Topband: 75 ohm coax switch

[Bill Wichers]

It's easy to homebrew something using small-signal relays. This has all sorts of added benefits (remote control, automatic switching, etc.). There have been lots of discussions on here about the correct contact type you want in those relays since they don't switch any significant current. Cost is low, and it's probably the only way to handle more than a few ports with readily available parts.

You can build these on perfboard and still get pretty good isolation between ports if you're careful with your internal wiring.

You could also try a telecom patch bay for T3/DS3 signals. Those run over 75 ohm cabling too. You'd have a patch bay with a cable to move, but you could use it as a multiway switch. ADC makes a lot of these, Ebay #311293334088 is an example (they can be used for video too). Everything comes out to 75 ohm BNC connectors on the back, the front uses a sleeve-type connector for the patch cable that I can't remember the name for. All the telco coax cable is 734 or 735 type (734 is like RG59, 735 is like RG179 in terms of physical size) and is 75 ohm. If you want some 12-count 735A cable I have a big roll I can cut a little from. We hardly ever use this stuff anymore at work -- everything is higher capacity and fiber now.

 -Bill

> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Art
> Snapper
> Sent: Monday, April 20, 2015 12:06 PM
> To: 160
> Subject: Topband: 75 ohm coax switch
> 
> What do you use for switching your receive antennas?
> 
> I have been adapting the RG-6's F connectors, to PL-259s to use a regular
> ham coax switch.
> 
> The 75 ohm (TV) type switches show a minimum frequency of 5MHz.
> 
> Is there a better solution?
> 
> Art NK8X
> _________________
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