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Fire related monitoring with Pro-96 and Pro-97

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#1
A few quick questions...

When using the Pro-96 and Pro-97 with any of the original, extended and/or 800 MHz antennas, I experience great reception through the frequencies listed in the RR DB. As in dispatch, police on their location and the fire station close by.

What I don't understand is when the fire station begins on their trip to location, they are loud and clear, repeated through the same frequency they were dispatched from. Why would I lose the signal if they are still running through the same frequency? This signal is repeated, right?

What is odd is, I found the Police 'input' for my area is a bit choppy when used (besides the repeater) but as for the Fire discussions, they are close to zero all the time using this same process, unless they are right by the house. Is this normal or do I need to program more than what is coming up for listings in RR? If so, where can I find this information? I'm looking in the DB online and also through the XML import but see nothing more than the following listed in the fire section:

http://www.radioreference.com/apps/db/?ctid=639

It would be nice to hear something more than "On location, single story home, nothing showing..." -- I'm looking for discussions between the firefighters or anything beyond these comments.

Thank you.
 

N9JIG

Sheriff
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#2
Most fireground communications are on low power simplex channels such as 153.830 or 154.295. These communications are usually only able to be heard locally, such as within a few blocks. This way the channels can be used at multiple locations without interference.

Dispatch channels are often on repeaters or the rig radios using high power mobiles, they need this in order to be heard by the dispatcher. The dispatcher does not normally need to monitor fireground communications.

What you are hearing is normal.
 
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#4
N9JIG said:
Dispatch channels are often on repeaters or the rig radios using high power mobiles, they need this in order to be heard by the dispatcher. The dispatcher does not normally need to monitor fireground communications.
Yep and since police often use their (much higher powered) mobiles, you can hear them on the input from further away.

I used to scan the PD inputs but found I'd sometimes miss the dispatcher/other unit's replies.
 
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#5
Very good point. I noticed the same thing with the inputs.


I would like to increase the signal from my location, without mounting something
outside. I don't have this option just yet.

Here is what I'm looking at doing. This will be for the Pro-96 and Pro-97 units.


1. New Antenna

I would like to either purchase or MAKE (DIY) this product and hang it in my room:
http://www.radioshack.com/product/i...Type/Scanner/HAM&fbc=1&parentPage=family


2. New Antenna

I would like to purchase or MAKE (DIY) this one as well:
http://info.maplin.co.uk/Module.asp...cessories - Desktop Discone Antenna


Which would be best for a Pro-96 and Pro-97 indoor application?


The closest plans I found to achieve this build would be found here:

http://www.sentex.net/~mec1995/ham/scanant.html


This build targets the 148-155 VHF band and 450-460 UHF frequencies
and requires the SO-239 chassis mount connector + RG-58 cable.


3. Regarding Cable, I have read in many places that RG-6 would be better than RG-58.

I found multiple types of RG-6* with:

RG-6
RG-6U
RG-6QS


Quoted from Strong Signals:

Cable Types
The basic co-ax types you run across in our hobby are
RG-58, RG-59, RG-174, RG-8, RG-6, RG-11 and 9913 (which is really a form of RG-8).

You are also going to find that cables come in two different types of resistances :
50- and 75-ohm. RG-8/58/174 are all 50-ohm while RG-6/11/59 are 75-ohm.

While most scanners/receivers specify a 50-ohm load at their antenna jack, either
type cable can be used. Why? Because the impedance of the entire scanner/cable/antenna
system as a whole changes radically over the wide range of frequencies that such radios cover.

http://www.strongsignals.net/access/content/co-ax.html


CABLE dB Loss

RG-6/U 2.0 - 2.1 <- Suggested by others

RG-11 1.4 <- Why not use this?
RG-8/U 1.3 - 1.9 <- Why not use this?
RG-11/U 1.2 - 2.0 <- Why not use this?



Quoted from FixYa:

Connecting an Optional External Antenna
The antenna connector on your scanner makes it easy to use the scanner with a variety of
antennas, such as an external mobile antenna or outdoor base station antenna.

Your local RadioShack store sells a variety of antennas. Always use 50-ohm coaxial cable,
such as RG-58 or RG-8, to connect an outdoor antenna. For length over 50 feet, use RG-8
low-loss dielectric coaxial cable.

http://www.fixya.com/support/p136869-radio_shack_pro_96_scanner/manual-18419/page-29




I'm confused by this statement. Is this opinion or something based on damaging the unit if
something other than RG-58 is used?

Do you have input for my options here? What would you do in my situation?
 

N9JIG

Sheriff
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#6
Scanners work with 75 ohm cable as good as or even better than they work with 50 ohm cable. I use RG6 cable for several or my RX only antennas and they outperform the exact antenna using 50 ohm RG8.

I like the RS 20-176, it works very well in both the UHF and VHF ranges and is nice and compact. I have several in my attic.
 
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Messages
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#7
Thanks for the tip on the antenna. I think that's going to be perfect for me to get started with. I just read all the reviews and find it's going to more than cover my needs.

I was going to ask about cable and the BNC when I remembered my "15 bins of things" I was told to throw away a while back. I now have three lengths of RG-58/U with BNCs already attached from an old project on a LAN. All I need is the antenna.

Your suggestion helped me a great amount. Thank you again. :)
 

N9JIG

Sheriff
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#8
hdesign said:
Thanks for the tip on the antenna. I think that's going to be perfect for me to get started with. I just read all the reviews and find it's going to more than cover my needs.

I was going to ask about cable and the BNC when I remembered my "15 bins of things" I was told to throw away a while back. I now have three lengths of RG-58/U with BNCs already attached from an old project on a LAN. All I need is the antenna.

Your suggestion helped me a great amount. Thank you again. :)
On the antenna end you will need to either change the BNC to a PL259 or use a BNC-PL259 adaptor.
 
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Messages
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#9
OK, I will grab one of those.

I'm doing a test right now with the Pro-97, running RG-58/U and the original antenna hung on the wall. I can't believe the difference already. It's piped through the PC now and crystal clear, even on the EDACS system. I expect the antenna you suggested is going to give me the range now.

I can even hear Fire conversations I never heard before and this antenna is just 7' off the ground at most. Crazy.
 
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