power save function

At 19:21 16/04/2003 +0000, you wrote:
>   From: Dan Jacobson <[email protected]>
>Subject: power saver function, pros and cons please
>
>(Manual, page 26)
>    Power saver
>
>    The power saver function reduces the current drain to conserve
>    battery power.
>
>Great!  A clear choice that anyone in their right mind would
>make. Just like if there was a
>    Power waster
>
>    The power waster function increases the current drain to waste
>    battery power.
>A clear choice that anyone in their right mind would not
>make.
>
>OK, so what are the pros and cons of this "power saver" function?

In "power save" mode, the microcontroller inside the radio shuts down most 
of the receiver circuitry most of the time, thus saving the current that 
would otherwise be consumed by it.  The receiver is powered up periodically 
just long enough to check whether there is any activity on the channel, then 
it goes off again.  If you disable power save mode, the receiver stays on 
all the time.

The tradeoff is this:  In "power waster" mode, the radio will detect carrier 
and unsquelch almost instantly after someone else starts transmitting.  
You'll always hear everything transmitted.  In power save mode, you may miss 
the first few syllables of a transmission, depending on how long the period 
between checks is, and plain luck (how long it is to the next check when a 
transmission begins).

My FT-50 allows setting the check time to a value between 200 ms and 1 
second, depending on the tradeoff you want to make between power consumption 
and missed syllables.  The R2 doesn't let you set the time; it has only 
"auto" mode.  Auto adjusts the delay depending on recent activity.  For the 
first 5 seconds of silence, the R2 receiver remains on full-time, so in a 
back-and-forth conversation you won't miss anything.  After 5 seconds of 
silence, the R2 starts checking about 4 times per second.  After another 32 
seconds of silence, the R2 drops back to once every 1.2 seconds.  I haven't 
been patient enough to see if there's another even slower rate, but I'd 
guess not.  It stays at 1.2 seconds for at least 15 minutes.

So the R2 can miss up to a second at the beginning of a transmission 
in power save mode (worse case).  If you don't need maximum battery life, 

>  The radio drains about 100mA when power save is not engaged and during
>  scanning (squelch closed), 110 mA and a little more at squelch open
>  depending on the volume setting, about 45mA when power save
>  engages. The LCD backlight adds just 10mA to these values, thus it can
>  be left to "AUTO" even during daylight without sacrifice.

As you can see, the backlight and audio power amplifier take relatively 
little power when on.  (The audio amp is unpowered except when squelch is 
open - that's why you hear a "thump" at the beginning of any audio).  But 
turning off all the receiver stages cuts power consumption to less than 
half.  With little activity on a channel, it could double battery life.

>By the way, how about power drained when monitoring one frequency,
>vs. programmed scan, vs. memory scan, all when there are no
>transmissions to open the squelch?

Power save only operates when you are monitoring a single frequency.  In 
that case, if there wasn't any activity a second ago, the odds are good that 
it's still quiet.  But in all of the scan modes, the receiver is hopping 
from one frequency to the next as fast as it can, and it is turned on all 
the time.  Even if you're scanning just one bank, it is still several 
seconds between checks of any one frequency, and you wouldn't want to make 
those even further apart.

>BTW, to test this does one just put their multimeter in series with
>the batteries?

You could do that.  I just connected the R2 to a power supply and watched 
the ammeter bounce to make the timings above.  Looking into the battery 
compartment from the rear of the radio, the two contacts on the left 
actually connect to the R2 circuitry, while the contacts on the right side 
just connect the two batteries to each other.

>PS2: is the R5 generally available now making all of us "passed by the
>wayside of history", "vintage owners club", etc.?  <or> "Well, the R5
>is more expensive, plus there is less software available for it, so
>there, I don't regret having the older model."

The R2 does what I want fine.  I haven't run out of channels or banks yet, 
so I don't need the extra memories.  Alpha labels on the channels would be 
nice; I miss that from my ham HTs.  The ferrite AM antenna would be nice, 
but the R2 actually picks up strong local AM stations fine with its stock 
antenna.

But what I *really* want most, if I ever buy another receiver, is a numeric 
keypad to enter frequencies directly - and the R5 doesn't have that.

        Dave  


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