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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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 Posted: Wed Nov 06, 2019 6:04 pm Post subject: AeroElectric-List: Using a BNC “T” |
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What are you trying to do? Why would you want a Tee? If I understand
correctly you want to connect one antenna to panel mount radio, then
connect the second antenna to your handheld. You do NOT want to tie the
two antennas together.
On 11/6/2019 5:23 PM, Carlos Trigo wrote:
| Quote: | Guys
I’m sure this has been asked (and answered) before, but I am too old for
my memory to remember of it, and too lazy to look for it in the archives...
I have just installed a 2nd Comm antenna in my aircraft, a plain vanilla
RAMI AV-10, which is intended to be used either by a future Comm 2 radio
or by a hand-held radio which I will carry in my flight bag.
For that purpose I installed 2 antenna cables, one which goes from the
antenna to the place where I planned to put the future Comm 2 radio, and
the other cable goes from the antenna to somewhere near the pilot seat,
where a loose end with a female BNC connector will be connected to the
hand-held radio in case I need to use it.
So, the question is: is it ok to install a “T” like these
below the antenna, and connect to it the 2 cables mentioned above?
Thanks
Carlos
Enviado do meu iPhone
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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Eric Page
Joined: 15 Feb 2017
Posts: 251
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| Posted: Wed Nov 06, 2019 9:14 pm Post subject: AeroElectric-List: Using a BNC “T” |
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On Nov 6, 2019, at 4:23 PM, Carlos Trigo <trigo(at)mail.telepac.pt (trigo(at)mail.telepac.pt)> wrote:
| Quote: | I have just installed a 2nd Comm antenna in my aircraft...
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Carlos, the short answer is no. The extra length of open-ended coax will ruin the impedance match between either radio and the antenna, and transmitting on one radio with the other connected through the tee might well result in (expensive) tears.
This situation calls for either:
1) A coaxial switch that connects the antenna to only a single radio at a time and disconnects the other; or,
2) Delete the tee and leave both lengths of coax in place. Connect the antenna to the coax feeding your handheld for now. When you later install the Comm 2 radio, connect that coax at the antenna and remove or abandon the one to the handheld.
Eric
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trigo(at)mail.telepac.pt
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| Posted: Thu Nov 07, 2019 5:06 am Post subject: AeroElectric-List: Using a BNC “T” |
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Thank you Eric
Is there any automatic coaxial switch?
Can you please point me out to a suitable coaxial switch (eBay, Amazon, mouser, ...).
Cheers
Carlos
Enviado do meu iPhone
| Quote: | No dia 07/11/2019, às 05:20, Eric Page <edpav8r(at)yahoo.com> escreveu:
On Nov 6, 2019, at 4:23 PM, Carlos Trigo <trigo(at)mail.telepac.pt (trigo(at)mail.telepac.pt)> wrote:
| Quote: | I have just installed a 2nd Comm antenna in my aircraft...
|
Carlos, the short answer is no. The extra length of open-ended coax will ruin the impedance match between either radio and the antenna, and transmitting on one radio with the other connected through the tee might well result in (expensive) tears.
This situation calls for either:
1) A coaxial switch that connects the antenna to only a single radio at a time and disconnects the other; or,
2) Delete the tee and leave both lengths of coax in place. Connect the antenna to the coax feeding your handheld for now. When you later install the Comm 2 radio, connect that coax at the antenna and remove or abandon the one to the handheld.
Eric
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Thu Nov 07, 2019 5:22 am Post subject: AeroElectric-List: Using a BNC “T” |
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I am not aware of any suitable switch. Icom used to offer, (and King
before them) a small box that made the switch when antenna cable for
handheld was plugged in. Not elegant, but mostly worked.
If you terminate the cable in location easily reached, it may be better
to simply disconnect cable from one radio and connect it to the other.
Kelly
On 11/7/2019 6:04 AM, Carlos Trigo wrote:
| Quote: | Thank you Eric
Is there any automatic coaxial switch?
Can you please point me out to a suitable coaxial switch (eBay, Amazon,
mouser, ...).
Cheers
Carlos
Enviado do meu iPhone
> No dia 07/11/2019, às 05:20, Eric Page <edpav8r(at)yahoo.com> escreveu:
>
>
> On Nov 6, 2019, at 4:23 PM, Carlos Trigo <trigo(at)mail.telepac.pt
> <mailto:trigo(at)mail.telepac.pt>> wrote:
>
>> I have just installed a 2nd Comm antenna in my aircraft...
> Carlos, the short answer is no. The extra length of open-ended coax
> will ruin the impedance match between either radio and the antenna,
> and transmitting on one radio with the other connected through the tee
> might well result in (expensive) tears.
>
> This situation calls for either:
>
> 1) A coaxial switch that connects the antenna to only a single radio
> at a time and disconnects the other; or,
>
> 2) Delete the tee and leave both lengths of coax in place. Connect
> the antenna to the coax feeding your handheld for now. When you later
> install the Comm 2 radio, connect that coax at the antenna and remove
> or abandon the one to the handheld.
>
> Eric
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| | - 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 |
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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deej(at)deej.net
Guest
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| Posted: Thu Nov 07, 2019 7:06 am Post subject: AeroElectric-List: Using a BNC “T” |
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Hi Carlos,
I have a Narco VP-16 antenna switch that I'm not using. Asking $25 +
s/h. It uses an electrical relay to switch between the two radios, so
you could have a toggle switch mounted on the panel to select which
radio is connected to the antenna for example, or possibly get fancy and
figure out a circuit to have it switch when you key the mic on the
second radio.
https://deej.net/forsale/#narco
IMHO it would be better to mount a second antenna on your plane and
have a dedicated antenna for each radio.
-Dj
On 11/7/19 8:04 AM, Carlos Trigo wrote:
| Quote: | Thank you Eric
Is there any automatic coaxial switch?
Can you please point me out to a suitable coaxial switch (eBay, Amazon,
mouser, ...).
Cheers
Carlos
|
--
Dj Merrill - N1JOV - EAA Chapter 87
Currently Flying: Glastar
Previously: Cessna 150 - Glasair 1 FT - Grumman AA1B
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