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How much do antennas help?

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NewSDScanner

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I'm thinking about getting this antenna for use with my GRE PSR-500 in my car to scan 800Mhz frequencies. How much will it help? Will I see a big difference in reception reach or reception quality? What makes the actual transceivers installed in police and fire vehicles get such good reception? Is it the antenna? Thanks.
 

zz0468

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An outside antenna is always better than one inside a vehicle. The manufacturer claims some gain, but the gain figures are frequently exaggerated. But it will be a marked improvement over a smaller antenna inside the car, and WELL worth the money.

Public service vehicles generally get better performance for several reasons. The quality and performance level of the radio is vastly superior to a scanner. They're usually professionally installed, with through-hole mounted antennas. And unlike scanner enthusiasts, who want to hear every system in the state, a public service vehicle is usually operated in the primary service area of the system they're affiliated with. Many systems are designed to NOT cover much outside their political boundary, so reception can be pretty cruddy when you get too far away.
 

n5ims

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I'm thinking about getting this antenna for use with my GRE PSR-500 in my car to scan 800Mhz frequencies. How much will it help? Will I see a big difference in reception reach or reception quality? What makes the actual transceivers installed in police and fire vehicles get such good reception? Is it the antenna? Thanks.
That antenna should do fine for 800 (and the nearby 700 & 900 MHz) bands on a scanner. That said, you may experience some systems that may perform poorly due to a too strong signal (although it'll mimic a too weak one). This is generally on a simulcast system where several towers broadcast on the same frequency (or frequencies) and with a strong signal the scanner tries to process the combined signals from multiple towers, which causes distortion and generally bad performance. With a weaker signal, only the closest tower comes through and there's no mixing and the associated distortion.

Why do actual transceivers work so well when scanners don't (a slight modification of your question, but one I think gets to the meat of your question)? Basically there are two reasons, bandwidth of the radio and cost.

A scanner is designed for a very wide frequency range to receive signals on, so the circuits must be designed to allow this wide path through (like the water flowing down a garden hose where the flow may move out a bit away from the end, but quickly drops to the ground). These circuits must be optimized to allow fair results over this wide frequency range (with nothing really great, but nothing really poor either). A transceiver is designed to work on a very narrow band of frequencies (as compared to a scanner at least). The circuits can be designed very optimally for best performance over that narrow frequency band. Since they don't need to worry if they work at all outside of that range, they can be made to work really well within it (like that same garden hose after you stick your thumb over the end to create back pressure, causing a long powerful stream when the water leaves the hose).

The relatively low cost of a scanner forces the design and components to be lower than a high priced transceiver would allow. This allows specialized designs and higher quality components to be used. While adding a specialized circuit to correct issues (like the simulcast distortion problem) is easily funded in the multi-thousand dollar radio, it may not be possible (financially) on a scanner selling for a small fraction of that.
 

NewSDScanner

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Thanks for the explanation! That antenna comes with a 17 foot cable. I'm going to use it on a Honda Civic so I don't need nearly that much cable. How should I handle this? I am not familiar with working with coax cable.
 

Rt169Radio

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Thanks for the explanation! That antenna comes with a 17 foot cable. I'm going to use it on a Honda Civic so I don't need nearly that much cable. How should I handle this? I am not familiar with working with coax cable.
Well there are two ways you could handle it,the first one is to roll up the excessive coax and zip-tie it.The second way requires soldering skills,you cut the coax at whatever point you think would be long enough to reach your scanner,then you strip it and then solder on whatever connection you need for your scanner,to connect to your scanner you would need a bnc male connection.
 

woodylarkin

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I have had that DPD 800MHz antenna for about a year. It performs very well. It does have more gain (on 800MHz) than a simple whip, since it is a double 5/8 over a half wave collinear. As for the excess coax, I would simply coil it up as was suggested; the only concern would be not to cause any kinks which might damage it.
 

NewSDScanner

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Thanks. How should I run that cable though? I have a Honda Civic and right now I have no idea how to pull panels off or tuck the cable in neatly. I am in an Automotive Electronics/Electrical class though so I will learn some of this soon and could probably ask my teacher. I actually know about wire harnesses and stuff but I don't know how to remove panels to get into the wiring areas.
 

Rt169Radio

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Thanks. How should I run that cable though? I have a Honda Civic and right now I have no idea how to pull panels off or tuck the cable in neatly. I am in an Automotive Electronics/Electrical class though so I will learn some of this soon and could probably ask my teacher. I actually know about wire harnesses and stuff but I don't know how to remove panels to get into the wiring areas.
You could try asking in the installation part of this website.
 
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