[TowerTalk] Multi-station antenna selection patch panel
krishna kanakasapapathi
kkanakas at cisco.com
Sat Jan 18 17:54:59 EST 2014
Thank you all for the inputs. I think we now have a good deal of data to
start an in-depth investigation.
73s
krish
w4vku
On 1/18/2014 2:16 PM, Jim Lux wrote:
> On 1/18/14 4:07 AM, David Robbins wrote:
>> Agree, any to any gives lots of relays no matter how you do it. but you
>> really don't need vacuum relays, most of the common switch boxes
>> today just
>> used regular frame relays. If you want to keep cost down by using
>> off the
>> shelf parts try looking at the rcs-10 remote switches that do 8 to 1,
>> I am
>> using them for my rx antenna switching:
>> http://wiki.k1ttt.net/2011%20Maintenance%20and%20Upgrade%20Blog.ashx#bevswit
>>
>> ch and they work well... of course there is no lockout, you would
>> have to
>> come up with that in whatever provides the control power. I think
>> k1xm was
>> working on something like that, but not sure how far it ever got.
>>
>>
>
>
>
> I think it's the port to port isolation requirement that is going to
> drive the design.. Regular old power relays, if chosen wisely, will
> probably work just fine, but you might need to come up with switch
> architectures that cascade two or short unused ports, etc. to get
> enough isolation.
>
> I doubt a single relay will get you 60 dB of isolation for instance.
>
> There's a fair number of posts to TT over the years with suggested
> part numbers for the relays, and for such a big project, I'd go out
> and get a few and rig up some test fitures before committing
> (although, if you got a good deal on surplus and they cost $1/each in
> that quantity...)
>
> Another aspect to consider is failure modes: if one of those dozens of
> relays sticks or fails to change positions you don't want to be
> blowing up radios with the output of the linear. This is one of the
> advantages of the various schemes where you have two SPDT relays in
> the path: if one fails, you've still got the other one to prevent
> disaster.
>
> I've found that it's the driving circuitry that is often the more
> complex aspect. Although.. these days, there are people selling nifty
> computer controlled relay drivers AND decent software that can be
> configured appropriately, so you probably don't have to spend hours
> figuring out diode matrices.
>
>
>
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