Splitter/diplexer/duplexer for 2 COM radios

[Jim Stewart]

Is there a product that will allow me to
share one antenna with 2 COM radios or
a COM and a handheld?

[RST Engineering]

There are a couple of ways of doing it, none of them particularly
inexpensive or practical. If you are asking if there is a product on the
market that will do it, I believe that the answer is no.

Jim

--
"Life is not a journey to the grave with the intention of arriving safely in
a pretty and well preserved body, but rather to skid in broadside,
thoroughly used up, totally worn out, with chocolate in one hand and wine in
the other, loudly proclaiming 'WOO HOO What a Ride!'"
--Unknown

"Jim Stewart" > wrote in message
.. .

> Is there a product that will allow me to
> share one antenna with 2 COM radios or
> a COM and a handheld?

[ktbr]

Jim Stewart wrote:

> Is there a product that will allow me to
> share one antenna with 2 COM radios or
> a COM and a handheld?

Nothing as cheap, simple and reliable as installing another antenna.

[Mike Noel]

A 'cheap' way to share an antenna with a hand-held when the official com
goes belly up is to cut the coax where it is easily accessible during flight
(like under the instrument panel near your knees) and installing the
appropriate coax couplers to rejoin the cable (something like a double
female bnc coupler and a couple of male bnc connectors on the two coax
ends). You can connect an adapter coax between the hand held and the
antenna side of the split coax for using the handheld in an emergency. One
down side to such an arrangement is that you obviously don't want to
accidentally plug your handheld into the wrong side of the split coax and
transmit into the expensive com radio. And wasn't it Jim at RST who wrote
an article in one of the homebuilt magazines about a panel plug in for
attaching a hand-held to the com antenna?
--
Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

It is not work that kills men; it is worry. Worry is rust upon the blade.
"Jim Stewart" > wrote in message
.. .
> Is there a product that will allow me to
> share one antenna with 2 COM radios or
> a COM and a handheld?

[RST Engineering]

It was indeed Jim in Kitplanes March 2002 (Good memory, Mike) that used a
cheap 3.5mm "transistor radio" set of jacks to automatically disconnect the
com radio when you plugged in the portable radio.

Jim

--
"Life is not a journey to the grave with the intention of arriving safely in
a pretty and well preserved body, but rather to skid in broadside,
thoroughly used up, totally worn out, with chocolate in one hand and wine in
the other, loudly proclaiming 'WOO HOO What a Ride!'"
--Unknown

"Mike Noel" > wrote in message
...
>A 'cheap' way to share an antenna with a hand-held when the official com
>goes belly up is to cut the coax where it is easily accessible during
>flight (like under the instrument panel near your knees) and installing the
>appropriate coax couplers to rejoin the cable (something like a double
>female bnc coupler and a couple of male bnc connectors on the two coax
>ends). You can connect an adapter coax between the hand held and the
>antenna side of the split coax for using the handheld in an emergency. One
>down side to such an arrangement is that you obviously don't want to
>accidentally plug your handheld into the wrong side of the split coax and
>transmit into the expensive com radio. And wasn't it Jim at RST who wrote
>an article in one of the homebuilt magazines about a panel plug in for
>attaching a hand-held to the com antenna?

[David Lesher]

Jim Stewart > writes:

>Is there a product that will allow me to share one antenna with 2 COM
>radios or a COM and a handheld?

My position is, you have a 2nd radio for redundancy. Any sharing scheme
introduces a new single point of failure that will negate that redundancy.

Add a 2nd antenna.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[Gus Cabre]

http://www.rst-engr.com/kitplanes/KP0203/KP0203.htm


"Mike Noel" > wrote in message
...
>A 'cheap' way to share an antenna with a hand-held when the official com
>goes belly up is to cut the coax where it is easily accessible during
>flight (like under the instrument panel near your knees) and installing the
>appropriate coax couplers to rejoin the cable (something like a double
>female bnc coupler and a couple of male bnc connectors on the two coax
>ends). You can connect an adapter coax between the hand held and the
>antenna side of the split coax for using the handheld in an emergency. One
>down side to such an arrangement is that you obviously don't want to
>accidentally plug your handheld into the wrong side of the split coax and
>transmit into the expensive com radio. And wasn't it Jim at RST who wrote
>an article in one of the homebuilt magazines about a panel plug in for
>attaching a hand-held to the com antenna?
> --
> Best Regards,
> Mike
>
> http://photoshow.comcast.net/mikenoel
>
> It is not work that kills men; it is worry. Worry is rust upon the blade.
> "Jim Stewart" > wrote in message
> .. .
>> Is there a product that will allow me to
>> share one antenna with 2 COM radios or
>> a COM and a handheld?
>
>

[Jim Stewart]

Gus Cabre wrote:
> http://www.rst-engr.com/kitplanes/KP0203/KP0203.htm

Thanks but no thanks. I think I have a proper
Dow-Key coax relay in one my junkboxes and if I
decide to go forward, I'll use it.

>
> "Mike Noel" > wrote in message
> ...
>> A 'cheap' way to share an antenna with a hand-held when the official com
>> goes belly up is to cut the coax where it is easily accessible during
>> flight (like under the instrument panel near your knees) and installing the
>> appropriate coax couplers to rejoin the cable (something like a double
>> female bnc coupler and a couple of male bnc connectors on the two coax
>> ends). You can connect an adapter coax between the hand held and the
>> antenna side of the split coax for using the handheld in an emergency. One
>> down side to such an arrangement is that you obviously don't want to
>> accidentally plug your handheld into the wrong side of the split coax and
>> transmit into the expensive com radio. And wasn't it Jim at RST who wrote
>> an article in one of the homebuilt magazines about a panel plug in for
>> attaching a hand-held to the com antenna?
>> --
>> Best Regards,
>> Mike
>>
>> http://photoshow.comcast.net/mikenoel
>>
>> It is not work that kills men; it is worry. Worry is rust upon the blade.
>> "Jim Stewart" > wrote in message
>> .. .
>>> Is there a product that will allow me to
>>> share one antenna with 2 COM radios or
>>> a COM and a handheld?
>>
>
>

[Ron Natalie]

My avionics guy (unsolicited, it's just one of those things he does)
put a BNC male to female fitting in the com cable and routed it just
under the control yoke. All you have to do is reach up, disconnect
the antenna cable from the wire to the comm radio and plug in your
handheld.

The only thing would have been nice was if he had told me he did it.
I found it while under the panel for other reasons.

[RST Engineering]

And you think that relay, with operation measured in hundreds of
milliseconds, is going to protect tens of watts from frying your fractions
of microvolts front end measured in tens of microseconds?

What a maroon.

Jim



--
"Life is not a journey to the grave with the intention of arriving safely in
a pretty and well preserved body, but rather to skid in broadside,
thoroughly used up, totally worn out, with chocolate in one hand and wine in
the other, loudly proclaiming 'WOO HOO What a Ride!'"
--Unknown




"Jim Stewart" > wrote in message
.. .
> Gus Cabre wrote:
>> http://www.rst-engr.com/kitplanes/KP0203/KP0203.htm
>
> Thanks but no thanks. I think I have a proper
> Dow-Key coax relay in one my junkboxes and if I
> decide to go forward, I'll use it.

[Jim Stewart]

RST Engineering wrote:
> And you think that relay, with operation measured in hundreds of
> milliseconds, is going to protect tens of watts from frying your fractions
> of microvolts front end measured in tens of microseconds?

I have both an FCC commercial and ham license
and have a passing knowledge of RF. The
relay would be controlled by a manual switch
and would connect one radio to the antenna
and the other to a dummy load.

> What a maroon.

Great way to treat a customer. I didn't
complain when you took 4 weeks to send me
an intercom kit. Now you insult me on the
internet. Time to call it quits.

> Jim
>
>
>

[john smith[_2_]]

In article >,
Jim Stewart > wrote:

> > What a maroon.
>
> Great way to treat a customer. I didn't
> complain when you took 4 weeks to send me
> an intercom kit. Now you insult me on the
> internet. Time to call it quits.

What? You don't like dark purple?

[RST Engineering]

"Jim Stewart" > wrote in message
.. .

> RST Engineering wrote:
>> And you think that relay, with operation measured in hundreds of
>> milliseconds, is going to protect tens of watts from frying your
>> fractions of microvolts front end measured in tens of microseconds?
>
> I have both an FCC commercial and ham license
> and have a passing knowledge of RF. The
> relay would be controlled by a manual switch
> and would connect one radio to the antenna
> and the other to a dummy load.

Most DowKey coaxial relays that we have "on our shelf" are of the
SO-239/PL-259 variety that were made by the bazillions in the '50s and '60s.
Two things are wrong with them. One, this non-constant impedance connector
variety isn't too much good above 30 MHz.. Two, unless you got the (rare)
gold-flashed version of the relay, the receive side of the relay with the
silver contacts will oxide and sulphide up in a few years and there is no
known way of getting inside to clean the contacts. You can remove the relay
from service and "flash" the contacts with a DC voltage/current source, but
this is a temporary fix at best.

Three, you now have trashed your dual radio redundancy with a single point
failure. When (not if) the relay goes TU, you have lost your communications
capability.

As somebody else pointed out, a second antenna is the optimum solution.
Whether or not you choose to take this good advice is up to you.

>
>> What a maroon.
>
> Great way to treat a customer. I didn't
> complain when you took 4 weeks to send me
> an intercom kit. Now you insult me on the
> internet. Time to call it quits.


The day I don't call it like I see it for fear of ****ing off a customer, a
constituent, or an FAA inspector is the day they take me out the door feet
first.

Jim

[Thomas Borchert]

RST,

> The day I don't call it like I see it for fear of ****ing off a customer, a
> constituent, or an FAA inspector is the day they take me out the door feet
> first.
>

Adding arrogance to insult in a public forum. Great business strategy. I
cannot believe it works. For me, the day I do business with your company is
the day they take me out the door feet first.

And have a nice day.

--
Thomas Borchert (EDDH)