Posted: 10/14/2016 1:55:37 PM EDT
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Hey ArfHams,
I'm still new to the HF world and hope some of you more experienced guys and gals can help me out. Right now I have a 40 mile commute from my house in the TX Hill Country into the city, four days a week. In the event of a major event that would prevent or delay me from getting home what are my options to communicate with my family at home? Right now I'm the only family member with a license, so the comms would be one way, but at least I could give updates and/or requests for help. Also a neighbor is licensed, so they could act as a relay. I'm thinking of an NVIS setup, but not sure which bands are most useful under the current conditions. I do have a HT but don't want to rely on repeaters for this. ETA: right now I have a QRP HF rig (X1M) that works on 10,20,40,80 bands and I have a 10,20,40 dipole linked antenna right now. Thanks for advance for any help! PropellerHead |
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80 meters is your best bet for NVIS. BUT the big thing here is getting an antenna to work right on your vehicle for NVIS. That's next to impossible.
Your best off with VHF or UHF comms with an antenna up in the air on the base side and a 50 or so watt mobile in your vehicle. ETA: Are you in the ATX area? |
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Sorry I should have added that I'm not expecting to run HF on the go from my vehicle. I'm thinking of taking the time to put up a EFHW 80 meter antenna somewhere around 6' off the ground so that I don't skip my place 40 miles away. I just wasn't sure if 80 meters or 40 meters would be the better band to be on.
We live North of Boerne and I work near the San Antonio Airport. |
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If you're not looking to operate mobile in NVIS, then build an AS-2559 Clone!
Get 15 feet of 2" PVC, a cap and some couplers for the upright, a bulkhead type SO-239, some wire and a little more PVC per this: Modified AS-2559 Clone Optimized for 40 and 80m |
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Quoted:
TX is flat right? There is a reason they call it the Texas Hill Country. 
But it's not exactly the Rocky Mountains, either. Texas is pretty darn big, and you can find all sorts of terrain here. |
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Don't forget the 60M band, it's prime real estate for NVIS, which is why there's so little spectrum available.
I'd second the advice in exploring 2M SSB. Decent chance between knife-edge and tropo you might get a path, and if you do it'll likely be more reliable than NVIS would be. |
This may be the hillbilly approach, but if you have a neighbor with HF capability, why not take your QRP HF rig with you to work one day, toss a simple random wire as high as you can get away with, and try a scheduled contact with Mr. Friendly Neigbor? Agree in advance on a few different frequencies or use the cell phone to correlate your plan on the fly. Regardless of what you find out, these little experiments are always fun. 
Even if you don't plan on having that HF capability with you every commuting day, it would sure be simple to make up a QRP "grab and go bag" to add to your vehicle if you have any reason to suspect difficult times are near. Just a thought... Jim |
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40 miles?!?! Why mess around this craziness, instead of just using a repeater?
If you had decent line of sight from "hill country" to the city you make it on FM simplex with reasonable antennas. It's all for naught if there isn't someone on the other end to talk to. They need licenses. If your family is simply unwilling/unable to get licensed, GMRS might be an available options if there are GMRS repeaters available that would give you the coverage you need. |
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Sorta what SpanishInquisition posted above - that's exactly what you want *FOR* NVIS ops.
Every NVIS setup that I've seen at a show or in-field demo has been an inverted-V up 20 or 25 feet or so at the apex. Balun and sometimes also the tuner at the feedpoint. Random wires not surprisingly give random results, usually not of the good kind - especially if shorter than 1/4 wavelength or so, and especially-squared if a formal radial / counterpoise system is not employed. It's easy to get into the single-digit, or lower, efficiency range that way. And end-feds are best used for portable - there's usually no reason to use a compromise antenna at the base station or remote location. And hopefully you can get whatever you decide upon up higher than 9 feet - there's mucho ground loss at such a low height. |
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Wow, over-complication in the extreme in this thread.
1. Do you have 2M and/or 70cm repeater coverage that will work for you? 2. If the answer to (1) above is "no", then put a 100W HF unit in the vehicle with a screwdriver type antenna and use 40, 60 or 80M as conditions permit. We have a bunch of guys up here in the Northeast who regularly run 40M mobile during most of the day and 80M mobile at night. They get 100+ mile range easy, primarily ground wave, with no special measures other than a good, workmanlike HF vehicular installation. 3. QRP is not going to work well, if at all, for NVIS. For reliable NVIS comm's you need 20W min. and, preferentially, 100W. This is especially true because as hams we do not have the luxury of 1MHz NVIS channel spacing. This means that you will often need to work the F-layer of the ionosphere several MHz below the critical frequency and the F-layer gets quite absorptive the further you are from the critical frequency. |
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Wow, over-complication in the extreme in this thread. 1. Do you have 2M and/or 70cm repeater coverage that will work for you? 2. If the answer to (1) above is "no", then put a 100W HF unit in the vehicle with a screwdriver type antenna and use 40, 60 or 80M as conditions permit. We have a bunch of guys up here in the Northeast who regularly run 40M mobile during most of the day and 80M mobile at night. They get 100+ mile range easy, primarily ground wave, with no special measures other than a good, workmanlike HF vehicular installation. 3. QRP is not going to work well, if at all, for NVIS. For reliable NVIS comm's you need 20W min. and, preferentially, 100W. This is especially true because as hams we do not have the luxury of 1MHz NVIS channel spacing. This means that you will often need to work the F-layer of the ionosphere several MHz below the critical frequency and the F-layer gets quite absorptive the further you are from the critical frequency. Yup... That or 50W VHF and a 2m or 6m Yagi... (try running SSB as well with these modes) and use a mast to get is as high as you can (painters pole or something easy/cheap) ETA, FWIW, I've seen QRP NVIS vastly over-hyped in the "survival" literature both online and in books. I'm pretty sure some of these guys have no experience, but I also know for a fact some of the guys do have experience that should know better. Can it work? Yes it can, BTDT. Will it work with a high degree of reliability like they portray it to? Probably not all of the time. There are alot of reasons that the military went heavy on satcom/tacsat, but link reliability and ease of use was pretty much top of the list when compared to HF for longer ranged comms. |
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FWIW, I've seen QRP NVIS vastly over-hyped in the "survival" literature both online and in books. This^87. And it's not limited to QRP either. HF is an entirely different can of worms and until you have experience with it you just do not know what you're up against. NVIS is held out as some miracle solution to all survival communications needs. |
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Since you are in the hill country of Texas I would suggest that you have three options.
1) If you have a gain antenna, say a four to eleven element yagi vertically polarized at home and a one hundred watt 2 meter FM radio in your vehicle with a stacked collinear vertical antenna centrally located on the roof, you will probably be 100% reliable or nearly so. Keeping that yagi at home pointed in the direction you are driving to will be critical. 2) With the efficiency of hf mobile antennas being somewhat lackluster, I would think the 100 watt hf radio on SSB on 80 or 40 meters would traverse the 40 mile path, assuming a dipole or better antenna at home with the major lobe oriented in the direction you are going to travel. Obviously, with the solar cycle null on the horizon and propagation changes that exist during the greyline traversing your area may result in hf not being the best choice. 3) Back when low band vhf was popular with state patrols and other emergency services there were some pretty fair distances being covered. 100 watts of FM on the six meter band may be an even better bet using vertical polarized antennas. Antennas will be larger than on two meters and much small than hf bands. Not that people can't be taught, but, an hf radio that is not tuned to the correct frequency will be nearly useless. Additionally, it will need an all-mode squelch or it will be turned off, as no one likes to listen to white noise of off frequency SSB or carrier heterodynes. Obviously, it will be best to have both antennas on hill tops, most especially the stationary one. I would think that 40 miles is doable, 60 miles brings about some other demands. You might find this link interesting. Radio horizon vs antenna height Good luck with your project. |
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This^87. And it's not limited to QRP either. HF is an entirely different can of worms and until you have experience with it you just do not know what you're up against. NVIS is held out as some miracle solution to all survival communications needs. Quoted:
Quoted:
FWIW, I've seen QRP NVIS vastly over-hyped in the "survival" literature both online and in books. This^87. And it's not limited to QRP either. HF is an entirely different can of worms and until you have experience with it you just do not know what you're up against. NVIS is held out as some miracle solution to all survival communications needs. There used to be a good post over on the KY repeater network about one of their EMCOMM exercises, they were RELYING on HF NVIS for local comms, now mind you this is with 100W rigs, data modes the whole 9 yards, not some rinky dink wire in a tree and a QRP radio. And they had massive failures with this, It didn't work very well even with tons of power, and decently setup antennas, the ionosphere happened to be a bitch that day. The post was unfortunately removed for reasons unknown (maybe they didn't want folks to learn from their experience, that or they didn't want to look bad once it started getting cited as the wrong way of doing things). My main point, is whatever EMCOMM plan you have, you better practice doing it when its not an emergency to see how well it works in the real world and not on paper. Actually I think the old exercisze Pic ran of getting traffic coast to coast was interesting. And if you can find some like minded folks, setting up skeds to make comms at appointed times isn't too much of a PITA, we could even get a thread going on that. |
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Since you are in the hill country of Texas I would suggest that you have three options. 3) Back when low band vhf was popular with state patrols and other emergency services there were some pretty fair distances being covered. 100 watts of FM on the six meter band may be an even better bet using vertical polarized antennas. Antennas will be larger than on two meters and much small than hf bands. Its all about siting with Low band VHF, but I can highly endorse either 6m or 10m as options if you want to FM. SSB will actually work way better thought. You gotta make sure the antenna polarization is the same for both stations (probably vertical). Same story for low band HF (i.e. 40-80m) with a vehicle setup. Ground prop gets better the lower the frequency, SSB is the most efficient voice mode in common use but it is a bear to monitor compared to squelched VHF. |
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TLF, Thanks. As soon as I get my radio back from being repaired, we'll see if we can schedule a QSO. Count me in…I'm up in Wilco and occasionally roll with TLF. Might check out the Armadillo intertie…TLF and I are both members. VHF/UHF are much better options for you're application. You could use low band but you probably won't actually see much of a difference if repeater coverage will work for you. Hill country repeaters actually work better in most instances than many flat land (like you'd find in Lubbock and/or Midland) repeaters. For example, coming in on FM2325 just outside of Wimberley, clean signal on simplex to Boerne. From Kyle you can easily hit a repeater in Llano… Not to mention the coverage on the Armadillo repeaters is downright amazing. The Rabbit repeater covers Airport Blvd and I35 in Austin all the way to the North side of Belton… |
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Count me in…I'm up in Wilco and occasionally roll with TLF. Might check out the Armadillo intertie…TLF and I are both members. Quoted:
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TLF, Thanks. As soon as I get my radio back from being repaired, we'll see if we can schedule a QSO. Count me in…I'm up in Wilco and occasionally roll with TLF. Might check out the Armadillo intertie…TLF and I are both members. Def need to! I just moved and don't have my HF back up yet but I have a portable antenna so I can get on the air easily. Hopefully will be putting up a full wave 80 meter loop. 
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