Diplexer question on multiple antenna setup

[scottmarlowe]

Good morning. I am new to scanning and I have scoured these forums to help me get my scanner system up and running. I have never posted a question but have spent countless hours looking up answers to my questions. I have hit a snag and cant quite find the answer that I am looking for, I will give you my setup specifics and then ask my question.

I have a uniden home patrol scanner connected to a discone antenna with 9913 feedline mounted about 30' up on my chimney. I get great service in the 150 range and 400 range and can hear several counties away. BUT, our local digital system where fire, police and ems operate is low 700's. It is Coweta County, Georgia which is part of the WARRS system here in West Georgia.

I compared what I can hear on my scanner radio app compared to my scanner and its spotty only about 50% reception of the digital transmissions on my scanner. The tower that transmits the digital in the 700s is about 10-12 miles away.

I have ordered a yagi antenna designed for the 700 frequencies with 10db gain and plan to point it towards the tower and get better signal on the digital channels (hopefully). My perfect setup would be my discone antenna for up to say 500 and the yagi for the higher frequencies. I have read through these posts and it looks like my solution would be a diplexer. But, here is my question. It is probably a simple solution but, for a guy with 2 weeks scanning experience it has created a wall..lol

First, If a diplexer for example says the lower pass is 0 through say 170mhz, are those limits "hard" limits meaning no signals above 170mhz will pass to the scanner?

Second, all of the diplexers I have found (and I have looked a LOT) lump everything from 400mhz and up into the upper pass together. Is there a diplexer that handles everything up to say 600 in the lower pass and everything above 600 in the upper pass? Can I have one custom made?

Finally, when looking at diplexers and triplexers the frequency ranges seem to have "gaps" meaning low pass is 0-150 mid pass is 400-700 and upper pass is 800-1.3ghz. What happens in those "gaps" between the frequency ranges? can you still hear them?

Finally, Am I looking at this right? Is this the best path to getting a good scanner setup? I have come this far and just want the best system that I can have.

Sorry, if this is a rookie question but, I cant seem to find the answer. My end goal is the discone that handles everything up to say 600MHZ and let the yagi handle all of the digital stuff higher up.

Thanks in advance and again, all of the posts on this site are great for a guy who is just starting out

Scott

 

[KevinC]

This one will work...

Comet CF-413B - 1.3-460 MHz 840-1400 MHz Duplexer

The specs for the "high pass" show it starts at 840, but the sweep shows it closer to 700. Mines actually starts to roll off around 720 or so.

 

[scottmarlowe]

that answers most of my questions..the frequency ranges are not "hard" and can float up and down a bit...thanks for the quick response. I will get it ordered ASAP and let you know how it works

 

[KevinC]

And the "low" pass (on mine anyway) goes up to about 550 MHz or so.

I find it works well if you need to use a yagi for a 7/800 simulcast system, since you can have an omni for V/UHF and the yagi for 7/800.

 

[Ryangn]

I use that same duplexer with my ST2 and 800Mhz yagi and it works great for my setup. I do recommend as well. Make sure when you order it you don't forget to get any adapters you may need as well.