K8JHR wrote:
Maybe... I have found that not all switches are created equal. The
less expensive ones lack sufficient isolation. You want one with at
least 60 and maybe 70 dB isolation - better, if possible, but I am
hard pressed to say what model that would be.
I do know some guys use a time sequencer and/or an automatic receive
antenna switch to kill the receiver preamp or isolate the receiver
antenna when transmitting, but I would have to research them for this
particular application. DX-Engineering sells one:
http://www.dxengineering.com/parts/dxe-rtr-1a
This is very similar to the one that comes with the Pixel receive ant.
Seems like you could manually switch the receive antenna in or out (and
develop the habit of doing so), with a unit such as this as a failsafe
backup. Of course, as you say, you must be sure of the isolation that a
switch provides.
The time sequencer can be seen here:
http://www.dxengineering.com/parts/dxe-tvsu-1b
A quick email to DX-Engineering should answer whether or not it would
work with your rig and transmit antenna arrangement - it would be the
same answer for the Wellbrook loop as for their own active receive
antenna like I have.
Also they sell KD9SV Products SV-FESSS Front End Savers are designed
to eliminate the possibility of blowing out your receiver's or
transceiver's front end.
Front End Savers interrupt the receive antenna to receive antenna
input connection when the QSK-capable T/R line is keyed by the
transceiver's amplifier keying line. See it here:
http://www.dxengineering.com/parts/svp-sv-fesss
Many thanks for your suggestions!
================= JHR ========================
On 4/27/2014 8:39 PM, ny6p01@gmail.com wrote:
On Sun, Apr 27, 2014 at 08:29:25PM -0400, K8JHR wrote:
On 4/27/2014 5:05 PM, ny6p01@gmail.com wrote:
Only
problem is that I plan on employing it on the same mast with the
transmitting antenna. Is that bad practice? The reason is that I am
not
allowed an outdoor antenna, and I live in a small flat.
ER... um... maybe. Even Wellbrook says one should
locate it away from strong transmit antennas to
avoid overloading the receiver input.
I think the correct answer is that it all depends
on how well you isolate the receiver input from
the transmit antenna and whether or not you use
a separate receiver from the transmit radio, and
similar considerations. SO2R installations have
similar issues - sometimes guys use a "front end
protector" as is reviewed in QST this month, and
other guys use a "time sequencer" to kill the \
antenna when transmitting, tied to the PTT line
and still others use a separate receive-only
antenna input on the rig, as is available on the
Omni VII, but not the Eagle.
Yep... This COULD be a serious concern if not
fully thought out.
BUT YOU COULD TRY IT AND SEE HOW YOU LIKE IT
AS A RECEIVE ONLY ANTENNA AND DEAL WITH THE
TRANSMIT LOGISTICS LATER...
Would a dual position coax switch take care of all this?
Lee
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