[TenTec] receiver isolation

[Carl Moreschi]

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 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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