[TenTec] receiver isolation

[Barry N1EU]

The over-riding question is whether the Orion provides internal isolation
of the subrx antenna port.  The Orion schematics are somewhat challenging
to decipher without explanation of the complex control signals.  My
educated guess is that the subrx antenna port is disconnected via relay
during transmission and is therefore protected.  But I'm not 100% sure and
unless someone can authoritatively confirm my educated guess, the prudent
course of action is to add external protection.

Barry N1EU

On Thu, Dec 7, 2017 at 2:16 AM, Ken Brown <kenradiobrown at gmail.com> wrote:

> It all depends on the coupling between the antennas. I should really say
> antenna systems, because there could be crosstalk between transmission
> lines or other equipment, and not just the coupling from transmit antenna
> to receive antenna. The "receiver Guard"recommendation is a good one. If
> the receive antenna is far from the transmit antenna, and an inefficient
> one such as a Beverage, and your feedlines have good shielding and are not
> all bundled together. Cross polarization between the transmit antenna and
> receive antenna is another way to reduce coupling, or if you prefer to
> increase isolation.
>
> On Wed, Dec 6, 2017 at 12:05 PM, Kim Elmore <cw_de_n5op at sbcglobal.net>
> wrote:
>
> > I use the DX Engineering Receiver Guard for jut this purpose. I have K9AY
> > receive loops about 60-70 ft from my F12 Sigma 80 OCF vertical dipole. So
> > far, everything has been fine.
> >
> > Kim N5OP
> >
> > "People that make music together cannot be enemies, at least as long as
> > the music lasts." -- Paul Hindemith
> >
> > > On Dec 6, 2017, at 14:11, Barry N1EU <barry.n1eu at gmail.com> wrote:
> > >
> > > I interpreted the question to mean that he is transmitting legal limit
> > into
> > > his tx antenna, he has a receive antenna feeding the subreceiver
> through
> > > the rx antenna jack on the rear, and he wants to know if he needs to
> add
> > > external isolation/protection of the rx antenna during transmit.
> > >
> > > It's a good question that's come up before but I confess to not
> > > knowing/remembering the authoritative answer.  Conventional wisdom is
> to
> > > add external isolation/protection.
> > >
> > > 73, Barry N1EU
> > >
> > >> On Wed, Dec 6, 2017 at 7:24 PM, Ken Brown <kenradiobrown at gmail.com>
> > wrote:
> > >>
> > >> There should never be "legal limit" power level on any transceiver
> > antenna
> > >> port. The maximum power level should be the transceiver's transmit
> > power,
> > >> and it should only be on the tx/rx port when transmitting. The
> internal
> > >> switching in the transceiver will keep that transmit power out of the
> > >> receiver front end. There should never be any RF power other than
> > receive
> > >> signal levels from the antenna feeding into any antenna port on a
> > >> transceiver.
> > >>
> > >> Perhaps I am misunderstanding your question. How/why would you ever
> have
> > >> legal limit RF power going IN to your transceiver?
> > >>
> > >> DE N6KB
> > >>
> > >> On Wed, Dec 6, 2017 at 7:05 AM, Sandor Wetsel <kg4fet at bellsouth.net>
> > >> wrote:
> > >>
> > >>>
> > >>> I have blown front ends on radios before so for me this is a concern.
> > Is
> > >>> the isolation of the Sub receiver good enough to protect it from a
> > legal
> > >>> limit transmission on the Main? This would be using either antenna
> port
> > >> for
> > >>> the SUB RX antenna. I did not want to assume now that I am into this
> > >> (565)
> > >>> rig a week now.
> > >>>
> > >>> Thanks es Merry Cristmas
> > >>>
> > >>> Sandor KG4FET
> > >>>
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