distance between radio and antenna

[lancerice]

Dose it matter how far the radio is from the antenna and dose it matter how long the coax cable is. Can I cut it down to a 2ft length as the radio and the antenna are mounted about a ft apart.
It is a Motorola Radio VHF High Band 165MHZ

Thanks Lance

[Will]

7 feet is considered to be minimum distance from antenna and the operator at less than 10 watts transmitter power.

[lancerice]

this would be a mobile setup, the antenna is on the roof and the radio is mounted on the roof inside the vehicle, so the distance is very close but the coax cable is 5m long and when I wind it up the VSWR is out big time.
thanks lance

[N4KVE]

You can't wind coax. It acts as a coil & throws the SWR out of whack. GARY N4KVE

[com501]

Cut the coax to whatever length is convenient. Avoid multiples of quarter wave length. At VHF, you can't coil the coax tight enough to affect anything, unless you manage to wind it around a pencil....

[KitN1MCC]

something tells me you have a bad piece of coax

[Jim202]

I think it's time to get out the Ohm meter and start checking out the coax cable connections.

You didn't say what kind of antenna your running, so I would remove it from the roof mount. Take thew meter, with the radio disconnected from the coax and check to make sure you see infinity between the center conductor and the shield. Next make sure you see almost zero Ohms from the shell of the radio end of the cable to the outer ring of the roof mount connector. You should see almost zero Ohms. Now switch your measurement to the center pin of the radio end of the coax to the center of the roof mount connector. Again you should see almost zero Ohms.

If any of the measurements differ from what you should see, you need to correct the problem before going any further. Mu guess is that you might have either a short or the shield is messed up at the base of the roof connector. Either way, you might start by cutting off the connector at the radio and start the measurements again/ This way you will know if the installed connector at the radio was the problem or not. If you were going to shorten the cable, you would have to cut the radio end off anyway.

[com501]

The most common field failure is someone failed to install the connector correctly on the end of the coax.

[lancerice]

so on a mobile antenna that comes with 5m of coax cable I can cut it down to say 1m long and this will still work ok

thanks lance

[wavetar]

so on a mobile antenna that comes with 5m of coax cable I can cut it down to say 1m long and this will still work ok

thanks lance

Yes, it will work fine. The reason it comes that long is to accommodate the expected run length for most installations in most vehicles. It's not like the CB days where coax length was a critical component of the antenna.