[usa2003ardf] Transmitters

[Kuon & Dale Hunt]

Ken wrote:
>
>How do you charge the gel cells...

    The simple solution is to float them across a power supply set
    to 13.8V.  This doesn't get them to full charge, but you can't
    hurt them by leaving them on too long.

    I found some surplus wall warts designed for charging gel
    cells, at about $2 each.  My plan was to leave one in each
    box if I loaned them out, but haven't gotten it all set yet.
    At present I open the box, remove the battery lead from the
    transmitter and plug in the charger (a voltage/current limited
    power supply.)  I can't do them all at once, but that hasn't
    been a problem so far.

    One comment on the homing beacon in Ohio - it had a pair of
    binding posts on the outside for the battery.  This meant
    that the cable from the battery had a pair of banana plugs
    on the end.  When you are throwing everything in the car
    afterwards, it is quite easy for those plugs to short out to
    something accidentally.  A good safety rule is to use female
    connectors on the battery side and male connectors on the load
    to help prevent such situations.

>
>Also, for those who use ammo cases, have you ever had overheating problems?
>It can get really hot in Texas, and I wonder if anything goes wrong with
>gear when it gets really hot...
>


    I put a larger heat sink on the beacon transmitter on 80m because
    it was running full time, but otherwise haven't had problems
    with overheating.  But Oregon isn't as hot as Texas!

    That is one reason why I run only about 1 watt on all my
    transmitters (2m and 80m).  On one old HT I added a pot
    on the low power switch that allows me to adjust the level
    anywhere I want, while on other rigs I adjust the output
    by varying the DC voltage with a regulator.  (Running the
    transmitter on about 8V through a regulator means the
    battery voltage has to drop below 11 volts before the
    power output is affected.  This is a good thing.)

    I think Joe Moell uses the larger ammo boxes and has the
    whole circuit mounted to the lid (which is removable).
    You probably could arrange to heat sink the radio to
    the lid and/or box also.  I find a heat sink inside the
    box is sufficient as long as I don't have too much
    stuffing around it to keep everything in place.


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