Tim Mackey Posted July 17, 2008 Share Posted July 17, 2008 Roy Hill ( one of our regualr forumites ) was recently asked to help install a JR R921 2.4Ghz rx to replace a 35 meg unit on someones model. On the 921 rx there are two ports labelled - BAT1/bind at l/h side of rx, and BATT2/data at r/h end, however no mention of this is made in the info leaflet, or in the downloadable manual, so Roy wanted some clarification. Upon speaking to Macgregor customer services he was told that both batt ports positive and negative terminals are connected internally , so should NOT be used with 2 batts directly and simply plugged into each port, as some may imagine would be the case. However you can use either with a single supply - or both together if using 1 X battery and 2 seperate switches arranged such that power from that battery is fed to only 1 socket at a time. Now it is well known that some other brands of equipment also incorporate 2 x battery input sockets ( such as certain MPX rcvrs like the RX7 and 9 channel variants CAN be used with dual supplies to incorporate a degree of battery redundancy ( battery back - up ). However the difference here appears to be that Multiplex have incorporated a diode in the internal circuitry ( think of it as a one way valve ) which prevents one battery from being able to "reverse feed" into its partner battery, furthermore, the MPX system - AFAIK - also includes circuitry which only utilises the second battery if the voltage actually falls too low on the first. The JR R921 is NOT battery back up system enabled The two battery port designations are somewhat misleading, and I hope the following will clarify things. Port 1 ( marked batt1 / bind ) is the only port that can be used for binding the system, and after binding is completed and the bind plug removed, reverts to being simply the " normal" battery port. Port 2 ( marked batt2 / data ) is the port used to connect the optional flight data logging device.This can alternatively be used as the port into which your flight battery is connected, rather than batt1/bind.It should be remebered that in fact ANY receiver port can be used for the flght battery as they all have a common rail for both positive and negative power connections - indeed Spektrum advise that in the event of you not having 3 wire battery harness into which the bind plug is normally inserted, then simply insert the bind plug directly into the "batt/bind" socket and temporarily plug your battery into ANY free socket and then remove the bind plug after binding. I am not sure that it is wise to actually fly with this arrangemnent as the cross section and power handling capabilities of the other sockets may not be as large as the main "batt" sockets - it probably is.... but I could not say for sure. Thanks Roy for bringing this to peoples attention.I also show below a link which may be useful for those people using any JR / Spektrum equipment. Full listings of all JR manulas etc Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 17, 2008 Share Posted July 17, 2008 Must eat more Welch sticky buns ! Obviously is good for the brain cell .Sorry .Off thread again Quote Link to comment Share on other sites More sharing options...
2.4g Shaun Posted September 1, 2008 Share Posted September 1, 2008 Hi, DS on multiplex Rx's stands for DOPPEL SUPER... or Double Superhet in english.....It doesn't mean Dual Supply as you stated...I hope this clears up any confusion. . Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted September 3, 2008 Author Share Posted September 3, 2008 Thanks for that Shaun - I have edited my error Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.