[TenTec] New Jupiter on its Way _ A Few Questions

Rockinghorse Winner (Terry) ny6p01 at gmail.com
Sun Apr 27 23:02:17 EDT 2014


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 at gmail.com wrote:
>> On Sun, Apr 27, 2014 at 08:29:25PM -0400, K8JHR wrote:
>>>
>>>
>>>
>>> On 4/27/2014 5:05 PM, ny6p01 at 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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