Good day all. I've been away from the keyboard and radios in general in the recent past. I guess the best term to use would be "Sidetracked". The weather here has been horrendously cold, and so I had to take the head for my radio out of the car to prevent damage to the display. I did get on the air last weekend long enough to be net control for the weekly new ham net and to participate in the ARES net that follows the first one.
I'm still patiently working on my local repeater/link system. My most recent efforts have been to included a control link using FRS radios (Which I have many of). I'd like to keep all control off the primary channels. I'd also like to have some sort of combination DTMF control with Voice response system using text to speech synthesis. So my efforts since my last post have been along the lines of how to add those elements to this project. I've been doing copious amounts of research on text to speech trying to find something that sounds pretty natural without breaking the bank. There are lots of very robotic sounding text to speech applications, some of which would run quite handily on a Raspberry Pi. But I'm aiming for something that is completely understandable without having to do much fiddling with getting the sound I want from the voice.
The beginning of the solution that I've come up with is to use one of my old Android phones (I have two) with a great sounding text to speech dataset already loaded on it, and the write a simple text to speech app that I can connect to via bluetooth and send commands to produce speech from the phone.
The other side of the busy coin is that work has been an absolute zoo for the last couple weeks. By trade I'm a computer desktop support person. And we've had some real head scratchers come through the office in the last couple week. Most recently an HP laptop which needed a hard drive replaced. The factory restore disks turned out to have a bad driver on them which prevented certain things from taking place on the laptop. Installs and updates most notably. After beating my head against this for several days, I found an obscure reference to updating this particular driver along with links to it. Turned out to be an HP update for the driver in question. Installed the driver, and boom, things started working. Prior to that I had tried reinstalling the image 3 times, an in place upgrade once, and full on plain vanilla install once. The vanilla install actually worked, but the license key on the bottom of the laptop was unreadable, and the one I recovered from the semi-working image wasn't accepted by Microsoft as being valid.
Monday, I spent a morning in a snow drift on a county road just north of the Fayette/Buchannan County line. Had to wait for the county maintainer to show up with his plow and pull me out. Then I got stuck again while I was turning around. That was just plain embarrassing. I live in Iowa, so snow is inevitable. I'm not complaining about that at all. If I didn't want to be here, I'd move to a warmer climate. Although I think this year that might have to be South America since Florida and Texas are experiencing hard freezes and ice/snow storms.
Enough rambling. Hope you've had a fun filled couple weeks. When I get the chance to get back to it, I'll post updates on the repeater. It won't be this weekend though. Going to be doing a ham broadband seminar at the public library so that will keep me busy.
73
Steve
KDØWSW
Friday, January 31, 2014
Monday, January 20, 2014
It works . . . I think
After programming the Motorola GM300 VHF radio yesterday, I built a simple interface cable to be able to connect up a non-Motorola microphone and a PTT button. For that, I used a headset I had lying around and a big button designed to be used on a commercial video game. I also took the time to add a Dean's power connector to the pigtail I was using for the radio so I could connect it up to the power supply the right way. For the antenna, I picked up a mini-uhf to so-239 adapter at Radio-Shack and hooked up my usual 3 element yagi.
I was able to key the repeater, but the operator I talked with said my audio was low. And that's entirely possible. Motorola uses a pre-amplified microphone, so there may not have been enough output from the setup I was using.
So I'd say that this purchase was a qualified success. Qualified in that there will need to be more testing done to see if the radio is able to actually perform the functions I have in mind for it. Function one is as a digital coms radio. Both APRS and digital packet. APRS will require that I get a TNC, but general packet I can do with a simple homebrew interface and a computer. My junkbox has expanded enough that I should be able to bolt together the interface, and I have a spare quad core AMD computer around that I can use as the host system. Function 2 would be an Echolink radio. Again, I need the interface and computer. But I think I can use the same interface and computer for general digital and Echolink. The last function would be as a repeater system when combined with another radio. This fits in with my original overall project for this year.
Having worked with Motorola radios for years in law enforcement, I've come to view them as sturdy and well built. Pretty much able to take any punishment dished out to them. After some continued research on the net, I find that this isn't the case for the GM300. It's very much a consumer level device, meaning it's the standard 5-5-90 duty cycle. I'm hoping that by adding a temerature controlled fan or fans on the heatsink for the PA deck, that I can "adjust" the duty cycle into something a little more useable.
Time for work. Have a wonderful day!
73
Steve
KDØWSW
I was able to key the repeater, but the operator I talked with said my audio was low. And that's entirely possible. Motorola uses a pre-amplified microphone, so there may not have been enough output from the setup I was using.
So I'd say that this purchase was a qualified success. Qualified in that there will need to be more testing done to see if the radio is able to actually perform the functions I have in mind for it. Function one is as a digital coms radio. Both APRS and digital packet. APRS will require that I get a TNC, but general packet I can do with a simple homebrew interface and a computer. My junkbox has expanded enough that I should be able to bolt together the interface, and I have a spare quad core AMD computer around that I can use as the host system. Function 2 would be an Echolink radio. Again, I need the interface and computer. But I think I can use the same interface and computer for general digital and Echolink. The last function would be as a repeater system when combined with another radio. This fits in with my original overall project for this year.
Having worked with Motorola radios for years in law enforcement, I've come to view them as sturdy and well built. Pretty much able to take any punishment dished out to them. After some continued research on the net, I find that this isn't the case for the GM300. It's very much a consumer level device, meaning it's the standard 5-5-90 duty cycle. I'm hoping that by adding a temerature controlled fan or fans on the heatsink for the PA deck, that I can "adjust" the duty cycle into something a little more useable.
Time for work. Have a wonderful day!
73
Steve
KDØWSW
Sunday, January 19, 2014
Buyer Beware
I spent yesterday afternoon working on building my interface for the Motorola Radius GM300 I bought. Between that and having to watch the granddaughter, I didn't get the opportunity to test last night.
First issue. The GM300 RadioDoctor software that I downloaded couldn't find a dll file it was looking for. Seems that the file in question isn't necessarily available on Windows 7 x64. So after scouring the net, I found the file and instructions on where to put it and registering it on my system. After that, the program started up.
Hooked up the TTL converter to the computer, and Windows dutifully downloaded the correct drivers to make it work. Connected the other end to the radio, connected power to the radio, turned the radio on, and started up the software. The software was unable to find the radio. I looked to see if there was some way to set up the software to specifiy the com port to use, since I was sure it was a "non-standard" port number. No such setup was found, nor was any mention made of it on the net. Went into device manager, and changed the port so that it was COM1. That made a difference. At least the led's on the ttl interface were flashing indicating that the software was trying to communicate. But it was still unable to find the radio.
I pulled the plug out of the radio to check the wiring there. Pin 7 was supposed to be the serial data, Pin 4 is ground. There seems to be conflicting information on the web as to what constitutes Pin 1 on an RJ-45 connector when it comes to Motorola radios. The correct answer is, with the cable end of the plug facing you and the pin end facing away from you with the retaining clip side pointed toward the floor, Pin 1 is on your right and Pin 8 is on your left. I had connected to the wrong pins the first time around. I had used a short piece of CAT-5 cable to make that part of the programmer, so it was a matter of identifying the correct color wires for those pin positions and then connecting those to the DB-9F I was using.
Connected everything back up, tried the software again, still no communication. I had noticed and commented that on the blog of the Fireman that his schematic diagram differed from the original one in that the diode was pointed the opposite direction. I had taken it upon myself to flip the diode when doing my assembly. So on the off chance I was wrong, I took things apart and rewired it with the diode facing the direction that was indicated by the original poster.
Reconnected everything and tried again. This time both the tranmit and receive led's flashed, but still no communication with the radio.
As a final step, I went back to the Fireman's blog and re-read everything. Besides the diagram, he had also posted a picture of his final assembly on the DB-9F. After spending some time comparing the photo with the diagram, I came to the conclusion that the two didn't match. So I disassembled everything again, and built it so that it matched his picture from an electrical standpoint. I mention this because I was using axial lead parts that I had in the junk box, and he used chip style parts.
Plugged everything together, started up the software, turned on the radio, told the software to read from the radio. Drum roll please ... It worked! Wow. So I programmed in the frequencies for the local repeater. I have not tested the radio yet, but I'm hopeful. First I have to put together some sort of microphone for it since it didn't come with one. Should be able to bang that out in fairly short order.
On to the next order of business.
73
Steve
KDØWSW
First issue. The GM300 RadioDoctor software that I downloaded couldn't find a dll file it was looking for. Seems that the file in question isn't necessarily available on Windows 7 x64. So after scouring the net, I found the file and instructions on where to put it and registering it on my system. After that, the program started up.
Hooked up the TTL converter to the computer, and Windows dutifully downloaded the correct drivers to make it work. Connected the other end to the radio, connected power to the radio, turned the radio on, and started up the software. The software was unable to find the radio. I looked to see if there was some way to set up the software to specifiy the com port to use, since I was sure it was a "non-standard" port number. No such setup was found, nor was any mention made of it on the net. Went into device manager, and changed the port so that it was COM1. That made a difference. At least the led's on the ttl interface were flashing indicating that the software was trying to communicate. But it was still unable to find the radio.
I pulled the plug out of the radio to check the wiring there. Pin 7 was supposed to be the serial data, Pin 4 is ground. There seems to be conflicting information on the web as to what constitutes Pin 1 on an RJ-45 connector when it comes to Motorola radios. The correct answer is, with the cable end of the plug facing you and the pin end facing away from you with the retaining clip side pointed toward the floor, Pin 1 is on your right and Pin 8 is on your left. I had connected to the wrong pins the first time around. I had used a short piece of CAT-5 cable to make that part of the programmer, so it was a matter of identifying the correct color wires for those pin positions and then connecting those to the DB-9F I was using.
Connected everything back up, tried the software again, still no communication. I had noticed and commented that on the blog of the Fireman that his schematic diagram differed from the original one in that the diode was pointed the opposite direction. I had taken it upon myself to flip the diode when doing my assembly. So on the off chance I was wrong, I took things apart and rewired it with the diode facing the direction that was indicated by the original poster.
Reconnected everything and tried again. This time both the tranmit and receive led's flashed, but still no communication with the radio.
As a final step, I went back to the Fireman's blog and re-read everything. Besides the diagram, he had also posted a picture of his final assembly on the DB-9F. After spending some time comparing the photo with the diagram, I came to the conclusion that the two didn't match. So I disassembled everything again, and built it so that it matched his picture from an electrical standpoint. I mention this because I was using axial lead parts that I had in the junk box, and he used chip style parts.
Plugged everything together, started up the software, turned on the radio, told the software to read from the radio. Drum roll please ... It worked! Wow. So I programmed in the frequencies for the local repeater. I have not tested the radio yet, but I'm hopeful. First I have to put together some sort of microphone for it since it didn't come with one. Should be able to bang that out in fairly short order.
On to the next order of business.
73
Steve
KDØWSW
Saturday, January 18, 2014
Holding Pattern
Been quite silent again this week. Mostly because there's not much to report. I did order in and receive another radio to replace the one I toasted. I haven't done anything to it other than charge it up.
The reason I'm in a holding pattern is because I discovered Motorola Radius GM300 radios for sale on Ebay. I'm still looking for something that I can use for a dedicated APRS radio, and for something that's more of a tank (read indestructible) when it comes to constant usage. I still definitely want to do the repeater setup using the HT's but I'm also very intrigued by the idea of taking these business radios that are built for everyday constant usage and building repeater setups with them. I'm betting that there would less issues with the blanking describe early on in my blog. And while the radios I bought (I bought 4 of them. 2 VHF and 2 UHF) are all different versions and have 8 or 16 channels, I'm only expecting to use one channel on each of them anyway. If you keep an eye open and bid judiciously, you can ususally pick on up for $35 to $40 plus shipping. A word of warning though, you need to become familiar with the Radius model numbering system. Most sellers will put the model number in the auction details. Various parts of the number describe the band, the radio's output power, and the band split. There are plent of places on the net to find that information. Be sure to verify that the radio will suit your needs before you bid.
The catch is that I have to be able to program them. The original Motorola programming software is DOS based. And in 2014, running DOS programs is next to impossible. One possibility is and XP version of software that I found. That should run under Windows 7. The other possibility is to run the original software using something called DOSBOX. DOSBOX is a DOS emulator that runs in Windows either in a window or full screen. It has the ability to redirect calls to COM1 and COM2 to specific COM ports on the host operating system. I'm betting that it should be good enough to satisfy the Motorola RSS software.
The other issue is that I technically need something called a 'RIB'. I think it stands for "Radio Interface Box". That provides the interface between the radio being programmed and the computer. One end connects to the serial port on the computer, and the other is a cable that's designed to connect to the radio you're working on. One RIB box can connect to many different radios by swapping out the interface cable. However, as you might suspect, I don't have one. And to compound things, most modern computers don't have serial ports anymore. So in true DIY fashion, I'll build one.
I found an article by a volunteer firefighter here: http://mikepuchol.com/2007/06/25/building-a-usb-programmer-for-motorola-radios/comment-page-1/#comment-4772 Which details creating an interface from a USB to Serial converter. I'm going to approach it from a different angle. A company by the name of SparkFun makes a product they call a Breakout Board. This board has an FT232RL chip and a mini USB connector. This is already a USB to Serial TTL converter, so no additional chips or modifications are required to be able to use it! Here's the link: https://www.sparkfun.com/products/718.
My thought is that by using the schematic he published for the interface cable portion of the project with this breakout board, I should be in business.
I just need a couple things to get going, which I can pick up here in town, and of course it's snowing! Driving in the snow doesn't bother me in the least. It's all the other drivers that don't seem to have appropriate winter driving skills that bother me. So I'll hang back for a while and see what the weather does.
73
Steve
KDØWSW
The reason I'm in a holding pattern is because I discovered Motorola Radius GM300 radios for sale on Ebay. I'm still looking for something that I can use for a dedicated APRS radio, and for something that's more of a tank (read indestructible) when it comes to constant usage. I still definitely want to do the repeater setup using the HT's but I'm also very intrigued by the idea of taking these business radios that are built for everyday constant usage and building repeater setups with them. I'm betting that there would less issues with the blanking describe early on in my blog. And while the radios I bought (I bought 4 of them. 2 VHF and 2 UHF) are all different versions and have 8 or 16 channels, I'm only expecting to use one channel on each of them anyway. If you keep an eye open and bid judiciously, you can ususally pick on up for $35 to $40 plus shipping. A word of warning though, you need to become familiar with the Radius model numbering system. Most sellers will put the model number in the auction details. Various parts of the number describe the band, the radio's output power, and the band split. There are plent of places on the net to find that information. Be sure to verify that the radio will suit your needs before you bid.
The catch is that I have to be able to program them. The original Motorola programming software is DOS based. And in 2014, running DOS programs is next to impossible. One possibility is and XP version of software that I found. That should run under Windows 7. The other possibility is to run the original software using something called DOSBOX. DOSBOX is a DOS emulator that runs in Windows either in a window or full screen. It has the ability to redirect calls to COM1 and COM2 to specific COM ports on the host operating system. I'm betting that it should be good enough to satisfy the Motorola RSS software.
The other issue is that I technically need something called a 'RIB'. I think it stands for "Radio Interface Box". That provides the interface between the radio being programmed and the computer. One end connects to the serial port on the computer, and the other is a cable that's designed to connect to the radio you're working on. One RIB box can connect to many different radios by swapping out the interface cable. However, as you might suspect, I don't have one. And to compound things, most modern computers don't have serial ports anymore. So in true DIY fashion, I'll build one.
I found an article by a volunteer firefighter here: http://mikepuchol.com/2007/06/25/building-a-usb-programmer-for-motorola-radios/comment-page-1/#comment-4772 Which details creating an interface from a USB to Serial converter. I'm going to approach it from a different angle. A company by the name of SparkFun makes a product they call a Breakout Board. This board has an FT232RL chip and a mini USB connector. This is already a USB to Serial TTL converter, so no additional chips or modifications are required to be able to use it! Here's the link: https://www.sparkfun.com/products/718.
My thought is that by using the schematic he published for the interface cable portion of the project with this breakout board, I should be in business.
I just need a couple things to get going, which I can pick up here in town, and of course it's snowing! Driving in the snow doesn't bother me in the least. It's all the other drivers that don't seem to have appropriate winter driving skills that bother me. So I'll hang back for a while and see what the weather does.
73
Steve
KDØWSW
Sunday, January 12, 2014
I killed it (the radio that is)
Started working today on the external electronics required to make all of this work together. Step one was to breadboard a simple 4n33 opto-isolator to connect the radio to the outside world. But when I checked the circuit as connected to the radio, I was getting voltage where I shouldn't.
So I ended up taking the radio apart again. I found that I had misconnected a wire. I hooked up some 30ga wirewrap wire to the correct locations, and then connected those to the 24ga I had originally used. Tested with the radio disassembled, it worked, and so I put it back together. Things sort of devolved from there.
The radio no longer transmits or receives, although the cpu still seems to be working. So something is fried on the back side of the board. I'll keep it for spare parts for the other UV-5R I have. And this particular project is now dead.
I'd still like to do a combo cross-band/in-band portable repeater system, and I may still using some small mobiles of some sort. Something that's easier for me to work on.
If something breaks loose, I'll post it. But for now, I'm done.
** Edit **
After considerable thinking about the problem, I've decided to re-activate the project and order in another UV-5R from Amazon.
I know where I made my mistakes, and I intend to fully document this in case anyone else decides to do the same thing.
Issue one was that I originally used 24ga solid wire that I had around. If I had connected everything up right the first time, it would have been ok. But when I put everything back together, I pulled the excess wire out of the radio because there was no place for it to go. That made disassembling the radio again next to impossible because of how I attached the 3.5mm jack to the side of the radio. There was no slack to allow the radio to be taken apart again if necessary.
Issue two was that in adding the additional length of 30ga wire, the original 24ga wires were no longer routed as they had been initially and were subject to pinch points during re-assembly of the radio. This cause shorting between the wire carrying the positive power and ground as represented by the metal frame around the display. So by repeated disassembly and reassembly the radio finally decided it had had enough.
On the next try, I need to see if I can work out a better routing for the wires. Something that will avoid the metallic pinch points.
That's all for now.
73
Steve
KDØWSW
So I ended up taking the radio apart again. I found that I had misconnected a wire. I hooked up some 30ga wirewrap wire to the correct locations, and then connected those to the 24ga I had originally used. Tested with the radio disassembled, it worked, and so I put it back together. Things sort of devolved from there.
The radio no longer transmits or receives, although the cpu still seems to be working. So something is fried on the back side of the board. I'll keep it for spare parts for the other UV-5R I have. And this particular project is now dead.
I'd still like to do a combo cross-band/in-band portable repeater system, and I may still using some small mobiles of some sort. Something that's easier for me to work on.
If something breaks loose, I'll post it. But for now, I'm done.
** Edit **
After considerable thinking about the problem, I've decided to re-activate the project and order in another UV-5R from Amazon.
I know where I made my mistakes, and I intend to fully document this in case anyone else decides to do the same thing.
Issue one was that I originally used 24ga solid wire that I had around. If I had connected everything up right the first time, it would have been ok. But when I put everything back together, I pulled the excess wire out of the radio because there was no place for it to go. That made disassembling the radio again next to impossible because of how I attached the 3.5mm jack to the side of the radio. There was no slack to allow the radio to be taken apart again if necessary.
Issue two was that in adding the additional length of 30ga wire, the original 24ga wires were no longer routed as they had been initially and were subject to pinch points during re-assembly of the radio. This cause shorting between the wire carrying the positive power and ground as represented by the metal frame around the display. So by repeated disassembly and reassembly the radio finally decided it had had enough.
On the next try, I need to see if I can work out a better routing for the wires. Something that will avoid the metallic pinch points.
That's all for now.
73
Steve
KDØWSW
Saturday, January 11, 2014
Silence is golden
It's been eerily silent this week. Both at work and from me. I think possibly the extreme cold has kept people indoors.
The project it still on. I did get one radio modified as mentioned in my last post, but I still haven't tested it. Time that I would have used for testing was spent helping a fellow ham with his computer issues. Both over the phone and then at his house. That took a considerable amount of time. Not complaining here. I was more than happy to help. Just took time away from the project.
Before I go on with the project, I need to do some additional parts recovery from some old circuit boards I've collected. So that will be this evenings procedings. If I can move forward, I will put together a simple repeater circuit to test with and work from there.
Until next time,
73
Steve
KDØWSW
The project it still on. I did get one radio modified as mentioned in my last post, but I still haven't tested it. Time that I would have used for testing was spent helping a fellow ham with his computer issues. Both over the phone and then at his house. That took a considerable amount of time. Not complaining here. I was more than happy to help. Just took time away from the project.
Before I go on with the project, I need to do some additional parts recovery from some old circuit boards I've collected. So that will be this evenings procedings. If I can move forward, I will put together a simple repeater circuit to test with and work from there.
Until next time,
73
Steve
KDØWSW
Sunday, January 5, 2014
The $30 lesson revisited
I may have been premature in declaring my radio dead. Further investigation revealed that what I had broken was the back light assembly. The display rests on top of it. The LED is on the side post and the side post appears to have been glued to the part of the back light that runs under the display. So I made the "executive" decision to complete the mod and reassemble the radio. At this moment I'm waiting on some Oogoo to set. Once that's done and I get some final pictures taken I'll put up a post about the whole process.
** Edit **
Just tested the reassembled radio. Guess I was worried about nothing. The display worked, the backlight worked, and the transmit/receive LED's worked. I haven't tested the wires I brought outside the radio yet, but they are attached to the receive LED, and I ohmed them out before I put the case back together so they should be good.
73
Steve
KDØWSW
** Edit **
Just tested the reassembled radio. Guess I was worried about nothing. The display worked, the backlight worked, and the transmit/receive LED's worked. I haven't tested the wires I brought outside the radio yet, but they are attached to the receive LED, and I ohmed them out before I put the case back together so they should be good.
73
Steve
KDØWSW
Saturday, January 4, 2014
The $30 lesson
I'm sure you can guess what's coming based on the dollar amount in the title.
Today, to get started on my cross-band repeater, I needed to modify one of the UV-5R Baofeng radios to have a COR output. This output, also known as COS, is a way to tell the repeater controller that a valid signal is being received and that the transmitter should be keyed. Since this is a cross band system, both radios need to provide that signal. This is going to require that I disassemble the radios, locate that signal, add a couple parts, and then put things back together. Fortunately, another ham has already taken one of these apart and posted instruction. So I got to follow in his footsteps.
Basically, the process is to remove the antenna, the volume knob, the battery, the round nuts securing the antenna jack and the volume control. On the back, remove all the screws you can see. You will need both a philips and a torx bit screw driver. The torx bit I used was a T9.
With the screws removed, you need to separate the heatsink from the front of the radio. I used a very small flat bladed screw driver and gently pried up starting in the middle of the bottom in the slot I found there. I had to gently help it along by prying in various places on each side. It finally came loose enough to remove. At this point, the speaker which is mounted in the face of the radio will still be connected to the radio circuit board. You can disconnect it or not. It's up to you. I left mine connected this time, but on the next one I will probably disconnect it.
The places I needed to access are on what would be the back side of the circuit board. I didn't remember to take pictures of this part but I'll do my best to describe it. As you're looking at the radio, you will see several philips screws scattered around the circuit board. Those all need to be removed. Here's the gotcha. ** There are 3 screws under the LCD display that have to be removed to get the circuit board off the heatsink. ** This requires that the LCD display be removed. This removal was not covered in the original instructions other than to say that it needed to be done. And this is where the lesson comes in.
The LCD is held in place by two screw facing the bottom of the radio, which you should have already removed in the previous step. On the opposite side, there are two tabs that bend over the edge of the circuit board. I mistakenly believed that the display was connected with some sort of connector or contact device similar to what ICOM does or did with their displays. I was *wrong*. The display is actually soldered to the circuit board on one end.
This is a picture of the LCD connector, minus the LCD display where it connects to the circuit board. I presume that this needs to be unsoldered prior to attempting to remove the display. Based on my previous erroneous assumption, I broke the display from its connector when I was trying to remove it. The $30 lesson learned. So this radio is toast. But I can still use it as a learning tool. Doesn't make me any happier though.
So here is a picture of the whole circuit board.
73
Steve
KDØWSW
Today, to get started on my cross-band repeater, I needed to modify one of the UV-5R Baofeng radios to have a COR output. This output, also known as COS, is a way to tell the repeater controller that a valid signal is being received and that the transmitter should be keyed. Since this is a cross band system, both radios need to provide that signal. This is going to require that I disassemble the radios, locate that signal, add a couple parts, and then put things back together. Fortunately, another ham has already taken one of these apart and posted instruction. So I got to follow in his footsteps.
Basically, the process is to remove the antenna, the volume knob, the battery, the round nuts securing the antenna jack and the volume control. On the back, remove all the screws you can see. You will need both a philips and a torx bit screw driver. The torx bit I used was a T9.
With the screws removed, you need to separate the heatsink from the front of the radio. I used a very small flat bladed screw driver and gently pried up starting in the middle of the bottom in the slot I found there. I had to gently help it along by prying in various places on each side. It finally came loose enough to remove. At this point, the speaker which is mounted in the face of the radio will still be connected to the radio circuit board. You can disconnect it or not. It's up to you. I left mine connected this time, but on the next one I will probably disconnect it.
The places I needed to access are on what would be the back side of the circuit board. I didn't remember to take pictures of this part but I'll do my best to describe it. As you're looking at the radio, you will see several philips screws scattered around the circuit board. Those all need to be removed. Here's the gotcha. ** There are 3 screws under the LCD display that have to be removed to get the circuit board off the heatsink. ** This requires that the LCD display be removed. This removal was not covered in the original instructions other than to say that it needed to be done. And this is where the lesson comes in.
The LCD is held in place by two screw facing the bottom of the radio, which you should have already removed in the previous step. On the opposite side, there are two tabs that bend over the edge of the circuit board. I mistakenly believed that the display was connected with some sort of connector or contact device similar to what ICOM does or did with their displays. I was *wrong*. The display is actually soldered to the circuit board on one end.
So here is a picture of the whole circuit board.
The larger chip on the left is the CPU for the radio. The chip on the right is the radio itself. I have to go back to the original poster's instructions to find the chip that has the output I'm looking for, but both chips are identified there.
So there you have it, the $30 lesson. At this point I'm going to fall back and regroup. As much as I want to do this project, I really can't afford to continue learning these types of lessons.
I'll keep you posted.
Steve
KDØWSW
Friday, January 3, 2014
To blank or not to blank, that is the question.
Although I'm ready to proceed full speed ahead with my cross-band repeater project, I thought it might be prudent to do some initial testing to check on some of my theories.
Specifically, and I'm not sure of the correct technical term here I think it's saturation, the blanking of the receiver that occurs when a receiver is close to a transmitter on an adjacent frequency. This is especially true when using these low cost radios. They don't have the selectivity to reject close by, slightly off frequency signals. In this case, slightly off frequency is 600 KHz, which is the standard offset of 2 meter amateur radio repeaters. Why is that important?
Well, even though the stated goal of this project is a cross-band repeater, which would involve band seperation of several hundred MHz, my original desire and goal prior to this project was to assemble a portable special event/emergency deployment repeater system that could be used on 2 meters.
My desired configuration of these radios is shown in the picture below:
The picture here shows the two radios, positioned with the transmitter on the top and the receiver on the bottom. In actual operation, they will be separated by a center compartment of aproximately 8 to 10 inches. It was my hope that that distance combined with some metal shielding between the radios would eliminate this blanking. Thus eliminating the need for the costly and bulky system of caveties that are normally required in permanent repeater installations. Unfortunately, this doesn't appear to be the case. And to be fair, I'm not the first person to consider using HT's as a temporary repeater. I've seen on the web at least a couple "kits" that consists of a metal briefcase, pluckout foam, and a repeater controller. Many commenters on those pages ask the same questions I'm asking myself about the blanking and intermod without having the cavities in place. And so far I've not seen any real answers. That's why I'm experimenting.
In a different test, I turned the transmitter down to one watt and then stepped about 5 feet away from the receiver. That test produced good results. I was able to trip the repeater with the transmitter, and the receiver picked it up during the whole test without the blanking effect.
So the next question is, how far do the antennas have to be separated to allow the transmitter to work at full power? And rather than physical spearation, would it make a significant difference if a non-standard offset was used. Some research indicates that it would be possible to get a 2.4 MHz separation, and still stay within the published national band plan. (Iowa doesn't have a "published" band plan, at least not one that's readily accessible to regular operators like me.)
I would expect that as long as this is used on a temporary basis, is low power (5 watts or less), is within the established band plan, and in all respects in compliance with part 97 that the repeater would not have to be coordinated at the state level and could use a non-standard offset.
In order to test this with a non-standard offset, I'll need to go forward with modifying the radios to have a COR output and build a rudimentary repeater controller and use a couple additional radios to test with. Rather than a full-on build of the controller, I'll try putting something together on my breadboard. Anything I come up with I can transfer to something more permanent later.
That's all for today. The weekend is coming, so I hope to get started on more stuff.
73
Steve
KDØWSW
Specifically, and I'm not sure of the correct technical term here I think it's saturation, the blanking of the receiver that occurs when a receiver is close to a transmitter on an adjacent frequency. This is especially true when using these low cost radios. They don't have the selectivity to reject close by, slightly off frequency signals. In this case, slightly off frequency is 600 KHz, which is the standard offset of 2 meter amateur radio repeaters. Why is that important?
Well, even though the stated goal of this project is a cross-band repeater, which would involve band seperation of several hundred MHz, my original desire and goal prior to this project was to assemble a portable special event/emergency deployment repeater system that could be used on 2 meters.
My desired configuration of these radios is shown in the picture below:
The picture here shows the two radios, positioned with the transmitter on the top and the receiver on the bottom. In actual operation, they will be separated by a center compartment of aproximately 8 to 10 inches. It was my hope that that distance combined with some metal shielding between the radios would eliminate this blanking. Thus eliminating the need for the costly and bulky system of caveties that are normally required in permanent repeater installations. Unfortunately, this doesn't appear to be the case. And to be fair, I'm not the first person to consider using HT's as a temporary repeater. I've seen on the web at least a couple "kits" that consists of a metal briefcase, pluckout foam, and a repeater controller. Many commenters on those pages ask the same questions I'm asking myself about the blanking and intermod without having the cavities in place. And so far I've not seen any real answers. That's why I'm experimenting.
In a different test, I turned the transmitter down to one watt and then stepped about 5 feet away from the receiver. That test produced good results. I was able to trip the repeater with the transmitter, and the receiver picked it up during the whole test without the blanking effect.
So the next question is, how far do the antennas have to be separated to allow the transmitter to work at full power? And rather than physical spearation, would it make a significant difference if a non-standard offset was used. Some research indicates that it would be possible to get a 2.4 MHz separation, and still stay within the published national band plan. (Iowa doesn't have a "published" band plan, at least not one that's readily accessible to regular operators like me.)
I would expect that as long as this is used on a temporary basis, is low power (5 watts or less), is within the established band plan, and in all respects in compliance with part 97 that the repeater would not have to be coordinated at the state level and could use a non-standard offset.
In order to test this with a non-standard offset, I'll need to go forward with modifying the radios to have a COR output and build a rudimentary repeater controller and use a couple additional radios to test with. Rather than a full-on build of the controller, I'll try putting something together on my breadboard. Anything I come up with I can transfer to something more permanent later.
That's all for today. The weekend is coming, so I hope to get started on more stuff.
73
Steve
KDØWSW
Wednesday, January 1, 2014
The build is on
OK, It's a new year. So time for a new project. I went ahead and ordered in 2 of the Baofeng UV-5Rs. (Amazon for $29 each plus shipping) They arrived yesterday as scheduled.
I've been doing lots of research in preparation for this project. So far, I've determined that this repeater will be housed in 4 inch foam-core PVC pipe. The foam-core pipe is lighter weight by about 50% than its regular counterpart. I'm estimating that it will have to be a 2 foot section to hold everything. It will be divided into 3 sections. One for each radio, and one for the batteries and support electronics. The center cavity will have a metal or mesh top and bottom to prevent RF saturation and block a certain amount of RF between the top and bottom compartments.
You might ask why I decided on this configuration. I think it actualy dates back to the mid 80's to something a business radio repair person told me when I was helping him work on a base radio at a tower site. The radio of course was in the shack, and the antenna was about 100 feet up. I stepped out the door with my HT to test, and the radio guy called out after me to expect it to not work, at least not well. When I questioned him, he told me that there is essentially a cone of silence below an antenna. And depending on how high up the antenna is, the base of that cone can extend for quite some distance. So I thought I would incorporate that into the design to help cut down on blanking and intermod since I was not planning on using any caveties with this setup.
Lots of great ideas found when doing the research. I'm looking forward to woking them into the design.
Enough for now. As the project progresses, I'll take pictures and document it.
73
Steve
KDØWSW
I've been doing lots of research in preparation for this project. So far, I've determined that this repeater will be housed in 4 inch foam-core PVC pipe. The foam-core pipe is lighter weight by about 50% than its regular counterpart. I'm estimating that it will have to be a 2 foot section to hold everything. It will be divided into 3 sections. One for each radio, and one for the batteries and support electronics. The center cavity will have a metal or mesh top and bottom to prevent RF saturation and block a certain amount of RF between the top and bottom compartments.
You might ask why I decided on this configuration. I think it actualy dates back to the mid 80's to something a business radio repair person told me when I was helping him work on a base radio at a tower site. The radio of course was in the shack, and the antenna was about 100 feet up. I stepped out the door with my HT to test, and the radio guy called out after me to expect it to not work, at least not well. When I questioned him, he told me that there is essentially a cone of silence below an antenna. And depending on how high up the antenna is, the base of that cone can extend for quite some distance. So I thought I would incorporate that into the design to help cut down on blanking and intermod since I was not planning on using any caveties with this setup.
Lots of great ideas found when doing the research. I'm looking forward to woking them into the design.
Enough for now. As the project progresses, I'll take pictures and document it.
73
Steve
KDØWSW
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