[FORANE]

So the 39R is designed to be remote mounted, I get that. But, does it offer any tangible benefits over the 39? Looks like I read the 39R does not come with an antenna; does it just need a gps antenna or an external ads-b antenna or both? The 39R is priced $100 more than the 39; why would I want to pay more and have to buy an antenna (or 2?) on top of that?

 

[SteinAir]

Inside I think they are identical units, but the enclosure is significantly different. The "R" has a nice square box that is easy to mount, has a regular Dsub for a connector (vs. the wonky plug in one for the dash mount), and normal BNC connectors for the antenna (unlike the SMA and push fit connector for the portable). Basically it's just designed to stay in the plane and is easier to install. That said, I do have customers who have semi-permanently mounted the regular one under their panel, but realize if you do that you STILL would then need a separate antenna anyway...so unless you are putting it on your dash you still need the separate antenna. Regarding the antenna, if you have this hooked to a G3X you don't necessarily need the GPS antenna, just the Transponder type antenna.

Hope that makes sense!

Cheers,
Stein

 

[FORANE]

Inside I think they are identical units, but the enclosure is significantly different. The "R" has a nice square box that is easy to mount, has a regular Dsub for a connector (vs. the wonky plug in one for the dash mount), and normal BNC connectors for the antenna (unlike the SMA and push fit connector for the portable). Basically it's just designed to stay in the plane and is easier to install. That said, I do have customers who have semi-permanently mounted the regular one under their panel, but realize if you do that you STILL would then need a separate antenna anyway...so unless you are putting it on your dash you still need the separate antenna. Regarding the antenna, if you have this hooked to a G3X you don't necessarily need the GPS antenna, just the Transponder type antenna.

Hope that makes sense!

Cheers,
Stein

Thanks for the reply.
I do not have a G3X; plan to display on Aera 560.
If I mounted the gdl 39 under the cowling I would not need anything more? Also, by antenna, the gdl 39R only takes a standard gps antenna?

by the way, check your email; I emailed over the weekend requesting a quote on a harness...

 

[g3xpert]

Hello Forane,

Thanks for your questions about the GDL 39/39R products. As Stein mentioned, the major difference between the GDL 39 portable unit and the GDL 39R installed unit is the enclosure and the connectors used. The GDL 39R features a rectangular enclosure with mounting flanges, and is designed to be semi-permanently mounted in an out-of-the-way location in the aircraft. The GDL 39R also uses the same type of high quality D-sub connector we use throughout our G3X system and in our certified avionics.

Both the GDL 39 and GDL 39R have an internal GPS receiver as well as an internal GPS antenna. The use of the unit's built-in GPS receiver is optional, since both units can receive GPS position data from a G3X system, GPSmap 69x portable, or aera 5xx/7xx portable. So if you have a compatible cockpit display, there is no need for a separate GPS antenna for the GDL 39/39R.

Both units require an antenna to receive ADS-B In data. The GDL 39R uses a transponder-type antenna on the bottom of the aircraft, which attaches with a standard BNC connector. The portable GDL 39 has a portable antenna included, or can optionally connect to a transponder-style antenna using an SMA-to-BNC adapter.

Both units can send position, traffic, and weather data to the Garmin Pilot app on iOS or Android via a Bluetooth connection.

Mounting the GDL 39/39R inside the aircraft's engine compartment is discouraged as these units are not designed for firewall-forward temperatures. You can find a full list of specifications for the GDL 39R here.

- Matt

 

[FORANE]

Both units require an antenna to receive ADS-B In data. The GDL 39R uses a transponder-type antenna on the bottom of the aircraft, which attaches with a standard BNC connector. The portable GDL 39 has a portable antenna included, or can optionally connect to a transponder-style antenna using an SMA-to-BNC adapter.

- Matt

Thanks for the reply Matt. That definitely clears up most of my questions.
Can you point me to a list of compatible "antenna to receive ADS-B In data"?
If I get the 39R version I would need to buy one of those and I have no idea what / where / how much additional cost...I would get one.

 

[g3xpert]

Thanks for the reply Matt. That definitely clears up most of my questions.
Can you point me to a list of compatible "antenna to receive ADS-B In data"?

Forane,

In general, any DME/transponder antenna should work, including blade type antennas or the inexpensive "stick/ball" variety. Some non-certified antennas are also known to work. For further information, please see the GDL 39/39R manual, which includes antenna requirements and a list of known compatible antennas.

- Matt

 

[9GT]

Can you point me to a list of compatible "antenna to receive ADS-B In data"?
.

Deltapop makes a nice antenna: http://deltapopaviation.com/Delta_Pop_Aviation/ADS-B_Antenna.html

 

[Tooch]

GPS Antenna

Matt,
I was wondering, If you were to mount a gps antenna on the back of an airplane, could you use that antenna for any gps receiver or does each receiver (make and mode) have specific antennas.

 

[g3xpert]

I was wondering, If you were to mount a gps antenna on the back of an airplane, could you use that antenna for any gps receiver or does each receiver (make and mode) have specific antennas.

Hello Tooch,

It depends on the question you are asking, so I will give you two answers for the price of one.

Can you use one manufacturer's GPS antenna with another manufacturer's GPS receiver? For the most part, yes, as long as the voltage and current requirement of the antenna is compatible with the voltage and current output capability of the receiver. Remember that GPS antennas are powered devices, so the receiver needs to be able to supply adequate power to the antenna. As an example, the GDU 37x display unit used in our G3X system supplies the antenna with 5V at up to 50 mA. A good installation manual should include a list of compatible GPS antennas as well as specifications for antenna power.

Can you use a single GPS antenna with multiple GPS receivers? Practically speaking, no. Again, because GPS antennas are powered devices, any kind of "GPS antenna splitter" would be much more complicated than a simple nav antenna diplexer like the one I have in my RV-7 (to allow me to use one VOR antenna with two nav radios). In practical terms you should assume that a GPS antenna can be connected to only a single GPS receiver. On a related note, I will point out that in one of our G3X systems that has multiple GDU 37x displays, it is not necessary for each display to have its own GPS antenna, but this is accomplished by sharing position data between displays and not by sharing a GPS antenna.

- Matt

 

[flightlogic]

Ask the Garmin tech

On the Garmin 796, Is TX1 or TX2 data out appropriate? Or are they the same info? And on the GDL39, is RXB or RXA data in,used to feed the GPS data in? I like the idea of stowing even the portable GDL away out of sun and heat and feeding ads-b from a bottom mount Antenna and GPS from the main Garmin box. Am I thinking this through incorrectly?

 

[g3xpert]

On the Garmin 796, Is TX1 or TX2 data out appropriate? Or are they the same info? And on the GDL39, is RXB or RXA data in,used to feed the GPS data in? I like the idea of stowing even the portable GDL away out of sun and heat and feeding ads-b from a bottom mount Antenna and GPS from the main Garmin box. Am I thinking this through incorrectly?

Hello Flightlogic,

Yes, remote mounting both the GDL 39 and GDL 39R are popular for the reasons you state. Now that the G3X, Aera 5XX/79X, and GPSMAP 69X products provide GPS data to the GDL 39/39R, there is even less reason to have the GDL 39 on the glare shield. If you use the Bluetooth link to a tablet or phone, make sure you test the location you choose for a good BT connection.

The 796 to GDL39 interface is bidirectional and requires both TX1 (blue wire) and RX1 (yellow wire) wiring on the 796 bare wire cable. Serial port 1 is required.

On the GDL39 bare wire cable, RXA (white/green wire) connects to the blue wire on the 796 cable and TXA (green wire) connects to the yellow wire on the 796 cable.

Pages 188 and 189 of the 796 manual explain this wiring.

Let us know if you additional questions.

Thanks,
Steve

 

[FORANE]

The portable GDL 39 has a portable antenna included, or can optionally connect to a transponder-style antenna using an SMA-to-BNC adapter.

Mounting the GDL 39/39R inside the aircraft's engine compartment is discouraged as these units are not designed for firewall-forward temperatures. You can find a full list of specifications for the GDL 39R here.

In general, any DME/transponder antenna should work, including blade type antennas or the inexpensive "stick/ball" variety. Some non-certified antennas are also known to work. For further information, please see the GDL 39/39R manual, which includes antenna requirements and a list of known compatible antennas.

- Matt

Has anyone tried using the GDL 39 ads-b antenna but remote mounting it (say inside the lower cowling) by the use of a SMA cable?
I don't mind buying a blade antenna, but would rather not have additional drag outside (or additional bulk if mounted forward of the firewall inside the cowl down low).

 

[AllThumbs]

I've been using the GDL 39 as-is sitting between the seats in the RV-6 and it picks up stations in CA just fine. I stuck it there for a test one day and it worked so well I have not moved it yet. Despite the metal all around, even on straight-level flight, it seems to pick up the station info.

I suspect there's a lot of loss due to the location and I know the little antenna can be unscrewed. There should be no problem putting an SMA extension cable in between the GDL and the antenna. You'd just need some way of securing the antenna remotely; perhaps a nylon clamp.

I think I'll try that myself!