Analog tach replacement

I have suspected for a while that my old analog tach was lying to me. My
Archer's static RPM at take-off was measuring about 22k and the minimum spec
was 2325, but the plane seemed to have good cruise speed. When I pointed an
optical tach through the windshield I read a static RPM of 23.4K. At
cruise, 25K on the analog tach translated to 25.8K on the digital tach.

Any suggestions for a replacement digital instrument? It would be nice to
drop it into the old tach's mounting and possibly get a few more functions
from the same piece of real estate.


--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html

....and as Ken Reed has pointed out, it isn't 'K' but 'x100' for the RPM's I
mention.

--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html
"Mike Noel" wrote in message
...
I have suspected for a while that my old analog tach was lying to me. My
Archer's static RPM at take-off was measuring about 22k and the minimum
spec
was 2325, but the plane seemed to have good cruise speed. When I pointed
an
optical tach through the windshield I read a static RPM of 23.4K. At
cruise, 25K on the analog tach translated to 25.8K on the digital tach.

Any suggestions for a replacement digital instrument? It would be nice
to
drop it into the old tach's mounting and possibly get a few more functions
from the same piece of real estate.


--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html

In article , "Mike Noel"
wrote:

I have suspected for a while that my old analog tach was lying to me. My
Archer's static RPM at take-off was measuring about 22k and the minimum
spec
was 2325, but the plane seemed to have good cruise speed. When I pointed
an
optical tach through the windshield I read a static RPM of 23.4K. At
cruise, 25K on the analog tach translated to 25.8K on the digital tach.

Any suggestions for a replacement digital instrument? It would be nice
to
drop it into the old tach's mounting and possibly get a few more
functions
from the same piece of real estate.

originally posted 6 May 2003:

After spending some time troubleshooting an oscillating
tach needle, I decided to put in a digital tach in my cherokee.

There appeared to be two choices, a Horizon Instruments digital
tach, and an Electronic Instruments digital tach. Both are STC'd
for a cherokee 140, but neither STC specifically covered a
cherokee 140 with a 160 hp engine (the RAM Aircraft 160hp STC
requires the tach to be re-marked). I believe that both cost
about the same and both have simple electrical installation.

I decided to install the Electronic Instruments R-1 digital
tach primarily because, after talking with both EI and Horizon,
I thought the 377 approval would be easier with the EI R-1.
It turns out that there was no particular advantage to installing
the R-1 from an approval point-of-view. Getting the FSDO and IA
approval was pretty easy. Approving the P-1000 would not have been
more difficult.

The installation was easy, except that the EI R-1 tach doesn't fit
in the "normal" tach hole. The R-1 tach is deeper than the original
tach and makes contact with the top of the brake handle. As a result,
I had to swap around the GEM 602, digital OAT display, and the tach.
Not hard to do, but still a pain.

Bottomline: The R-1 works fine. But I think the Horizon P-1000
digital tach would probably have been better since, I believe, it
fits in exactly the same hole (at least a couple of other cherokees
didn't have an issue installing it). Also, the P1000 will annunciate
a bad mag, which the R-1 does not.


you can google for the entire thread.

--
Bob Noel

Bob Noel writes:

Also, the P1000 will annunciate
a bad mag, which the R-1 does not.

I highly recommend having this feature and its relative, "mag drop".
It would be a shame to switch to an electronic tach without getting
such basic features as a result.

--kyler

In article , Kyler Laird
wrote:

Also, the P1000 will annunciate
a bad mag, which the R-1 does not.

I highly recommend having this feature and its relative, "mag drop".
It would be a shame to switch to an electronic tach without getting
such basic features as a result.

In fairness to the R-1, it does have the "mag drop" feature.

--
Bob Noel

Bob Noel writes:

Also, the P1000 will annunciate
a bad mag, which the R-1 does not.

I highly recommend having this feature and its relative, "mag drop".
It would be a shame to switch to an electronic tach without getting
such basic features as a result.

In fairness to the R-1, it does have the "mag drop" feature.

O.k., I'm stumped. How can it tell you that it's measuring mag drop
without telling you that one of the mags isn't firing?

--kyler

If one mag goes off line, the P1000 turns on the appropriate LED. It
actually counts the number of times the mag fires and displays the warning
if signal to one is lost. When you switch to Right or Left, the
corresponding LED lights and the display shows the RPM drop.

There is also a yellow LED which lights if there is more than an 80 RPM
difference detected between the two mags. Obviously they are both turning
the same speed but, if one is firing intermittently, this will tell you that
the roughness is due to a mag malfunction and not something else in the
engine.

We have the P1000 in our 172 N and I really like it. It also has an RPM
trap feature so you can determine what the fastest engine speed during your
last flight was and the ability to turn off reading of either mag to help
diagnose mag malfunction.

The only problem we had with it was at the beginning when members would push
a button, put it in the diagnostic mode, and think there was a mag problem.
A couple flights were canceled but we haven't had a problem after the first
couple of weeks.

I highly recommend this unit. It is so accurate that you will notice any
RPM drop due to carb ice immediately. It is so accurate that it gives you a
faster indication of pitch up or pitch down (with a fixed pitch prop) than
the VSI. We also haven't had anyone leave the master switch on since we put
it in because the LED's and display make it very obvious that power is still
on.

You can read the manual he

http://www.baldeagleflyingclub.org/members/Tach.pdf

--

Roger Long



"Kyler Laird" wrote in message
...
Bob Noel writes:

Also, the P1000 will annunciate
a bad mag, which the R-1 does not.

I highly recommend having this feature and its relative, "mag drop".
It would be a shame to switch to an electronic tach without getting
such basic features as a result.

In fairness to the R-1, it does have the "mag drop" feature.

O.k., I'm stumped. How can it tell you that it's measuring mag drop
without telling you that one of the mags isn't firing?

--kyler

In article , Kyler Laird
wrote:

I highly recommend having this feature and its relative, "mag drop".
It would be a shame to switch to an electronic tach without getting
such basic features as a result.

In fairness to the R-1, it does have the "mag drop" feature.

O.k., I'm stumped. How can it tell you that it's measuring mag drop
without telling you that one of the mags isn't firing?

ah - I think I may have been confused and thus confused others. I read
"mag drop" and assumed you meant "RPM drop" when checking mags during
a run-up.

Is that clearer?

--
Bob Noel

The Horizon P1000 is excellent - perfect fit for my Arrow, good back
lighting, excellent diagnostics.

Its primary flaw is that it doesn't work with the new Unison LASAR
ignition system (I have confirmed this with Horizon). I've heard but
not confirmed that the EI tach does work with LASAR.