Using old FrSky receivers with your Tandem/Twin transmitter

 


Around five years ago I bought a new FrSky G-RX8 for a Horizon Hobby Radian.  I bound it up, put it in the plane and then lost signal and crashed it.  From the wreckage I pulled out this receiver and threw her into a box of spare FrSky parts, and there she sat for half a decade.  Newish, less than one flight.

I missed a key step in the process which would have saved me a Radian fuselage.  This topic also answers the question as to what to do when you have someone gives you a few older FrSky receivers, or if you have some in planes you've been flying with since the Taranis days.  Can you use older FrSky receivers? Better question, should you?

I am somewhat partial to the mid-fuselage pusher style planes. This is my favorite format for a hand launch glider. When I saw the ZOHD Drift come along a few years back my friends went crazy for them. I was skeptical.  Then this cool looking black one came along and I figured it may be worth trying. I managed to squeeze in an  Archer Plus SR8 into that fuselage and got stabilization working fairly quickly.  I had a blast with it.  Except for one issue.  Black planes are sometimes very difficult to see where I fly.  It's easy to momentarily lose orientation with it.  Not a problem, this will become a proximity FPV plane and I  ordered the white one for Line Of Sight flying.

Before I went the route of throwing in a new receiver I went back to my FrSky box (a box of receiver and parts mostly acquired from my years before working for FrSky, thus these were retail purchases) and dug up the old FrSky G-RX8 receiver.  Round 2 anybody?

In the big picture there is a transmitter, a receiver and firmware for each.  As for the transmitter, since I am using an X20S and I keep the firmware updated with Ethos Suite I know that this half of the equation is fine.  The second half of the equation is the firmware on the receiver. What is it? The older ACCST receivers came from an era before we could store the information about the receiver in the transmitter's model file.  All the modern FrSky receivers  (Archer, TD, TW, TD Pro) now store the receiver firmware in the model file which you can find under "info."  But, for the older ACCST receivers, they don't store information.

About three years ago I spent an evening updating all my ACCST receivers to ACCST V2. I think I had 30 planes at the time on the older ACCST V1. Each update took around 3 or 4 minutes.  I did it once, and I was done.  It wasn't the slightest bit difficult.  Now every plane can be used along with my Tandem transmitter. Clearly, this receiver in question was missed. 

Now, why did this plane lose reception and crash in the first place?  Knowing what I know now I can speculate that I had at the time a newer version of ACCST V1 firmware on my Taranis transmitter and this FrSky G-RX8 receiver was dealer old stock.  It may have had a very ancient version of ACCST on it, and I never updated the firmware before I put it in the plane.  There was a bug in ACCST V1 which does lock out the servo, momentarily.  The crash may have been caused by this bug.  Had I simply updated the receiver prior to putting it in the plane, the crash would have been avoided.

Updating old receivers

Part of my workflow with receivers is to check www.FrSky-RC.com and search for firmware.  I always update the receivers to the latest firmware. The Archer Plus SR8 received an "over the air' firmware update which means that the receiver stayed in the plane, no unplugging servos was required. This FrSky G-RX8 receiver needed an old school SmartPort update.  Here are the steps.

1. I found an update for this receiver which was only a few months old in the download section of for this receiver.  Yes, we do update receivers, even aging ones like this one on a fairly routine basis. 

2. I downloaded the firmware, extracted the file from the zip file.

3. I loaded the firmware  into a directory I made called "firmware" on my SD card of my Tandem transmitter. I created a subfolder known as RX and created a folder called G-RX.

4. I flashed the receiver via external device.  It required the strange little cable that came with the receiver in order to do this.

5.  I bound, and performed a range check.

A little gem of a receiver

The  G-RX8 is a glider receiver. The G for glider, RX for the series it came from and 8 for 8 channels.  The receiver has a variometer which allows me to keep track of altitude  and vertical airspeed. It also has link quality and RSSI.  More telemetry than I need for something that won't stray further than a few hundred feet at any given point.  

There is no need to fear the old stuff.  As long as it can be flashed to ACCST V2, you're golden

Should you use old receivers?

In the past year I've had a couple of people tell me that they crashed their plane and somehow the only logical conclusion was that it was due to the receiver.  We test them, found that they were working fine and ended up with a functioning receiver that we cannot resell.  So, I end up with them.    I've put them in my own personal planes just to prove the point that it's not the receivers that are at issue.  Six months to a year later, they are still fine.

I know it's taboo to pull out receivers from a crashed plane.  You never know how damaged the board may be.  Yes, it's a risk. If I was flying something large, and valuable I wouldn't hesitate to buy a new receiver.  Still, these receivers didn't have bent pins or signs that they had much impact damage.  

Which leads back to the main question, when someone hands you a box of old receivers, where have they been?  You can assume that they came out of crashed planes at one point or another and then decide what to do.  

The problem with FrSky is the receivers don't coast all that much.  You can buy a used X8R for $20 or buy a new Archer Plus R8 for  under $40.  The new R8 has better range, better interference protection, FBUS, assignable pins and has both ACCST v2 and ACCESS built in.  Plus it's factory new and potentially not out of a plane that went down in a horrific crash.

I've got a garage full of cheap foam planes that I've mostly had my fun with.  I've got planes I can easily risk a good  crash or two.  Dropping in a used receiver isn't much of an issue. Part of the fun I have these days is rehabbing my old planes and fixing my mistakes.    With that being said, every now and then I throw out the foam of a beloved plane, buy updated components and start all over again.  When it's a plane I toil over it gets a new receiver.