Spektrum transmitter antenna question
 

Ok, for a while now we have had a busted DX6 Antenna, just the casing, not the wire inside. Here is my question.

Horizon sells a replacement for the CX2 Tx but not the DX6. The only difference in the two is the length of the wire, the shorter one is out of the DX6 and the broken one. I can use the CX2 antenna in it very easily. they have the same connector type.

Attachment 68091 Attachment 68092

and it's mounting point in the case. the left pic below is the CX2 radio and the mount is on the board on the lower left. The DX6 mount is in the middle near the top, CX antennna alreday mounted.

Attachment 68089 Attachment 68090

I am guessing the length does not matter as they are both 2.4 systems. I could be very very wrong and that is the reason for the question.

comments...????

Bill,

Have you tried Range-Checking with the other antenna?

Also, I am guessing you'll be calling Horizon tomorrow?

Horizon seems concerned about the wire length, but didn't elaborate when I called. I was thinking to do the same thing, just haven't ordered the other antenna yet.
Bill, if you have the antenna already, hook it up and do a range check, please. I'd love to hear what you learn.

I have it on there now. I really do not use the radio anymore as I have a DX7 now. I am going to range check it this afternoon, weather permitting, and see what I get.

The thing that makes me think it will be ok is that we face the same thing or similar in our fire vehicles. Some trucks have a 20ft. cable run to the radio antenna and others only 3 or 4 ft. I know it is not exactly the same thing and I am no expert by any means.

And Yeah Kev, already called 'em and got a similar response as you Dennis. I think they kind of have to use that line as it is not a Spektrum part number I'm sure.

Actually, I would not be surprised if it is the same thing. I mean, first and foremost, it is a RADIO, plain and simple.

My gut tells me you would be fine. But I would hate to be the guy that says "Go for it", then you have a crash and blame me. Not that you scare me, but, yanno........:o

I agree Kev, I really don't think it is going to be an issue. Like I said earlier it's a brand thing I think more than anything.

Just like our light bar/siren units. Federal signal, that makes our sirens, do not recommend using code 3 light bars with them... They work fine and a light is a light. They just want you to use a Federal light bar with the federal siren... can't say as I blame them either, just trying to sell more product.

Or like buying a product that runs on batteries or a power supply, and they say to use THEIR power supply; use of another PS could void your warranty.....power is power.....or as you said, lights are lights.

I can't imagine that small of a length of wire to get to the antenna is going to change anything. Now the size of the radiating antenna, YES, that would be a different story, but a few extra inches to the antenna? Nah, I can't see it.

well we'll see what a range check this afternoon shows. Weather looks to be holding for now but it's supposed to be storming this afternoon.

Same here.....my knee was telling me this morning we are gonna get rocked with storms.....I'm hoping so, got a game to umpire and my knee don't feel up to it....

I'll wait for your range test, but i bet it checks out OK.

heres hoping it does well as i also have a busted antenna case on my dx7. it still works fine, but flops around.

Thanks Yaniel, the old one on this one still worked too, just the plastic pivot point was broken, if all else fails I can just put it back on there.

It's all Good!
 

Ok without a doubt it does not make a difference. I would not hesitate to fly an aircraft with this antenna at all.

Range check with the button pushed showed no signs of glitching at 100 feet+.

Mason got on his bike and headed down the street. 1000ft down the road it is still working perfectly, I cannot see him but he tells me over the radio everything is working like it should with no glitching whatsoever. The test was done with the DX6 Transmitter voltage at 9.8 and using the AR6000 receiver with three Spektrum DS821 digital servos on a fully charged 3s 1320 Thunder power lipo


So if you need an antenna replacement I can tell you in my experience the CX2 antenna will work just fine in a DX6. Probably a DX7 as well but I did not test that.

Bill as you have already found out...it works fine. And Kev you are correct. Speaking as an "expert" both these are 2.4 systems and the radiated length of antenna is the same so should therefore work. Now onto the length of wire leading to the antenna. It is just coax (shielded) to keep the signal from radiating prior to the antenna. Depending on the frequency of the signal and strength of the signal this length of line can become critical. All wire's will cause some attenuation of the signal run through it and present an impedance to the transmitter circuitry. This is where the concern for the length of "lead" wire comes from. You don't want to create a standing wave in the transmitter circuitry.

Now with all that said on this system @ 2.4ghz a few inches will not matter. Now if we were talking 5 or 10 meters that's a different story.

Bill,

I would venture to guess it makes no never mind which radio you put it in.....

Thanks for the experiment, Mr. Wizard..... :)

I figured as much Ray but elusive as the folks at Horizon were about giving an answer put that bit of doubt in my mind.

I was not surprised by the result at all really.

The guys at horizon did not "design" the equipment so they like you are hesitant to recommend this change. The output impedance of the transmitter circuitry is matched by the designer to the impedance of the coax that will be sending the signal to the antenna. Depending on the type of coax used (frequency/connector/signal strength/etc) could cause the transmitter to 'burn" out. so it is perfectly understandable for anyone but the designer to be hesitant about recommending anything other than OEM parts.

well that certainly makes sense when you put it that way.:)

Yeesh Ray,

Now you sound like the Motorola Techs that come to our dispatch center when something goes awry......

I bet I even have that glazed-look in my eyes as I tune it out.....LOL

Where's my donut? :)

LOL! Yup!:Q

great to hear bill! i'll be ordering one for my dx7 in the next few days to try out. i'll fly the superfly with it for a bit then if it goes smoothly, i'll try it in my 40 size birds

If anybody would like the OEM, I have a DX6 for parts.

Would you consider selling the antenna off of it? I have a DX6 with the exact problem Bill had. The knuckle joint is broke but the antenna and radio work fine. I just can't bend it since it's been glued straight.

That's good to know Bill. So how much does a CX2 antenna cost?

Tom,

I have a CX2 TX I can see about getting the antenna off for you if you are not in a hurry.....

I'm in no hurry at all Kev. That would be great.