REFLECTOR: Antennas

Brett Ferrell reflector at velocityxl.com
Wed May 22 11:17:24 CDT 2013


I haven't done any testing, but for reference mine was vertical, and
had to get past the SS on the firewall and through the hangar, and the
USAF was ringing every phone I own in milliseconds asking awkward
questions, so I know up-and-down works fairly well.



[1]http://www.velocityxl.com/attachment.php?attachmentid=4849&d=1276866
122



--
Brett Ferrell









On Wed, May 22, 2013, at 11:33 AM, Keith Hallsten wrote:

Brett,

I had considered placing the dual-band 406/121.5 ELT antenna in front
of the firewall, but thought the stainless steel sheet would distort
the radiation pattern so badly that there would be no coverage to the
rear at all.  I was therefore considering mounting the ELT antenna
laying horizontal in the back of the strake, along the spar.  I realize
that you would normally want it vertical, but figured the pattern
distortion would be less than it would be up against the firewall.  Has
anyone done any relative testing of those two (compromise) locations?

Keith

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brett Ferrell
Sent: Tuesday, May 21, 2013 5:12 PM
To: reflector at tvbf.org
Subject: Re: REFLECTOR: Antennas

Yep, and these work... I installed one of the standard fiberglass
antennas behind my false bulkhead and accidentally tripped the ELT...
it the satellite even inside a metal T hangar...

--

Brett Ferrell

[2]reflector at velocityxl.com

On Tue, May 21, 2013, at 07:51 PM, Bachman, Jonathan wrote:

The new 406 MHz ELT system is what I was going for
_______________________________________________________________________

From: [3]reflector-bounces at tvbf.org [reflector-bounces at tvbf.org] On
Behalf Of [4]nmflyer1 at aol.com [nmflyer1 at aol.com]

Sent: Tuesday, May 21, 2013 3:16 PM

To: [5]reflector at tvbf.org

Subject: Re: REFLECTOR: Antennas

Jon,

It is the same as building the comm antennas as per the plans in the
factory manual. Since it sits smack in the middle of the VHF com band,
it is adequate. Since I haven't crashed yet, and I don't have a SWR
meter, I relied on the old standby method of checking the ELT.

Here it is:

"There are two ways to test for sufficient antenna signal on a C91a
ELT. One is to evaluate the signal strength using a test box like those
made by QCAvionix or Whiffletree. The other method is to listen to the
signal using an AM-band radio receiver.

The FAA endorses the AM radio test and has codified this check in the
most recent update of Advisory Circular 43.13-1B (CHG 1). The test for
sufficient signal radiated from the antenna is as follows (Par 12-22):

"Active the ELT using the ON or ELT TEST switch. A low-quality AM
broadcast radio receiver should be used to determine if energy is being
transmitted from the antenna. When the antenna of the AM broadcast
receiver (tuning dial on any setting) is held about 6 inches from the
activated ELT antenna, the ELT aural tone will be heard."

"It has to be a cheap AM radio," said Bob Glorioso, president of
QCAvionix. "It can't be too well shielded. You're trying to overwhelm
the AM detector."

Many mechanics, perhaps unaware of the FAA's recommendations, listen
the ELT signal on the aircraft's VHF radio, set to receive on 121.5
megahertz. But this isn't a good test, because the aircraft radio's
receiver is extremely sensitive. The AM radio test, says AC43.13, "is
not a measured check; but it does provide confidence that the antenna
is radiating with sufficient power to aid search and rescue. The signal
may be weak even if it is picked up by an aircraft VHF receiver located
at a considerable distance from the radiating ELT. Therefore, this
check [VHF radio] does not check the integrity of the ELT system or
provide the same level of confidence as does the AM radio check."

What the FAA is saying is that simply listening to the ELT signal on
the aircraft's VHF radio does not meet the requirements of 91.207(d). "

Now if you wanted to change to a 406 ELT, you would have to find the
correct antenna lengths, but the idea should be the same.

Kurt

-----Original Message-----

From: Bachman, Jonathan <[6]jonathan.bachman at mtsi-va.com>

To: Velocity Aircraft Owners and Builders list <[7]reflector at tvbf.org>

Sent: Tue, May 21, 2013 2:53 pm

Subject: Re: REFLECTOR: Antennas

Kurt,

Do you have any more specifics?  I have a STD RG and am thinking
of upgrading to the new ELT freq.  But the thought of adding an
external antenna is holding me back.  Does the antenna you made perform
adequately?

Jon

N956DR
_______________________________________________________________________

From: [8]reflector-bounces at tvbf.org [[9]reflector-bounces at tvbf.org] On
Behalf Of [10]nmflyer1 at aol.com [[11]nmflyer1 at aol.com]

Sent: Tuesday, May 21, 2013 2:33 PM

To: [12]reflector at tvbf.org

Subject: Re: REFLECTOR: Antennas

I just made one similar to the com antenna. Put it on the inside of the
fuselage aft near the gear bulkhead area.

Kurt

-----Original Message-----

From: Dick Harpster <[13]Dick-CentralSecurity at nc.rr.com>

To: reflector <[14]reflector at tvbf.org>

Sent: Tue, May 21, 2013 2:09 pm

Subject: REFLECTOR: Antennas

I am currently building an XLFG and am looking for advice on antennas.
I of course have the nav / com antennas in the winglets and did the
marker beacon in the floor. My problem is I can’t seem to find a ELT
antenna that will work internally and I sure don’t want that ugly 18”
whip on the outside of the plane. With the new frequency, none of the
internal antennas are recommended.  Any advice?

Dick Harpster

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References

1. http://www.velocityxl.com/attachment.php?attachmentid=4849&d=1276866122
2. mailto:reflector at velocityxl.com
3. mailto:reflector-bounces at tvbf.org
4. mailto:nmflyer1 at aol.com
5. mailto:reflector at tvbf.org
6. mailto:jonathan.bachman at mtsi-va.com
7. mailto:reflector at tvbf.org
8. mailto:reflector-bounces at tvbf.org
9. mailto:reflector-bounces at tvbf.org
  10. mailto:nmflyer1 at aol.com
  11. mailto:nmflyer1 at aol.com
  12. mailto:reflector at tvbf.org
  13. mailto:Dick-CentralSecurity at nc.rr.com
  14. mailto:reflector at tvbf.org
  15. http://www.tvbf.org/mailman/listinfo/reflector
  16. http://www.tvbf.org/gallery
  17. http://www.tvbf.org/pipermail
  18. http://www.tvbf.org/archives/velocity/maillist.html
  19. http://www.tvbf.org/mailman/listinfo/reflector
  20. http://www.tvbf.org/gallery
  21. http://www.tvbf.org/pipermail
  22. http://www.tvbf.org/archives/velocity/maillist.html
  23. http://www.tvbf.org/mailman/listinfo/reflector
  24. http://www.tvbf.org/gallery
  25. http://www.tvbf.org/pipermail
  26. http://www.tvbf.org/archives/velocity/maillist.html
  27. http://www.tvbf.org/mailman/listinfo/reflector
  28. http://www.tvbf.org/archives/velocity/maillist.html
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