Handhelds and alkaline batteries

Jim Weir wrote in
:

Alkalines have a problem when you get to the power levels we are
talking about for transmit. They last a mercifully short time in most
HTs. We've found that popping for the NiMH cells is far better from a
time and life point of view.

The trouble with NiMH in a handheld used for emergencies (i.e. toss it
into the flight bag and forget it) is the HORRIBLE self-discharge rate.
Basically you need to recharge then every couple of months - especially
if they are kept in a warm environment. [Worst case self-discharge rate
is listed at 3% per day!!! NiCad is almost as bad, at 1% per day.
Note that both of these are WORST CASE.]

Alkalines are great at shelf life, but as Jim (furture govenor) says,
they may not support the current draw during transmit.

Two possible tests:

1. Put a scope directly on the battery pack during transmit - if you can
see the modulation (or any significant change), that's the problem.

2. If the result of step 1 is that you actually see the modulation (as
opposed to the overall voltage simply dropping too low) then it might be
possible to rig a super-cap across the battery.

What's the transmit power of that little handheld supposed to be anyway?

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James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
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