[Repeater-Builder] Re: Does anyone else think of Power Factor like SWR?
Very interesting theory. I am teaching SWR at present to my third year college students. Could be a good discussion point since they have already studied power factor. However, SWR can exist with a purely resistive mismatched load, so it needs a bit of modification to take all into account. 73 Nigel ve3id --- In Repeater-Builder@yahoogroups.com, Bob Witte K0NR [EMAIL PROTECTED] wrote: --- In Repeater-Builder@yahoogroups.com, kb9bpf kb9bpf@ wrote: Since I'm way more into RF than industrial power distribution, I've always been able to think of power factor on the electrical power grid in terms similar to antenna system reflections, which are commonly measured in terms of SWR. After all, both are AC systems where the voltage and current bear a phase relationship to each other. When they are perfectly in phase the power factor is 1.0, and a 60-Hz SWR meter would measure 1:1. When they are out of phase (power factor 1) that SWR meter would read greater than 1:1. I suspect, though I haven't done the math or looked up the specific matahematical definition of power factor, that it would be direcly proportional to the reciprocal of the power factor. And as we know, when that happens the power generating end has more difficulty delivering power efficiently to the load. A while back I was doing some analysis of power factor to understand it better and I found that it has a lot in common with SWR. Both are focused on the issue of power transfer, so I guess we shouldn't be surprised. The thing they really have in common is for max power with AC signals, the voltage and current need to be in phase (phase angle of zero). For linear systems with nice sine waves, PF = cos (phase angle) where phase angle = the angle between voltage and current sinusoids Wikipedia has a good explanation of PF at http://en.wikipedia.org/wiki/Power_factor Play around with some typical circuits and you'll find that an SWR of 1 also has voltage and current in phase. Again, not a surprise since it represents the best power transfer. This is from memory, so the usual disclaimers apply :-) 73, Bob K0NR
[Repeater-Builder] Re: Does anyone else think of Power Factor like SWR?
Good point Nigel. Back in the '60s I designed a video distribution amplifier for receiver video to tape recorders, O scopes and the like and I matched the input impedance to prevent reflections on the video line from distorting the signal. The output impedance of my amplifier was as low as I could get it, and it worked very well. I did not design the output impedance to be 50 ohms, the impedance of the cable we used to distribute the video. I depended on the load to be 50 ohms resistive to prevent any reflection. On the other hand, the audio distribution amplifiers were not matched on the receive end. I also designed the output impedance of an audio amplifier to be as low as I could get it, and was able to switch multiple loads on the output without changing the level. The input impedance of the audio circuits was always 600 ohms or higher. The power distribution grid is more like the audio and video situation than the SWR problems we see at RF. 73 - Jim W5ZIT --- In Repeater-Builder@yahoogroups.com, Nigel Johnson [EMAIL PROTECTED] wrote: Very interesting theory. I am teaching SWR at present to my third year college students. Could be a good discussion point since they have already studied power factor. However, SWR can exist with a purely resistive mismatched load, so it needs a bit of modification to take all into account. 73 Nigel ve3id
Re: [Repeater-Builder] Ge Mastr II Squelch
At 9/19/2008 21:48, you wrote: What signal are you using as the COS from the receiver? If you use RUS you will have a combination of the squelch and the CTCSS detect. The two are anded together so that both have to be present for RUS to be active. If you are using only the detected CTCSS you will have the hangover you mention as it takes a short time for the detected tone to clear out of the filter and turn the detect output off. Typical operation using RUS and a CTCSS decoder is that the RUS signal will delay slightly going active as the tone decoder is locking on. Even though the CAS has gone instantly to active, this slight delay will be present due to the AND gate action. At the end of a transmission, the RUS will go inactive instantly, as soon as the CAS signal goes away, even though a CTCSS signal detect is still present. So RUS gives you the best of both signals, delayed keying (only a few tens of milliseconds) and a fast unkey (the squelch mod comes into play). Only problem is the RUS signal is already ANDed in the radio. Most repeater controllers made today will perform this function for you, in addition some of the newer ones like the SCom 7330 have different access modes for voice DTMF paths. This is significant in that you can set your DTMF access to be pure CTCSS so that brief chops in your signal that would normally cause a brief closing of the noise squelch won't cause the controller to interpret that as the end of your transmission try to execute a partial command. IOW, you can achieve slightly improved commanding performance by using CTCSS only mode instead of CTCSS AND COS. If you have EOT command execution disabled it doesn't matter, since the carrier squelch chopping will have no effect. BTW, I found the RUS line in Mastr IIs MVPs to have a slight delay on opening even in COS mode, causing the chopping on weak signals to be much more noticeable. I use CAS instead, which has a faster attack time. Bob NO6B
[Repeater-Builder] Microphones for GM300s and a Desktrac Question
All: Kind of off topic, but thought I'd ask. We have 3 GM300's we got for our emergency communications trailer but we didn't get microphones. I have two desk mics that came with a couple repeaters we got a bit ago but we'd really like Hand mics for this application. I'd trade the desk mics (real clean) for hand mics (real clean) if anyone is interested. We are also a 501(c)(3), so donations welcome. Regarding the repeaters... We found two Desktrac repeaters that we're going to use at a museum ship here. They're all setup and ready to go. The one thing about them is that the TX frequency is all over the place for both of them. While warming up they can be more than 1 KHz off. They do drift in to about the correct frequency after warm-up, but still drift back and forth quite a bit (300-500 Hz). Is that normal for these things? (These have MaxTrac radios in them.) Chuck - N8DNX
[Repeater-Builder] Power Supply
Folks, I'm in need of the manual for a Motorola R1011B power supply. Anyone have a spare or a good electronic copy? Please reply direct if you have something that may help me. Thanks very much,
RE: [Repeater-Builder] Power Supply
Gary, The manual for the R1011B bench power supply is 6881069A94, which is still available for purchase from Motorola Parts for about $24. Call 800-422-4210 to order. I saw a few used manuals for sale on eBay, listed as 68P81069A94 for about the same price, not including some significant shipping charges... 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Gary Sent: Saturday, September 20, 2008 2:32 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Power Supply Folks, I'm in need of the manual for a Motorola R1011B power supply. Anyone have a spare or a good electronic copy? Please reply direct if you have something that may help me. Thanks very much,
RE: [Repeater-Builder] Power Supply
Thanks Eric, I didn't know the part number for the manual and a Resource Center search on MOL turned up nothing as did a parts search. I'll look again. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Saturday, September 20, 2008 3:06 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Power Supply Gary, The manual for the R1011B bench power supply is 6881069A94, which is still available for purchase from Motorola Parts for about $24. Call 800-422-4210 to order. I saw a few used manuals for sale on eBay, listed as 68P81069A94 for about the same price, not including some significant shipping charges... 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Gary Sent: Saturday, September 20, 2008 2:32 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Power Supply Folks, I'm in need of the manual for a Motorola R1011B power supply. Anyone have a spare or a good electronic copy? Please reply direct if you have something that may help me. Thanks very much, Yahoo! Groups Links
RE: [Repeater-Builder] Power Supply
Too many times, the available on-line Motorola resources are 100% useless. I find the human touch does a lot better. Call 1-800-422-4210, punch your way through to Parts ID, and ask the person for the right manual and/or part numbers. They have resources that aren't available to the order-takers. It's free too. They don't care who you end up buying it from, but they WILL give you the latest manual or part number to order. Bob M. == --- On Sat, 9/20/08, Gary [EMAIL PROTECTED] wrote: From: Gary [EMAIL PROTECTED] Subject: RE: [Repeater-Builder] Power Supply To: Repeater-Builder@yahoogroups.com Date: Saturday, September 20, 2008, 6:18 PM Thanks Eric, I didn't know the part number for the manual and a Resource Center search on MOL turned up nothing as did a parts search. I'll look again. Gary -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon Sent: Saturday, September 20, 2008 3:06 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Power Supply Gary, The manual for the R1011B bench power supply is 6881069A94, which is still available for purchase from Motorola Parts for about $24. Call 800-422-4210 to order. I saw a few used manuals for sale on eBay, listed as 68P81069A94 for about the same price, not including some significant shipping charges... 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Gary Sent: Saturday, September 20, 2008 2:32 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Power Supply Folks, I'm in need of the manual for a Motorola R1011B power supply. Anyone have a spare or a good electronic copy? Please reply direct if you have something that may help me. Thanks very much,
Re: [Repeater-Builder] Microphones for GM300s and a Desktrac Question
You can use microphones for MaxTracs in your GM300 radios. I'm pretty sure they will also work in the DeskTrac. EBay always has dozens for sale. It's just a matter of whether you want new or used. Some MaxTracs do drift. I've actually seen them go as much as 300 Hz off frequency while transmitting, and it's not as if something heats up. The microprocessor in the radio TELLS it to change frequency. Most annoying. GM300s suffer from dirty contacts between the logic and RF boards. MaxTracs could suffer from the same thing, but for some reason seem to be less prone to it. The only fix is to remove both boards, clean the pins on the connector, and reinstall everything. Not difficult, but you have to take just about the entire radio apart. This might fix the 1 kHz error but the 300-500 Hz error is well within the spec of the radio so there's not much you can do about it. Shouldn't hurt anything on a 5 kHz channel. Bob M. == --- On Sat, 9/20/08, Charles Scott [EMAIL PROTECTED] wrote: From: Charles Scott [EMAIL PROTECTED] Subject: [Repeater-Builder] Microphones for GM300s and a Desktrac Question To: Repeater-Builder@yahoogroups.com Date: Saturday, September 20, 2008, 2:52 PM All: Kind of off topic, but thought I'd ask. We have 3 GM300's we got for our emergency communications trailer but we didn't get microphones. I have two desk mics that came with a couple repeaters we got a bit ago but we'd really like Hand mics for this application. I'd trade the desk mics (real clean) for hand mics (real clean) if anyone is interested. We are also a 501(c)(3), so donations welcome. Regarding the repeaters... We found two Desktrac repeaters that we're going to use at a museum ship here. They're all setup and ready to go. The one thing about them is that the TX frequency is all over the place for both of them. While warming up they can be more than 1 KHz off. They do drift in to about the correct frequency after warm-up, but still drift back and forth quite a bit (300-500 Hz). Is that normal for these things? (These have MaxTrac radios in them.) Chuck - N8DNX
[Repeater-Builder] FS- New Motorola Load
By the way all, I have a new in the box/unused Motorola model T1013A load resistor (dummy load) available. Rated 150w continuous, 300w intermittent up to 1Ghz. These are still current and list for over $400 but I'll let this one go for $100 + shipping just to get it out of here and into the hands of someone that will use it (I have too many loads as it is). Continental U.S. sale only please, shipping out of the country these days is a nightmare. Please reply direct to me if interested. Paypal ok. Thanks, Gary R. N6LRV
RE: [Repeater-Builder] Re: Micor TPN1110A power supply parts ID
I found a junk TPN1110B power supply in my garage, and removed the two heavy diode assemblies. They are, indeed, 1N3492R diodes that are press-fitted into a small aluminum plate marked 64B83562D01 and ink-stamped 1V80739B59. Yes, the last digit is a 9 not a 7 on both of these diode assemblies. No matter, they're both NLA from Motorola Parts. Now, for the good news: Mouser Electronics carries exact-replacement diodes for the 1N3492R, made by NTE as part number NTE5963, for just $ 4.11 each. The NTE diodes have a higher PRV rating of 400 volts. An alternator repair shop can replace the diodes in less than a minute, but the job can also be done with a large bench vise and a couple of sockets. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of kk2ed Sent: Thursday, September 18, 2008 9:49 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Micor TPN1110A power supply parts ID Thanks for the reply/suggestion. A stud mount of greater current rating may be the way to go. I could just drill out of the existing mounting holes and use the stud mount and a nut/washer combo. However, after googling till my eyes fell asleep, I found a few sources on the web for the original diode - which turns out to be a 1N3492R. So that takes care of the diodes - snip Eric KE2D major snip
[Repeater-Builder] Update on the MICOR Community Repeater project
Well, I got this thing all reassembled and tuned up on the new frequency pair. a fellow ham (who used to work for the local Motorola shop) came over with his service monitor and we tuned and tested the system. It is still not passing PL to the transmitter. Some PL bleeds through from the receive, but I know that is not correct - nor is it of sufficient level. (I only get about 90 Hz of deviation with this PL.) We took a CLOSE look at the Master Decoder card itself and it appears to be configured VERY differently than the later version depicted in my manual. For example, the later version card (based on two ICs) has no connection on Pin 24 to the backplane. My card (an earlier version with discreet components) appears to have some sort of signal (audio) on Pin 24. So I need desperately to find either the manual pages pertaining to my older Master Decoder card, or I need a newer version card. If ANYONE has either of these, I'd be much obliged of you would contact me. The issue HAS to be the Master Decoder card - it is not passing any PL to the exciter. The problem is, I have about 8 of the same vintage Master Decoder card, so changing them out is not resolving the issue. For the time being, I am going to put the machine on the air as-is. it works just fine, other than it will have to be CSQ receive for all users. I'll decide later on whether I will put in a tone panel, or continue to operate it as it is now. Mark - N9WYS / WQIV271
RE: [Repeater-Builder] Repeater Audio War Stories (Story #741)
Nate - I still remember the album sleeve for the Rolling Stones' Let It Bleed album... Lower right corner: THIS RECORD SHOULD BE PLAYED LOUD Mark - N9WYS -Original Message- From: Repeater-Builder@yahoogroups.com On Behalf Of Nate Duehr Bob M. wrote: He was into the hard rock stuff in the 80s and his hearing has been poor since then. (snip) And then of course there's also a bit of that accursed evil rock and roll in my life... I try to keep it turned down, but every once in a while you just have to go with ... I hear if you mix it with a little Chopin and Bach, it all works out okay in the end. (GRIN) If it's too loud, you're too old! Rock on, Nate WY0X
RE: [Repeater-Builder] Re: Does anyone else think of Power Factor like SWR?
Yes standing waves can exist with a pure resistive load on a line but the mismatch of the load with the line impedance creates a reactance (depending on line length). A transmission line must be long enough (wavelength wise) for standing waves to exist. A short line (wavelength wise) like an audio cable, will not exhibit standing waves because it is too short for them to exist. Even a short (wavelength wise) RF cable will not exhibit standing waves. Keep in mind that the typical SWR and power meters that we use to measure SWR with are NOT really measuring SWR. They are measuring impedance mismatch of the internal impedance that the meter is set for, with a scale on the meter that converts the impedance ratio to a would be SWR. A very long power transmission line can have standing waves on it if the power factor problems are not kept in check. So power factor could be thought of like SWR but only on long distribution lines. Keep in mind that short transmission lines whether it be power, audio or RF do not have standing waves on them when they are very short wavelength wise. 73 Gary K4FMX -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:Repeater- [EMAIL PROTECTED] On Behalf Of Nigel Johnson Sent: Saturday, September 20, 2008 7:26 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Does anyone else think of Power Factor like SWR? Very interesting theory. I am teaching SWR at present to my third year college students. Could be a good discussion point since they have already studied power factor. However, SWR can exist with a purely resistive mismatched load, so it needs a bit of modification to take all into account. 73 Nigel ve3id --- In Repeater-Builder@yahoogroups.com, Bob Witte K0NR [EMAIL PROTECTED] wrote: --- In Repeater-Builder@yahoogroups.com, kb9bpf kb9bpf@ wrote: Since I'm way more into RF than industrial power distribution, I've always been able to think of power factor on the electrical power grid in terms similar to antenna system reflections, which are commonly measured in terms of SWR. After all, both are AC systems where the voltage and current bear a phase relationship to each other. When they are perfectly in phase the power factor is 1.0, and a 60-Hz SWR meter would measure 1:1. When they are out of phase (power factor 1) that SWR meter would read greater than 1:1. I suspect, though I haven't done the math or looked up the specific matahematical definition of power factor, that it would be direcly proportional to the reciprocal of the power factor. And as we know, when that happens the power generating end has more difficulty delivering power efficiently to the load. A while back I was doing some analysis of power factor to understand it better and I found that it has a lot in common with SWR. Both are focused on the issue of power transfer, so I guess we shouldn't be surprised. The thing they really have in common is for max power with AC signals, the voltage and current need to be in phase (phase angle of zero). For linear systems with nice sine waves, PF = cos (phase angle) where phase angle = the angle between voltage and current sinusoids Wikipedia has a good explanation of PF at http://en.wikipedia.org/wiki/Power_factor Play around with some typical circuits and you'll find that an SWR of 1 also has voltage and current in phase. Again, not a surprise since it represents the best power transfer. This is from memory, so the usual disclaimers apply :-) 73, Bob K0NR Yahoo! Groups Links
[Repeater-Builder] Midland 13-509
Anyone needing an original owners guide for the Midland 13-509, email me offline. Bruce K7IJ **Looking for simple solutions to your real-life financial challenges? Check out WalletPop for the latest news and information, tips and calculators. (http://www.walletpop.com/?NCID=emlcntuswall0001)
RE: [Repeater-Builder] Update on the MICOR Community Repeater project
Mark, I could not find the previous messages on your thread, so please restate the module numbers of the Master Decoder and Unified Chassis Backplane that you now have. Do all of the backplanes have the same number stamped in black ink on them? The number I am referring to is the number stamped along one edge of the PC board itself, not on sheet metal parts. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of n9wys Sent: Saturday, September 20, 2008 7:33 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Update on the MICOR Community Repeater project Well, I got this thing all reassembled and tuned up on the new frequency pair. a fellow ham (who used to work for the local Motorola shop) came over with his service monitor and we tuned and tested the system. It is still not passing PL to the transmitter. Some PL bleeds through from the receive, but I know that is not correct - nor is it of sufficient level. (I only get about 90 Hz of deviation with this PL.) We took a CLOSE look at the Master Decoder card itself and it appears to be configured VERY differently than the later version depicted in my manual. For example, the later version card (based on two ICs) has no connection on Pin 24 to the backplane. My card (an earlier version with discrete components) appears to have some sort of signal (audio) on Pin 24. So I need desperately to find either the manual pages pertaining to my older Master Decoder card, or I need a newer version card. If ANYONE has either of these, I'd be much obliged of you would contact me. The issue HAS to be the Master Decoder card - it is not passing any PL to the exciter. The problem is, I have about 8 of the same vintage Master Decoder card, so changing them out is not resolving the issue. For the time being, I am going to put the machine on the air as-is. it works just fine, other than it will have to be CSQ receive for all users. I'll decide later on whether I will put in a tone panel, or continue to operate it as it is now. Mark - N9WYS / WQIV271
