Today's Message Index:
----------------------
1. 12:36 AM - Re: noisy tach signal (Chris Hand)
2. 07:06 AM - antenna mounting (jetech)
3. 11:09 AM - Re: Re: Tyco Breakers (Robert L. Nuckolls, III)
4. 11:21 AM - Re: antenna mounting (Robert L. Nuckolls, III)
5. 11:23 AM - Re: noisy tach signal (Robert L. Nuckolls, III)
6. 06:39 PM - Re: antenna mounting (jetech)
Message 1
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| Subject: | Re: noisy tach signal |
Thanks Bob, fortunately it appears there was a simple solution that will
avoid troubleshooting efforts at the circuit level.....it appears the
720-14R hall effect sender I had installed was defective as I replaced it
with a new one this evening and after a ground run and short test flight,
everything seems to be working normally now.
Westach has been very good about helping me with this issue on getting their
sender to work with the IK unit and they sent me several sender types to
try, including a new replacement for what I was using. Excellent customer
service and tech support from Westach.
I didn't get to the point of using the other sender options they sent as the
first thing I did was try the straight replacement for what I had. So my
lesson learned is that yes, sometimes a brand new sensor/sender can be bad
right out of the box. What I don't understand is how a defective hall
effect sender would cause indications of noise issues when the mag it's
installed in is running but work normally when that mag is secured.....but
I've got a working tach now, so I'm happy!
Chris
> <nuckolls.bob@aeroelectric.com>
>
>
> Hmmm . . . see if the IK-Tech will share a sketch
> of a schematic for the first two stages of tach
> signal conditioning. The manner in which bias levels
> are established for any "squaring" or level sensing
> circuits can have a profound effect on noise sensitivity.
> The schematics (need parts values too) + 'scope trace
> will permit a simple-ideas analysis of the symptoms.
>
>
> Bob . . .
Message 2
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| Subject: | antenna mounting |
I am looking for ideas on mounting a antenna for a hand held VHF radio on a steel
tube fabric covered airplane.
The original idea was to just use the short supplied antenna but it has been suggested
that I could get better range with a mounted antenna.
Because of the original plan there wasn't any type of ground plane installed and
adding one may be difficult.
The plane is a Warner Sportster (new version of the Spacewalker II), it is a low
wing two place tandem open cockpit fuselage. There is a wood turtledeck that
runs from the aft cockpit to the tail.
About the best place would probably be on the belly but the ground plane would
probably have to be on top of the tubing (because of stringers) with some type
of spacer the length of the tube diameter to get the antenna base to the fabric.
I am guessing that a antenna mounted inside the tube fuselage would be a mute
point.
Any thoughts on this?
Thanks
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=249344#249344
Message 3
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| Subject: | Re: Tyco Breakers |
At 02:13 PM 6/20/2009, you wrote:
>
>[quote]
>But I am not, which is the source of our differing approach.
> My friend, the rich man's chief pilot, has just spent a
>large part of the last seven years fighting with the maker
>of their new model $47 million private jet over the fact
>they wanted to make all the fuses totally inaccessible in
>flight. Manufacturer lost the argument. Same principle
>applies to single pilot small aircraft with the automobile
>style fuse block.
>
>Tom Kuffel[/quote]
>
>
>Tom,
>
>I spend my life with private Jets. I've never seen fuses in the
>cockpit, only circuit breakers. Any fuses or current limiters in
>transport category aircraft, and there are hundreds, are always
>located where the crew can't touch them, along with many of the
>breakers they don't want the pilot to have access to. You just
>don't want some stupid pilot starting a fire playing with them. The
>rule that has always been pounded into my head is to accept the loss
>and fly the plane, not try and fix it. That's how L-1011's end up
>in the swamp while pilots are trying to change gear indicator bulbs.
Exactly. It's with this design goal in mind that
we strive for failure tolerant design. I.e., loss
of any single system should not put a mission at
risk for bent airplanes -OR- people. Better yet,
very low risk for even breaking a sweat.
To be sure, there are things we cannot make failure
tolerant. Wing struts, prop bolts, connecting rods,
etc. At the same time, we design those components with
some notion of robustness under normal use. Somehow,
it's easy to allow certain electro-whizzies to
take up residence in our "can't survive without it"
basket of thought. Hence, we worry about them a lot
and tend to get wrapped around a "push-the-breaker-
and-HOPE-it-will-stay on" mentality. But as I pointed
out some 15 years ago . . .
http://www.aeroelectric.com/articles/fuseorcb.html
and elaborated upon it further 4 years later . . .
http://www.aeroelectric.com/articles/fusvbkr2.html
. . . there are MANY ways an electro-whizzy can
wander into the weeds WITHOUT opening it's supply
circuit protection. Considering this inarguable fact,
it seems prudent to design one's electrical system
such that every device truly necessary for comfortable
termination of flight have an independent backup
. . . a Plan-B.
Once the design goal is achieved, then it matters
not what form the circuit protection takes nor
does it matter where that protection is located.
If one has plenty of panel space, low expectations
for overall electrical system reliability (day vfr,
fair weather flying) then covering the panel with
acres-of-breakers-and-switches may be satisfying
as a style statement . . . but adds nothing to
system reliability while adding burden to empty weight,
cockpit complexity, time to install and cost of
ownership.
The only aircraft I'm aware of that has few, but not no, breakers in
the cockpit is Bombardier's Global Express. It does, however, have
remote breakers controlled by screens in the cockpit. It saves a
huge amount of weight running wires all the way from the hell hole to
the cockpit and back. Also the usability for the crew goes way
up. They can see all systems effected when a breaker is popped and
can isolate a bus at will. Also, if one pops you get a message.
Yeah, I think Eclipse did this too.
Bob . . .
Message 4
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| Subject: | Re: antenna mounting |
At 09:04 AM 6/21/2009, you wrote:
>
>I am looking for ideas on mounting a antenna for a hand held VHF
>radio on a steel tube fabric covered airplane.
>
>The original idea was to just use the short supplied antenna but it
>has been suggested that I could get better range with a mounted antenna.
A belly mounted antenna (either full size or
a 'rubber duck') will perform better than
the antenna installed on the hand-held.
>Because of the original plan there wasn't any type of ground plane
>installed and adding one may be difficult.
Not a big problem. If you can get a mounting
bracket against the skin to support the antenna
that is also well connected to tubular structure,
then performance will not be appreciably enhance
with a 'proper' ground plane.
Try mounting a bulkhead mounted, BNC cable-connector
http://www.aeroelectric.com/Pictures/Connectors/Coax/BNC_Bulkhead_Female.jpg
on the bracket and just move the radio mounted
rubber-duck to this location. I think you'll find
the performance to be very close to an
idealized antenna installation.
I am guessing that a antenna mounted inside the tube fuselage would be
a mute point.
Correct. Radiation through the fabric from
inside the structure is pretty lame.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 5
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| Subject: | Re: noisy tach signal |
At 02:32 AM 6/21/2009, you wrote:
>
>Thanks Bob, fortunately it appears there was a simple solution that
>will avoid troubleshooting efforts at the circuit level.....it
>appears the 720-14R hall effect sender I had installed was defective
>as I replaced it with a new one this evening and after a ground run
>and short test flight, everything seems to be working normally now.
<snip>
Great! It would have been interesting to see
if a 'scope investigation would have revealed
the problem too . . . but I'm pleased to hear
that you can move on to more important things!
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 6
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| Subject: | Re: antenna mounting |
Thanks Bob, That sounds easy enough to do.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=249434#249434
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