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Grt magnetometer or old school?

C

coffeeboy

Member
I've been in the process of a complete panel overhaul/IFR upgrade (custom etched panel, second grt horizon screen, garmin 650, etc) but I just realized my RV6A doesn't have a digital magnetometer installed (I'm not the original builder).

Since I have to have a magnetic direction indicator, is it worth it to buy the grt digital one or should I just get an old fashion wet compass? How difficult would it be to install in an already flying RV6A?
 
Within the last month I received all my GRT components and have since ordered the magnetometer. Im going to mount mine under the tail fairing on the deck. Jon at GRT said to run 3 /22g wires to the rear. Within the wing is another mounting option.
They are 50. dollars off if you purchase before the 4th I believe. I picked one up at Oshkosh and they are super light weight.
A
 
AlphaCharlieBravo said:
Within the last month I received all my GRT components and have since ordered the magnetometer. Im going to mount mine under the tail fairing on the deck. Jon at GRT said to run 3 /22g wires to the rear. Within the wing is another mounting option.
They are 50. dollars off if you purchase before the 4th I believe. I picked one up at Oshkosh and they are super light weight.
A
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I really like the idea of under the tail fairing, seems a lot easier than trying to get it in the wing. What plane are you installing it in? I'd love to talk to you throughout your progress!
 
RV7..... Pm me your number and I can text you updates if you would like. Just getting started. All the avionics were at my house right before I left for Oshkosh. Took me two days to recuperate from the long drive home. 1900 miles 2.5 days....hahahah

I'll just add that GRT has a machined aluminum OAT probe for 107. that can work with your EFIS or EIS.
 
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coffeeboy said:
Any recommendation for an OAT? I don't believe I have one.
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I forgot to include density altitude in the calculations possible with the OAT and mag. Your best bet would be to go with the OAT that is offered by your EFIS vendor. My Dynon magnetometer includes the OAT, your system may be different.

The magnetometer has been riding on the deck under the vertical stab fairing on my RV-6 for over 20 years. It is easy to wire and access at that location.
 
coffeeboy said:
I've been in the process of a complete panel overhaul/IFR upgrade (custom etched panel, second grt horizon screen, garmin 650, etc) but I just realized my RV6A doesn't have a digital magnetometer installed (I'm not the original builder).

Since I have to have a magnetic direction indicator, is it worth it to buy the grt digital one or should I just get an old fashion wet compass? How difficult would it be to install in an already flying RV6A?
Click to expand...
I tried using my New Horizon without Magnetometer, it works, but…. Takes longer for boot up alignment, and as others stated you loose some info like wind direction. Here is a paste from email with GRT. I was upgrading from Sport SX to new Sport 10.1, then recently upgraded to Horizon. Wiring is simple, pwr, ground, signal. I have a small shelf behind baggage bulkhead for mine, along with my EchoUat ADSB IN/OUT.

“If you want magnetic compass headings you need the newer digital magnetometer. The unit does not include a magnetometer because it can use GPS track instead, or share a digitalmagnetometer with other equipment.”
 
Mine is mounted on my left wingtip as recommended by GRT. It should work on the aft deck also as long as there isn’t something made of steel close by that moves (like a control of some kind). Don’t use steel hardware to mount it - use brass, nylon, or aluminum. In my pic below, there is a pull wire (bundled) in case I need to add additional wires in the future. I’d recommend doing something similar if you are running wires back to the tail for possible future additions/changes. You could use wire or even a string. Wire pulls easier through conduit than string and is easier to connect the new wire to. It can be mounted sideways like mine, or flat - just make sure it’s pointed in the right direction.
 

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BH1166 said:
I tried using my New Horizon without Magnetometer, it works, but…. Takes longer for boot up alignment, and as others stated you loose some info like wind direction. Here is a paste from email with GRT. I was upgrading from Sport SX to new Sport 10.1, then recently upgraded to Horizon. Wiring is simple, pwr, ground, signal. I have a small shelf behind baggage bulkhead for mine, along with my EchoUat ADSB IN/OUT.

“If you want magnetic compass headings you need the newer digital magnetometer. The unit does not include a magnetometer because it can use GPS track instead, or share a digitalmagnetometer with other equipment.”
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Thanks for the extra info! Do you have any photos of the shelf you did? I think that would be a good idea for the magnetometer and relocating my ELT (it's currently on the floor in the baggage area... could easily be hit by baggage).
 
Scott Hersha said:
Mine is mounted on my left wingtip as recommended by GRT. It should work on the aft deck also as long as there isn’t something made of steel close by that moves (like a control of some kind). Don’t use steel hardware to mount it - use brass, nylon, or aluminum. In my pic below, there is a pull wire (bundled) in case I need to add additional wires in the future. I’d recommend doing something similar if you are running wires back to the tail for possible future additions/changes. You could use wire or even a string. Wire pulls easier through conduit than string and is easier to connect the new wire to. It can be mounted sideways like mine, or flat - just make sure it’s pointed in the right direction.
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Good advice for the mounting hardware and the extra wires! Would it be wise to run a magnet over my potential install location(s) to make sure there's no magnetic interference from other hardware/ controls/etc?
 
coffeeboy said:
Good advice for the mounting hardware and the extra wires! Would it be wise to run a magnet over my potential install location(s) to make sure there's no magnetic interference from other hardware/ controls/etc?
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Personally, I would NOT run a magnet over the space.

Like Sam Buchanan, I have had their magnetometers (old school analog and later new school digital) mounted on the rear deck. I have multiple ones back there.

I used nylon mounting hardware and they have been back there for nearly 20 year, I think.

The one problem that I had years ago was after leaving the plane parked outside (traveling, landed for overnight because a storm was coming), that area got DRENCHED with water. Tailwheel airplane so water DRAINED down from the fuselage. (The impact was that the next day when I fired everything up, the signal back to the EFIS was compromised and the EFIS went 'a spinning). After drying the connectors, everything worked fine ever since. I subsequently made a better "water seal" for the fairing AND I made sure that the connectors were "covered" to make them water "resistant". No other problems in about 20 years and yes, it has been out in the rain recently. (SnF storm)
 
I have an extremely low-tech moisture barrier for my deck-mounted magnetometer. Before securing it to the deck I wrapped it and the D-sub connector in a plastic bag and sealed it with packing tape. I've never had a moisture problem with the mag.
 
Sam Buchanan said:
I have an extremely low-tech moisture barrier for my deck-mounted magnetometer. Before securing it to the deck I wrapped it and the D-sub connector in a plastic bag and sealed it with packing tape. I've never had a moisture problem with the mag.
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Sam, it must have been something about that era. (20 years ago) I have a "similar" low-tech solution!!🙂🙂
 
coffeeboy said:
Thanks for the extra info! Do you have any photos of the shelf you did? I think that would be a good idea for the magnetometer and relocating my ELT (it's currently on the floor in the baggage area... could easily be hit by baggage).
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the shelf is here, but the magnetometer is sitting on a small 6x5” shelf , 24” or so off the fuse floor on part F-628. It is on drawings 32 and 30. Sorry only pic I have and it doesn’t show the shelf just outta sight on the center support #628. Been this way successfully for 10+ years. First the analog version and now digital version. For secu , good double side tape secured both.
 

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I'll add a point here for future readers who might stumble upon this thread...

A single GRT digital magnetometer is capable of feeding multiple EFIS devices. The RS232 output data from the magnetometer can be Tee'd to feed several EFIS displays. This is kind of a good thing because the GRT Inter-Display Link (IDL) that connects from one EFIS to the next is configurable to include a sharing of magnetometer calibration (MAG CAL) data between EFIS displays. This allows a single magnetometer to share its data with multiple EFIS displays and the same calibration data is shared by multiple displays over the IDL, thus all displays should show the same magnetic heading.

Now for the down-side... The magnetometer is powered from one EFIS. If that EFIS is powered off for any reason the magnetometer no longer is powered thus magnetic heading is lost for all connected EFIS devices.

In my aircraft I installed two magnetometers. One is tied directly to the GRT Mini EFIS - this forms a stand-alone EFIS system. The second magnetometer is tied to the Adaptive AHARS (yes, I have an older GRT HX EFIS which requires a stand-alone AHARS); its signal is also Tee'd off to feed the Sport EX EFIS. The IDL is configured to NOT share MAG CAL data. This means that I have to perform the magnetometer calibration routine three times, once for each EFIS. The up-side of doing this this way is that I have some degree of independence of the Mini from the HX/Sport EX devices.
 
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