? on sharing an antenna between a low-power xmiter and recei

[Dave]

Am just realizing that this is something I need to figure out, and have
never thought about it before. Would a simple SPDT relay do the trick
(switching the current path from one side to the other...)? Where could I
find info on this topic. Not even sure what to type into Google. Guess
I'll check my ARRL handbook, and see if it offers anything. Any advice
would be appreciated.

Thanks,

Dave

 

On Tue, 5 Jun 2012 17:40:24 -0500, "Dave" <db5151@hotmail.com> wrote:

Am just realizing that this is something I need to figure out, and have
never thought about it before. Would a simple SPDT relay do the trick
(switching the current path from one side to the other...)? Where could I
find info on this topic. Not even sure what to type into Google. Guess
I'll check my ARRL handbook, and see if it offers anything. Any advice
would be appreciated.

Thanks,

Dave

That's commonly done in transceivers, even some that are in the
hundreds of watts. There may also be a set of relay contacts that
grounds the receiver input when the transmitter is on and/or there may
be some protective device(s) on the receiver input..

1. How much power is "low power"?

2. Is the receiver solid state or tubes?
(Tubes can take a lot more abuse than solid state devices.)

 

[Dave]

<news@jecarter.us> wrote in message
news:isfts71l09uc42hi0rdijg3q4v8fg4scst@4ax.com...

On Tue, 5 Jun 2012 17:40:24 -0500, "Dave" <db5151@hotmail.com> wrote:

Am just realizing that this is something I need to figure out, and have
never thought about it before. Would a simple SPDT relay do the trick
(switching the current path from one side to the other...)? Where could I
find info on this topic. Not even sure what to type into Google. Guess
I'll check my ARRL handbook, and see if it offers anything. Any advice
would be appreciated.

Thanks,

Dave


That's commonly done in transceivers, even some that are in the
hundreds of watts. There may also be a set of relay contacts that
grounds the receiver input when the transmitter is on and/or there may
be some protective device(s) on the receiver input..

1. How much power is "low power"?

2. Is the receiver solid state or tubes?
(Tubes can take a lot more abuse than solid state devices.)

I'm thinking "low power" along the order of 10mW or so. Maybe less than
that.

Receiver is solid state.

Seems like I should be able to switch the antenna from RX to TX and back by
turning transistors on and off. Just never put my mind to it before...

Thanks.

Dave

 

[Dave M]

Dave wrote:

news@jecarter.us> wrote in message
news:isfts71l09uc42hi0rdijg3q4v8fg4scst@4ax.com...
On Tue, 5 Jun 2012 17:40:24 -0500, "Dave" <db5151@hotmail.com> wrote:

Am just realizing that this is something I need to figure out, and
have never thought about it before. Would a simple SPDT relay do
the trick (switching the current path from one side to the
other...)? Where could I find info on this topic. Not even sure
what to type into Google. Guess I'll check my ARRL handbook, and
see if it offers anything. Any advice would be appreciated.

Thanks,

Dave


That's commonly done in transceivers, even some that are in the
hundreds of watts. There may also be a set of relay contacts that
grounds the receiver input when the transmitter is on and/or there
may be some protective device(s) on the receiver input..

1. How much power is "low power"?

2. Is the receiver solid state or tubes?
(Tubes can take a lot more abuse than solid state devices.)



I'm thinking "low power" along the order of 10mW or so. Maybe less
than that.

Receiver is solid state.

Seems like I should be able to switch the antenna from RX to TX and
back by turning transistors on and off. Just never put my mind to it
before...
Thanks.

Dave

Here's how to use a relay to switch your antenna between the transmitter and
receiver.
Please view in a fixed-width font such as Courier.



#
# # Antenna
# #
# #
###|###
|
| o----------------Rcvr
| /
| /
-----------------/
|

| o----------------Xmtr

|

|

|

+--+
| |-----------+V
| |
Relay | |
| |
| |----------PTT
+--|


Use this configuration if your PTT provides a switched ground.
If PTT provides a + voltage, then change the +V on the relay
to ground.

--
Dave M
A woman has the last word in any argument. Anything a man says after
that is the beginning of a new argument.

 

[Dave]

"Dave M" <dgminala4444@mediacombb.net> wrote in message
newsY2dnZf0J_Kms0zSnZ2dnUVZ_jSdnZ2d@giganews.com...

Dave wrote:
news@jecarter.us> wrote in message
news:isfts71l09uc42hi0rdijg3q4v8fg4scst@4ax.com...
On Tue, 5 Jun 2012 17:40:24 -0500, "Dave" <db5151@hotmail.com> wrote:

Am just realizing that this is something I need to figure out, and
have never thought about it before. Would a simple SPDT relay do
the trick (switching the current path from one side to the
other...)? Where could I find info on this topic. Not even sure
what to type into Google. Guess I'll check my ARRL handbook, and
see if it offers anything. Any advice would be appreciated.

Thanks,

Dave


That's commonly done in transceivers, even some that are in the
hundreds of watts. There may also be a set of relay contacts that
grounds the receiver input when the transmitter is on and/or there
may be some protective device(s) on the receiver input..

1. How much power is "low power"?

2. Is the receiver solid state or tubes?
(Tubes can take a lot more abuse than solid state devices.)



I'm thinking "low power" along the order of 10mW or so. Maybe less
than that.

Receiver is solid state.

Seems like I should be able to switch the antenna from RX to TX and
back by turning transistors on and off. Just never put my mind to it
before...
Thanks.

Dave

Here's how to use a relay to switch your antenna between the transmitter
and receiver.
Please view in a fixed-width font such as Courier.



#
# # Antenna
# #
# #
###|###
|
| o----------------Rcvr
| /
| /
-----------------/
|

| o----------------Xmtr

|

|

|

+--+
| |-----------+V
| |
Relay | |
| |
| |----------PTT
+--|


Use this configuration if your PTT provides a switched ground.
If PTT provides a + voltage, then change the +V on the relay
to ground.

--
Dave M

Thanks for this, but I have to ask, what is PTT, and what is a switched
ground? And how will I know if PTT provides a + voltage? Sorry to be so
ignorant, but I just don't savvy even this much about radios and RF. My
currant project is to build an in-house intercom using simple low-power FM
transmitters to communicate from one end of the house to the other, cutting
down on the need for shouting. They will be battery powered, backed up by AC
adapters to give the batteries a rest when the hand-held unit is in its
cradle. No switch-mode power supplies, if that matters.

Thanks for the help.

Dave

 

[Peter Bennett]

On Sat, 9 Jun 2012 19:47:44 -0500, "Dave" <db5151@hotmail.com> wrote:

"Dave M" <dgminala4444@mediacombb.net> wrote in message
newsY2dnZf0J_Kms0zSnZ2dnUVZ_jSdnZ2d@giganews.com...
Dave wrote:
news@jecarter.us> wrote in message
news:isfts71l09uc42hi0rdijg3q4v8fg4scst@4ax.com...
On Tue, 5 Jun 2012 17:40:24 -0500, "Dave" <db5151@hotmail.com> wrote:

Am just realizing that this is something I need to figure out, and
have never thought about it before. Would a simple SPDT relay do
the trick (switching the current path from one side to the
other...)? Where could I find info on this topic. Not even sure
what to type into Google. Guess I'll check my ARRL handbook, and
see if it offers anything. Any advice would be appreciated.

Thanks,

Dave


That's commonly done in transceivers, even some that are in the
hundreds of watts. There may also be a set of relay contacts that
grounds the receiver input when the transmitter is on and/or there
may be some protective device(s) on the receiver input..

1. How much power is "low power"?

2. Is the receiver solid state or tubes?
(Tubes can take a lot more abuse than solid state devices.)



I'm thinking "low power" along the order of 10mW or so. Maybe less
than that.

Receiver is solid state.

Seems like I should be able to switch the antenna from RX to TX and
back by turning transistors on and off. Just never put my mind to it
before...
Thanks.

Dave

Here's how to use a relay to switch your antenna between the transmitter
and receiver.
Please view in a fixed-width font such as Courier.



#
# # Antenna
# #
# #
###|###
|
| o----------------Rcvr
| /
| /
-----------------/
|

| o----------------Xmtr

|

|

|

+--+
| |-----------+V
| |
Relay | |
| |
| |----------PTT
+--|


Use this configuration if your PTT provides a switched ground.
If PTT provides a + voltage, then change the +V on the relay
to ground.

--
Dave M


Thanks for this, but I have to ask, what is PTT, and what is a switched
ground? And how will I know if PTT provides a + voltage? Sorry to be so
ignorant, but I just don't savvy even this much about radios and RF. My
currant project is to build an in-house intercom using simple low-power FM
transmitters to communicate from one end of the house to the other, cutting
down on the need for shouting. They will be battery powered, backed up by AC
adapters to give the batteries a rest when the hand-held unit is in its
cradle. No switch-mode power supplies, if that matters.

Thanks for the help.

Dave

PTT is the Push-To-Talk button.

"Switched ground" means that the PTT switch is connected between
Ground and the thing being controlled.


--
Peter Bennett, VE7CEI
peterbb (at) telus.net
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca