HI Gary
The isolation between pairs on 160m is close to 80dB.RS485 does not
affected the Rx signal at all.Overall SWITCH isolation between antenna
ports are better than 78dB.(2 relays in series )Anyway CAT6 can offer
even more crosstalk isolation but the price concern was here.
The LNAs design was driven by OIP3 and NF too.
I will return with more LNA details later.
Bela OM8AW
On Sunday, February 9, 2025 at 04:44:51 PM GMT+1, Gary NA6O via TowerTalk
<towertalk@contesting.com> wrote:
Very nice work Bela. One question for you. I have never measured crosstalk in
CAT5E cable so I was wondering if the RS485 couples into the receive signals at
all. From the data that I have seen, isolation should be very good in the HF
bands, at least 60 dB. Good thing you have a LNA for each signal.
73,
Gary NA6O
>
> From: Vojtech Ritzko <om8aw@yahoo.com <mailto:om8aw@yahoo.com>>
> Subject: [TowerTalk] CAT5E based RX SWITCH for remote RX ANT
> distribution
>
> HI ALL
>
> Our QTH at OM0M ?islimited in space and there is not room for extended phased
> beverage systems.
> I am trying my best to build system with RDF well over 14dBon limited space
> QTH.
>
> (Kill the side lobs and your RX will love you too.)
>
> W1FV-9 circle for 4 directions as well as linear 4el inlinesystem for USA
> were built in field day styleprior the CQ 160.
>
> Well done, but how to connect the hamshack with RX HUB?
>
> Single RG6 and CAT5E FTP ?cable were directly ?buried ?undersurrounding road?
> in past.
>
> Initial design - RG6 for RF and CAT5E for relay control isnot sufficient nova
> day.
>
> No cable duct = no way to extend anything.
>
> The only chance is to use the unoccupied 100 Ohms pairs inCAT5E to carry RF
> too.
>
> CQ WW 160 was the best chance to test RX systems in toughcontest conditions.
>
> Technicaldetails on enclosed google disk file:
>
> PDF :
> https://drive.google.com/file/d/1gTtywxB_sgZYRfgy42YB9wCTE9RqV3Cr/view?usp=sharing
>
> Eznec for 9CC:
> https://drive.google.com/file/d/1idf6JsQ32UrEQNs_7yc3hrrMWKT77DQH/view?usp=sharing
>
> Eznec for 4el:
> https://drive.google.com/file/d/19E_VXwYVG1HiDWNU9yybygsKPt0yjeKY/view?usp=sharing
>
> VY73 DX
> BelaOM8AW
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