Today's Message Index:
----------------------
1. 06:52 AM - Re: Aux power to learn avionics (rampil)
2. 06:53 AM - Re: Using the "Poor man's 4-wire milliohmmeter" (user9253)
3. 07:58 AM - Re: Re: Using the "Poor man's 4-wire milliohmmeter" (Kent or Jackie Ashton)
4. 10:02 AM - Re: Using the "Poor man's 4-wire milliohmmeter" (user9253)
5. 01:17 PM - Re: Re: Using the "Poor man's 4-wire milliohmmeter" (Robert L. Nuckolls, III)
6. 02:11 PM - Re: Using the "Poor man's 4-wire milliohmmeter" (Robert L. Nuckolls, III)
7. 02:45 PM - Re: Using the "Poor man's 4-wire milliohmmeter" (Robert L. Nuckolls, III)
8. 03:21 PM - ADS-B Antenna (Roger)
9. 03:55 PM - Re: ADS-B Antenna (user9253)
10. 04:33 PM - Re: Re: Using the "Poor man's 4-wire milliohmmeter" (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Aux power to learn avionics |
BTW, Batteries are made to be drained!
No harm, no foul! You just need to recharge your lead acid battery
when you are done studying. Discharging your battery to the point where
your avionics quits (probably about 10 volts(here I am guessing that the avionics
is universal 12-24 compatible)) will not harm the battery.
Some avionics (with poor design) may complain more.
And yes, The voltage was probably declining due to current draw in
excess of charger supply
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459155#459155
Message 2
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
Another option: Disconnect the aircraft battery negative terminal. Assuming that
the master contactor has a single coil terminal and the starter contactor
has two coil terminals, unbolt the master contactor from the firewall and isolate
it from ground. Energize both contactors with an aux battery. The aux battery
positive should be connected directly to the battery contactor positive
stud, not to the nuts.
Now the resistance of the starter circuit can be measured at any location between
the aircraft battery positive post and the disconnected negative battery-cable
end.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459156#459156
Message 3
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
> On Aug 3, 2016, at 9:51 AM, user9253 <fransew@gmail.com> wrote:
>
>
> Another option: Disconnect the aircraft battery negative terminal. Assuming
that the master contactor has a single coil terminal and the starter contactor
has two coil terminals, unbolt the master contactor from the firewall and isolate
it from ground. Energize both contactors with an aux battery. The aux
battery positive should be connected directly to the battery contactor positive
stud, not to the nuts.
> Now the resistance of the starter circuit can be measured at any location between
the aircraft battery positive post and the disconnected negative battery-cable
end.
Yes, I can see that. This is a Long-EZ with battery & master solenoid in the
nose on fiberglass structure and a starter solenoid on the aft metal firewall.
I dont see the need to dismount the solenoids but your suggestion would allow
me to test the whole circuit from the battery area.
I dont know the internal resistance of my Skytec starter. I suppose I can measure
it separately.
However, I think today Ill just measure the resistance of some assembled joints
on various large cables I have in the shop and compare that to some of the roughly
soldered joints in the airplane cables. If that doesnt reveal a bad joint,
Ill try something else.
Thanks for the help.
-Kent
Message 4
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
The reason that I suggested isolating the battery contactor from ground is because
its coil is connected in parallel with the starter motor when the starter
contactor is energized. Your fiberglass airplane might be wired differently than
metal aircraft.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459167#459167
Message 5
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
> Yes, I can see that. This is a Long-EZ
> with battery & master solenoid in the nose on
> fiberglass structure and a starter solenoid on
> the aft metal firewall. I don=99t see the need
> to dismount the solenoids but your suggestion
> would allow me to test the whole circuit from the battery area.
What gage wire is used for
battery and ground leads that
run the length of the aircraft?
Bob . . .
Message 6
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
At 02:01 PM 8/2/2016, you wrote:
>Jackie Ashton <kjashton@vnet.net>
>
>Hi Bob,
>
> I made one of these to troubleshoot a
> sluggish starter on a Long-EZ from your
> excellent discussion
> here
> http://www.aeroelectric.com/articles/grnding.pdf
> I suspect I have some bad solder joints in
> connectors on copper-clad aluminum cables and
> thinking of the best way to test for excessive resistance. I am thinking:
>
> I could test each connector joint by
> isolating the cable & connector and probing
> between the clean bare cable and the connector, or
>
> Alternatively, perhaps I could test the
> entire cable run and the solenoids by
> disconnecting the cable it at the battery and
> the starter, activating the master and starter
> solenoids with a portable battery and probing
> between the battery-end and the starter-end.
>
> Or could I disconnect the starter cable
> at the starter, active the master and starter
> solenoids with the usual switchology and probe
> between the battery post and the starter-end of
> the cables. Does connection to the battery affect the test?
>
> What=99s your preferred strategy here? Thanks.
>
>-Kent
>
Bob . . .
Message 7
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
At 02:01 PM 8/2/2016, you wrote:
><kjashton@vnet.net>
>
>Hi Bob,
>
> I made one of these to troubleshoot a sluggish starter on a
> Long-EZ from your excellent discussion
> here http://www.aeroelectric.com/articles/grnding.pdf I suspect
> I have some bad solder joints in connectors on copper-clad aluminum
> cables and thinking of the best way to test for excessive
> resistance. I am thinking:
Hmmmm . . . that tool is useful for evaluating
the quality of any one joint and it assumes that
you have some notion of the resistance value
representing a quality joint . . .
> I could test each connector joint by isolating the cable &
> connector and probing between the clean bare cable and the connector, or
>
> Alternatively, perhaps I could test the entire cable run
> and the solenoids by disconnecting the cable it at the battery and
> the starter, activating the master and starter solenoids with a
> portable battery and probing between the battery-end and the starter-end.
>
> Or could I disconnect the starter cable at the starter,
> active the master and starter solenoids with the usual switchology
> and probe between the battery post and the starter-end of the
> cables. Does connection to the battery affect the test?
One of my favorite tools for chasing this
dragon (and similar issues) is this modified
battery tester from Harbor Freight.
Emacs!
In this instance, the device is also used as a high
current load for my test bench . . . you may not want
to cut the leads so short. In any case, this mod
allows you to bolt the load into the system with
good mechanical/electrical integrity.
When you strip the wires to attach fat-wire lugs,
be sure to find ANOTHER wire buried in with the
strands of the fat-wire. This is the SENSE wire
for the voltmeter.
To troubleshoot integrity of your cranking
circuit, connect (-) lead to crankcase. (+)
lead to the BATTERY side of your starter
contactor. With the master switch ON, you
should read battery voltage. Then crank the
puppy up to some handy value . . . say 150
amps. The voltage should NOT be less than
9v.
If less, the next handy-tool for one-man
diagnostics is a very long set of leads for
your multimeter that will let you clip to
the (-) side of the battery and then take
successive measurements of VOLTAGE at battery(+),
battery side of battery contactor and crankcase
while generating the same, test load as before.
These readings will let you evaluate ground and
supply segments of the cranking circuit INDEPENDENT
of starter controls.
The next test may be a two person test . . . disconnect
the (+) lead from your starter motor and connect
(+) lead of your HarborFreight tool to the starter
motor power lead. While someone presses the start
switch in the cockpit, repeat the votlage measurement
under the 150A load. You need to do this with some
dispatch . . . starter contactors should not be
energized for more than 10 second or so without a cooling
period of a minute or so.
Once you have the numbers observed in these
experiments, the combination of conditions that
add up to your perceived performance issue will
be easily deduced.
Bob . . .
Message 8
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I am in the process of gathering information for the installation of an ADS
-B in my all wood airplane. The Transponder that I am considering uses 2 a
ntennas for the UAT 978 MHz portion. I am considering using the small rod
antenna which is similar to that used for the transponder. Since it is a d
ifferent frequency than the xponder I will purchase the one specifically fo
r the UAT. I am assuming that it is OK to mount this antenna inside the wo
od fuselage. Is this correct? Also I believe that it will need a ground p
lane. Is there a recommended configuration for the ground of this antenna?
Would the 2 antennas be set up identically?
Roger
Sent from Mail for Windows 10
Message 9
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| Subject: | Re: ADS-B Antenna |
There was a recent thread about transponder antennas that might help:
http://forums.matronics.com/viewtopic.php?t=16762861&sid=0fdc43cf144daf15623736558e046890
I have read that a transponder antenna may also be used for 978 MHZ.
At the iFly booth in OSH, I was impressed by the pinBuddy dual band ADS-B receiver
that is a fraction of the size and uses a fraction of the power of the Stratux.
http://www.uavionix.com/
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=459185#459185
Message 10
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| Subject: | Re: Using the "Poor man's 4-wire milliohmmeter" |
At 04:11 PM 8/2/2016, you wrote:
>
>Disconnect the starter and replace it with a high wattage
>load. Connect the negative side of the high wattage load to the
>starter housing. Turn on the battery contactor and the starter
>contactor. Connect the RED voltmeter lead to the POSITIVE battery
>post. Then using the black voltmeter probe, measure the voltage
>drop at various points between the positive battery post and the
>high wattage load. Harbor Freight sells a 100 amp battery load tester for $22.
>http://www.harborfreight.com/100-amp-612v-battery-load-tester-61747.html
Agreed. This is a useful tool for chasing this
dragon (and similar issues). I've modified this
one for improved electrical/mechanical integrity.
Emacs!
In this instance, the device is also used as a high
current load for my test bench . . . you may not want
to cut the leads so short.
When you strip the wires to attach fat-wire lugs,
be sure to find ANOTHER wire buried in with the
strands of the fat-wire. This is the SENSE wire
for the voltmeter.
To troubleshoot integrity of your cranking
circuit, connect (-) lead to crankcase. (+)
lead to the BATTERY side of your starter
contactor. With the master switch ON, you
should read battery voltage. Then crank the
puppy up to some handy value . . . say 150
amps. The voltage should NOT be less than
9v.
If less, the next handy-tool for one-man
diagnostics is a very long set of leads for
your multimeter that will let you clip to
the (-) side of the battery and then take
successive measurements of VOLTAGE at battery(+),
battery side of battery contactor and crankcase
while generating the same, test load as before.
These readings will let you evaluate ground and
supply segments of the cranking circuit INDEPENDENT
of starter controls.
The next test may be a two person test . . . disconnect
the (+) lead from your starter motor and connect
(+) lead of your HarborFreight tool to the starter
motor power lead. While someone presses the start
switch in the cockpit, repeat the votlage measurement
under the 150A load. You need to do this with some
dispatch . . . starter contactors should not be
energized for more than 10 second or so without a cooling
period of a minute or so.
Once you have the numbers observed in these
experiments, the combination of conditions that
add up to your perceived performance issue will
be easily deduced.
Bob . . .
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