Specific question about using a scanner with 2 antennas

[jsncrso]

Alright, so I have a BCD996XT and want to monitor UHF and VHF from a discone, and an 800MHz simulcast system from my yagi.

I need something that will completely split the signals, meaning I can't have any 800MHZ coming through the discone or I will get multipath distortion.

What's the best way to do this? I was thinking of each antenna having it's own band filter then running into a multicoupler. Is this the best way to do that?

[maalox]

[QUOTE=jsncrso;1907441]Alright, so I have a BCD996XT and want to monitor UHF and VHF from a discone, and an 800MHz simulcast system from my yagi.

I need something that will completely split the signals, meaning I can't have any 800MHZ coming through the discone or I will get multipath distortion.

What's the best way to do this? I was thinking of each antenna having it's own band filter then running into a multicoupler. Is this the best way to do that?[/Q how about one antenna 2 scanners theres an a +b swithch u hook the discone in middle a switch for discone ant b for yagi antenna grove http://www.grove-ent.com there phone is 800-438-8155! they also have a bargain been with used equiptment happy scanning i have the 996xt if

[jsncrso]

Sorry, but I need to scan both bands at the same time on one scanner so that won't work.

[maalox]

Originally Posted by jsncrso

Sorry, but I need to scan both bands at the same time on one scanner so that won't work.

ok i got you can by from the store a 2 way splitter about $3.00. and others to meet your needs the person name to speak is shanel.

[jsncrso]

Originally Posted by maalox

ok i got you can by from the store a 2 way splitter about $3.00. and others to meet your needs the person name to speak is shanel.

Yes I know this, but if you read my question, I need the VHF/UHF and 800MHz, bands separated from each antenna or I will get severe multipath distortion. I need to attenuate as much 800MHz as I can from the discone. A $3.00 splitter is not going to do that.

[n5ims]

What you're looking for is called a duplexer - also may be called diplexer - (something like this MFJ Enterprises Inc., but designed for 800 MHz on one side and below 600 MHz or so on the other). Attach the yagi to the 800 MHz side, the discone to the other and your scanner to the output.

Another option may be swapping out the discone for a dual band ham antenna (VHF/UHF type) which would give you some gain on those bands and less 800 MHz signal. To help further reduce the 800 MHz signal from that antenna, also get a low pass filter designed to pass everything below 600 MHz or so and reject everything above that frequency and place it on the lower frequency side antenna. That should pass most of the 800 MHz signals from the yagi and most of the lower frequency signals through the other antenna/low pass filter setup.

[zz0468]

Originally Posted by jsncrso

I was thinking of each antenna having it's own band filter then running into a multicoupler. Is this the best way to do that?

Yes. That would be the best way to do it. If you need to over come the loss of the splitter/combiner, the right way of doing it would require two preamps, one after each filter, and before the splitter/combiner. Since you want both UHF and VHF on the discone, a low pass filter with a cutoff of 470 MHz (or 520 if you want T-Band) and a bandpass filter for 800 would work.

A "multicoupler", btw, is generally understood to be a single input (antenn system) and multiple outputs to more than one receiver. What you want is a "splitter/combiner" which is passive and bi-direction, depending on how it's hooked up.

A multicoupler with gain is useless. The the degradation of noise figure from the filters and the splitter cannot be recovered. Putting preamps between the filters and the splitter/combiner is most effective way of eliminating losses.

[rfradioconsult]

Put a 860 MHz notch filter in the line between your Multi-coupler and your discone, connect your yagi directly to your Multi-couplet.

[RadioDaze]

What about enabling attenuation on a per-channel basis?