Question About Using Multiple Antennas w/ a Single Amp and Coax Run

[sstephenson]

Here's a little background: I recently installed an outdoor omnidirectional 800 MHz antenna for use with my RS PRO106 scanner. I have an amp mounted at the base of the antenna and I have about a 50 foot run of lmr-400 going to the scanner. I recently got interested in SDR (software defined radio) and have a DVB-T USB Dongle installed on my laptop for 50MHz-1700MHz reception. I'd like to mount a discone antenna on the same mast as my omnidirectional antenna for use with the dongle.

Here's the question: I'd like to be able to use the same lmr-400 coax and amplifier that I'm currently using with the 800MHz antenna. I don't mind going outside and climbing a ladder to switch antennas if I have to (though it's not ideal). Is there a way that I can use the same run of coax and amp with some sort of antenna selector or switcher that will allow me to do this? Is there a way to remotely switch antennas from inside?

Thanks.

 

[K9DAK]

Google is your friend . . . a quick search for "remote antenna switch" turns up dozens of hits, ranging from $75 to $500+. Finding one that meets your price range and frequency requirements may be a challenge, but they're out there. And if you don't mind homebrewing, some of the links are for DIY projects.

Great idea . . . good luck!

 

[sstephenson]

Thanks K9DAK. I'll check it out. I do want to emphasize that my primary consideration is to be able to switch from one antenna to another using the same coax and amplifier for both antennas. A kind of antenna A-B switch with the amp mounted between the switch and the receiver. What I don't know is this: are there special considerations that I need to know about in terms of frequency compatibility, signal loss, etc. Is there a switch made specifically for this purpose that mitigates these concerns? Again, remote switching would be a bonus, but is not required.

 

[sstephenson]

Here's a crude drawing to illustrate my question:

 

[VE3CRO]

Before investing in a relatively expensive switch I would try using a PL259 Y adapter.

 

[sstephenson]

Is there an issue combining inputs from two antennas before going to the receiver? Out-of-phase signal cancellation/degradation?

 

[VE3CRO]

No. Actually a discone is an extreme example of the same thing.

 

[sstephenson]

Hmmm... Interesting point. Thanks!

 

[prcguy]

Search Ebay for coaxial relay and you'll find plenty of remote switches in any voltage and connector combination from a few $ on up. $30 should get you a new surplus switch with 12v or 24v coil, N connectors and good to several GHz or more.
prcguy

 

[sstephenson]

Excellent prcguy. That's perfect.