Topband: Post contest season: TX antenna vs RX antennacros-stalk. What do you do?

[Mark van Wijk, PA5MW]

Hi Kees,

That is what I successfully do at home, because my 160m vertical re-radiates 
to my RX antennes.

But at the recent RDXC PI4YLC FD contest station both the 40 and 80m 
full-size deltaloops were not detuned or switched to GND or anything.
The YL ops wanted to be able to listen to them as well as the separate RX 
antennes anyway.

73 Mark, PA5MW


-----Original Message----- 
From: Kees Nijdam
Sent: Thursday, March 24, 2016 11:05 AM
To: Mark van Wijk, PA5MW
Subject: Re: Topband: Post contest season: TX antenna vs RX 
antennacros-stalk. What do you do?

Hi Mark,

When receiving on my RX antennas, my transmit verticals are detuned by
decoupling them from the feedline.
A floating 1/4 wave verical is completely dead and not reradiating signals.

Kees, PE5T

--------------------------------------------------
From: "Mark van Wijk, PA5MW" <pa5mw at home.nl>
Sent: Thursday, March 24, 2016 7:38 AM
To: "william radice" <k4owr at outlook.com>; <topband at contesting.com>
Subject: Re: Topband: Post contest season: TX antenna vs RX
antennacros-stalk. What do you do?

> Hi Bill,
>
> I think this is not what I meant here; I also do use BPF's and the Front 
> End Savers.
>
> The problem is that while listening to your receiving antennas, there is 
> also some signal from the transmit antenna getting through thanks to the 
> internal cross-talk of your rig's TX/RX relay.
>
> I was wondering what people do besides the obvious 'kill the TX antenna 
> input during RX mode' ?
>
> 73 Mark, PA5MW
>
>
>
> -----Original Message----- 
> From: william radice
> Sent: Tuesday, March 22, 2016 2:05 PM
> To: topband at contesting.com
> Subject: Re: Topband: Post contest season: TX antenna vs RX antenna 
> cros-stalk. What do you do?
>
> :::: Serious multi-op contest stations face this issue all the time.
> Most use individual band filters and they almost completely eliminate
> the issue.
> At our station we used the Dunestar filters for operating positions on
> different bands. As for 160 I personally use the KD9SV "front end saver"
> and it does the job completely.
> BILL K4OWR
>
> On 3/22/2016 5:44 AM, Mark van Wijk wrote:
>> Now that we are  'sort of in post contest season mode' and sharing some 
>> good
>> ideas, there is another question:
>>
>> During recent Field-day setups I noticed severe cross-talk issues between 
>> TX
>> antennas and the separate RX antenna circuits.
>> For sure any TX/R relay circuitry offers roughly 50-65 dB dampening. So, 
>> during
>> a contest with >S9+30 signals received on the large TX antennas 
>> (Deltaloop for
>> 40m and 80m) these would still show up S1 - S4 on the FD station's K3 RX 
>> input.
>> At home I normally de-tune my backyard TX antenna(switch to GND during 
>> RX) to
>> avoid noise pickup at the RX antennas, so I never noticed this.
>>
>>
>> Question 1: how do you manage the TX-RX cross-talk at your setup?
>>
>> - switch TX antenna to GND during RX
>> - switch-in en external attenuator, so the cross-talk is below noise 
>> level, but
>> you are still able to use the TX antenna during RX
>> - any other solution?
>>
>>
>> Question 2: is there any other basic circuitry or setup in a basic 
>> contest
>> station which offer possible similar negative side effects?
>>
>>
>>
>> 73, Mark PA5MW
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