One Antenna from Two Coax Cables
 

I am putting a VHF/UHF antenna in my attic and have run coax into two
different rooms in the house. I would like to be able to access the
antenna, on both bands, from both rooms in the house (not at the same time,
however). Is there a "remote" way I can do this, meaning without running
any more wires? I have been searching for an rf triggered relay that would
ground the second coax when a signal came down the first, but I can't find
anything like that. A duplexer won't work because I want to be able to
access both bands from both rooms. Certainly there is someone else in this
hobby who has done this, but I can't find anything on the Internet about it!

ANY suggestions would be welcome.

73,
Brett
KG4KLR

Only suggestion I'd have is a standard antenna switch. You'll have to move
the switch to the position for whichever room you're in, but that might be
the only way.

--
73! de Andy KC2SSB
Beachwood, NJ USA! Grid FM29vw
http://shorecogs.tripod.com
AIM: shorecogs

"BW" wrote in message
...
I am putting a VHF/UHF antenna in my attic and have run coax into two
different rooms in the house. I would like to be able to access the
antenna, on both bands, from both rooms in the house (not at the same
time,
however). Is there a "remote" way I can do this, meaning without running
any more wires? I have been searching for an rf triggered relay that
would
ground the second coax when a signal came down the first, but I can't find
anything like that. A duplexer won't work because I want to be able to
access both bands from both rooms. Certainly there is someone else in
this
hobby who has done this, but I can't find anything on the Internet about
it!

ANY suggestions would be welcome.

73,
Brett
KG4KLR

"Andy in NJ" SHORECOGS at COMCAST DOT NET wrote in message
...
Only suggestion I'd have is a standard antenna switch. You'll have to move
the switch to the position for whichever room you're in, but that might be
the only way.

Use a three-way switch arraingement.

BW wrote:
ANY suggestions would be welcome.

One common approach is to run some DC voltage through the coax
to energize an antenna relay. The DC voltage is isolated from
the RF equipment using caps. A series DC relay is bypassed
for RF by a cap. A parallel DC relay is isolated from the RF
by an RF choke. The configuration is a little different
depending upon whether the antenna is a DC short or not.
--
73, Cecil, W5DXP



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Play around with the coax lengths so that the "unused" cable doesnt
present a lump to the other one in use maybe? ie multiples of half
wavelengths from the "star" connection point out.. Obviously the bands
would need to be harmonically related.

Anyone care to shoot me down on this one go right ahead!

Cheers Bob VK2YQA

BW wrote:
I am putting a VHF/UHF antenna in my attic and have run coax into two
different rooms in the house. I would like to be able to access the
antenna, on both bands, from both rooms in the house (not at the same time,
however). Is there a "remote" way I can do this, meaning without running
any more wires? I have been searching for an rf triggered relay that would
ground the second coax when a signal came down the first, but I can't find
anything like that. A duplexer won't work because I want to be able to
access both bands from both rooms. Certainly there is someone else in this
hobby who has done this, but I can't find anything on the Internet about it!

ANY suggestions would be welcome.

73,
Brett
KG4KLR

Sounds good. What I would do is this: say you have radios A and B. Run 12V
up the coax when radio B is turned on. Arrange the relay so that the antenna
feeds radio A when there is no DC on the line. Strictly speaking, you should
use a coaxial relay, but a cheap SPDT relay will usually work. I would put
the relay within about an inch or so of the antenna feedpoint.

Tam/WB2TT
"Cecil Moore" wrote in message
...
BW wrote:
ANY suggestions would be welcome.

One common approach is to run some DC voltage through the coax
to energize an antenna relay. The DC voltage is isolated from
the RF equipment using caps. A series DC relay is bypassed
for RF by a cap. A parallel DC relay is isolated from the RF
by an RF choke. The configuration is a little different
depending upon whether the antenna is a DC short or not.
--
73, Cecil, W5DXP



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