REFLECTOR: GRT Ammeters

[Craig and Denise Woolston]

Bill-

  Can't offer a solution but one thing that got me on GRTs with SF and
Offset is at least for the fuel pressure sensor (which is also done with the
4.8 excitation voltage), you had to use literally a odd number only for the
SF and offset.  In my constant adjusting with Sandy on the other end of the
phone it didn't become obvious that she really meant 1,3,5,7,9,11, etc. NO
2,4,6,8,etcs allowed.

Sorry didn't put in amps on our setup so can't completely help you out.

FYI, we put a temp sensor at the top of the cowl b/t the runners also.
Never seen more that about 105 degrees in flight.

Craig
XL-FG Flying in Lancaster, CA
(197 hrs) 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of LAURA WALKER
Sent: Sunday, December 09, 2007 8:51 AM
To: reflector at tvbf.org
Subject: REFLECTOR: GRT Ammeters

Hi All,

Anybody else have problems with GRT's Ammeter SF and Offset settings? I have
two, and am using them through the EFIS analog inputs at the #4 and #5 pins
on the B connector. The problem is that using the factory's SF and Offset
settings results in either battery reading a 14 amp current draw when
disconnected from the bus, and the remaining battery showing a 20 amp draw
for just the two EFISs and the EIS running. Even when I completely
disconnect either battery's cables from the system, it still shows a 14 amp
draw. I talked to Sandy, Jeff, and Carlos: they all think I made some weird
mistake in my wiring. I told them Aerotronics did the system...I just hooked
up three wires each, and yes, my 4.8V output is correct at 4.8 Volts. 

I played with the above settings, and with some slight massaging so that the
disconnected battery reads 0 current draw, the other one shows 2-3 amps for
the 2 EFIS and EIS running. This seems about right to me, and as I add
loads, it seems to come up appropriately. When I bring both batteries
online, the total is split correctly. My problem is that now I don't trust
them to be reading correctly with the changed parameters. Sandy is stymied.

My instinct told me to find a clamp-on DC load meter, so through E-Bay,
that's what I am waiting for to arrive sometime next week. 

Just wondering if anyone else has experienced this problem.


Bill Walker


PS  I have had good luck using two of the AUX channels on the EIS with fluid
temp sensors to create engine compartment fire detection sensors. I have one
at the top of the firewall between the air inlets and one above the fuel
spider glassed into the engine plenum. On the EFIS they are named FIRE and
ENG FIRE and are assigned to B1 and B2 bar graph positions. This way, with
the gauges page they are invisible unless either goes above it's warning
parameter. They both tested fine throughout their temperature ranges with
the thermometer and hot water test. After flying, I will adjust their
warning range to about 50 degrees above their temps on a warm-day, sustained
high alpha climb. A manual cable-operated extinguisher system from Safe-Air
with the cable running the length of the overhead plenum will complete the
system.
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