Radio Transmitting in Proximity of BCD 396XT

[Pueo]

Having shelled out the cash for the Uniden BCD 396XT I want to ensure that I do not fry the head unit by transmitting with my Patrol Handheld Motorola XTS 5000 which transmits on the P25 digital freqs. I believe the transmit wattage on the XTS in the 700/800 mhz is about 3 watts and worst case 5 watts if in the UHF mode. I normally wear the mobile on my left hip and carry the BCD 396XT in the center console or passenger seat. I have noticed degrading of my analog scanners over about a 3-4 year period and want to insure I do not burn this unit out. So what is a safe stand-off distance for the scanner when transmitting with my service radio? Oh and thanks to this site and the SEARCH mode I have found all my answers up til now on all things radio related. Brian on the Big Island of Hawaii, Mahalo!

 

[W8RMH]

I have transmitted on a 50 watt mobile through a roof antenna on my Tahoe with my 396 in a dash cup holder, and used a 4 watt handheld within about 18 inches of it with no ill effects, so I believe you should be fine.

From what I have read here I believe the problems occur when using two mobile antennas in close proximity or placing the radios right next to each other.

 

[ofd8001]

If you have an assigned vehicle and would be allowed to do so, I'd suggest an outside antenna on your vehicle. (Though it might be a pain to connect and disconnect if you take your scanner from your vehicle frequently).

This would serve a couple of purposes. One you'll get a better comfort level of not overloading the scanner receiver. The other is a handheld scanner in a vehicle doesn't receive very well given it being surrounded by metal.

 

[ko6jw_2]

Be careful

I burned out the RF amp in my 396T by transmitting on 6 meters in close proximity to the radio. A trip back to Uniden restored it as good as new, but I'm very careful now. These radios don't have the protections built into ham and commercial rigs. Maybe the 396XT is improved in this regard, but I would not count on it.

 

[Pueo]

All good ideas and food for thought. I've tried the external antenna and since we Hot Seat our vehicles I don't want the hassles of attaching and removing antenna each shift change. Now I'm wondering if the antennas(directional) from the Mounted radar unit could have an effect on my portable scanner placement. Can't be too careful now days given the cost of digital scanners. Perhaps I can have our Radio shop contractor check for transmission output levels on the Radar unit and my Patrol radios with my scanner in its usual spot. I'm sure they have a meter for that? I'll post any findings on the next radio maintenance cycle.

 

[ko6jw_2]

Proximity issues

I doubt if the radar will have much effect on the scanner since it is so far away from the passband of the receiver. That said, it is possible that strong signals will lower sensitivity even if they don't cause interference or damage to the radio. This is because the strong signal will be present in the receiver's front end and will cause the radio's limiters to reduce gain. This is true even if you don't hear the other signal.

If you were in your own car, you might look at some sort of filter set up (assuming what you listening to on the scanner is not in the same band as your regular radio). In your case, that probably won't work.

I doubt if your radio techs can help too much. You would need a spectrum analyzer to look at the signals present in the car and they are probably not equipped or inclined to do that.

I would suggest experimenting with the placement of the scanner in the car and not worrying too much about damage. My problems came from a 100 watt transmitter a few inches from the scanner. You're not running that kind of power.

Best of luck.

 

[Pueo]

ko6jw 2 thanks for pointing out the passband difference with the Radar unit I'm not a radio guy but I do understand the band gap. 100 watt transmitter! I haven't dealt with that much radio power since my days as a Marine Corps Helicopter crewchief and our HF radio antennas. I believe you and the others who responded answered my concern and I'll continue to use the scanner as I normally do but, I'll be aware of locating scanner next to any transmitting radio antennas. As for filter, game stopper I am scanning on same net/groups as my mobile transmits so maybe I will try to come up with a quick setup external antenna. If Hawaii County LE/EMS weren't analog and up on the P25 I wouldn't have these issues as we could add them to our PACMERS group. Thanks again I have no other concerns.