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#1
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RST Engineering - JIm schreef:
NiMH a c. Are relatively inexpensive (check out thomasdistributing.com) Jim, thanks for enlightening me on the ecological aspect, I must admit I never looked into that. Could it be you are in Caleefornyeah? As for the economic side: that must depend much on location. I never did any research, but have a feeling that NiMH is rather expensive here in Europe, plus requires special charger. Of course NiMH have better capacity, but Murphy says they'll be full anytime anyway, except when you need them. |
#2
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"jan olieslagers" wrote in message
... Of course NiMH have better capacity, but Murphy says they'll be full anytime anyway, except when you need them. That's why I don't particularly like rechargeables of any type for emergency use. A good fresh set of non-rechargeable alkalines will give you about 5 years of shelf life depending on how they are stored and lithium batteries will last a bit longer. The manufacturers sometimes spec 10 years or more on lithiums, but you're getting down to 50-70% of capacity at that point which is not exactly what I'd like to be thinking about in IMC. Most of the portable transceivers have battery pack options that allow you to use alkaline or lithium batteries along with rechargeables. It's very nice to have both packs so you can swap them around when you're using the transceiver for non-emergency uses. |
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Enough about batteries. Want portable/back up comm recommendations -
Icom, Sporty's etc? Have portable GPS, so Nav is not that important. |
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On Jul 27, 9:32*pm, bobengr wrote:
Enough about batteries. *Want portable/back up comm recommendations - Icom, Sporty's etc? *Have portable GPS, so Nav is not that important. You can't go wrong with Icom. I have had an A2 for over 20 years, and have had no trouble (other than batteries). Don't waste your money on an optional Nav function. Regarding batteries, I use alkalines exclusively. Rechargeables need to be cycled regularly (run down then charged up) to be dependable. The batteries in a backup tranceiver tend to see only very occasional use (with long periods of neglect in between). Alkalines have an excellent shelf life. The only downside is that they have a higher internal resistance, and don't put out current as well as the others. That translates into "use low power on transmit unless absolutely necessary to use high power". Dave |
#5
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"bobengr" wrote in message
... Enough about batteries. Want portable/back up comm recommendations - Icom, Sporty's etc? Have portable GPS, so Nav is not that important. I had a Vertex that failed completely after about 5 years. I now have the Icom A4 and I like it just fine. It's no longer being made, but you can still find them for sale new. It's been replaced by the A14. I think it might have a slightly lower power output than most, but it wasn't enough that I could notice any difference compared to my old Vertex. None of them work very well unless you're reasonably close to the ATC radio anyway, although if you have an externally mounted antenna you can increase your range somewhat. All of them are limited by power output, so most are going to have virtually the same range. |
#6
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Given the fact that a 1 watt transmitter on one end and a 1 microvolt
receiver on the other end have a maximum theoretical range of 1800 miles, how in the world can you say that a 4 watt transmitter is "limited by power output"? The limitation is always by line of sight or antenna configuration. Jim "Mike" nospam @ aol.com wrote in message ... .. I think it might have a slightly lower power output than most, but it wasn't enough that I could notice any difference compared to my old Vertex. None of them work very well unless you're reasonably close to the ATC radio anyway, although if you have an externally mounted antenna you can increase your range somewhat. All of them are limited by power output, so most are going to have virtually the same range. |
#7
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"RST Engineering - JIm" wrote in message
... Given the fact that a 1 watt transmitter on one end and a 1 microvolt receiver on the other end have a maximum theoretical range of 1800 miles, how in the world can you say that a 4 watt transmitter is "limited by power output"? The limitation is always by line of sight or antenna configuration. Since all transceivers of this type are limited by the FCC in regards to how much power they can output(and most of them develop the max power allowed at about 1.5w nominal) and since all of them come with essentially identical omnidirectional antennas, I can pretty much assume they will all have very similar ranges, since obviously the transmitter is going to be the limiting factor seeing as how the other end is putting out roughly 7db more power. So you can use the opportunity to mentally masturbate your "engineering" knowledge and talk about theoretical true parabolic reflectors and receiver sensitivities that don't even approach practical applications, but you're not really contributing much to the OP's question. |
#8
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"Mike" nospam @ aol.com wrote in message
... "RST Engineering - JIm" wrote in message ... Given the fact that a 1 watt transmitter on one end and a 1 microvolt receiver on the other end have a maximum theoretical range of 1800 miles, how in the world can you say that a 4 watt transmitter is "limited by power output"? The limitation is always by line of sight or antenna configuration. Since all transceivers of this type are limited by the FCC in regards to how much power they can output(and most of them develop the max power allowed at about 1.5w nominal) and since all of them come with essentially identical omnidirectional antennas, I can pretty much assume they will all have very similar ranges, since obviously the transmitter is going to be the limiting factor seeing as how the other end is putting out roughly 7db more power. So you can use the opportunity to mentally masturbate your "engineering" knowledge and talk about theoretical true parabolic reflectors and receiver sensitivities that don't even approach practical applications, but you're not really contributing much to the OP's question. I don't always agree with Jim; but he is absolutely right on this one. When I worked as an avionics technicial, most of the problems that I saw were ultimately wiring issues of the coaxial cables (frequently broken at the antenna connector) and only occasionally degraded sensitivity of the receiver. That was long ago, and more modern receivers should suffer far less degradation. The most entertaining case was a Bellanca on which one of the two comm transceivers would successfully receive the tower frequency about 6 miles from the airport and transmit just a little further. It turned out that there was an in-line coax connector which had become disconnected and the radio signals both transmitted and received were only through the braiding of the coax cable! Peter |
#9
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![]() "Mike" nospam @ aol.com wrote in message ... Since all transceivers of this type are limited by the FCC in regards to how much power they can output(and most of them develop the max power allowed at about 1.5w nominal) and since all of them come with essentially identical omnidirectional antennas, I can pretty much assume they will all have very similar ranges, since obviously the transmitter is going to be the limiting factor seeing as how the other end is putting out roughly 7db more power. There are various ways of measuring the output power of an AM transmitter. One manufacturer's 1-watt transmitter may be much the same as another manufacturer's 4-watt transmitter. There are other important issues, such as the type and quality of the modulation and the audio processing. The devil is in the details. Actually, the quality of the receiver is (in general) more important than transmit power. In my experience, both Vertex and Icom are good brand names for that type of equipment. Vaughn |
#10
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![]() "Mike" nospam @ aol.com wrote in message ... "RST Engineering - JIm" wrote in message ... Given the fact that a 1 watt transmitter on one end and a 1 microvolt receiver on the other end have a maximum theoretical range of 1800 miles, how in the world can you say that a 4 watt transmitter is "limited by power output"? The limitation is always by line of sight or antenna configuration. Since all transceivers of this type are limited by the FCC in regards to how much power they can output(and most of them develop the max power allowed at about 1.5w nominal) 47CFR87.131 gives the maximum power permitted in the VHF com band as 55 watts carrier. WHere do you get your misinformation? and since all of them come with essentially identical omnidirectional antennas, An omnidirectional (isotropic) antenna is an impossibility, although we do some mathematical "tricks" to reference all antenna gain to isotropic. Gain (dbi - decibels above or below isotropic or dbd - decibels above or below a dipole) by definition are 2.14 dB different, the dipole having gain perpendicular to the elements of 2.14 dbi. Tell me what the form factor is for an antenna putting out a radiation pattern resembling a grapefruit? I can pretty much assume they will all have very similar ranges, since obviously the transmitter is going to be the limiting factor seeing as how the other end is putting out roughly 7db more power. Either you have no idea what you are talking about or it is well into beer-thirty for you. So you can use the opportunity to mentally masturbate your "engineering" knowledge and talk about theoretical true parabolic reflectors Who said anything about parabolic reflectors? I used a plain old ground plane at both ends. 2.14 dbi gain. End one. One watt AM carrier power into a ground plane. End two receiver with one microvolt sensitivity for 10 dB S+N/N being fed by an identical ground plane. If you like, you can replace the ground plane antennas with a plain old straignt dipole with no measurable gain or loss. Actual range at 127 MHz. is 1366.7 statute miles. How the hell do you think we talk to the space shuttle with essentially the same equipment a few MHz. higher with 1 watt handhelds? and receiver sensitivities that don't even approach practical applications Every transceiver on the market today will give you at least half a microvolt for 10 dB S+N/N. I was being generous by saying a full microvolt, which will give you a much better s/n ratio. Haven't designed many VHF radios, have you sonny? , but you're not really contributing much to the OP's question. Perhaps. Perhaps not. But at least I knew what the hell I was talking about. Jim |
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