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Re: [TenTec] receiver isolation

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] receiver isolation
From: Carl Moreschi <n4py3@earthlink.net>
Reply-to: n4py3@earthlink.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 07 Dec 2017 09:06:57 -0500
List-post: <mailto:tentec@contesting.com>
I have a one wire mod that simply brings the sub receiver antenna connection out to the spare jack. This works well for adding panadapters. I have been using this for years. It has to be protected enough to protect the sub-receiver antenna jack. I see signals of about s9+20 on my panadapter when I transmit, even with an amplifier. So this certainly is a good way to do this.

My N4PY software keep everything in sync.

Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com

On 12/7/2017 7:16 AM, Barry N1EU wrote:
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@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@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@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@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@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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