Topband: Wired/wireless Beverage hub progress.

[ZR]

Absolutely!  Switching multiple RX antennas is always a major headache. Ive 
been scratching my head so long trying to figure out how to handle 3 hubs 
Ive worn down my fingers since the skull is so thick!!

How about more info on what and where you actually bought?

Carl
KM1H


----- Original Message ----- 
From: "Pete Smith N4ZR" <n4zr at contesting.com>
To: <Topband at contesting.com>
Sent: Wednesday, February 22, 2012 5:16 PM
Subject: Topband: Wired/wireless Beverage hub progress.


>I hooked up the hub today, and initial results are excellent.
>
> For those who missed earlier messages - here's the story.  I ran across
> an inexpensive 8-way relay board on E-bay for less than $20.  It is
> controlled by a 300-MHz radio remote, and I figured I might be able to
> use it for remote switching of receiving antennas.  Rather than try to
> boost the radio control signal with a directive antenna, Ian, GM3SEK
> encouraged me to experiment with coupling the RF from the remote to the
> 350 feet of coax out to the planned hub location, using a 1-inch loop at
> each end.  It worked!
>
> As with many such projects of mine, this one mushroomed a little bit.  I
> added a 20dB ARR preamp at the hub, using DC sent to the hub from the
> shack with a DC bias tee, which was needed for the relay board anyway.
> Rationale for putting it out there, rather than in the shack, was that I
> plan to use low-output antennas (BOG, K9AY, etc.) and wanted the desired
> signal to be as loud as possible relative to any common-mode pickup on
> the feedline.  I also used a super common mode choke near the hub, per
> ON4UN and K9YC.
>
> Since I only had one good 9:1 binocular transformer, I decided to share
> it among the antennas that will be connected to the hub.  A little
> fiddling with TLW and various impedances and reactances convinced me
> that the extra cable loss caused by mismatches will be quite manageable
> for 160 and maybe 80 meters.
>
> I was worried about isolation between antennas, because the relay board
> was not designed for RF, but early indications are positive.  A local
> broadcast station, on 1550 KHZ, is S9+60 on the BOG, and just S9 when I
> switch to an unused terminal, even the one physically adjacent.  Signal
> level is only slightly below that received on my shunt-fed tower
>
> Now to build a proper control unit - For $18.50 I'll buy another relay
> board and use it with push-button switches and LEDs to display which
> antenna is selected.  Thanks to Grant, KZ1W for this suggestion!
>
> I'm curious - does anyone think there would be enough interest to
> warrant writing this up for one of the mags?
>
> -- 
> 73, Pete N4ZR
> The World Contest Station Database, updated daily at 
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at 
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000 and
> arcluster.reversebeacon.net, port 7000
>
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