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Re: Topband: RX antenna switch

To: Dave G4GED <radiodave.g4ged@tiscali.co.uk>, "Dave Anderson, K4SV" <davek4sv@yahoo.com>, TopBand Reflector <topband@contesting.com>
Subject: Re: Topband: RX antenna switch
From: Brian Moran <brianmo@yahoo.com>
Reply-to: Brian Moran <brianmo@yahoo.com>
Date: Fri, 30 Dec 2011 11:19:04 -0800 (PST)
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Here's one that works for TX & Rx. 
http://www.qsl.net/k5lxp/projects/CoaxSwitch/CoaxSwitch.html With lockout, etc. 
A homebrew version of the '6 pack' kind of box from array solutions. I have the 
Array Solutions one, and it works great.


I have built a small one for RX only that uses SMD relays, however it does NOT 
prevent the same antenna from used simultaneously. I wanted a small footprint, 
so used RJ45's to handle the switching signals to the switching boxes. It's 
great with a K3 to put different antennas in different ears with diversity 
mode, and makes it easier to pick out geographically distinct stations in the 
sound field. If you want the PCB layout, I can email it to you; the RX 
switchbox is in daily use.


If you're really going to build one of these, you should also see what VP6DI 
did (Eric Scace K3NA has an article you can google for) as far as equalizing 
signals when multiple radios listened to the same antenna, minimizing leakage 
of signals BACK INTO the antennas from a transmitting radio (it happens, even 
with the best of radios); he also went as far as breaking out 160m listening 
from 80m listening, and segregating 80m phone from 80m cw portions of the band.

If it were the 'ideal' thing, there'd be a box with a matrix of switches (A x 
B), gain blocks that could be put in/out of the circuit, BPFs that could be put 
in and out, 'muting' of any RX output that is connected to a transmitter that 
is transmitting, RX overload protection, and some general purpose inputs to 
select the 'configuration'. Probably a PIC to run it, with a nice GUI app to 
configure it.   


- Brian N9ADG





________________________________
 From: Dave G4GED <radiodave.g4ged@tiscali.co.uk>
To: "Dave Anderson, K4SV" <davek4sv@yahoo.com>; TopBand Reflector 
<topband@contesting.com> 
Sent: Friday, December 30, 2011 7:15 AM
Subject: Re: Topband: RX antenna switch
 
----- Original Message ----- 
Got a note from Gary K9AY, he says no time to make the RAS8x2 switches, real
work is too busy. So I suspect until Gary can make more they are not
available.
Dave Anderson, K4SV
----------------------------------------------------------

That's a pity, I was just about to order one!

I haven't a clue of the methods of interlock switching the RAS8x2 uses but
as it looks like we're going to have to make our own and my need to keep to
simple click-clunk technology. I believe that using relays with a spare 
contact in such a cicuit that disables any other relay once operated, would 
do the job?

Before I set about reinventing the wheel, does anyone have the knowledge or
a basic circuit diagram for this sort of relay interlocking please?
Tnx Dave

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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK

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