Spektrum antenna wire
03-22-2009, 03:16 PM
#4
RE: Spektrum antenna wire
well I've come to understand things on the other side of the big pond don't work the same way as they do on this side, but all Spektrum receiver antennas on this side have a center conductor and an outer shield, this is by definition coaxial.
a message from Spektrum themselves.......
a message from Spektrum themselves.......
Avoid sharp bends, pinching, smashing or cutting the coax (covered gray section) portion of the antenna. The coax is susceptible to damage and if severed, or if the insulation is damaged, reduced receiver performance can result. If you should damage the coaxial antenna replacement is necessary............
03-22-2009, 06:59 PM
#5
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RE: Spektrum antenna wire
If the AR9000 is the same as the AR9000 as shown here, [link]http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMAR9000[/link] , then you can plainly see that in the 1st graphic in the Service Bulletin the cable in use is not coax.
Plus as this is the same receiver as the JR 921, when you open it up, it again shows that it is not coax cable. The cable length is too short for it to be coax. If it was coax at that length, then it would be a poor antenna.
If you have one handy, open it up and look at the soldering of the cable to the pcb.
Plus as this is the same receiver as the JR 921, when you open it up, it again shows that it is not coax cable. The cable length is too short for it to be coax. If it was coax at that length, then it would be a poor antenna.
If you have one handy, open it up and look at the soldering of the cable to the pcb.
03-23-2009, 03:07 PM
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RE: Spektrum antenna wire
I have opened my rx anyway. The antenna seems like a normal multi-strand wire with a stiff plastic cover in order to ensure rigidity. On the pcb is only a single soldered joint, so no screen was observed as one would've expected with coax. I measured the length of the antenna and it is 31mm. Calcs shows that the quarter wavelength for 2.4 GHz to be 31.25mm, which ties up with my rough measurement.
My only fear is that with microwave RF certain plastics become conductive and all sorts of parasitic capacitances etc etc might play a role here. RF is, afterall, a black art.....
My only fear is that with microwave RF certain plastics become conductive and all sorts of parasitic capacitances etc etc might play a role here. RF is, afterall, a black art.....
