Today's Message Index:
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1. 05:20 AM - Re: Manual intercom PTT (Jeff Point)
2. 08:18 PM - Re: Voltmeter & Ammeter normal ranges (Sebastien)
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Subject: | Re: Manual intercom PTT |
All,
Thanks for all the responses on this thread. I wanted to post an update
for anyone interested, as I've made significant progress towards solving
this noise issue.
The headset is a DC H10-20 that is nearly 30 years old. Around 12 years
ago I installed the Headsets Inc. ANR kit but the mic is original. I'm
not sure if electret mics "wear out" or degrade over time, but I decided
to replace it with a new one, and after some research went with the
Pilot Communications PA-9EHN, designed for high noise environments.
That mic made all the difference. Wind noise only breaks squelch when I
turn my head significantly, and in this environment I can live with
that. The mic was $80 and I plan to buy another one for the pax headset.
Also, and counterintuitively, I removed the leather cover over the foam
and used just the foam cover. Oddly this really improved the resistance
to wind noise. I read this tip online somewhere and tried it- glad I did.
I found a software setting buried deep in the MGL V6 menu that changes
the mic from "VOX" to "HOT." This controls how the mic responds when
the transmit button is pressed. I'm not sure why one would ever use the
"VOX" setting but it was set to it by default. To be clear- this has
nothing to do with the VOX intercom, just the mic setting on transmit.
Anyway, after changing it to HOT, and installing the new mic, I got the
"loud and clear" response from a tower 10 miles away.
So I've solved the two issues that I had- nuisance VOX activation by
wind noise and poor transmit quality, and I now have an acceptably good
intercom/ radio setup without installing an intercom PTT.
At Bob's suggestion I bought one of the el cheapo ($10) throat mics and
played with it. It did show some initial promise but was, well, el
cheapo. The next step would be to order a better model (around $150
with great reviews from the motorcycling crowd.) Because of the success
I've had improving the conventional headset, I've shelved this for now.
Thanks again for all the help.
Jeff Point
Milwaukee
>
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Subject: | Re: Voltmeter & Ammeter normal ranges |
Thank you all for your input. I've eliminated the warning function and chang
ed the ammeter band to green only. No more annoying warnings! Well, we still
have very high CHT warnings but we have a plan to deal with that. These rec
ording engine monitors sure make it easy to test a new plane. You can concen
trate on working the problem without worrying about recording which cylinder
was the highest or lowest or whatever the issue may be.
Biggest lesson learned here is that for future early flights only critical i
tems will have warnings enabled. Today I went along with a friend for moral s
upport on his first flight in his new (to him) Searey Amphibian after a year
of repairs and improvements. The previous owner thoughtfully included a swi
tch for turning on or off the audio warnings from the engine monitor. I turn
ed it off for takeoff and sure enough, the bloody thing lit up like Apollo 1
2 but my buddy climbed straight ahead ignoring everything while I cancelled o
ne spurious warning after another. Not sure he would have been able to be so
disciplined if it had been yelling in our ears.
Sebastien
> On Sep 24, 2017, at 09:57, Robert L. Nuckolls, III <nuckolls.bob@aeroelect
ric.com> wrote:
>
> At 06:09 PM 9/23/2017, you wrote:
>> I am doing the test flying on a friend's RV-6 and as part of the preparat
ion I set up the engine monitor (Dynon 120) to display the following on the v
oltmeter and ammater:
>>
>> Voltmeter: Red below 10V, Yellow 10-13.8V, Green 13.8V-14.5V, Red > 14.5V
>> Ammeter (wired to show current flow in to the batter): Red < 0A, Green 0 -
5A, Yellow 5-30A, Red > 30A.
>
> Assuming you do monitor bus voltage and have
> active notification of low voltage, then there
> is no operational value for monitoring battery
> current.
>
> Battery ammeters in airplanes were a carry-over
> from the terrestrial vehicles where the minus-zero-plus
> instrument in the battery charge/discharge line
> was the simplest single monitor of system health
> during normal vehicle operations.
>
> The ammeter would be expected to show a heavy
> recharge rate right after cranking the engine . . .
> or after a jumper cable start on a dead battery.
>
> After some interval of normal operation, the battery
> accepts less and less recharge energy and the needle
> migrates toward zero. Under normal ops (votlage about
> right, battery charged) the needle would rest at or
> just slightly above zero.
>
> If generator output was insufficient (low engine rpm,
> high system loads, regulator voltage drifting downward,
> generator failing) the needle would present some
> value below zero.
>
> While truly an analog instrument, its BEHAVIOR was
> closer to 'digital' in that it was never intended to
> be READ so much as observed as a go/no-go panel
> instrument.
>
> Ammeters of all types are of little to no value as sources of
> operational data in flight. Ammeters in the battery
> lead are pretty much useless when compared to an accurate
> voltmeter paired with active notification of low
> voltage.
>
> Calibrating a battery ammeter with alarm settings
> will be an exercise in futility.
>
> Suggest you move the ammeter sensor to the alternator
> b-lead and eliminate any alarm functions from this
> reading. The ammeter is most useful as a maintenance
> tool for diagnosing why the VOLTAGE is low and/or
> the LOW VOLTS warning light was illuminated in the
> air.
>
> Bob . . .
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