Peter Christy

In the module section of the transmitter setup, one of the variables is the receiver number. This is a number that you set for each receiver so that the transmitter can warn you if you have the wrong model selected. This also clearly means that you cannot use the same number for different receivers - or different Tx modules using the same receiver. That is what the message is trying to tell you. Simply choose another number that is not already in use, and you should be good to go. If you set the number to zero, then this safety feature is turned off. You could try that for experimental purposes, but don't make a habit of using it!

I think T9 get their receivers "bare", ie with no firmware installed, and then flash them with whatever the customer orders. It could be that yours have slipped through the net and haven't had any firmware installed at all. Happened to me a while ago. A quick phone call to T9 should confirm this. I already had the firmware, so I just flashed it and all was well. -- Pete

Yes, I'm talking about relatively small packs. I've only got one model I would call "big", and it isn't that big in the greater scheme of things! 😁 However, I'm still very wary of LiPos and LiIons. Its not that long ago that laptops and cell-phones were catching fire in airliners and on trains! The technology hasn't changed, though the quality control has, hopefully! I do use both LiPos and LiIons. The LiPos because for traction motors there is no real substitute, and the LiIons because I've got two transmitters that came with them. My preferred technology for both transmitters and receivers is either NiMh or (if the system can take the higher voltage) LiFe - purely on the grounds of safety! Remember that even Boeing were having trouble stopping LiIons catching fire in their Dreamliners! Mind you, given their recent history, that's probably not a good example....! 🤣 If you are comfortable charging them in situ, then that's your call. Personally, I'm not. But that's just me being very cautious. I have seen a couple of horrible accidents caused by momentary short circuits when the chap connecting things got distracted for a moment. There's an awful lot of energy stored in those cells, and you don't want it being released all at once! <Gets off soapbox!> 😁 -- Pete

They are fine for Tx use. Many modern Txs use them (FrSky, Radiomaster, etc). For Rx use, they are heavier than LiPos for the same capacity and the voltage is slightly different. These observations assume that the voltage is correct for the application. Most modern transmitters (2.4 GHz) are quite happy operating in the 6-8volt range. Older transmitters (27/35MHz) require either 10 or 12 volt, depending on their age. Similarly, for LiPo/LiIon use in receivers, you need to be sure that both the servos and receiver can accommodate the higher voltage. My own preference is either Eneloop NiMhs or LiFe cells for airborne use. Both can be charged safely in situ. LiIon and LiPo both have a chequered history in that respect.....! I wouldn't want to charge them in a model.

X6R receivers readily available: https://www.t9hobbysport.com/frsky-rx6r-receiver

E.D.: Genuine Eneloops still available from Overlander (AAA-800mAH, AA-2000mAH).

It is in a Hirobo Bell 47 helicopter (an early Mk 1). On the AA cells it couldn't get off the ground! The engine sounded fine, no misfires or anything, just a severe lack of power. It would get light on the skids, and you might see daylight under them momentarily, but it certainly wouldn't "fly". Switching to sub-C cells restored normal power. It would lift off, hover and fly round with no problems. To be fair, it is NOT over-powered! But neither is the full-size one! It does force me to fly it in a realistic manner! 🤣 -- Pete

Quite correct! In AA sizes, anything over 2000mAH is pushing your luck! You will be much better off sticking with 2000mAH rather than going for the higher capacity. 2000mAH is quite adequate for most of our applications. Don't get fooled by "the bigger the number, the better" syndrome. It ain't necessarily so! I've never had an issue with genuine 2000mAH Eneloops. My personal experience with Vapex has been mixed... -- Pete

Well, the genuine FrSky X4R receiver is only £26 and is tiny. These are full range receivers. I've used one in a smallish helicopter (Micro-Mold Lark) without any issues. Why mess with a clone, when the genuine article is so cheap? https://www.t9hobbysport.com/frsky-x4r-receiver (No connection to T9, other than as a happy customer!) -- Pete

My Rxcel is an early version, and the instructions contained dire warnings against using more than 4-cell NiMhs. I believe the later ones are more tolerant, but I can't speak from experience with those. AA-cells are NOT sufficient. Although the average current draw is only a few hundred mA, the PEAK draw (when charging the capacitor) is a lot higher, and AAs cannot meet that peak quickly enough. I switched to 4x sub-C cells (nominally 4.8V), which instantly solved all my power loss issues. -- Pete