Transponder ANTENNA question/help

[Jim Peace]

I have a small antenna now that I have to keep replacing due to its location and how delicate it is.  I have enclosed a picture of it.  

Question: If I want to replace it with a blade antenna which one do I get?  I have a GTX345, and ADS out.  I do not have DME.  I am attaching a link here to see if something like this would work?  I also see similar ones on sites for hundreds of dollars.  Not sure what to get to make it right.  I want to show up to my annual with the part so they dont have to source it and waste time.

Link to what I want to replace it with:

https://www.aircraftspruce.com/catalog/avpages/comant105.php?clickkey=5060

[kortopates]

By a far margin, the appropriate version of the Comant CI-105 is the most popular transponder antenna installed. 

[Jim Peace]

8 minutes ago, kortopates said:

the appropriate version of the Comant CI-105 is the most popular transponder antenna installed. 

so which 105 antenna is appropriate?  there are many versions.  Does the one for 200 bucks that I selected work or are some others better?

[OR75]

The ball antenna and the blade antenna have different TSOs

the equipment it is connected to and it’s approval determines which one to use . You may have the option of different footprints with a blade antenna (the positions of the holes for the screws)

[Fly Boomer]

32 minutes ago, kortopates said:

By a far margin, the appropriate version of the Comant CI-105 is the most popular transponder antenna installed. 

Here's one for $195 under TSO specification C66A:
https://www.pilotshop.com/catalog/avpages/comant105.php

and another for $526 under TSO specification C66B:
https://www.pilotshop.com/catalog/avpages/comantci1053.php

They have similar specifications.  What is the difference (besides $331)?
EDIT:  Found it:  3 holes vs 2.  So, a hole costs $331.

[kortopates]

The CI-105 is perfect for the GTX-345. All the CI-105 are same except for method of mounting, possible connector and speed restrictions. Some are made to be compatible with a different brand of mount like a King antenna. So I would have your installer check your present antenna mount so he can match it up for an easy install but most likely the basic CI-105 will work for you.

[Jim Peace]

11 minutes ago, OR75 said:

The ball antenna and the blade antenna have different TSOs

the equipment it is connected to and it’s approval determines which one to use . You may have the option of different footprints with a blade antenna (the positions of the holes for the screws)

Thank you.....I think.....

 

1 minute ago, kortopates said:

The CI-105 is perfect for the GTX-345. All the CI-105 are same except for method of mounting, possible connector and speed restrictions. Some are made to be compatible with a different brand of mount like a King antenna. So I would have your installer check your present antenna mount so he can match it up for an easy install but most likely the basic CI-105 will work for you.

okay thank you...I just have the small ball one now....so no blade mount currently there....seems like the inexpensive one for 200 should work...maybe the higher price ones are for 400 knots...

 

[PT20J]

Garmin specifies that the antenna for a GTX 345 meet TSO-C66() or C74().

The Comant CI105-20/25 meet TSO-C66b, Class 1, C74c and are electrically identical.

The -20 has a BNC connector; the -25 has a Type N connector.

According to Comant's specs, the ball antenna (CI-306) is not TSO'd. It has a narrower bandwidth and I would replace it with a CI105-20.

Skip

[Jim Peace]

1 hour ago, PT20J said:

According to Comant's specs, the ball antenna (CI-306) is not TSO'd. It has a narrower bandwidth and I would replace it with a CI105-20.

Skip

I think I have the CI 101...not sure away from my plane

 

[PT20J]

44 minutes ago, Jim Peace said:

I think I have the CI 101...not sure away from my plane

 

Sorry about that -- I looked at the wrong section of the Comant catalog. (Always be wary of advice from the Internet ). 

https://www.cobhamaerospacecommunications.com/media/2204897/cobham_comant_2021_catalog.pdf

You undoubtably have a CI101, and it is TSO'd to C74c, so it is good. But, since you want to replace it, any of the CI 105's are TSO'd. The primary difference between the different dash numbers is mounting method and connector type. A straight CI 105 (no dash) has two hole stud mounting with a BNC connector and should be fine. The antenna is glossy white but they also make a -16 version that is unpainted white plastic to match the finish of a Bendix-King KA60 if you prefer that. I have the KA60 on my airplane and find that it gets dirty on the belly from exhaust and oil and I would suggest the gloss version.

Skip

[47U]

10 hours ago, Jim Peace said:

I have a small antenna now that I have to keep replacing due to its location and how delicate it is.

My question is, what is unique about the location that you’re damaging antennas to the point that it need replacing?  Pictures?

[N201MKTurbo]

Save a few bucks and use this one:

https://www.aircraftspruce.com/catalog/avpages/av74_ant.php
 

[Schinderhannes]

Page 3-8 of the installation manual specifies exactly which antennas you can use. IMHO you can’t use an antenna that is not listed. Go down the list and select the the lowest cost option that is readily available. 

[N201MKTurbo]

28 minutes ago, Schinderhannes said:

Page 3-8 of the installation manual specifies exactly which antennas you can use. IMHO you can’t use an antenna that is not listed. Go down the list and select the the lowest cost option that is readily available. 

The GTX 3X5/3X5R must have an UHF antenna. The antennas in table 3-7 are approved for use with the
GTX 3X5/3X5R. Other antennas are permitted if they meet these specifications:
• Standard 50 ohm vertically polarized antenna with a VSWR < 1.7:1 at 978 MHz and < 1.5:1 at
1090 MHz
• TSO-C66( ), TSO-C74( ), or TSO-C112( ) antennas that also meet the VSWR specification

 

The RAMI antenna easily meets these specs.

[Jim Peace]

21 hours ago, 47U said:

My question is, what is unique about the location that you’re damaging antennas to the point that it need replacing?  Pictures?

It is located under the forward right wing root. Always in the way when sumping fuel or placing chalks or reaching for the airplane cover straps. If I dont occasionally hit it the line guys do. I figure a blade will have more presence and be a bit more robust. 

[OR75]

1 hour ago, Jim Peace said:

It is located under the forward right wing root. Always in the way when sumping fuel or placing chalks or reaching for the airplane cover straps. If I dont occasionally hit it the line guys do. I figure a blade will have more presence and be a bit more robust. 

Sounds the antenna location should be changed 

[Jim Peace]

8 hours ago, OR75 said:

Sounds the antenna location should be changed 

perhaps....A blade at that location would look kind of weird as well.....

[glbtrottr]

It is located under the forward right wing root. Always in the way when sumping fuel or placing chalks or reaching for the airplane cover straps. If I dont occasionally hit it the line guys do. I figure a blade will have more presence and be a bit more robust. 

Mine is located in the exact same place. White blade antenna on my 252 against a metallic red contrast…

PT20J and 201mkturbo for the win- Rami’s are great, and so are CI105’s.

Don’t waste unneeded cash to keep up with the joneses


Sent from my iPhone using Tapatalk