ad: M2Ant-1

Radio application for emergencies

Discussion in 'Ham Radio Discussions' started by KJ7UJF, Mar 3, 2021.

ad: L-HROutlet
ad: l-rl
ad: l-BCInc
ad: Subscribe
ad: l-gcopper
ad: Left-3
ad: abrind-2
ad: Left-2
ad: L-MFJ
  1. KJ7UJF

    KJ7UJF Ham Member QRZ Page

    A large motivator for me to finally get my license was to have access to a solid means of communication that wouldn't (likely) be flooded like I know cell towers are during emergencies. They also work if there's no power, at least for simplex.

    However, I have a relatively limited set up currently with upgrades beginning to seem a bit further off into the future for me. Short of simply relying on simplex, what are some other tips that I don't know about, or should know about for such situations?

    Before the comments about ARES and RACES, I have looked into my local groups for that, and when I feel I have a better, more reliable setup I intend to join!
    K1LKP likes this.
  2. N1YR

    N1YR Premium Subscriber QRZ Page

    You have two choices for radio communication: using infrastructure, or not using infrastructure.

    Repeaters, repeater linking or remote base operations connected by radio (including microwave), by internet, by dial-up or by private circuit are all infrastructure modes. Infrastructure can be 'hardened.' A ham repeater in a recently constructed Public Safety tower with backup power might not go down when the landlines do.

    Non-infrastructure operation would be communicating direct from an antenna at your location to an antenna at the other operator's location. Whether it's LF, MF (160M), HF, VHF, UHF, or microwave, it's all "direct."

    "Simplex" means alternately transmitting and receiving on a single frequency. Simplex is usually but not necessarily direct, as simplex sometimes can use infrastructure.

    Besides the other station possibly using a remote base, there are store-and-forward devices which will record your simplex transmission, and "play it back" afterwards on the same or another frequency to a wider or different area. They are available but not common for voice, but much packet radio and APRS operate store-and-forward. They have a place but are not very popular, as the message throughput is necessarily cut in half. After you transmit, you wait once while the replay of your transmission goes out to the distant station, and wait once more while that station 'loads' a response, before you hear the response play back to you.

    So, what can you do as a new technician to increase your non-infrastructure dependent coverage? After you make sure you have a back-up power source, of course.

    1. If you are using an indoor antenna, put one outdoors if where you live allows it.

    2. If you have an outdoor antenna, raise it above all the nearby obstructions. It doesn't have to touch the moon, just get it up above anything fairly nearby that blocks the view of the horizon.

    3. Look at coax losses, but don't go crazy worrying about it. Fractions of one dB don't matter that much.
    - RG-58/U is OK for up to 25 feet on 440 MHz, and maybe 80 feet on 2 meters.
    - If you have to run 300 feet of cable to reach the antenna, and can't mount the antenna closer, at least use quality
    RG-8/U or RG-213/U coax so there is some signal left at the far end. 300 feet of RG-58/U is a approaching a dummy load above 100 MHz.

    4. Get on six meters. The FM range is about three times as much as on two meters. But the dead spots are also three times as large, and there is more noise near computer devices. If you don't have a radio that includes six meters, look for surplus fire department FM radios from departments that migrated off of 46 MHz to new systems. Departments might even give them away, if you can find someone who can reprogram newer radios or re-crystal older ones.

    5. Get on Single Side Band. I don't have a rule of thumb for the distance, But I would guess that SSB on VHF or UHF through a horizontal antenna would have about double the range of an FM signal on the same frequency through a vertical antenna.

    6. Upgrade your license, and add HF capability. Put together cheapo dipole antennas with wire from Home Depot or even the Dollar Store. You don't need a whiz-bang radio to get your feet wet, an old used 5-band radio in good condition will do for now. Talking to the other side of the world on 20 meters probable isn't helpful in an emergency, but regional coverage on 40 meters plus 75 meters at night might be.

    There are service nets on 40 meters which would be excellent places to communicate in an emergency. East CARS, South CARS, MidCARS, California ARS, etc. I don't know what's in the Pacific Northwest, but expect that if there's not one local, one of the other service nets would be happy to help if you need them.
    Last edited: Mar 3, 2021
    US7IGN, WA8FOZ, AE7LP and 9 others like this.
  3. WA9SVD

    WA9SVD Ham Member QRZ Page

  4. WA9SVD

    WA9SVD Ham Member QRZ Page

    3. Look at coax losses, but don't go crazy worrying about it. Fractions of one dB don't matter that much.
    - RG-58/U is OK for up to 25 feet on 440 MHz, and maybe 80 feet on 2 meters.
    - If you have to run 300 feet of cable to reach the antenna, and can't mount the antenna closer, at least use quality
    RG-8/U or RG-213/U coax so there is some signal left at the far end. 300 feet of RG-58/U is a approaching a dummy load above 100 MHz.

    I'm afraid I'd take issue with that. I would NOT use RG-58 for ANYTHING on 70 cm, save for jumpers between say an exciter and amp. The loss is just TOO great to use as an actual feedline of any meaningful length. Even RG-8x (aka RG-8mini) performs poorly at 70 cm. And 80 feet of RG-58also has an unacceptable amount of loss even on 2 Meters.
    True RG-8/U cable no longer exists; it has been replaced by RG-213/U. But either cable has appreciable loss at V/UHF, and there are foam insulated versions of RG-8 TYPE (i.e., size) cable (such as LMR-400, some cable types made by Belden, etc.) that are far preferable to RG-213/U for VHF/UHF. And the above is especially important if one is using low power, such as an H-T and an outdoor antenna. While ANYTHING may work in an emergency, a permanent installation should use a good choice/selection of coax.
  5. N3HGB

    N3HGB Ham Member QRZ Page

    Question 1: Communicate with whom?
    A satellite phone or device for texts/emails will probably be more useful in an emergency situation than a whole house full of ham gear.
    If you want comms with family members in the local area, you'll have to decide how much you trust various repeater systems run by various people you don't know to stay up and running and then plan accordingly.
    If you are worried about lack of human contact and being bored sitting around in the dark, get your general, set up for HF, get some batteries, and get familiar with various nets, probably mostly on 40 meters.
    KB7NRN, KB2SMS, US7IGN and 7 others like this.
  6. AG6QR

    AG6QR Premium Subscriber QRZ Page

    That, and its corollary, "For what purpose?" are the crucial questions.

    For emergency communications to be effective, a person in need must be able to contact a person who is willing and able to render assistance in the face of the disaster that just happened. Too many people say, "I need to be able to call for help in an emergency", and not so many worry about "I need to provide help in an emergency".

    For example, if you want to be able to call an ambulance, I can appreciate that desire, but it's simply unrealistic in the face of a disaster that's big enough to wipe out ordinary communications over a large area. Do a survey of the number of ambulances in your community. Consider your community's population. Imagine a disaster where one half of one percent of your community's population needs an ambulance.

    Communities vary widely, but a typical round number is around one ambulance per 30,000 people. If half of one percent of the population need an ambulance, there would be 150 people in need per ambulance. If it takes the ambulance a half hour per call, it will require more than six days to get through the backlog.

    Communications isn't always the bottleneck.

    A disaster that destroys ordinary communications ability is likely to also cause problems with the road network. If nothing else, people trying to evacuate will cause traffic jams. So when you call for help, it's got to be to someone close enough to reach you despite the problems with the road network.

    Back to ham radio: you can put up a modest HF station that will easily have range to contact someone half a continent away, presumably unaffected by the disaster, but how is that person going to help you? They may be able to relay a message to family members, which may provide some comfort, and that's a real benefit, but it's not going to bring help fast.

    If you actually want to help save lives, you can probably limit your communications to fairly short-range local communications, to reach the people who are close enough to be able to help. Even 2m FM may be cluttered with communications from too far away.

    But more importantly, make sure your neighbors have communications ability, too, and make sure all of you do some preparation work for all the non-communications necessities for survival, such as water, food, shelter, warm clothing, etc.

    Get to know your neighbors, and don't just focus on communications, but look at the bigger picture. CERT, NERT, ARES, RACES are all worth looking into.
    N0TZU, WA3VJB, AE7LP and 4 others like this.
  7. N1YR

    N1YR Premium Subscriber QRZ Page

    I agree the losses with RG-58/U are high for a station designed for maximum performance. But I was looking at it from the angle of putting something on the air on a shoestring budget, as opposed to not getting on the air at all. In that situation, I'm going to stretch 'acceptable' cable loss out to about 3 dB. That's only half an 'S' unit.

    I know loss in 80 feet of that cable on 2 meters goes beyond that, and I knew I was pushing the length for the sake of discussion. I guessed that distance off the top of my head late at night without re-checking the loss. If I had said 50 feet on 2 meters and 25 feet on 440 MHz, each would be about -2.8 dB. That's not great, but it's better than nothing.

    RE: LMR 400. I know it has good numbers, and people love it for that, but my experience with it has been inconsistent. Even with the special (expensive) tools, it is hard even for professionals to get the connectors on securely with a solid 'ground' connection to the shield.

    I only allowed Andrew (now Commscope) heliax for new construction at my commercial sites. At one office built before I took over, there were about six 5o-foot runs of VHF cables onto a short tower. During an annual maintenance inspection, two older runs of heliax (with older flared connectors) were fine, but all four newer runs of LMR-400 professionally installed required new connectors at both ends in order to pass inspection.

    I've seen similar 'popular due to good numbers' versus installation issues with Belden 9913, which won't take normal 'N' connectors. As always, your mileage may vary.
    WA4SIX likes this.
  8. W1VT

    W1VT Ham Member QRZ Page

    I used to be able to walk to the top of the nearest hill in ten minutes before I moved to my current location. That may be more cost effective than a tower and expensive coax.

    In the early days of the ARRL there weren't any repeaters. A popular way of passing messages across the country was to relay them between stations.
    One way of getting around skip zones on HF is to send a message out of the skip zone and have someone relay it back into the skip zone.

    Zak W1VT
    US7IGN and N1YR like this.
  9. W4IOA

    W4IOA Ham Member QRZ Page

    Cans and a long string always works
    KE0GXN likes this.
  10. KJ7UJF

    KJ7UJF Ham Member QRZ Page

    Asking the right questions here. I wouldn't have much family to chat with as they're all too far away and entirely uninterested in radio. My lady has her interest piqued, so there's hope (and some prodding) for her so she and I could at least have that together.

    I think you hit the nail on the head with satellite phones, honestly. Could be a good catch for what I'm fishing for.
    AB2YC and WA3VJB like this.

Share This Page