REMINDER: MAPOA NVIS Contest 30 SEP 17

IMG_0601

Shoot, Move, Communicate. Time to get out and train. No excuse not to, and here’s an opportunity. Mid Atlantic Portable Operator’s Association NVIS contest– put that snazzy field rig to work amid the horrible solar conditions. Kit bash your gear and make it better. There’s only one way to know and that’s by doing it.

Like the Patch? 144:1 will square you away. Like the chest rig? UW Gear will do the same.

 

Advertisements

6 thoughts on “REMINDER: MAPOA NVIS Contest 30 SEP 17

  1. Scurvy

    Nice to see you’re insulating your battery terminals.

    Did you learn the hard way when you brushed some metal across or do one of the old timers enlighten you before it happened?

    Thanks for providing the venue to learn from those that I would never have the opportunity to meet.

    Liked by 1 person

      1. LodeRunner

        When dealing with any type of high-current source, good insulation is mandatory – and for field gear, that should include abrasion resistance sufficient to prevent a short-circuit caused by 10,000+ repetitions of load-shifting in your pack. The alternative is to invite a ‘hot surprise’ at the worst possible moment, i.e. when your urgently engaged with other activities — such as moving to cover under direct fire.

        Liked by 1 person

  2. LodeRunner

    Mike B. et all;

    “Resonant” antennas are only important if you want to minimize the losses common to nearly all commercial “antenna tuner” units A.K.A. an “ATU” or “Transmatch”.

    And while those losses may not mean much when you’re running a hundred watts and a “big” antenna – they can mean the difference between success and failure when running QRP (low power) and/or with small, compromise antennas – as is common when running mobile, and in field-expedient setups.

    “Tuners” are most efficient when the VSWR of the antenna itself are 2:1 or less, and you’re just ‘touching up’ the match to optimize it. But running blind into the end of a random wire [or any other non-resonant radiator] the VSWR may be 20:1 or worse. The worse the natural VSWR of the antenna at the operating frequency, the worse the losses in the ‘tuner’ will be. This applies equally to BALUNs and UNUNs operated in a mis-matched condition. When the natural VSWR of the antenna is 20:1 or worse, you’ll be lucky to get 10% of your power into the air as signal – that’s a 90% power loss!

    The same [probably] applies to your received signals – you may be deaf because of the losses in the sytem. Some radio/ATU combinations are more forgiving of mismatch on RX than others – do you know how your radio and ATU behave under such conditions? Some radios with built-in ATUs give you the option to include/exclude the ATU on receive – do you know how yours is set up, and have you tested the difference between your available options? You should.

    To say “DGAF” about something, when you have no knowledge of the magnitude of loss(es) it will cause, is not a wise approach – get an antenna analyzer and test your antenna *without* a tuner or balun in line, and see what its natural feed impedance is on the band(s) you intend to operate it on. You may discover that some changes are in order.

    And that is why taking your kit to the field and testing it is an essential part of readiness – unless being ready to fail is part of your plan.

    Operated with a friend and ally for the MAPOA contest yesterday. Not much activity was heard, but we did learn some important weaknesses [failure modes] about his current digital kit. Weaknesses which have now been resolved —
    and THAT turned out to be the most valuable part of the day.

    Liked by 1 person

Comments are closed.