Kannad ELT VSWR antenna problem

[Romeo Victor]

Dear fellow builders,

I have the Kannad Integra installed in my Vans RV8.
Months ago I contacted Kannad to find out for the best suitable antenna. The recommendation was the ELT10-773-3. The version I have is S/N 10363.
After performing the self test, the radio starts with a long beep (according manual) followed by three short beeps and another 5 short beeps, indicating a VSWR problem with the antenna (as far as I understood the manual).
The antenna cable between the unit and the antenna measures 130 cm.
I tried the portable antenna for the Integra, directly installed on the unit. That antenna worked properly, no alerts. I changes the antenna cable, no result. I tried the 10-773-3 with a different antenna cable, same fault.

Ideas, solutions, faults????

Best Regards from Bavaria

Thanks for answering
Stephan

[JFRV8]

Stephan:

Where and how did you mount the antenna?

Can you post a picture?

[Canadian_JOY]

Antenna location and installation method will have a big impact on VSWR.

Also, when you are using the "portable antenna" you are also eliminating the coax cable which can also have significant impact on VSWR if not properly fabricated and terminated. You'd be surprised how VSWR goes nuts when a coax is bent sharply around an aluminum corner or a BNC connector doesn't have its center pin!

Pictures of the installation would be a big help.

[81270]

Most whip antennas mounted on a metal frame/skin use that metal for earth/ground plane. This ground plane is important so check to see of the antenna socket is making good electrical contact with the metal skin (i.e. no paint on the inside).

[AAflyer]

My new Kannad Integra is giving me an external antenna fault. Could anyone comment on whether the problem might be where my antenna is mounted? This photo is from the rear seat, looking up, under the rear, right armrest. The whip portion of the antenna is slightly curled around the turtledeck with a couple of small adels to prevent interference with the canopy.

[IMG][/IMG]

[Carl Froehlich]

You simply cannot mount the antenna like this. You have created a coupling to ground at the high current part of the antenna (the part near the base).

Mount it horizontally under the empennage fairing. Ignore the "it must be vertical" noise as if you really need the ELT to work it may well end up vertical.

Carl

[AAflyer]

the newer 406 ELT antennas are too long to mount in the tail, like everyone used to do.
I must ask, though, why isn't my mounting essentially the same as mounting it on the outside fuselage skin?

[Walt]

The install manual gives you pretty good instructions on mounting the antenna, bottom line is without a proper ground plane the antenna will not function correctly.

(try mounting your com antenna like that and see how good it works)

[Carl Froehlich]

Originally Posted by AAflyer

the newer 406 ELT antennas are too long to mount in the tail, like everyone used to do.
I must ask, though, why isn't my mounting essentially the same as mounting it on the outside fuselage skin?

My ACK 406 ELT antenna fits fine under the empennage fairing.

Your mounting is a close couple to the fuselage. The empennage also presents this issue, but the spacing is much wider than your 1/4" or so. Think cube function for this type of interaction.

Bottom line is any antenna is better than no antenna. I like the empennage area as the intersection between th VS and HS seems to be the most survivable location for the ELT antenna.

Carl