mobile vs portable reception

[dbfd588]

I have a dumb question. When I hook a mobile to a antenna it picks up great. Whether im moving or not. But I can hook a portable or a scanner to the same antenna it u get alot of static and choppy sound. why does a mobile pick up and sound so much better. Also, I have a toolbox on the back of my truck. I have a quater wave mounted to the lid. I thought about drilln and putting it up on top of the cab. Is it worth moving it?

[Jim2121]

3 different radios (scanner, mobile, portable) Antenna connection lose? Using same antenna with mobile & portable/scanners? Any connectors in btw. the coax connecting to the radio that are different? ie: BNC's can get lose in time. Then you get static. Tell us more about the antenna connections, type of, connection type, scanner? type of portable/mobile? any FME, TNC, SMA, connecting in between? ect..ect..

[dbfd588]

just say my spectra with mini uhf connector. its picks up excellent. But just say I throw on a BNC adapter and hook it to a portable scanner. Its dont pick is as good. Here is another way to look at it. Just say Im in the next town over from our repeator. My mobile can pick up the signal. But I can take a cp200 and put right beside my mobile antenna and it may not even pick up. Why does a radio made for mobile use pick up so much better?

[Jim2121]

glad your mobile spectra is working ok! I never needed to connect a portable to a mobile antenna in a truck. I would guess your coax connections, If your using a BNC? shack the BNC to whatever its connected to. Or find another BNC. Location could be a factor.

quote: Just say Im in the next town over from our repeator. My mobile can pick up the signal. But I can take a cp200 and put right beside my mobile antenna and it may not even pick up. Why does a radio made for mobile use pick up so much better? quote

A mobile antenna is going to pick up signals, better than a rubber duct. I've seen portables move them 4 inchs either way & the signal you hear is gone. I'm guessing you have a lose connector when you leave your spectra to connect to another radio. I would look at the connections on the coax 1st. don't know where you are, but some mobiles will pick up a repeater while the portable does not. Location/buildings/hills, ect.. my 2 cents.

[Tom in D.C.]

The reason your good radio is better than the scanner is that the
front end (RF amplifier, etc.) on the scanner is inferior to the front
end of the good (Motorola) radio, one reason being that the scanner
has to cover a much, much wider range of frequencies than the other
radio has to cover. This means that the overall construction, components, and
design of the scanner's front end may be considerably inferior to the
Motorola's. A rough way to judge sensitivity is how many microvolts
of signal are needed to open the squelch of a radio. On pro-grade comm
radios this figure can be much less than one microvolt, whereas on a
scanner it may well be somewhere above 1 microvolt or even more. These are just
rough figures but you get the idea.

[Wowbagger]

I have a dumb question. When I hook a mobile to an antenna it picks up great. Whether I'm moving or not. But I can hook a portable or a scanner to the same antenna and get a lot of static and choppy sound. Why does a mobile pick up and sound so much better? Also, I have a toolbox on the back of my truck. I have a quarter wave mounted to the lid. I thought about drilling and putting it up on top of the cab. Is it worth moving it?

It sounds like you have a bad ground on the antenna cable. When connected to a mobile, the mobile is grounded through the chassis and that helps to provide the connection to the antenna. When connected to the scanner or to the portable, there is no redundant ground path, and the intermittent connection manifests itself.

First, make sure the ground on the cable is not faulty. Second, insure the antenna is grounded to the vehicle.

As for moving the antenna: having the antenna on the top of the cab is better from an RF standpoint.