EMF returns to the radiator, wire, before the next cycle can force it out. This is a problem in some applications, but since most do not want radiation it is not. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/31 Fri PM 05:59:28 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Are you sure that the impedance meter you used was speced for operation below .5 MHz? Yes all capacitors have inductance. Lead length is particularly a problem. 15 KHz can be treated as RF or audio it all depends on what transducer you are using it to couple it with. Use a speaker and it is audio. Use an antenna it is RF. All RF propagates the same on a transmission line. 15 KHz or even 1 KHz propagates as RF just like any RF signal does through the air and even thru the ground as in the case of low frequencies. Read about what some of the VLF guys are doing. On a video cable remove the termination on the far end of the cable and look at the reflected energy. It has the same effect at those frequencies as it does at HF or VHF. Yes long runs of video cable can be a problem. Long runs of cable in the catv industry have the same problems of frequency roll off. They call it tilt and their amplifiers have compensation for cable attenuation in order to make the system flat. I have an HP signal level meter that measures RF from 10 Hz to 30 MHz. I can feed an audio oscillator set to 1 KHz or 1 MHz into the same input as I feed a 1 MHz RF generator into. The signal level meter handles it the same. Only difference is the output impedance of the audio oscillator is 600 ohms rather than 50 ohms. The instrument doesn't know or care if we want to call it audio or RF. As far as it is concerned it treats it as RF. I have an audio amplifier that has just about a flat response from around 5 Hz to 1 MHz. Is that an audio amplifier or an RF amplifier? :) 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Friday, August 31, 2007 7:12 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary,
RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Yes Ron, a tongue in cheek reply, but not entirely. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Sunday, September 02, 2007 6:40 AM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Gary, Now I know you are kidding, hi. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 08:58:13 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers How do you know it is not 75 ohms at DC? How long do you think it will take for the DC signal to reach the other end of the coax if it is applied at one end? Will it be at the speed of light? 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:02 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Jeff, The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. I would think you would agree one will not see RG59 being 75 Ohm at DC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/01 Sat PM 01:18:35 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. If what you say is true, can you tell me, using sound engineering and math, why you can carry DC on coax if it has a low-frequency cutoff? --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links
RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
I was wondering when someone was going to dredge that up from the Beldon papers. Good going Jesse. But that still doesn't mean or show that coax cable has a low frequency cutoff or that it stops looking like or acting like a coax cable at low frequencies. It tells us that other factors come into play at low frequencies. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 12:38 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Ok. Coax doesn't have an impedance at DC it has a resistance. Coax impedance is found by: Zo = sqrt [ (R +j 2 pi f L ) / (G + j 2 pi f c) ] where: f is frequency L is inductance C is capacitance R is the resistance G is shunt conductance in mhos caused by the dielectric j is of course the imaginary number At extreamly low frequencies 2 pi f L and 2 pi F c are small compared to R and G, So you can now rewight as: Zo= sqrt (R/G) once f gets large enough, R and G can be neglected so the equation then is: Zo= sqrt [j 2pi f L / j 2pi f L) or Zo = sqrt (L/C) So as you can see the equation for transmission lines involves f, therefor f does have an effect on imedance... Ron's right. Jesse On 9/2/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Yes DC is steady state. Guess you can get the simple stuff. No a coax will not function the same at 5 Hz as it does at 2 meters. Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh well. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/09/02 Sun AM 09:01:03 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. You said coax has a low-frequency cutoff. I'm asking about that specifically. I didn't ask about about impedance. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. Under steady-state conditions, yes, you'd be right. At DC, I would think you would agree one will not see RG59 being 75 Ohm at DC. At steady-state DC, there's no such thing as impedance, there's only resistance. By definition, impedance is the opposition to a varying electric current, i.e. it only applies when we're talking about AC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. No, it can't. If you had a piece of cable long enough, it would behave the same way at 5 Hz as would a 100 foot piece of cable on 2m. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. I'm not trying to rake you over the coals Ron, but I *am* trying to prove a point: there is no low-frequency cutoff for coaxial cable, period. You may experience (or even measure) behavior at very low frequencies when the cable is a small fraction of an electrical wavelength that might make you want to think otherwise, but it's not due to transmission line theory, math, or physics breaking down at some low-frequency cutoff. --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links
RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
My reply was a tongue in cheek reply to try and inspire some explanations rather than the just because it is kind. You are correct about steady state DC. Just food for thought In order to get to that steady state at the far end of the cable you must first apply the DC at the opposite end. It takes time for that DC signal to reach the other end and that time will be the velocity factor of the cable. After that you have steady state DC. Upper frequency roll off of coax cable is mainly a function of the AC resistance (caused by skin effect) of the center conductor. Dielectric loss comes into play above VHF frequencies. Larger diameter coax has less loss because it has a larger center conductor with less AC resistance. During propagation of a signal down a coax line the energy is swapped between the magnetic and electric fields in the cable. I.e. The capacitor charges and discharges into the inductor and back again. Inductive and capacitive reactances have nothing to do with loss. There is no high frequency cutoff but as the spacing of the center conductor and shield gets larger compared to frequency a point is reached where the propagation mode of the cable changes and other modes come into play (where multiple propagation modes exist) and the multiple modes can interfere with each other causing partial cancellations. This causes additional losses. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Condit Sent: Saturday, September 01, 2007 10:24 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Hi all! If a piece of coax is sitting at ground and you suddenly attach a battery (DC) across it, you're really talking about a step function change in voltage which carries a wide spectrum of high frequencies The 'change' propagates down the coax at near the speed of light as expected. True DC, on the other hand, means nothing is changing. Everything is constant forever. In this case speed of propagation is a moot point. Regarding the upper frequency rolloff its pretty easy to see how it comes about. Current flowing in a straight wire give rise to a magnetic field around it. Since it takes energy to create the field and whe the field collapses it returns the energy, we're talking about series inductance. Yes, the central conductor of a piece of coax exhibits a certain number of nH per inch. It also has parallel capacitance to the outer braid or cylinder in terms of pF per inch. As frequencies increase the series inductive impedance increases which tends to block the series flow. Simultaneously, as frequencies increase the parallel capacitive impedance decreases tending to shunt the flow to the shield. The combination of these two effects are what gives rise to the high frequency rolloff characteristics. Larger diameter coax has less capacitance per inch and so has less rolloff for a given frequency. There is one other effect that also causes rolloff at even higher frequencies, and that is increased dielectric loss. Hope this helps. - Original Message - From: Gary Schafer mailto:[EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 01, 2007 6:58 PM Subject: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers How do you know it is not 75 ohms at DC? How long do you think it will take for the DC signal to reach the other end of the coax if it is applied at one end? Will it be at the speed of light? 73 Gary K4FMX -Original Message- From: Repeater-Builder@ mailto:Repeater-Builder@yahoogroups.com yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] .com] On Behalf Of Ron Wright Sent: Saturday, September 01, 2007 8:02 PM To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Jeff, The question is way off base. No one said one cannot carry DC or any other signal on coax. The question was what was the impedance of a coax at given frequencies. At DC I can guarantee you RG59 is not 75 Ohms unless you got enough to get enough R and this is totally another discussion. I would think you would agree one will not see RG59 being 75 Ohm at DC. The same can be said at 1 Hz or 2 Hz or 5 Hz...etc. There is a point at which it starts to propergate and does look like 75 Ohms. I think you might understand this. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] mailto:jeff%40depolo.net net Date: 2007/09/01 Sat PM 01:18:35 CDT To: Repeater-Builder@ mailto:Repeater-Builder%40yahoogroups.com yahoogroups.com Subject: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers I don't know where the confusion is...all coax and feedline has a upper and lower freq limit. Might try to learn something about this. If
[Repeater-Builder] Re: Cleaning of duplexers...pt 2
Wow that stuff is expensive...when I did a search on it. What were you paying for that. Skipp...I know what you are saying on cleaning of them. I guess I am looking at trying to make the things as clean as possible. You would think that a tuned circuit would have issues with extra stuff collecting inside. However...I bow to the experts on here. That is why I ask the questions ;-) Thanks guys...keep you posted on the progress... Robert --- In Repeater-Builder@yahoogroups.com, crackedofn0de [EMAIL PROTECTED] wrote: --- In Repeater-Builder@yahoogroups.com, georgiaskywarn kd4ydc@ wrote: Had an experience with using TarnX in cleaning some Moto cans. Had a friend of mine that used this with great success. I used it...had issues. The difference is he used running water when I used a pan of water. Didn't clean off very well...so corrosion came on even faster because the Murratic Acid (sp?) didn't clean off very well. Got to thinking (because I have to do this again), why not just use Murratic Acid which is used in pool cleaning products. A gallon of this...deluted...is MUCH cheaper than the smallish bottles of TarnX. Anybody use this before??? 73 Robert Robert, Try rinsing metal polish away with plain water, then blast the clean surface with contact cleaner and watch the black grime sheet off. I've found that not all contact cleaners are created equal. I've been using WAXIE #410510 which has a high-velocity/high-volume spray. James K7ICU
RE: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Isn't it interesting to note that the impedance goes UP at low frequencies but not by leaps and bounds. However you didn't say if the R resistance in the equations is DC resistance or AC resistance? If you also look in those Beldon papers you will see that the characteristic impedance of coax is not a specific number but rather an average number. The impedance swings all over the place with change in frequency. There are many high and low swings in impedance at specific frequencies. At low frequencies (or most any frequency) a coax cable does not start to exhibit coax cable (transmission line) properties until the length of the cable approaches 1/10 wavelength. Yes this means that with most common lengths of cable at audio frequencies for example, a piece of coax cable only looks like a piece of shielded cable with capacitance across it. But lengthen that same cable with the same frequency to 1/10 wave length or more and the cable now looks like a transmission line. This same thing happens with power distribution lines. The long lines are transmission lines (appropriately named) and suffer from the same problems as any other transmission line including standing waves. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, September 02, 2007 4:10 PM To: Repeater-Builder@yahoogroups.com Subject: Re: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers So to plug some numbers in: Say you have a cable with the following specs (50 ohm cable) Capacitance of 100.3 pF/m Inducatance of 251 nH/m Resistane of 0.164 ohms/m Shunt conductance of 12.8 mS/m Zo = sqrt [ (R + j 2 pi f L ) / (G + j 2 pi f C ) ] at 100 Hz= 113 ohms at 1 Khz= 111 ohms at 10 Khz= 97 ohms at 100 Khz= 65 ohms at 1 Mhz= 52 ohms at 100 Mhz= 50 ohms at 1 Ghz= 50 ohms Proved.com Jesse On 9/2/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, I have plenty of text books here, oh well. All refer to impedance as Z and Z=R+jX or Z = magnitude and phase angle. A 500 Ohm resistor has an impedance of 500 Ohms or 500+j0 or 500 0 deg phase. I think in Jesse's and my last posting you might see about the low and high freq differences in coax. Maybe not. Oh well. Good discussion. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] mailto:jeff%40depolo.net Date: 2007/09/02 Sun PM 12:12:51 CDT To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers Impedance refers to both R and X, resistance and reactance. Impedance affects all current flow, DC and AC. X affects AC only. Impedance is specific to AC. There's no such thing as impedance at DC, only resistance. Look up in the definition of impedance in any engineering text and you'll find that it only applies to AC. A cable's characteristic impedance is determined by the ratio of E to I when there are no reflections on the line. Reflections can only exist when the current being carried is varying, i.e. an AC waveform. A coaxial cable that has a 75 ohm characteristic impedance will conduct steady-state DC at any E to I ratio, and will do so without reflection. The cable does not perform any transformation regardless of the load, unlike the AC case. No a coax will not function the same at 5 Hz as it does at 2 meters. Why not? Evidently you have not had the previledge of working with equipment or engineers that allows one to look at some of these issues. Oh, I think have... --- Jeff Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
RE: [Repeater-Builder] DB224 Survival in Florida
Ron, I can't stress the importance if tightening ALL of the hardware on the DB antennas, they were built for the low mount and top of tower installations. It sounds like loose connections from the factory is what your static problems are. I can't tell you the number of antennas I have prepared that seemed to have hardware only finger tight. Scotchkote is dark brown and so far is the only thing I have seen that stands up to Texas Florida Sun. Careful, if you get it on your skin you have to wear it off or use MEK. Remember, lightning will exit a tower usually around 150 feet down from where it strikes the tower and can wipe out fiberglass antennas even when side-mounted on a tower. I will say that I have some fiberglass antennas on my 500 foot towers but in every case there are DB folded dipole antennas above them. I am about to raise a TXRX broadband 860-930 MHz 4 degree down-tilt antenna to the top platform to replace a DB-806 that was used by a old paging company. That will be my receive antenna for the 900 MHz Ham repeaters. That antenna at $1,400.00 would be a very expensive lifetime supply of toothpicks if hit by lightning. It will almost be surrounded by folded dipole antennas. Will also be raising another DB-420 antenna to the 400 foot platform for my second transmit combiner. It sounds like the guy that mentioned coating the whole antenna may have a good idea but I would also coat the connections with Scotchkote beforehand. I never found anything that I thought would stick that well to aluminum that you could coat the whole antenna with. As you can tell, I like DB antennas, just think they need some quality control or at least someone that has strength enough to tighten the screws the way they should. Paul -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright Sent: Sunday, September 02, 2007 6:24 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] DB224 Survival in Florida Paul, Prior to putting up our DB224 we coated the connections with a commerical coating for antennas. It was from a local broadcast station who uses it. Not sure if same 3M product you mentioned. It was gold in color and really stands out on the antenna. This has been done on a number of exposed dipoles like the DB408s here and it last less than 10 years, some as short as 6 years. I like the DB224, but do not trust it for the salt air and will go with a RFS/Cel Wave 200 with both a bottom and top bracket. Another problem with these is with mounting only at the bottom and they do not like waving the wind. We had another UHF system install a new one and from the start static when windy. A top bracket solved the problem...this goes back about 4 years and it is still in service and is about 1/2 mile from the salt water. We did the same for the DB224 install. Thanks for the info. I am sure many here can use the experience and advice. 73, ron, n9ee/r From: Paul Finch [EMAIL PROTECTED] Date: 2007/09/02 Sun PM 04:55:00 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] DB224 Survival in Florida Ron and Eric, I emailed this out before, here goes again. I learned all I know about the DB antennas from two of the engineers that designed the antenna many years ago. My Boss at the time was a personnel friend of one and the other ended up at Wacom where I did a lot of business with him. I have a lot of respect for both. First, when you get a DB folded dipole antenna, disconnect all connections at the dipoles and tighten everything and put it back together. After that, put as many coats as you can of Scotchkote from 3M on every connection, especially if dissimilar metals are present. Coat every knot, terminal and joint on the antenna with Scotchkote that you can. Coat the whole thing if you can. That keeps the salt from getting to those parts. Do this and the antenna will last much longer and outlive the fiberglass antennas every time. I was Director of Field Engineering for a nationwide paging company, we had a office in Tampa Florida and all we used were the DB-224 antennas. I threatened to fire anyone that put an antenna in the air without tightening the connections and sealing it first. Never had to fire anyone over that, they knew how important it was to me. We still had a few problems mainly from the first batch of Phelps Dog (Dodge aka Celwave aka RF Industries or whatever they call themselves now) antennas we put up. The difference between the folded dipole antenna and fiberglass radome antennas in lightning was not worth the chance in a emergency system. Hope this helps, Paul Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Yahoo! Groups Links No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2 - Release Date: 9/1/2007 12:00 AM No virus
[Repeater-Builder] Intergrating comspec ts-64 to MSR2000
Does anybody have and notes or down n' dirty drawings on best practice for integrating a ts-64 to the msr2000? I think my PL card is flaky, and I have a space ts64... -- Jay Urish W5GM ARRL Life MemberDenton County ARRL VEC N5ERS VP/Trustee Monitoring 444.850 PL-88.5
Re: [Repeater-Builder] Intergrating comspec ts-64 to MSR2000
I mean spare ts-64 :) Jay Urish wrote: Does anybody have and notes or down n' dirty drawings on best practice for integrating a ts-64 to the msr2000? I think my PL card is flaky, and I have a space ts64... -- Jay Urish W5GM ARRL Life Member Denton County ARRL VEC N5ERS VP/Trustee Monitoring 444.850 PL-88.5 -- Jay Urish CCNANetwork Engineer http://jay.unixwolf.net Home)972.691.0125Cell)972.965.6229
RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
Correction to below: Change the word frequency to wavelength. It should read; There is no high frequency cutoff but as the spacing of the center conductor and shield gets larger compared to WAVELENGTH a point is reached where the propagation mode of the cable changes and other modes come into play (where multiple propagation modes exist) and the multiple modes can interfere with each other causing partial cancellations. This causes additional losses. There is no high frequency cutoff but as the spacing of the center conductor and shield gets larger compared to frequency a point is reached where the propagation mode of the cable changes and other modes come into play (where multiple propagation modes exist) and the multiple modes can interfere with each other causing partial cancellations. This causes additional losses. 73 Gary K4FMX
Re: [Repeater-Builder] Re: Frequency coordinator authority (was Re: subaudibe tones..)
While that is true, when an applicant applies for frequency coordination, he is asking for specifications that will allow him to receive a coordination. As such, those limitations/specifications are largely self-imposed. That is what he is willing to do to receive coordination. Some people will go to great lengths to get a coordination on a particular frequency - even if it means running watts of power with directional antenna systems. For example, if there is another repeater to his north, a null may be required as part of the coordination in that direction. If he wants the coordination, he will accept that limitation. If he does not accept it, he doesn't get the coordination. A coordination is almost always issued based on a set of technical criteria. IF you exceed that criteria, you are not operating within the limits of your coordination which means you are operating uncoordinated. As far as a coordinator imposing technical minimum requirements, those too usually come from the repeater trustees themselves, and again are self-imposed. It's how those trustees decide it is best for them to operate. So, it is coming through the coordination body, but the authority is coming from those upon whom it is imposed. All the authority comes from the FCC or the licensees. There is nothing in Part 97 that specifies that you cannot agree to a higher standard. Period. Joe M. George Henry wrote: - Original Message - From: [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Sunday, September 02, 2007 11:50 AM Subject: Re: [Repeater-Builder] Re: subaudibe tones.. [snip] CORRECTION: 97.3 (a)(22) says recommends, NOT establishes technical parameters... ...and frequencies. That's what a coordination is: a recommendation. Technical parameters in the above context carries as much weight as the frequency coordination itself Bob NO6B Good luck convincing a judge of that... I repeat, with emphasis: 97.3(a)(22) does not grant any statutory authority to a frequency coordinating body to impose any technical standards upon any equipment owned, built, or operated by a duly-licensed amateur radio operator, above and beyond those technical standards already imposed by the FCC. PERIOD.
[Repeater-Builder] Zetron ZR340 Controller Manual Needed
Might anyone have a configuration manual for the ZR340? I had one, but can't seem to find it at this time. It's only a few pages. Maybe scanning and e-mailing it to me. If so, many thanks ! Paul Metzger K6EH [EMAIL PROTECTED]
[Repeater-Builder] Re: Ramsey COM3010 Service Monitor Opinions
I purchased a COM3010 shortly after it was released and have been extremely happy with it. It has gone back to the factory for complete software and calibration upgrade once since new. Ramsey says they have sold over 400 of them since release. Pros: Small, light, easy to operate and carry to sites. Simple straightforward operation. Long battery life. Full duplex operation Signal generator down to -140dBm RSSI meter. Major Cons: No scope No spectrum analyzer I wanted a NEW service monitor with a warranty so I didn't consider an old IFR unit. I have an Areoflex 2944B on the horizon but for basic day to day ham operation where I just need to check radios and repeaters to ensure they are on frequency, check power, do SINAD measurements, and ensure deviation is set correctly, while not lugging around a Motorola R2600D, the COM3010 is ideal in my opinion. I have a scope and have access to separate spectrum analyzers and have also considered an Instek GSP-810, Hameg, or BK unit that run in $3000 range to compliment my 3010. That's still half the price of the 2944B or other monitor. I highly recommend the COM3010. I could do a lot more with a higher end service monitor but I am not rich and felt this was a good investment and it has proved to be. I still see some hams putting stuff on the air without virtually any checks and folks setting audio levels by ear without any test equipment. A COM3010 moves that process forward considerably even without a scope and SA. Again, an old used service monitor was not an option for me. I heartily recommend the COM3010, especially if you have no service monitor at all now. 73, Chuck KX7ID Disclaimer: I have no connection whatsoever with Ramsey other than being a customer of a few of their kits and a COM3010. --- In Repeater-Builder@yahoogroups.com, Vincent Caruso [EMAIL PROTECTED] wrote: I am seriously thinking of purchasing a Ramsey COM3010 Service Monitor for my home bench and was wondering if anyone else on the list is familiar with this, owns one or has worked with one. I would love to hear the pros and cons on this product before taking the 4K plunge. Thanks in advance
