Today's Message Index:
----------------------
1. 01:57 AM - Re: 30V battery for Tripplet 630 meter (Robert L. Nuckolls, III)
2. 02:39 AM - Re: Why did this AMP crimp on connection get singed and fail? (Robert L. Nuckolls, III)
3. 10:13 AM - Re: Pitot tube slightly plugged... (Robert L. Nuckolls, III)
4. 03:01 PM - Suggestion for Adjustable Regulated DC Power supply (plevyakh)
5. 08:09 PM - Re: Suggestion for Adjustable Regulated DC Power supply (Robert L. Nuckolls, III)
6. 09:45 PM - Re: Re: Pitot tube slightly plugged... (Mike Wynn)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: 30V battery for Tripplet 630 meter |
At 08:35 PM 9/20/2012, you wrote:
>Greetings Listers.
>
>For those that are interested, here is my solution to the 30V
>battery question for the Tripplet 630 meter.
Great work-around! Thanks for sharing.
Bob . . .
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Why did this AMP crimp on connection get singed |
and fail?
>
>Everything about the crimp appears fine to me. I used a band saw to
>cut half way thru it but it looks solid.
>
>Any thoughts about what would cause the singeing and the variable
>voltage? I'd like to understand what went wrong with this crimp.
The rubber hits the road for crimped terminals inside the
wire grip area. The terminal's wire grip barrel must
be closed down over the wire strands such that no voids
exist within the stranding.
Here's a microscopic photo of how the gas-tight
crimp looks when cross-sectioned.
http://www.aeroelectric.com/articles/CrimpTools/GR.jpg
I wish I had the polishing jig we used at HBC to
smooth these cuts. When really smooth, you can
see the squashed wires because each strand is 'ringed'
by its tin coating.
When the crimp height is too tall, moisture laden air
can get between the strands and a corrosion cycle
starts with subsequent increases in resistance for
the joint. The small voltage drop x load current is
a few milliwatts to begin with but as the corrosion
(aggravated by rising temperatures) advances, the
rate of joint degradation accelerates.
Time to operational failure can be long . . .
as some have noted, hundreds of flight hours over
years of calendar time.
Strobe supplies are the most likely to manifest
this failure due to their 100% duty cycle, significant
current draw in most airplanes. Unless the current
is high enough to start the corrosion acceleration,
poorly crimped terminals may never manifest failure.
See:
http://tinyurl.com/93yweyd
http://tinyurl.com/bqznffp
The inline splice of spade terminals in this photo
http://rv6aproject.ckhand.com/panelAndElectrical/electrical/electricalPg6.htm#photo3
would best be replaced with PIDG butt splices or
lap-solder/shrink joints. Ideally, the ship's harness
would have been extended on down to pins in the
connector that mates with power supply.
Bob . . .
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Pitot tube slightly plugged... |
At 06:21 PM 9/20/2012, you wrote:
<snip>
Called the factory in OH, and related a new-to-them technique of
removing the obstacle. Good feeling to re-invent the wheel, a bit.
BTW, the manufacturing process and subsequent internal road map
knowledge IS proprietary... short of destroying the $600 p-tube.
It would be really interesting to know the
makeup of the obstruction.
The interior passages for a pitot tube are
a maze of holes, turns, drains and baffles
designed to strip high velocity moisture
(wet or frozen) from the air sample, keep
it warm enough remain liquid, and allow
a real sample of dynamic pressure to be
impressed upon ship's instruments.
http://aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg
The fact that you were unable to physically
dislodge it suggests it was buried around
a sharp turn or hiding behind a baffle. I'm
thinking that it was probably a spider nest
where adult but tiny creatures carried a succession
of materials inside and built an obstructing
volume. Pitot tube covers are a GOOD thing
and it wouldn't hurt if they were TIGHT. Perhaps
a piece of slip-fit hose or tubing.
I got to work with the folks at Aero Instruments
when HBC was wrestling with what appeared to
be 'clear air' blocking of one and sometimes
both pitot tubes on airplanes cruising a
high altitude. The instruments always recovered
at lower altitude/warmer atmosphere.
It had to be ice accumulating in a poorly
deiced volume within the tube. The problem
was to figure out exactly where and how.
Not all spaces within the dynamic pressure
vessel are held above freezing when the
OAT is -50C or so.
Interesting story . . . and I'm please to
hear that you were able to salvage an otherwise
useless piece of expensive hardware!
Bob . . .
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Suggestion for Adjustable Regulated DC Power supply |
Can anyone suggest a decent Adjustable Regulated DC Power supply I could use to
perform the OVM-14 protection module calibration?
How about something from MFJ enterprises? Per the attached bench test from Bob,
I'd need something adjustable up to 16.25 volts.
Thanks for your suggestions and help here.
Howard
--------
Howard Plevyak
GlaStar / North Bend, Ohio
hplevyak@mac.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=383744#383744
Attachments:
http://forums.matronics.com//files/ovm_14_module_bench_test_851.gif
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Suggestion for Adjustable Regulated DC Power |
supply
At 04:59 PM 9/21/2012, you wrote:
>
>Can anyone suggest a decent Adjustable Regulated DC Power supply I
>could use to perform the OVM-14 protection module calibration?
>
>How about something from MFJ enterprises? Per the attached bench
>test from Bob, I'd need something adjustable up to 16.25 volts.
>
>Thanks for your suggestions and help here.
This item on eBay is a lot of $value$
for and adjustable 150w power supply.
I gave twice that for it's great grandfather
in a 90W version about 10 years ago.
http://tinyurl.com/8pw7xdg
Bob . . .
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Pitot tube slightly plugged... |
Thanks for the illustrative cutaways and info Bob. These PT's are much more
sophisticated than at a 2nd glance. And your pix do indicate the same
pathway my safety wire probe was trying to navigate. The "remains" are
stored for photo-micro graphing later on in the slightly "green" depleted
battery acid. However, the heater elements still perform per Aero
Instruments test-for-certification specs on element amp draw and resistance.
So, despite a little brightening of the copper and identical air-flow based
on a non-plugged same model p-tube, all is well. Life is interesting.
Heater element test specs on Aero Instruments' Pitot Tube model PH502
series: 12 vdc pitot element should draw 6.34 to 8 amps after 2 minutes
operation.
A 24 vdc pitot element [same model] should draw 3.17 to 4 amps after 2
minutes operation.
Resistance in ohms should range from 0.1 to 400. This info is also available
as a .pdf at their web site: www.aero-inst.com/products/aeroph502.php.
Mike
**********
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Friday, September 21, 2012 11:11 AM
Subject: AeroElectric-List: Re: Pitot tube slightly plugged...
> <nuckolls.bob@aeroelectric.com>
>
> At 06:21 PM 9/20/2012, you wrote:
>
> <snip>
>
> Called the factory in OH, and related a new-to-them technique of removing
> the obstacle. Good feeling to re-invent the wheel, a bit. BTW, the
> manufacturing process and subsequent internal road map knowledge IS
> proprietary... short of destroying the $600 p-tube.
>
> It would be really interesting to know the
> makeup of the obstruction.
>
> The interior passages for a pitot tube are
> a maze of holes, turns, drains and baffles
> designed to strip high velocity moisture
> (wet or frozen) from the air sample, keep
> it warm enough remain liquid, and allow
> a real sample of dynamic pressure to be
> impressed upon ship's instruments.
>
> http://aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg
>
> The fact that you were unable to physically
> dislodge it suggests it was buried around
> a sharp turn or hiding behind a baffle. I'm
> thinking that it was probably a spider nest
> where adult but tiny creatures carried a succession
> of materials inside and built an obstructing
> volume. Pitot tube covers are a GOOD thing
> and it wouldn't hurt if they were TIGHT. Perhaps
> a piece of slip-fit hose or tubing.
>
> I got to work with the folks at Aero Instruments
> when HBC was wrestling with what appeared to
> be 'clear air' blocking of one and sometimes
> both pitot tubes on airplanes cruising a
> high altitude. The instruments always recovered
> at lower altitude/warmer atmosphere.
>
> It had to be ice accumulating in a poorly
> deiced volume within the tube. The problem
> was to figure out exactly where and how.
> Not all spaces within the dynamic pressure
> vessel are held above freezing when the
> OAT is -50C or so.
>
> Interesting story . . . and I'm please to
> hear that you were able to salvage an otherwise
> useless piece of expensive hardware!
>
> Bob . . .
>
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|