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ELT upgrade

Tankerpilot75

Well Known Member
I currently have the EDMO E-01 121.5 ELT installed in my RV7A. I read where the FCC no longer allows the sale or support of these ELT units therefore I?m thinking it?s time to upgrade to a 406 MHz unit on my next condition inspection. I understand the unit, antenna and remote switch must be replaced when upgraded.

From what I read it appears there are two units that are comparably priced (under $550) and are direct replacements for my current unit. One is the ACK 406/121.5 MHz E04 ELT; and the other is the ARTEX 345 gps 406/121.5 MHz ELT. Both units appear to meet FAA requirements without a gps input but obviously work better with a RS232 feed from a Garmin 430 (non-WAAS) unit. According to Aircraft Spruce customer reviews both units have their pros and cons.

The ACK unit requires three different types of batteries with different replacement schedules. However it has a twenty degree sweep back antenna with a molded plastic base. The ARTEX unit uses one 6 year lithium battery to power everything but has a straight black whip antenna that some customer reviews didn?t like. My questions:

1. If you?ve installed or replaced your ELT recently which unit did you use and why?

2. If you ran a wire from a 430 gps unit to the ELT which ?pin? did you use for the gps feed on the 430?

3. Overall, how difficult was the swap out?

Thanks in advance for your input.
 
1) Went with the ACK-04

2) I'm using a GTN 625 for the GPS data so I can't help with that one
3) Very easy upgrade. Took about 1 1/2 hours and that was a very leisurely pace.
I hope that helps some, at least.
 
Check your Garmin manual. IIRC there are about 4 RS232 outputs from your GPS; any unused one should work.
I recently had to install an RS232 output from my G420W for an ADSB source. Getting into that backshell connector, on my back, under the panel, was not fun.
 
Getting into that backshell connector, on my back, under the panel, was not fun.

No it?s not fun getting on one?s back to access to the back of the Garmin rack. I had to get back there once before and that was why I was hoping that someone could easily identify the correct pin. Oh well, if nothing else works ?RTFM.?

From what I?m seeing the ACK-04 is the ELT of choice so far.
 
Here you go:
Connector P4001:
pin 41 RS232 out#3
pin 54 RS232 out #4
pin 56 RS232 out#1
pin 58 RS232 out #2

These are "high density" pins. Pick one that's not currently being used. (Or, if you're lucky, find one already wired to the connector but not being used. I sure wish I had told Stein to wire all of them, and I'd just tie up the unused ones.)
Edit: don't forget a ground return, if not there already.
 
Here you go:
Connector P4001:
pin 41 RS232 out#3
pin 54 RS232 out #4
pin 56 RS232 out#1
pin 58 RS232 out #2

These are "high density" pins. Pick one that's not currently being used. (Or, if you're lucky, find one already wired to the connector but not being used. I sure wish I had told Stein to wire all of them, and I'd just tie up the unused ones.)
Edit: don't forget a ground return, if not there already.

Thanks Bob.
 
Hi Jim,

Might be too late for you, but I figured I'd answer anyway. I installed the Artex and am happy with it. The only issue was the antenna, which as mentioned is kind of big and not universally liked. We have a -8, and with the long sliding canopy there really isn't a good place to mount it. Ultimately I mounted it on the backseat armrest, right by the rear bulkhead. The antenna sticks up into the canopy space, and I fitted a piece of clear tubing over it. Surprisingly this worked pretty well. It doesn't interfere with the passenger or the baggage box access, doesn't scratch the canopy, and gives the antenna a good bit of clear area to transmit in.

I did not hook up the GPS position. A couple years ago I had the misfortune of a 406 ELT going off in my garage. When the Canadian Coast Guard called (apparently they take turns with the US Air Force covering North America) they narrowed it's position down to my home address. I figured in a real emergency that was close enough. If you do want to hook up the GPS, apparently you have to buy a slightly different version of the Artex ELT. At least that's what they said when I bought mine. Price was the same, so I don't know what was different.

I've seen the 406 ELT system in action a few times over the years, and it is impressive how quick and how well it works. There just isn't any comparison to the old 121.5 passive system. I know it seems like every time we turn around the Feds are nickel and diming us with another requirement, and it can be tough to justify spending money on something you will most likely never need. However both Artex and ACK have a done a good job getting the price down and I think you are getting your money's worth.

DEM
 
The ACK unit requires three different types of batteries with different replacement schedules.
True, but the lithium batteries in the remote and the audible alarm have something like ten year lifetimes. The main battery is supposedly good for five years but I had to change mine after three after it failed the load test. The reason I performed the load test was because I was getting a VSWR Fail on the quarterly self test. A low battery can also cause that failure. The main battery pack is temperature sensitive and doesn't perform well in the cold. I've had to heat mine up with a heat gun in order to pass the battery test.
 
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Dennis and John,
Thanks for your input. Since I posted my initial thread the weather and my own schedule these last few weeks has kept me away from the airport. I went ahead and ordered the ACK-04 and hopefully will be installing it this week.

Right now my thinking is that I?ll install the new antenna as prescribed by the installation instructions and not under the rear fiberglass fairing on the horizontal stabilizer where the existing 121.5 MHz ELT antenna is located. While it was suggested that using the prior antenna?s location would work if an aircraft accident occurred, because the nose of the aircraft would likely be nose down placing the ELT antenna on a near vertical plane, I decided to go ahead and mount it vertical to start with. I do have (just barely) the required minimum three feet between the new antenna?s location and my comm antenna. I?m connecting gps input to the ELT because it doesn?t make sense to not utilize gps location otherwise why change!

Unfortunately this location will require using a 2? square doubler and drilling some holes on the top of the fuselage just behind the rear cargo panel. I?m not real excited about this because the aircraft is nicely painted. I thinking if I secure the doubler using four stainless steel #6 screws with locking nuts and the antenna through the middle, it will both look okay and meet sufficient strength mounting requirements. I?ve already ran a new four wire shielded cable from behind the cargo area underneath the seats to the panel supporting gps and powe connections. The test switch will use the existing set of wires.

ADS-B out and 406 MHz ELT, I wonder what the next FAA change is around the corner?
 
New ELT Install Update and Question

After talking to my A&P (local EAA Tech Counselor), Steinair and ACK Tech support I went ahead and installed my new ELT’s antenna in the same location as the old one under the fiberglass horizontal stabilizer fairing. To avoid having to fight the Garmin rack battle, I decided upon an alternative gps source (the serial port six output on my Horizon WS EFIS) for the ELT’s gps source. This caused some configuration conflicts on my lower WS EFIS but I think those are now resolved.

However my problem now is the Coax Cable going from the ELT itself to the antenna. ACK supplied a 5’ RG58 cable. I originally tried to reuse my RG400 coax cable but kept getting a “5 beep error code” which translates to “HIGH VSWR OR HIGH CURRENT.” Talking to ACK they said Their experience with RG400 cable led them to use the five foot RG58 that was now included in the kit. I then tried their supplied cable (ELT loose from its housing straps) and it passed the beep test. I then called ACK and told them the kit included cable was at least a foot short for my installation so they recommended I either make or purchase a longer RG58 cable - which I did on Amazon last week.

The new cable is 10 feet with the appropriate BNC connectors already attached. Prior to use I checked the new cable for pin and ground continuity and it checked okay. Unfortunately when I installed this new cable it gave me once again the five beep error code. Called ACK again and they said send the ELT unit to them with the new ten foot cable and they would test things themselves.

Question: Has anyone else experienced this problem? If so how did you eventually resolve it? ACK indicated a ten foot coax cable should work.

Frustrated!!
 
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Laying the antenna under a fiberglass fairing of a metal airplane is not going to work.

Or, likely, I don't have the picture. The antenna has to be away from the metal structure except at the base or you WILL get high VSWR.

Ron
 
Laying the antenna under a fiberglass fairing of a metal airplane is not going to work.

Or, likely, I don't have the picture. The antenna has to be away from the metal structure except at the base or you WILL get high VSWR.

Ron

Ron,
I sent the ELT back to ACK and they checked it out using the 10 foot RG58 cable I bought. It seems the cable (Amazon purchase) either isn?t RG58 or its defective because that cable caused ACK issues with their test equipment. They?re sending me two of their 5 foot cables which I?ll use a coupler to marry them together and hopefully that?ll work.

Here my question about your comment: if it tested fine with ACK?s 5 foot cable why wouldn?t it work okay with a 10 foot cable? I?m not sure what VSWR measures but I assume it?s some type of resistance. Hopefully I?ll have my unit back from ACK early next week and I?ll find out if using two of their cables coupled together will work. I?ll let you know.
 
Ron,
Here my question about your comment: if it tested fine with ACK?s 5 foot cable why wouldn?t it work okay with a 10 foot cable? I?m not sure what VSWR measures but I assume it?s some type of resistance. Hopefully I?ll have my unit back from ACK early next week and I?ll find out if using two of their cables coupled together will work. I?ll let you know.

Glad you asked.:D
Well, VSWR or voltage standing wave ratio is a number that says in its own way the ratio of reflected power; that is, how much power is bouncing back from the antenna.

A bad antenna will have most of the power coming back (high VSWR).
Depending in the length of the cable, the device will see this as a near short, a near open, or reactance.

While a VSWR meter or thruline wattmeter measurement is generally immune to line length, I suspect the ELT contains a simple circuit that will be effected by line length. Its purpose may be to call out a condition that has the most potential for causing damage to the unit, and that would be effected by cable line length. At 406 MHz, the effect of cable length will repeat every 2 feet or so.

BTW, one of my hobbies is GA antenna research, so I like the subject and am glad to comment.

Tankers? JP4.. or Firetrol?

Ron
 
This is the craziest thing I have ever heard. No real coax cable is perfect, but RG400 is closer to ideal than is RG58. Maybe Ack meant that their connector is designed for RG58, not 400?
SWR is a measure of reflected energy due to impedance mis-matches, usually where the coax meets the antenna. Putting the radiating element in close proximity to the metal stabilizer is one way this can happen.
 
Tankers? JP4.. or Firetrol?

Ron

KC-135 A/R/E models. I was one of the early instructor pilots in the KC-135/R model when it initially came into the Air Force inventory in 1984/85. Checked out a bunch of pilots in the R model and helped develop a number of the simulator training profiles for the ?R? model. Back then, a full motion simulator with visual graphics was quite new to Tanker pilots. Left McConnell AFB in 1986 for a four year tour in Washington DC. Big professional mistake but once again learned a lot about the business side of the military/government which served me well during my post military career. Retired in 1992 at Tinker AFB flying the EC-135/E model.

Started my military career in 1967 with 3 1/2 years in the Army (year and a half in Vietnam 1969 - 70) and finish in the Air Force (19 years) after flying support missions in Desert Storm. People today often say, ?thank you for your service? but I got a lot of good out of those service years and really have benefited from the military?s education, medical and retirement programs. I truly mean it when I say, ?thanks for the opportunities.?

My youngest son is a physician in the Navy having benefited from their financial assistance while in medical school. He?s married to a civilian NCIS agent (nothing like the TV program) who earned her opportunities also in the military.
 
You guys were right!

Ron and Bob,
ACK returned my ELT after checking it out. They also sent two new five foot coax cables to couple together. Installed the ELT with the two coupled coax cables and guess what? Got the same five beep error code - High VSWR! Too much reflected energy from the surrounding fuselage area now definitely confirmed.

Moved the antenna from under the horizontal stabilizer fairing to a new location on top of the fuselage behind the cargo compartment and added a doubler to strengthen the installation. I really didn?t want to drill holes in my nicely painted aircraft and put another antenna on top but there was no other choice if I was going to upgrade to the ACK E04 406 MHz ELT. It now works as advertised without any error codes.

I?m still deciding whether it was worth the expense and effort. Hopefully I?ll never need to find out. Now to complete the condition inspection.
 
This is a bit of a tangent, but it seems the most likely time to *really* need an ELT is in an off-airport forced landing. In which case, the Master is almost certainly going to be off when the impact happens. Will the panel mounted GPS position source be any help with the ELT triggers? Are these new ELTs always active and listening/remembering last known position, so they can tell the satellite? (I'd suspect not, with a 10 year life expectancy for the battery.)
 
This is a bit of a tangent, but it seems the most likely time to *really* need an ELT is in an off-airport forced landing. In which case, the Master is almost certainly going to be off when the impact happens. Will the panel mounted GPS position source be any help with the ELT triggers? Are these new ELTs always active and listening/remembering last known position, so they can tell the satellite? (I'd suspect not, with a 10 year life expectancy for the battery.)

Ummm... this assumption, that the pilot is prepared for a crash, is one that needs to be examined. A cursory examination of accident reports will show that most are very unplanned in nature, or occurred with so little advance warning that a conscious decision to turn off the master was not possible.

Having said that, some ELT's use a memory device to store "last known" GPS position. Admittedly most of these ELT's are ones that use an interface box to talk to the GPS, unlike the majority of the ELTs intended for the GA fleet.

If you really want to know the answer to this question, ask your ELT manufacturer how their device works - most will be happy to give you this level of detail.
 
Who plans an accident? :)

My assumptions are only that away-from-the-airport crashes tend to be either in-flight loss of control resulting in the ELT alerting the coroner, or forced landings with some warning, where the pilot would hopefully be working his emergency landing checklist, including powering down the electrical system prior to impact.

Regardless, unless an ELT is powered from ship's power, I don't see how it can be updating *and storing* GPS position prior to activation, and still have a battery with a 10 year life. Are the 406 ELTs connected to ship's power?
 
Who plans an accident? :)
Regardless, unless an ELT is powered from ship's power, I don't see how it can be updating *and storing* GPS position prior to activation, and still have a battery with a 10 year life. Are the 406 ELTs connected to ship's power?

The answer to your last question ("Are 406 ELT's connected to ship's power") is yes, at least in the case of an ACK E04. You need to ask an expert, but my guess is that these units use some form of non-volatile memory, like "flash" chips. These chips can store data even in the complete absence of power.
 
GARMIN GTX 335 ADS-B RS-232 Serial Data to Artex ELT 345 Format

We are considering installing an ARTEX ELT 345 and sending it position data from a GTX 335. We are currently trying to figure out what serial dat format out of the 335 is compatible with the ELT.

The Artex specifies two acceptable serial data formats:
1) NMEA 0183 baud rate is 4800.
2) Aviation protocol baud rate is 9600.



In another installation the ELT 345 is being sent data from a 430W using the AVIATION output of the 430W and works fine.

We are not sure which output format to configure the GTX-335 in this application. Any assistance would be appreciated.

-larosta
 
The answer to your last question ("Are 406 ELT's connected to ship's power") is yes, at least in the case of an ACK E04. You need to ask an expert, but my guess is that these units use some form of non-volatile memory, like "flash" chips. These chips can store data even in the complete absence of power.

Thanks; that explains it. Nonvolatile memory is a piece of cake, but continually writing to it requires power.
 
We are considering installing an ARTEX ELT 345 and sending it position data from a GTX 335. We are currently trying to figure out what serial dat format out of the 335 is compatible with the ELT.

The Artex specifies two acceptable serial data formats:
1) NMEA 0183 baud rate is 4800.
2) Aviation protocol baud rate is 9600.



In another installation the ELT 345 is being sent data from a 430W using the AVIATION output of the 430W and works fine.

We are not sure which output format to configure the GTX-335 in this application. Any assistance would be appreciated.

-larosta

It is my understanding that the 335/345 transponders will not output gps serial data to another device. That?s why I had to decide where to get my gps source information. Getting a wire run to my Garmin rack seemed very difficult because of limited space so that is why I chose my lower GRT WS EFIS. The ACK ELT allow you to set your input baud rate. I suspect ARTEX is the same.
 
Mystery

Regardless, unless an ELT is powered from ship's power, I don't see how it can be updating *and storing* GPS position prior to activation, and still have a battery with a 10 year life. Are the 406 ELTs connected to ship's power?

Regarding the mystery of an inactive ELT being able to store GPS data with power off, here is my guess:
It is possible and not uncommon to harvest a little power from the RS-232 signal itself. The RS-232 signal is very robust. Further, some newer chips can operate on microwatts, so there is more power available than needed. Very feasable. This is how I would have designed it.

Jim, my major involvement with a (K)C-135A was long ago with Gen. Old's 15th AF flying command post aircraft here at March. I was asked to do a new secure system since I was about the only asset with some digital background. They loved me. But you guys had all the fun. I must have been great going from a slug A model to the R.

Ron
 
ELT is powered whenever aircraft is powered

In regards to the ACK E04 ELT vs the old ACK E01 ELT, there is a new four pin plug that required me to run a shielded four wire cable from my panel to the ELT. This new four wire plug has pins for 12v (40 MAmp) power, ground, gps serial data in from a gps output source, and gps return data (for gps source testing). I used an existing one amp clock C/B for the power source, an existing ground block for ground connection, and as said earlier my lower GRT WS for serial gps data sourcing. The fourth wire (gps data source testing) is loose (but labeled and shrink wrapped at the end) in case I ever need to re-test the gps data source.

I?ve heard some people say conversion from the E01 to the E04 was quick and easy. That WAS NOT my experience. Running the new wire, locating and wiring up a suitable gps source, installation of a new remote switch and warning device plus eventually relocating my ELT antenna all together involved a solid week of work spread over a month and a half of actual effort.
 
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