Antenna cable split for duel use?

[Rescue611]

Hi there,

I just installed a Larson "Motorola Type" Tri-Band antenna using a trunk gutter mount. The primary use will be for Uniden 996XT scanner. But, I wondering if I could install a splitter on the cable so I could also attach the antenna to 5 watt handheld transceiver I frequently use. I'm pretty certain I could not use the scanner and the handheld at the same time, but it one or the other were turned off, would the other function well?

Forgive my ignorance. i'm pretty new to this stuff.

Many thanks in advance.

[n5ims]

Originally Posted by Rescue611

Hi there,

I just installed a Larson "Motorola Type" Tri-Band antenna using a trunk gutter mount. The primary use will be for Uniden 996XT scanner. But, I wondering if I could install a splitter on the cable so I could also attach the antenna to 5 watt handheld transceiver I frequently use. I'm pretty certain I could not use the scanner and the handheld at the same time, but it one or the other were turned off, would the other function well?

Forgive my ignorance. i'm pretty new to this stuff.

Many thanks in advance.

Chances are that even if the scanner was off when you transmitted, you'd fry the front end. There's be enough energy from the 5 watt transmitter to overload the scanner components that are designed for only a few microwatts of signal, causing them to fail.

What you could do is connect only the scanner when you're using that and connect only the HT when you're using that. The issue would come from having both connected at the same time. There is something that might allow both to work, but you'd basically splitting the bands up (VHF-Hi to the HT and the rest to the scanner). You may not get much 800 MHz signals at all, depending on what model you use. Something like this is what I'm talking about --> MFJ Enterprises Inc.

[Rescue611]

n5ims,

That's what I was afraid of. Unfortunately, the scanner will be hidden (using a remote head) so switching the main cable really isn't all that practical. I do have a mag mount for the HT - I was just hoping to clean up the outside with a single antenna. I currently have a mag mount for HT.

I suppose if I had a splitter easily accessible I could just unscrew the scanner from the splitter when I wanted to use the handheld.

[k3cfc]

I would not pump 5 watts in to any thing but an antenna that was for it. on the other hand you can get an antenna switch to switch the radios.

[Rescue611]

K3cfc,

That sounds promising. Can you recommend one? I'll look into it. Thanks!

[searingxheretic]

Just my .02 but I'd rather take 3 seconds to switch the feed line from the scanner to the HT than assume a splitter/switch will isolate an expensive scanner from being fried. I don't think it is worth taking the chance.

Sent from my cm_tenderloin

[k3cfc]

Originally Posted by Rescue611

K3cfc,

That sounds promising. Can you recommend one? I'll look into it. Thanks!

Alfa delta makes a quality one.

[k3cfc]

Originally Posted by searingxheretic

Just my .02 but I'd rather take 3 seconds to switch the feed line from the scanner to the HT than assume a splitter/switch will isolate an expensive scanner from being fried. I don't think it is worth taking the chance.

Sent from my cm_tenderloin

Read permalink #3 specially the part about the remote head.

[mmckenna]

Absolutely not, this will not work with just a splitter. The RF energy from your hand held radio won't know that it should turn right and go to the antenna, and not left and run into the front end of your scanner.

Doing this will destroy the front end of your scanner, it'll turn on, but you won't receive anything ever again. The front end of a receiver is designed to sense very tiny signals, hitting it with the 5 watts from your radio will completely damage the components.

The antenna system would likely no longer be resonate with this set up either, while it would be unlikely to damage the radio, it is something you wouldn't want to intentionally do.

Easy solution: two antennas, and separate them enough that when transmitting, there is enough space between the antennas to provide some protection. Usually a foot or two is a good amount, more for higher power.

Slightly harder solution: Antenna switch.

More expensive solution: You could install a duplexer that would allow your antenna to connect to the common port, your handheld to connect to the appropriate port for your tx frequency, and the other side to the scanner. This will provide enough isolation, HOWEVER, the duplexer will only route frequencies to the ports as it is tuned for, so, VHF would ONLY go to the VHF port, and to your hand held transceiver, the other port, UHF and up, or VHF low and down, would go to your scanner. Your scanner would now not receive on the VHF portion of the band.

If you were only transmitting on one frequency, and only ever one frequency, you can do some interesting stuff with tuned length stubs, but that's getting really deep and would require some skill and test equipment to set up correctly. Likely not a solution that would work for you.

Anyway, more antennas adds to the fun.