🚀 go-pugleaf

In article <1990Aug30.131140.20946@phri.nyu.edu>, roy@alanine.phri.nyu.edu (Roy Smith) writes:
> 	I just bought an ICOM M-11 handheld VHF tranciever.  It comes with
> a removeable NiCd battery pack and a 110V recharger.  The manual says you
> can charge the battery pack while it is still attached to the radio, but
> you should make sure the radio is off because you might damage it.  Can
> anybody think of any good reason why you shouldn't be able to run it while
> plugged in?

	I have no knowledge of your specific radio, but based upon some
familiarity with other rechargeable radio apparatus, I can give you
some general reasons why such a caution notice might appear:

1.	Many chargers have little voltage regulation beyond I^2R across
	a dropping resistor and/or inherent transformer loss current
	limiting.  If the battery were disconnected, the open circuit
	voltage might be as high as twice the battery voltage.  If the
	battery pack developed an open circuit fault (perhaps an internal
	fuse blew) && if the charger were connected to the radio &&
	if the radio were turned on, the charger circuit could present
	a substantial overvoltage to the power input of the radio,
	thereby causing damage.

2.	Same scenario as (1) above, but consider that some chargers have
	no filter capacitor, so there could be some pretty ugly DC
	powering the radio if the battery were open.  While there might
	not be any damage (except for possible overvoltage), the radio
	would not likely operate with such huge ripple.

3.	Same scenario as (2) above, but with the battery okay and charging.
	There might still be an excessive amount of ripple introduced into
	the radio, preventing its proper operation.  No real damage here,
	but the manufacturer might simply want to avoid any possible
	customer complaint.

4.	Many chargers do not have the current capacity to run the radio
	itself, especially in transmit mode.  If the battery were deeply
	discharged && if the charger were connected to the radio &&
	if the radio were turned on, the current capacity of the charger
	might be exceeded, thereby causing damage to the charger.

5.	A remote possibility: there may be two much RFI radiated back
	through the AC powerline were a charger to be connected, but the
	radio itself meets type acceptance when operated as an isolated
	device.

> 	While playing with the scan feature, I noticed it always stops on
> 24 and 70, even though there isn't anything there.  Why should it do that?
> It's almost as if somebody was broadcasting unmodulated carrier on those
> channels.  Is that possible and/or likely, or is there a better
> explanation?

	You live in New York City, right?  Isn't New York City known
as "The Intermodulation Capital of the World"?

	Need I say more?  :-)

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231   {boulder, rutgers, watmath}!ub!kitty!larry
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