VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #1  
Old 09-10-2015, 06:33 PM
maus92 maus92 is offline
 
Join Date: Nov 2013
Location: Annapolis MD
Posts: 457
Default Odd BNC device

I found this device attached to the old GPS antenna in my plane. Can anyone identify it? Is it some sort of attenuator? The GPS was a Garmin 250XL.

__________________
CA
2000 RV-8A | O-360, SDS CPI, FP, G3X Touch, VP-X, EarthX | Eastern Shore | KESN
Reply With Quote
  #2  
Old 09-10-2015, 06:37 PM
flightlogic's Avatar
flightlogic flightlogic is offline
 
Join Date: Nov 2013
Location: Prescott, AZ
Posts: 1,684
Default

It's a small hammer..... just put it in your toolbox.
__________________
"Kindness is never a bad plan."

exemption option waived. Donation appropriate.
Reply With Quote
  #3  
Old 09-10-2015, 07:09 PM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
Posts: 11,422
Default

It's a notch filter to prevent the harmonics from your comm radio from interfering with your GPS.
__________________
Mel Asberry, DAR since the last century. Over 1,000 certifications accomplished. Discount for Veterans, Law Enforcement, Fire Fighters.
EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
RV-6 Flying since 1993 (sold)
<rvmel(at)icloud.com>
Reply With Quote
  #4  
Old 09-10-2015, 07:10 PM
noelf noelf is offline
 
Join Date: Nov 2007
Location: Solomons, MD.
Posts: 1,276
Default

It is a NOTCH FILTER and is used to attenuate unwanted frequencies that may be presented to the receiver.
__________________
Noel
RV-6A N6NF
tip-up
flying
Reply With Quote
  #5  
Old 09-10-2015, 07:42 PM
FasGlas's Avatar
FasGlas FasGlas is online now
 
Join Date: Mar 2014
Location: Idaho ID40
Posts: 811
Default

Quote:
Originally Posted by noelf View Post
It is a NOTCH FILTER and is used to attenuate unwanted frequencies that may be presented to the receiver.
Yup... That's what it is
Reply With Quote
  #6  
Old 09-10-2015, 07:48 PM
N941WR's Avatar
N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 12,884
Default

They are all wrong. It is a DHS tracking device!
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
Reply With Quote
  #7  
Old 09-10-2015, 08:39 PM
GeraldC GeraldC is offline
 
Join Date: Sep 2013
Location: Buda, TX
Posts: 56
Default

You put it inline with the antenna to prevent that water hammer noise you'd get if you end a radio transmission to abruptly.
Reply With Quote
  #8  
Old 09-10-2015, 08:58 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 9,975
Smile

Quote:
Originally Posted by Mel View Post
It's a notch filter to prevent the harmonics from your comm radio from interfering with your GPS.
Even the later Garmin navigators need checking for this interference to meet their STC requirements.

For the early 430 units the frequencies to check are -

121.150
121.175
121.200
131.250
131.275
131.300

With the ADS-B accuracy requirements coming up you certainly don't want to lose that certified 2020 GPS position when you transmit on one of the above frequencies.

Re-install the notch filter with your present GPS, it can't do any harm, and check your installation manual for the specific critical frequencies for your present GPS unit.
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
  #9  
Old 09-10-2015, 10:01 PM
maus92 maus92 is offline
 
Join Date: Nov 2013
Location: Annapolis MD
Posts: 457
Default

Interesting. I will reconnect it. But it raises a question about the new GPS 20A position source that I am installing. The existing antenna is mounted on the glare shield, which will feed the GPS in the GDU 460, and will serve as the backup GPS source. The new GPS antenna for the GPS 20A necessary for ADS-B integrity is mounted behind the canopy slide rail. Will it require a notch filter as well?

C.
__________________
CA
2000 RV-8A | O-360, SDS CPI, FP, G3X Touch, VP-X, EarthX | Eastern Shore | KESN

Last edited by maus92 : 09-10-2015 at 10:04 PM.
Reply With Quote
  #10  
Old 09-10-2015, 11:53 PM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 9,975
Thumbs up

Quote:
Originally Posted by maus92 View Post
Interesting. I will reconnect it. But it raises a question about the new GPS 20A position source that I am installing. The existing antenna is mounted on the glare shield, which will feed the GPS in the GDU 460, and will serve as the backup GPS source. The new GPS antenna for the GPS 20A necessary for ADS-B integrity is mounted behind the canopy slide rail. Will it require a notch filter as well?

C.
Check the installation manual for post-installation testing, but since it's a new device specifically for ADS-B compliance it probably has a good filter internally.
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 07:35 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.