Re: GPSmap60C - External Antenna Jack Voltage Output?
From: Jonas Lonnroth (y#y#z#_at_griffel.se)
Date: 09/21/04
- Next message: Thomas Borchert: "Re: GPS and Beyond: The SatNav Transition for aviation"
- Previous message: R. Dale Shipp: "Re: Microsoft Streets & Trips 2005 with GPS Locator vs. DeLorme Earthmate GPS Receiver with Street Atlas USA 2005"
- In reply to: w a y p o i n t: "GPSmap60C - External Antenna Jack Voltage Output?"
- Messages sorted by: [ date ] [ thread ]
Date: Tue, 21 Sep 2004 09:02:25 +0200
"w a y p o i n t" <waypoint@ARMY.com> wrote in message
news:cimo3m$tbh$1@nobel.pacific.net.sg...
>
> Hi All,
>
> I've tried emailing Garmin, looked through my manual and even read Joe and
> Jack's review. But for the life of me still cannot find the voltage output
> from the external antenna jack. Anyone here know? I'm thinking of getting
> either the MM-II or one of the other many generic low-mA OEM antennas but
do
> not know if they will work right; the minimum voltage required for the
> internal antenna to shutdown and switchover to the external one. I
currently
> have an old LOWE and was thinking of replacing it due to the 60C's use of
> only 2-AAs.
>
> Can anyone here enlighten me?
Not so easy to answer, since the voltage drops with load. On my Garmin iQue,
unloaded output is 2.66 volts. With a Gilsson antenna, voltage drops to
1.99. The Gilsson is still a low consumer, drawing about 10 mA if I
remember correctly. If I insert a bias tee to feed it more, I will gain a
few dB on the signal bars. Best way to know is obviously to hook up a cable
with mcx connectors and insert instruments to measure. That's what I did. I
didn't have the opportunity to try the 60 C though.
There are many antennas that work well on the new range of low voltage GPS
receivers, among them the Gilsson, Garmin 27 C and Wi-sys 3910. The Gilsson
has by far the best performance/price ratio. If voltage goes below 1.7
volts, I believe the Garmin 27 C is to be preferred but it has less
amplification than the others when fed more than 2.5 volts. It might only
contain one amplifier stage, whereas others contain two.
This said, all these antennas work at the very lower end of their power
range as voltage drops. I believe the amplifier circuits in these antennas
are 3 volt circuits (or 3.3). The internal working voltage of the Gilsson
when fed 9 volts to the voltage regulator is 2.93 volts.
Antenna makers are aware that there is room for antennas optimized to work
at around 2 volts and I believe some are working on it. This conclusion is
drawn from the fact that they were initially inclined to discuss the problem
and to gather information, but then turned silent.
Jonas Lonnroth
Brussels
- Next message: Thomas Borchert: "Re: GPS and Beyond: The SatNav Transition for aviation"
- Previous message: R. Dale Shipp: "Re: Microsoft Streets & Trips 2005 with GPS Locator vs. DeLorme Earthmate GPS Receiver with Street Atlas USA 2005"
- In reply to: w a y p o i n t: "GPSmap60C - External Antenna Jack Voltage Output?"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
