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Re: MTT4BT and Garmin Montana APRS
Compton,
Certainly. When the MTT4BT or even more so, the MTT4BT-40 (40 Watt MTT4BT transceiver) have a high SWR during transmission, the processor may become "Swamped" with RF voltage building up on the board, and the TT4 loses control.? You will typically see the two bi-Color LEDs continuously flash, as if the four individual LED's are showing the same pattern as they do on immediate powering of the unit. This is typically what the lower power (10) Watt unit will do when the antenna has a very poor match, and is generally harmless. It may potentially toast the final amplifier, and/or result in corrupt firmware, but this can be reloaded by the end-user or by us ( Byonics) You may hear the T/R relay clicking while this is happening.?
?When the high power MTT4BT-40 goes into continuous reset, the device may lock up in the transmit-mode. Nothing but a carrier will be transmitted, and if this goes on too long, the final amplifier, and even the PCB and case can melt. That's the expensive smoke.??The units that have been melted into hideous globs of stinky plastic have usually been caused by things like people removing their antennas before entering car washes and forgetting to turn of the MTT4BT-40's power when disconnecting the antenna. Note that the RF output from either the low power unit ( up to 14 Watts) or the High power unit ( Up to 40 Watts) can cause RF burns and tattooing. ( Important safety tip!)?
Other issues are crappy coax and bad antennas, coax pinched or strangled in car door frames, etc. This is also a problem we have seen in our MT-RTG-50 ( 50 Watt Transmit-only device? that can actually have as much as 90 Watts output, depending upon power supply voltage and impedance) The little "Hershey's kiss" antenna that we provide for free with our low power RTG transmitter is a great example of an awful antenna for the MTT4BT. RG-174u coax, questionable SWR, and low magnet mass are not good things for a higher power transmitter.
The Mass of an MTT4BT transceiver is less than 4 ounces. Imagine putting a rubber duck antenna on a 40 Watt handheld transceiver! It would be bad. The MTT4BT transceivers?were designed for mobile APRS, which means a fairly low duty cycle, and relying on the Mass of an automobile to act as a counterpoise "Ground" for the transceiver. Consider this as if you were a person floating in space, trying to throw a heavy weight,?Isaac?Newton conspires against your putting very much force into the throw. ( This is not a perfect analogy, so physics?people don't go postal on me) As a practical matter, this effectively means as we increase the output power of a transmitter, we need to increase it's Mass for two reasons. One, we need a heat sink that can handle the wasted power, On the MTT4BT this is the PCB itself; there is no other heat sink, but since APRS duty cycles are very low, the PCB is enough. The second reason is that we need enough Mass in the transmitter?to act as a counterpoise to the antennae. That Mass must increase directly to handle the poorer antennas. The MTT4BT's are happiest with a mobile antenna, like an NMO or big magnet mount.?
For the last few months,? all the stocked? MTT4BT-40's and RTG-50 Transmitters ( And a few rare RTG-100 Watt transmitters) have had thermostatic switches added to the power amplifiers. If the amp gets hotter than 50 C, it gets turned off until the unit cools down substantially below that. This should prevent expensive smoke from leaking out of the units if they get locked on. (BTW, if anyone wants to have me add the thermal circuit breaker to their older MTT4BT-40 or RTG-50, I will do so for the cost of return shipping- I understand that return shipping to Australia is a horribly expensive thing, so I will be producing a set of instructions on how to add one yourself if you are so inclined)?
It was suggest in one of the recent posts to use an antenna that does not require a substantial ground plane. We have found that our V6 antenna ( A center-fed, half-wave dipole) works quite well with the MTT4BT-40, although it would not work well on a motorcycle. a 5/8ths wave antenna might also be a good choice.
73,
Allen AF6OF
-----Original Message-----
From: Compton <comptonallen@...> To: [email protected] Sent: Sun, Jun 27, 2021 8:15 pm Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS Hi Allen,
Are you able to describe the symptoms of continuous reset you note? ? -- Compton VK2HRX Sydney, Australia |
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Re: MTT4BT and Garmin Montana APRS
¿ªÔÆÌåÓý
Use a ground independant mobile antenna. This means you can mount it anywhere you like. I don't know what is available on your side of the world, so I can't recommend one.
Also ground independant mobile antennas make great home base antennas, as you can mount them on top of a pole and they work beautifully. I run a small pigtail lead of RG58 and then step it up to RG213 to reduce the losses over the run.
Regards,
Doug VK2XLJ From: [email protected] <[email protected]> on behalf of toy4trax@... <toy4trax@...>
Sent: Monday, 28 June 2021 8:18 AM To: [email protected] <[email protected]> Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS ?
Final question before I put in my order- What antennas are appropriate for an ATV/Motorcycle (not much metal). Will a HT
Nagoya NA-771whip be appropriate?
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Re: MTT4BT and Garmin Montana APRS
Probably the best solution is a simple 1/4 wave verticle.? Since the 1/4 wave on 2 meters is only about 20 inches, you can probably find a way / place to mount one 1/4 wave (driven) element vertically and one or two horizontal (or slightly sloped) in a way that fits a motorcycle. I've seen these types of antennas on short poles so that they are just above anyone on the motorcycle seat.? You will need to get a little creative. Robert Giuliano
On Sunday, June 27, 2021, 7:22:03 PM EDT, vhsproducts via groups.io <vhsproducts@...> wrote:
The MTT4BT will not work with a rubber duck antenna. You need a mobile-style mount and whip to load it properly. Excessive SWR will cause the unit to go into continuous reset. Rubber duck whips are in general, the work of the devil. Motorcycle antennas are always a challenge, but I have seen good results with mobile mounts ( NMO, etc) mounted to the chassis or license frame brackets. I am sorry that I don't have an easy turn-key solution for bikes.?
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Sun, Jun 27, 2021 3:18 pm Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS Final question before I put in my order- What antennas are appropriate for an ATV/Motorcycle (not much metal). Will a HT Nagoya NA-771whip be appropriate?
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Re: MTT4BT and Garmin Montana APRS
The MTT4BT will not work with a rubber duck antenna. You need a mobile-style mount and whip to load it properly. Excessive SWR will cause the unit to go into continuous reset. Rubber duck whips are in general, the work of the devil. Motorcycle antennas are always a challenge, but I have seen good results with mobile mounts ( NMO, etc) mounted to the chassis or license frame brackets. I am sorry that I don't have an easy turn-key solution for bikes.?
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Sun, Jun 27, 2021 3:18 pm Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS Final question before I put in my order- What antennas are appropriate for an ATV/Motorcycle (not much metal). Will a HT Nagoya NA-771whip be appropriate?
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Re: compatible weather station for MTT4B-Mini
Dj,
What I know about using weather stations on APRS can comfortably be written on a matchbook with a crayon. The two main systems that are APRS compatible are some of the Peet Brothers. and the Davis units. My understanding is that APRS friendly? devices from both families have adapters that will allow the devices to put out compatible strings. I believe the Peet unit speaks KISS and the Davis Speaks a proprietary format ( If I have these backwards, it can be easily rectified by browsing the manual) Both as I understand it have RS-232 Serial outputs.
This would not present any special problems with the MTT4BT, because it is set up to handle "true" RS-232 serial data. The MTT4B-Mini only accepts TTL data, so you would need to add an inverter ( Like the MAX232 chip we use in the MTT4BT) to convert the serial to TTL. All things being equal, it may be wiser to use an MTT4BT transceiver for a variety of reasons. One, it is designed to accept serial, Two, the two serial inputs are readily connectable using off-the-shelf Byonics or simple homemade cables, and Three, the MTT4BT can have its output power dialed down for applicable conditions including range and power savings, whereas the MTT4B-Mini is always going to be a very-QRP transmitter, and adding output power would be considerably more involved.
73,
Allen AF6OF -----Original Message-----
From: Dj Merrill via groups.io <groupsio@...> To: [email protected] Sent: Sat, Jun 26, 2021 5:39 pm Subject: [TinyTrak] compatible weather station for MTT4B-Mini We want to setup a remote weather station powered by solar/battery.? I'm looking at the MTT4B-Mini that states in the addendum manual, "for stand-alone battery or solar powered digipeaters, weather stations, etc".
I'm making an assumption that this implies that a weather station can be directly connected to the MTT4B-Mini with no need for an intermediate computer like a Raspberry Pi. My questions are, what weather stations would be compatible, and is there a "how-to" guide describing how to set this up (physical wiring as well as the MTT4B programming setup)? Thank you, -Dj |
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compatible weather station for MTT4B-Mini
We want to setup a remote weather station powered by solar/battery.? I'm looking at the MTT4B-Mini that states in the addendum manual, "for stand-alone battery or solar powered digipeaters, weather stations, etc".
I'm making an assumption that this implies that a weather station can be directly connected to the MTT4B-Mini with no need for an intermediate computer like a Raspberry Pi. My questions are, what weather stations would be compatible, and is there a "how-to" guide describing how to set this up (physical wiring as well as the MTT4B programming setup)? Thank you, -Dj |
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Re: MTT4BT and Garmin Montana APRS
Good time to update the firmware. I can think of 3 options for improvement: 1. Ignore the message "Talker ID" ($G?) and look at the 4th, 5th, and 6th characters 2. Parse out the 3 common options (all three have the messages decoded by TT# for APRS): ??? $GPS - North America variant and common Talker ID ??? $GPL - GLONASS ??? $GPN - combination -> Now most common as GPS units used more than 1 set of satellites 3. Leave it as is and hope users can change the settings of the attached GPS ??? Or miss a lot of the newer capabilities and Robert Giuliano
On Friday, June 25, 2021, 4:31:00 PM EDT, vhsproducts via groups.io <vhsproducts@...> wrote:
Garmin certainly does not make it easy to find out about? their products! It looks like you can get serial (RS-232) NMEA out of a Montana if you have the mounting bracket option. otherwise, it appears to just have a USB port that won't work with a TT4. It is not completely clear to me from a search of their documentation if the GLONASS sentences are included with their NMEA serial output, or if they can be deactivated. Every GPS module that I have seen with dual capabilities squeezes the GLONASS data into the serial, semi-NMEA data stream, but with any luck, the 700 is a bit more advanced than just a CHICOM GPS module.?
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Fri, Jun 25, 2021 11:40 am Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS This is for the Montana 700 series.
The 600 series appears to be the same, but doesn't give the detail. |
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Re: MTT4BT and Garmin Montana APRS
My use case will be on the amps mount which does include data wiring. From another page(gpscity.com I think¡) I understand that the Garmin serial usb cable will work as well if you get a 5pin mini to micro adapter. |
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Re: MTT4BT and Garmin Montana APRS
Garmin certainly does not make it easy to find out about? their products! It looks like you can get serial (RS-232) NMEA out of a Montana if you have the mounting bracket option. otherwise, it appears to just have a USB port that won't work with a TT4. It is not completely clear to me from a search of their documentation if the GLONASS sentences are included with their NMEA serial output, or if they can be deactivated. Every GPS module that I have seen with dual capabilities squeezes the GLONASS data into the serial, semi-NMEA data stream, but with any luck, the 700 is a bit more advanced than just a CHICOM GPS module.?
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Fri, Jun 25, 2021 11:40 am Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS This is for the Montana 700 series.
The 600 series appears to be the same, but doesn't give the detail. |
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Re: MTT4BT and Garmin Montana APRS
Thanks for the link!? Which unit of the Montana species is this spec sheet for? All the units I have checked not only have multi-GNSS, which is a problem for the TT4-based products unless they can be deactivated. Even worse, they only have I/O's that are USB, ANT, Wifi or Audio Bluetooth, also not things that are particularly MTT4BT compatible without adding a PC to the loop.
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Thu, Jun 24, 2021 9:58 pm Subject: Re: [TinyTrak] MTT4BT and Garmin Montana APRS I was able to dig this up:
Based on the MTT4BT being able to take APRS audio, and convert it to NMEA serial waypoints ($GPWPL & $PGRMW), I think this is a go! |
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Re: MTT4BT and Garmin Montana APRS
I was able to dig this up:
Based on the MTT4BT being able to take APRS audio, and convert it to NMEA serial waypoints ($GPWPL & $PGRMW), I think this is a go! |
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Re: How can I do this? toggling between two APRS messages.
Bear,
If you end up with a Garmin Colorado, would you mind telling us which one you bought, and whether you could turn off the GLONASS sentences?
73,
Allen AF6OF -----Original Message-----
From: Bear Albrecht <W5VZB.NM@...> To: [email protected] Sent: Wed, Jun 23, 2021 4:32 pm Subject: Re: [TinyTrak] How can I do this? toggling between two APRS messages. OK, I'm looking at the TT4 hardware manual and I have yet to figure out what to ground-or-not ...?
The word "bank" doesn't appear in that document at all. ;B -- Bear Albrecht? W5VZB? OOOTC |
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Re: MTT4BT and Garmin Montana APRS
Rob,?
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Re: MTT4BT and Garmin Montana APRS
Brian - Can you give a better description of what you are having an issue with on your MTT4B and Garmin? From your message, I gathered the issue is waypoints. From Allen's message, it appears you may not be getting GPS messages. According to the video, the Garmin (400t) does use NMEA sentences. The video shows the D710 has the ability to filter which type of information received over the air is sent to the Garmin GPS as waypoints.? The MTT4B does not have that feature. There is a setting to send your position to the GPS when . The MTT4B manual does not give as much information about settings as the TT4 firmware manual does. You may want to download that manual for more details on the options Other related settings are: ? TSWPT TRUE????????????? (send a waypoint to the GPS of your position when you send it over the air) ? GWAYLEN #??????????????? (zero disables.? Common I think is 8 - check GPS manual for max length of waypoints) ? GWAYMODE NMEA??? (options are NMEA, KENWOOD, or MAGELLAN.? Video says to use NMEA) Robert Giuliano
On Thursday, June 24, 2021, 2:22:07 AM EDT, vhsproducts via groups.io <vhsproducts@...> wrote:
Brian,
I believe that all the new models of the Montana series all put out the GLONASS sentences. Older units were plain old NMEA serial. If you have a newer unit, you will have to find out how to stop it from putting out the GLONASS sentence, otherwise the MTT4BT won't recognize the GPS. I suppose a review of the Garmin manuals would be a good thing, I don't know if they can do that.
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Wed, Jun 23, 2021 7:10 pm Subject: [TinyTrak] MTT4BT and Garmin Montana APRS I am looking to replicate what the Kenwood D710 can do with the Garmin system, but in a much smaller package. I want a headless APRS tracking system, with just the waypoints popping up on the garmin.
Example video:
I understand the MTT4BT is up to the task. Anybody doing this or have experiences to share? -Brian KG7KHL |
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Re: MTT4BT and Garmin Montana APRS
Brian,
I believe that all the new models of the Montana series all put out the GLONASS sentences. Older units were plain old NMEA serial. If you have a newer unit, you will have to find out how to stop it from putting out the GLONASS sentence, otherwise the MTT4BT won't recognize the GPS. I suppose a review of the Garmin manuals would be a good thing, I don't know if they can do that.
73,
Allen AF6OF -----Original Message-----
From: toy4trax@... To: [email protected] Sent: Wed, Jun 23, 2021 7:10 pm Subject: [TinyTrak] MTT4BT and Garmin Montana APRS I am looking to replicate what the Kenwood D710 can do with the Garmin system, but in a much smaller package. I want a headless APRS tracking system, with just the waypoints popping up on the garmin.
Example video:
I understand the MTT4BT is up to the task. Anybody doing this or have experiences to share? -Brian KG7KHL |
Compton
Doug J
Dj Merrill
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