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1. 09:55 AM - Re: Tachometer (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E)
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I agree with George that there is always risk involved when you start
messing around with P Leads and connecting anything to them. If not
done with careful design and proper caution, hooking anything (else) to
the P Leads can also easily result in a massive increase in radio noise
as well. That said, this model: HORIZON INSTRUMENTS MODEL P-1000 TACH
has worked extremely well in at least five M-14 equipped aircraft that I
am aware of, and allows you to totally remove the mechanical TACH
TRANSMITTER that attaches to the engine, which in my experiece tends to
have a rather poor track record for long term reliability.
The P-1000 Tach also gives you a safety BENEFIT in that it will
instantly tell you if you have a failed mag. I mean really... How many
of us fly along and check the mags while airborne? This device will
give you an immediate indication of a mag failure, which is a lot better
than finding that out just before taking off when doing your usual mag
check. In addition, it has engine overspeed LED's that will alert you
should your engine go over a certain "limit" speed. And, it also
includes engine time recording, etc., etc. This model includes an
internal opto-isolator design that makes the possibily of it causing a
mag failure to be extremely remote, although of course nothing is
impossible.
Here is a place to read about it. Out of all the "P Lead" tachs, this is
the only one I would recommend. Be advised of one big point though...
In every case where someone else installed one of these things on their
own aircraft, there has been a very real and noticable increase in "P
Lead" induced radio noise. I have had to go back and rip out poor
wiring, and use high quality shielded wire and proper lead bonding and
grounding to deal with this, so it is best the wiring of this device to
an A&P or otherwise highly qualified Avionics type of guy. STRONG
emphasis on this.
http://www.aircraftspruce.com/catalog/inpages/p1000digitaltach.php
Mark Bitterlich
N50YK
-----Original Message-----
From: owner-m14pengines-list-server@matronics.com
[mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of George
Coy
Sent: Monday, January 19, 2009 8:49 AM
Subject: RE: M14PEngines-List: Tachometer
Mechanical tachs generally work on the speed of the camshaft. That is
50% of the crankshaft speed. The only place that the cam speed is
available to drive a tachometer on the M14 is at the center of the air
start. The magneto rotor is the only other part that rotates at 50% of
the crankshaft speed.
There are many tachometers that run from magneto electrical pick up will
also work. Be wary of the ones that actually connect to the "p" lead as
a tachometer failure could result in a magneto failure.
You could also have your Russian tachometer face remarked to
actual RPM instead of % RPM.
George Coy
Coy Aircraft Sales
714 Airport Rd.
Swanton VT 05488
802-868-5633 off
802-363-5782 cell
george.coy@gmail.com
SKYPE george.coy
-----Original Message-----
From: owner-m14pengines-list-server@matronics.com
[mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of HBaker
Sent: Sunday, January 18, 2009 5:31 PM
Subject: M14PEngines-List: Tachometer
--> <henry.baker@nf.sympatico.ca>
Is there a mechanical tachometer out there that is not in % of rpm that
I can put on the M14P, and does it install in the center of the air
start?
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Currently building a Murphy Moose - any help would be appreciated.
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http://forums.matronics.com/viewtopic.php?p=225531#225531
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