motorola gtx model m11wgd4cb1an
Can anyone tell me what the proper fuse sizes for the power and ingnition are on this radio?
motorola gtx model m11wgd4cb1an
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motorola gtx model m11wgd4cb1an
Joel
KE7JOI
1 900 Spectra
1 VHF Spectra
3 900 GTX Portables
1 900 GTX Mobile
KE7JOI
1 900 Spectra
1 VHF Spectra
3 900 GTX Portables
1 900 GTX Mobile
1. Fuses are sized by the capacity of the wire used to feed power.
2. Wires are sized by the current required to power a device.
3. For ignition sense, current required is nil; use an AWG18 or larger wire and a 2A fuse.
4. I did not look up model number, but I'm guessing that the radio is an 800 mobile rated at about 25 watts. Wire with AWG12 and a 15A fuse for openers; if that causes a voltage drop, increase the wire size to AWG8 and fuse to 25A.
5. Foregoing assumes that feed line runs are nominal in length (i.e., within a typical MV).
2. Wires are sized by the current required to power a device.
3. For ignition sense, current required is nil; use an AWG18 or larger wire and a 2A fuse.
4. I did not look up model number, but I'm guessing that the radio is an 800 mobile rated at about 25 watts. Wire with AWG12 and a 15A fuse for openers; if that causes a voltage drop, increase the wire size to AWG8 and fuse to 25A.
5. Foregoing assumes that feed line runs are nominal in length (i.e., within a typical MV).
Huh? 8AWG to run a GTX? You're kidding, right?RKG wrote:4. I did not look up model number, but I'm guessing that the radio is an 800 mobile rated at about 25 watts. Wire with AWG12 and a 15A fuse for openers; if that causes a voltage drop, increase the wire size to AWG8 and fuse to 25A.
Wire sizing is a function of equipment current draw and length of wire. Whelen has a pretty decent chart:
http://www.sirennet.com/pdf/14010_CenCom_install.pdf
15A is more than sufficient for a GTX (a 45-watt Spectra draws 13A). So, if your run is 13 feet, run 14AWG per the chart.
I wasn't kidding, though (as I thought I had expressed, but possibly not) I was operating under a limitation that I could not remember what the power of a GTX mobile is.
In any event, my statement was that IF the AWG12 installation showed a voltage drop, I'd go up two wire sizes and fuse accordingly. There is no downside to bigger wire than you need.
I found the Whelan chart you refer to interesting: it strikes me both as excessively conservative in some places and excessively ambitious in others. For instance, I wouldn't run 15A of current through any length of AWG20 wire.
In any event, let's say that this is a 30-35W radio (output), drawing about 100W input or about 10A at 12VDC (nominal). Given that in a DC circuit, wirerun is the sum of both the hot lead and the ground return, the Whelan chart recommends AWG14 up to 19.5 feet (round trip) and AWG12 beyond 19.5 feet and up to 31 feet. My AWG12 is, therefore, right in the ball park. (I tend to be a bit conservative on this point, anyhow.)
If I wired it this way, and IF I nonetheless saw a voltage drop (and necessarily knowing nothing more), I'd decide to up wire size, and when I do that I up two sizes. I don't think that's unreasonable advice. If what you're saying is that there is no likelihood of seeing a voltage drop using the AWG12 -- i.e., that the condition on my upgrade recommendation is unlikely to be fulfilled -- I can't argue that one way or the other.
In any event, my statement was that IF the AWG12 installation showed a voltage drop, I'd go up two wire sizes and fuse accordingly. There is no downside to bigger wire than you need.
I found the Whelan chart you refer to interesting: it strikes me both as excessively conservative in some places and excessively ambitious in others. For instance, I wouldn't run 15A of current through any length of AWG20 wire.
In any event, let's say that this is a 30-35W radio (output), drawing about 100W input or about 10A at 12VDC (nominal). Given that in a DC circuit, wirerun is the sum of both the hot lead and the ground return, the Whelan chart recommends AWG14 up to 19.5 feet (round trip) and AWG12 beyond 19.5 feet and up to 31 feet. My AWG12 is, therefore, right in the ball park. (I tend to be a bit conservative on this point, anyhow.)
If I wired it this way, and IF I nonetheless saw a voltage drop (and necessarily knowing nothing more), I'd decide to up wire size, and when I do that I up two sizes. I don't think that's unreasonable advice. If what you're saying is that there is no likelihood of seeing a voltage drop using the AWG12 -- i.e., that the condition on my upgrade recommendation is unlikely to be fulfilled -- I can't argue that one way or the other.