Today's Message Index:
----------------------
1. 06:19 AM - Re: Comm Antenna (Robert L. Nuckolls, III)
2. 07:14 AM - Re: Torque Values (Henry Trzeciakowski)
3. 07:20 AM - Re: Epoxy to Aluminum (John Morgensen)
4. 10:07 AM - AC switches in DC applications (Dennis Jones)
5. 10:59 AM - Re: AC switches in DC applications (Ron Shannon)
6. 02:54 PM - ANL Current Limiter to protect 10 AWG Wire (Larry Rosen)
7. 05:35 PM - Re: KY-97 Power Pins (Matt Prather)
8. 07:28 PM - Re: ANL Current Limiter to protect 10 AWG Wire (Ron Shannon)
9. 07:32 PM - Re: ANL Current Limiter to protect 10 AWG Wire (Ron Shannon)
Message 1
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| Subject: | Re: Comm Antenna |
>It seems that the cable between the ELT and the cockpit control is
>acting as an antenna, picking up COM transmissions, and feeding it
>into the ELT. This signal coming in on the cable is somehow
>interpreted as if the cockpit control had been activated. So, I
>wonder if there is a way to shield the cable between the ELT and the
>cockpit control, to reduce the amount of energy that it is picking up
>from COM transmissions. Also, rerouting that cable further away from
>the COM antenna would reduce the energy level it sees.
I've heard this about the ACK ELTs in the past. I
'presume' they've done their homework and meet all
the test requirements levied on them for qualification
in metal airplanes.
>Bob - the ACK ELT uses a length of apparently conventional telephone
>cable to connect the ELT to the cockpit control. Is it worth trying
>to replace that telephone cable with some sort of shielded cable,
>splicing it into a piece of telephone cable at each end so it has the
>correct connectors? If that was tried, where should the shield be
>grounded (keeping in mind this is a composite aircraft, and that the
>ELT enclosure and cockpit control are both made of plastic)?
I presume the problem goes away when the cable is unplugged?
Hmmm . . . shielding a bundle is almost never the best way
to go after an RFI problem. A filter assembly at the ELT's
remote switch connector is the best shot at it. Do you know
which wires in the conductor are common or ground? A few
chokes and capacitors from Digikey could be crafted into
a compact filter that would have high attenuation at
VHF Comm frequencies.
Bob . . .
Message 2
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| Subject: | Re: Torque Values |
Bob:
I just can't find any info on what the torque values are for the large
and small terminals on the Battery Contactor and Starter Contactor.
Any assistance appreciated.
Hank
Message 3
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| Subject: | Re: Epoxy to Aluminum |
Has anyone tried re-using the click-bond "worms" with standard K1000
plate nuts? It seems to me that the rivet holes would aid in bonding and
the rubber "worm" provides alignment, compression, and protects the
threads from the adhesive.
john
bakerocb@cox.net wrote:
>
> 4/28/2008
>
> Hello Dennis, Thanks for your interesting input.
>
> One technique that may be used, if appropriate to the situation, to
> improve joint holding, is to make holes in the aluminum. This permits
> the epoxy to ooze through and form sort of a rivet effect for the glue
> line.
>
> 'OC' Says: "The best investment we can make is the effort to gather
> and understand knowledge."
>
> -----------------------------------------------------------
>
> Time: 10:11:16 AM PST US
> From: "Dennis Johnson" <pinetownd@volcano.net>
> Subject: AeroElectric-List: Epoxy to Aluminum
>
> Greetings,
>
> As part of building a composite airplane, I studied everything I could
> find about epoxies, materials, and adhesive bonding in general. I
> concluded that I did not have the ability to make an epoxy bond to
> aluminum that I could be confident that it wouldn't fail.
>
> The problem is that aluminum begins oxidizing immediately after
> cleaning. No matter how quick you are, unless you use extraordinary
> measures, there will be aluminum oxide on the surface you are bonding.
> Aluminum oxide has relatively low strength. The epoxy bonds well to the
> aluminum oxide, but the aluminum oxide isn't stuck very well to the
> underlying aluminum. After some number of hot/cold and wet/dry cycles,
> the bond may weaken enough to fail.
>
> Obviously, Boeing and others solved this problem long ago. However,
> based on the great reference book, "Composite Basics," by Andrew
> Marshall, their methods aren't practical for most of us homebuilders.
>> From chapter 11, Marshall says, "Unfortunately, both the FPL etch and
> the PAA treatments (the ones widely and successfully used in the
> industry) involve extensive chemical control and a large investment in
> equipment."
>
> As an interesting aside, he describes an industry standard "wedge" test
> where two .125" thick aluminum pieces are bonded together. After
> curing, a wedge is driven into the end of the assembly, between the two
> pieces of aluminum, which forces the bond to break at that point. A
> mark is placed at the point where the fracture stops. The test piece is
> then placed into a warm, wet chamber for one hour. The assembly is then
> removed and the additional distance the crack propagated during the
> warm/wet test is measured. If the crack grew less than three-fourths of
> an inch, the bond is considered to be good for life. Marshall says that
> if the aluminum was cleaned but not chemically treated, the assembly
> will likely totally delaminate during the one hour test!
>
> Since I didn't have the ability to duplicate Boeing's chemical treatment
> process, I didn't make any bond to aluminum that would cause anything
> more than inconvenience if it failed. Heat and humidity seem to be the
> culprits, which might explain why some people report long lasting bonds
> and others have failures.
>
> Best,
> Dennis
>
>
Message 4
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| Subject: | AC switches in DC applications |
Bob
I know this has been discussed before. I'm unable to find the reference
in the connection about AC switches, there ratings and how to make sure
you are using an appropriate AC switch in a DC application.
Thanks
Jonsey
Message 5
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| Subject: | Re: AC switches in DC applications |
You may find at least some of the answers you need in Bob's article here:
http://www.bandc.biz/swtchrat.pdf
Ron
On Sun, May 4, 2008 at 10:00 AM, Dennis Jones <djones@northboone.net> wrote:
> Bob
>
> I know this has been discussed before. I'm unable to find the reference in
> the connection about AC switches, there ratings and how to make sure you are
> using an appropriate AC switch in a DC application.
>
> Thanks
> Jonsey
>
Message 6
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| Subject: | ANL Current Limiter to protect 10 AWG Wire |
I need some guidance.
I want to use 10 AWG wire from my SD-20 alternator to feed my endurance
bus.
I would like to use an ANL current limiter to protect the wire.
B&C sells a 40 amp ANL and Bussman makes a 35 amp ANL (does anyone have
a source for this 35 amp ANL)
The wire table (Fig 8-3) in the connection suggests 30 amp protection
for 10 AWG wire.
Is 35 or 40 amp protection on this wire acceptable?
Would I be better off using a 14 AWG fusible link?
In addition in this circuit I want to use a S704-1 relay that is rated
at 20 amps, do I need to protect the relay? The maximum loads off the
relay are well below the 20 amps, but if it does see excessive currents,
how does it fail?
Larry Rosen
Message 7
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| Subject: | Re: KY-97 Power Pins |
Thanks for the input Bob. They KY-97 is a comm radio however.
I wired the unit according to the manual (a copy of which Bill posted),
and it seems to power up okay - no antenna hooked up so haven't tried
transmitting/receiving yet. I had speculated that the loop put an
internal regulator in the correct mode, but still not sure.
Regards,
Matt-
> <nuckolls.bob@cox.net>
>
> At 02:49 PM 5/3/2008 -0600, you wrote:
>
>> <mprather@spro.net>
>>
>>Hey group,
>>
>>I am helping to install a King Ky-97 comm into a friend's airplane and
>>have a question about wiring the power pins. The manual lists "SWITCHED
>>A/C POWER", "13.75 A/C POWER" along with "13.75V POWER". Does anyone
>> know
>>how these pin groups differ in function? Would it be safe to connect
>> them
>>all together?
>>
>>
>>Regards,
>>
>>Matt-
>
> If I read the data at:
>
> http://www.aeroelectric.com/Installation_Data/KY97A.pdf
>
> correctly, pins 14 and "R" are the ship's power input
> from the bus.
>
> Pins 11, 13, "M" and "P" according to Note 4 all get
> tied together. If we had a schematic of the radio, I
> think we would find that two of the four cited above
> are switched power FROM the bus and two others are
> power INTO the transponder's electronics. This pair
> of pathways are brought out downstream of the transponder
> power switch to allow you a switched source of power for
> the encoder.
>
>
> Bob . . .
>
>
Message 8
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| Subject: | Re: ANL Current Limiter to protect 10 AWG Wire |
Larry,
FWIW, I was convinced by a number of folks that #12 AWG was adequate for
both my Jabiru 3300's nominal 20A alternator AND for the SD-20S backup,
which have separate charging output circuits, of course. If you look at
AC43, you'll see that in short lengths, #12 is plenty big enough for even
30A. I don't expect to ever draw more than 25A from either alternator, and
then only for rare, short periods, after a long cold start followed by
fairly immediate high RPM, i.e., poor battery mgmt.
On advice of B&C, for over current protection I went with an 30A ATC inline
blade fuse, one for each alternator, and the S704-1 relay to provide
switching for one leg of the Jabiru PM alternator's output (no field circuit
there) for OV protection. I don't think you need a relay for the SD-20,
because the OVP scheme (whether inboard with the LR3C regulator, or one of
the outboard "crowbar" circuits) will shut down the alternator by cutting
the field circuit, wired in series with your panel ALT switch.
Ron
On Sun, May 4, 2008 at 2:50 PM, Larry Rosen <LarryRosen@comcast.net> wrote:
> LarryRosen@comcast.net>
>
> I need some guidance.
>
> I want to use 10 AWG wire from my SD-20 alternator to feed my endurance
> bus.
> I would like to use an ANL current limiter to protect the wire.
> B&C sells a 40 amp ANL and Bussman makes a 35 amp ANL (does anyone have a
> source for this 35 amp ANL)
> The wire table (Fig 8-3) in the connection suggests 30 amp protection for
> 10 AWG wire.
> Is 35 or 40 amp protection on this wire acceptable?
> Would I be better off using a 14 AWG fusible link?
> In addition in this circuit I want to use a S704-1 relay that is rated at
> 20 amps, do I need to protect the relay? The maximum loads off the relay
> are well below the 20 amps, but if it does see excessive currents, how does
> it fail?
>
> Larry Rosen
>
Message 9
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| Subject: | Re: ANL Current Limiter to protect 10 AWG Wire |
Forgot to mention that Potter & Brumfield, makers of the S704-1, rate it for
30A through the N.O. contact when used in SPST configuration. If I'm paying
attention, it should hardly ever see more than 20A, and never more than 30A
from the Jabiru's PM alternator.
Ron
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