Today's Message Index:
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1. 01:37 AM - best contactor reliability -- mechanical, solid state, or manual? (D Wysong)
2. 02:35 AM - Re: best contactor reliability -- mechanical, solid state, or manual? (Kevin Horton)
3. 12:33 PM - Re: Re: Low transmit volume on Valcom 760 (Charlie England)
4. 02:32 PM - CDI Switch? (Eric Parlow)
5. 02:54 PM - Re: Circuit for automatic fuel pump engageing (Robert L. Nuckolls, III)
6. 03:02 PM - Re: Z-19 (Robert L. Nuckolls, III)
7. 04:14 PM - Re: Antenna (jetboy)
8. 06:54 PM - Annunciator success! (Fiveonepw@aol.com)
9. 07:03 PM - BRAVO, GRT!!! (Fiveonepw@aol.com)
10. 08:30 PM - Connecting a Garmin (Apollo) SL40 COM to a PS Engineering PMA4000 Audio Panel (Jeff)
Message 1
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| Subject: | best contactor reliability -- mechanical, solid state, |
or manual?
I have a remotely operated application where the loss of the
master battery contactor will result in the loss of
data/money/time (... and dignity!). My baseline design
resembles a "Z" diagram (thanks Bob!) and I planned to use a
mechanical, continuous duty contactor like the S-701 from
B&C. However, a buddy of mine recently experienced a
contactor failure in flight and it caused me to experience a
few "What If!?" nightmares. I'm back to reconsidering my
original decision...
I wish I could skip the contactor entirely, but the
components hanging off the master bus aren't switched (no
ON/OFF control) so I need a master contactor to switch power.
The options I toyed with initially were a mechanical can
(S-701), a solid state relay (Crydom D06D series), or a "hot
rod" manual switch.
I've had good personal experience with the cans (no failures
yet in hundreds of hours of flying). Sure, they get hot and
use/waste a little power but they have a good heritage. Had
my buddy not experienced a failure, I probably wouldn't have
worried at all. Now, I can't avoid worrying.
I've had good experience with the Crydom SSRs, too, and have
only seen one coaxed to failure by a well-intentioned
technician (25 Adc through a 7 Adc device... poof!). Low
power consumption, rugged, compact, moderately priced.
I've quizzed folks here about using manual "hot rod"
contactors and received some great feedback (e.g. - don't
use the cheap ones!). Seemed bulletproof at first, but
recent posts suggested these things can/have/will fail, too.
Perhaps it's just a problem with the cheap ones? Dunno.
So, I'm sitting at square one (again!) trying to determine
which of these options is most likely to keep me out of hot
water. I realize there is no "100% reliable" solution, but
I'm weighing my options to get the greatest number of 9's in
the long run.
Any feedback/wisdom from you folks will be greatly appreciated.
D
Message 2
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| Subject: | Re: best contactor reliability -- mechanical, solid |
state, or manual?
On 13 Jul 2007, at 04:38, D Wysong wrote:
>
> I have a remotely operated application where the loss of the master
> battery contactor will result in the loss of data/money/time (...
> and dignity!). My baseline design resembles a "Z" diagram (thanks
> Bob!) and I planned to use a mechanical, continuous duty contactor
> like the S-701 from B&C. However, a buddy of mine recently
> experienced a contactor failure in flight and it caused me to
> experience a few "What If!?" nightmares. I'm back to reconsidering
> my original decision...
>
> I wish I could skip the contactor entirely, but the components
> hanging off the master bus aren't switched (no ON/OFF control) so I
> need a master contactor to switch power.
>
> The options I toyed with initially were a mechanical can (S-701), a
> solid state relay (Crydom D06D series), or a "hot rod" manual switch.
>
> I've had good personal experience with the cans (no failures yet in
> hundreds of hours of flying). Sure, they get hot and use/waste a
> little power but they have a good heritage. Had my buddy not
> experienced a failure, I probably wouldn't have worried at all.
> Now, I can't avoid worrying.
>
> I've had good experience with the Crydom SSRs, too, and have only
> seen one coaxed to failure by a well-intentioned technician (25 Adc
> through a 7 Adc device... poof!). Low power consumption, rugged,
> compact, moderately priced.
>
> I've quizzed folks here about using manual "hot rod" contactors and
> received some great feedback (e.g. - don't use the cheap ones!).
> Seemed bulletproof at first, but recent posts suggested these
> things can/have/will fail, too. Perhaps it's just a problem with
> the cheap ones? Dunno.
>
> So, I'm sitting at square one (again!) trying to determine which of
> these options is most likely to keep me out of hot water. I
> realize there is no "100% reliable" solution, but I'm weighing my
> options to get the greatest number of 9's in the long run.
>
> Any feedback/wisdom from you folks will be greatly appreciated.
I assume that this is not an aircraft we are talking about.
If you have an application where you must absolutely ensure
continuity of power, then you have to assume that any single
component could someday fail, no matter how good quality that
component is. How about two contactors in parallel, with some sort
of periodic check to ensure that they are both working, or some way
to monitor them to have evidence that they are both working? For
monitoring, you could have each contactor feeding through a diode,
and monitor the voltage between the contactor and the diode. If the
contactor fails, that voltage will drop. If the voltage shows that
both contactors are closed, you could monitor that voltage to show
that each contactor can be opened (one at a time, so you don't stop
providing power to your application).
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 3
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| Subject: | Re: Low transmit volume on Valcom 760 |
Assuming that you've already tried a different headset to be sure it's
not the headset mic, check with VAL on whether there's a mic gain
control in the radio. (not the volume control on the front panel)
Some headsets with electret condenser mics have a gain control in the
mic itself. It would be a tiny recessed screw in the mic housing.
Charlie
Chad wrote:
>
> I don't have access to SWR but I went further away with the handheld
> (couple hundred feet I guess) and it's the same thing. You can hear and
> it's relatively clear, just really quiet.
>
> chad
>
>
> Subject: Re: Low transmit volume on Valcom 760
> From: Robert Feldtman (bobf@feldtman.com)
> Date: Thu Jul 12 - 3:57 AM
>
> Might be okay - Automatic gain control (AGC) on handheld may have
> cut down
> the volume - try to talk to somebody a further distance away. check
> your
> SWR. probably okay
>
> bobf
>
> On 7/11/07, Chad <avidflyerss@ameritech.net> wrote:
> >
> >
> >
> > Hello all, new subscriber here looking for some helpful advice.
> >
> > I'm finishing up my instrument panel and did some radio testing
> > tonight. I have a Valcom 760 radio hooked up to a fiberglass rod
> type
> > antenna. I can receive great, in fact I was picking up traffic in
> the
> > pattern at an airport about 40 miles north of here with the
> airplane in
> > my garage. That said, I switched to a known unused channel and tried
> > some transmitting (listening on my handheld about 15 feet away)
> but the
> > volume was almost inaudible. I had to practically shout into my
> headset
> > mic in order to really hear and understand anything. I've checked
> some
> > of the basics with the wiring and don't see anything obvious.
> >
> > Anyone have any tips on what to check or what the problem might
> be? I'm
> > afraid that everyone will be able to hear me key the mic, but will
> > struggle understanding me with this low output volume.
> >
> > Regards,
> >
> > Chad
> >
Message 4
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What's the best way to switch the CDI input from GPS-WAAS to Nav1 to Nav2?
I have the Garmin GI106A, GNS430W, SL30 combination.
The GNS430W allows you to switch between GPS-WAAS and NAV1 internally.
Also the GNS430W and the SL30 are feeding GPS/VOR/ILS to the Blue
Mountian(BMA) EFIS/One.
The GNS430W via an analog connection and SL30 via the serial link.
The BMA autopilot is only able to be driven by the BMA EFIS/One.
Sincerely,
ERic--
RV-10, N104EP
Message 5
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| Subject: | Re: Circuit for automatic fuel pump engageing |
At 12:20 AM 7/9/2007 +0200, you wrote:
>Hello all,
>
>I am looking for some hints / circuits for automatic switching of my fuel
>transfer pumps. As it is standard with the Lancair 360, I have two wing
>tanks and a header tank. As I do not want to switch on the transfer pumps
>manually every 30 minutes, probably forgetting it at all, I want to build
>in an "intelligent" circuit doing it for me.
>My set up is, that I have a capacitive level sensor in the header tank,
>providing 0 to 5 Volt depending on the fuel level. In addition, I have an
>independent sensor at about 15 gallons which will give me a last warning
>in case the circuit or transfer pumps isnot working.
>
>Does someone already went through this experiment and is willing to share
>his wiring drawings with me ? Even it is possible to develop something
>like that by my one, one does not have to re-invent the wheel.
The board that assembles the product described
in these documents . . .
http://www.aeroelectric.com/Catalog/AEC/9011/
Has up to 4 a/d inputs and up to 3 open collector,
moderate current pull-downs (1A) and good program
space. If you could send me a schematic of your
"manual" system and a brief Product Performance
Specification as to how you'd like the thing to
work, I'll have my software guy look at it.
Bob . . .
----------------------------------------
( "Physics is like sex: sure, it may )
( give some practical results, but )
( that's not why we do it." )
( )
( Richard P. Feynman )
----------------------------------------
Message 6
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At 06:52 PM 7/10/2007 -0400, you wrote:
>I am going with the Z-19 Rear batteries in an RV-8 with the 2.5 SC engine
>with Supercharger.
>My question is why not be able to operate the second Fuel Pump from either
>battery?
>Seems like it would give another option for keeping the fuel flowing. Mine
>will be wired this way.
How many failures are you planning to stack? I've seen some
airplanes wired where the owner was able to select backups
to backups . . . the architecture offered a hose of variables
for powering things up in case this failed, and then that failed
too, etc.
The probability of dual failures on any one tank of fuel is
exceedingly low. Properly maintained RG batteries (when
installed to accommodate relatively fragile lead posts)
are exceedingly reliable. The failure mode effects analysis
process is a deduction of all the what-if's but for our
purposes, we don't need to go more than one layer deep.
Given the quantum jump in alternator and battery reliability,
you can comfortably assume that altenrator failure will be
rare and both properly maintained batteries will be there
when you need them.
>Thanks to Bob N. for all he does.
My pleasure sir. I'm pleased that you find the efforts
useful.
Bob . . .
Message 7
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Bob,
Normally a metal cage type structure will shield the antenna from radiating, if
the cage openings are smaller than around 3 feet, that is assuming you mean to
have the antenna inside the fuselage.
It is possible to actually connect to parts of the structure, at strategic points,
and use the structre to radiate, in some cases, but this is a difficult process.
If the matching point is not correct, the cable will radiate and cause
problems for other avionics too.
For a tube / fabric airframe, antenn drag is not an issue, use a normal or swept
back wire antenna, mounted at a tubing juncion or on a pice of metal panel as
far away from the engine as practicable. For an Avid flyer, the rear turtledeck
is aluminium and works well.
Ralph, radio tech in NZ
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=123680#123680
Message 8
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| Subject: | Annunciator success! |
I would like to express my extreme gratitude to all who offered suggestions
for my annunciator difficulties, specifically for turning OFF an LED indicator
when Trutrak autopilot engages- the dual-transistor circuit suggested by Dick
Tasker worked flawlessly and I was able to package the whole thing inside the
d-sub connectors (as suggested by Bob N.) between ships wiring and the
6-function annunciator so that no external circuit board is required. Pretty damn
slick!
You folk are the best- A-list RULES!
Mark Phillips do not archive
************************************** Get a sneak peak of the all-new AOL at
http://discover.aol.com/memed/aolcom30tour
Message 9
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I would like to express my sincerest thanks to Mark and Sandy at GRT for
doing far more than their paychecks require in helping me out recently. If these
folks made anything from satellites to Margaritas, this is where I'd get 'em!
Won happy customer, and will always be, XOXOXO to GRT (had enough?!) 8-)
Mark Phillips, Columbia, TN
do not archive this well-earned giddyness...
************************************** Get a sneak peak of the all-new AOL at
http://discover.aol.com/memed/aolcom30tour
Message 10
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| Subject: | Connecting a Garmin (Apollo) SL40 COM to a PS Engineering |
PMA4000 Audio Panel
Since I'm a rookie at this, I just re-read the section in the Aerolectric
Connection about Audio Panels. The answer to this is not in there. I am
having trouble with the naming conventions provided by two different vendors
in their documentation. I believe that they are calling the same things by
different names. That would be a great injustice on their parts if
intentional, so I am sure that it is just my inexperience playing the major
role here. Anyway, for connecting the COM to the Audio Panel, here are the
pertinent connection labels and pins:
On the Garmin SL40 COM:
Headphone - 14
Audio Ground - 13
Mic 1 - 8
Mic Ground - 7
TxKey - 4
On the PMA4000 Audio Panel:
Com 1 Audio HI - Top-19
Com 1 Audio LOW - Top-7
Com 1 PTT - Bottom 22
Com 1 Mic Audio HI - Bottom 21
Com 1 Mic Audio LO - Bottom 9
What I'd like is for some to confirm that they match up (are connected ) as
follows:
Headphone - 14 to Com 1 Audio HI - Top -19
Audio Ground - 13 to Com 1 Audio LO - Top - 7
Mic 1 - 8 to Com Mic Audio HI - Bottom - 21
Mic Ground - 7 to Com 1 Audio LO - Bottom 9
TxKey - 4 to Com 1 PTT - Bottom - 22
Thanks for suffering thought these details with me. It seems that PS
Engineering refers to the ground as "LO" consistently.
Jeff Davidson
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