Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

VOR/LOC/GS antenna question

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
fasilpereira



Joined: 17 Jul 2011
Posts: 86
Location: Brazil

PostPosted: Mon May 08, 2023 9:04 am    Post subject: VOR/LOC/GS antenna question Reply with quote

I'm installing a GNS-430W on my composite aircraft. I already have 2 VOR antennas that are currently not in use because I didn't had any NAV radio installed.

I just realized that the GNS-430W requires an input for both VOR/LOC and GS. The common solution for this is to install a Diplexer on a NAV antenna to break the signal 2 outputs, one output for VOR/LOC and other for GS. I have seen that some users reports a loss in VOR range due to the diplexer and I'm worried about it because the VORs are far from each other here where I live.

I'm considering to plug one antenna to the VOR/LOC input of the GNS and the other to the GS. I'm not sure if I'll need to add a diplexer to the GS cable and if I do, can I leave the VOR connector of the diplexer open? Additionally, if a diplexer is necessary, is there any DIY that could be used, instead of the $150-$200 ones?

Thank you,

Fabricio


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Fabricio Pereira
Engineer / Pilot
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Wed May 10, 2023 7:09 am    Post subject: VOR/LOC/GS antenna question Reply with quote

At 12:04 PM 5/8/2023, you wrote:
Quote:
--> AeroElectric-List message posted by: "fasilpereira" <fasilpereira(at)yahoo.com>

I'm installing a GNS-430W on my composite aircraft. I already have 2 VOR antennas that are currently not in use because I didn't had any NAV radio installed.

I just realized that the GNS-430W requires an input for both VOR/LOC and GS. The common solution for this is to install a Diplexer on a NAV antenna to break the signal 2 outputs, one output for VOR/LOC and other for GS. I have seen that some users reports a loss in VOR range due to the diplexer and I'm worried about it because the VORs are far from each other here where I live.

Yes, 'diplexers' are a signal splitting network
that routes energies from a common antenna to two
or more receivers. A well crafted VOR-LOC/GS splitter
should not seriously affect the performace of either
system. Advertised losses through such devices
are generally on the order of 1.0 dB or less.

https://tinyurl.com/2uams5xp

On the other hand, there are VOR-LOC power
'dividers' that optimize the function of TWO
VHF receivers on a single antenna. Of necessity,
these devices route 1/2 of the power from the
antenna to each receiver. Hence, a 3+ dB loss
of signal to each receiver.


Quote:
I'm considering to plug one antenna to the VOR/LOC input of the GNS and
the other to the GS. I'm not sure if I'll need to add a diplexer to the
GS cable and if I do, can I leave the VOR connector of the diplexer open?

Don't need one. The 'barefoot' VOR/LOC
antenna is quite efficient when operated
at the third harmonic of it's fundamental
design frequency 108-118 MHz. GS signals
cover range of 329-335 MHz.


Bob . . .

////
(o o)
===========o00o=(_)=o00o=========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
=================================

In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
fasilpereira



Joined: 17 Jul 2011
Posts: 86
Location: Brazil

PostPosted: Wed May 10, 2023 9:45 am    Post subject: Re: VOR/LOC/GS antenna question Reply with quote

Bob,

So I understood that I can connect the spare VOR/LOC antenna that I have direct to the GS BNC in the back of the GNS and that will work just fine, with no need of any additional device between. Is that correct? I thought a 1 pF capactitor could be required, but I was not sure....

Thanks again,

Fabricio


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Fabricio Pereira
Engineer / Pilot
Back to top
View user's profile Send private message
wsimpso1



Joined: 04 Nov 2018
Posts: 26
Location: Saline MI

PostPosted: Thu May 11, 2023 10:28 am    Post subject: Re: VOR/LOC/GS antenna question Reply with quote

The expensive commercial splitters and decouplers are one option. The other is building them from Jim Weir's Attenna Reference Text. It is available on this page of his website.at:

http://www.rstengineering.com/rst/products/plasticplaneantenna/plasticplaneantenna.htm

The highlighted Antenna Reference Text has a whole bunch of guidance on the topic and is downloadable as a .pdf file. Page 34 shows both his NAV splitter applying one NAV antenna to two VOR recievers, it also shows the GS splitter to get a GS off that one NAV antenna. Yeah, you have to roll up a couple 16" cables into a little box and stash it someplace, but it is way cheaper than the commercial gadget.

Have fun.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group