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Blowing up my BC 780XLT with my ICOM IC-V8000 ?

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I have a BC 780XLT scanner installed in my car (powered through cigar lighter) with a 48-in whip on my trunk lid. I also have an ICOM IC-V8000 2-meter transceiver (25/50/75 watts output) installed in the same car; the antenna for the ICOM is a ¼-wave whip on the roof top. Power to the ICOM is hard wired to the battery; return is ground bus to chassis under hood.

Question: Will I damage my scanner if I transmit on my 2-meter rig, whether or not I have the power of the scanner turned on (assuming the antenna to the scanner is not disconnected)? I have used the transmitter with now apparent damage to the scanner (scanner still receives the same). I have tranmitted only on low (25w) power to nearby repeaters.

Thanks.
 

n3zra

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I have a v-8000 installed in my vehicle, scanner antenna and 5/8 wave 2m antenna are seperated by about 2 feet, (on oppisite sides of the trunk of the car, only problem is slight desense of the scanner on the vhf high band, or rarely feedback through the scanner on another frequency because of RF overload (usually only occours in high RF areas when using the 2m rig).
 

hsdtech

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I would think that if you have the scanner ON it will be damaged. I don't see how TX would affect the scanner when it is OFF.
 
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hsdtech said:
I would think that if you have the scanner ON it will be damaged. I don't see how TX would affect the scanner when it is OFF.
Even with the scanner power off, the scanner antenna is physically and electrically connected to the scanner's front end electronic hardware. I can't seem to make myself believe that just because my scanner power is off, my transceiver rf power refuses to get into the scanner's FET front end. There is still a return path in the scanner even with the scanner power turned off. Ideally, I would like to short (shunt to ground) the scanner antenna input at the scanner whenever I transmit. Maybe that would be a good invention for some ambitious hobby-ist (electronically short scanner antenna input when when keying transmitter). This is most likely done internally in the ICOM transceiver (transmitter/receiver).
 

K5MAR

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I've got two 780s in my truck, along with two 100 watt Motorola rigs, a VHF and a UHF. Other than feedback and desensing, I don't have any problems. Both Motorolas have a combination of ham and public safety/commercial freqs. Both 780s still work fine.

Consider: there are plenty of public safety vehicles that have scanners along with their "business" radios. There are also plenty of TV station vehicles that have scanners along with their various "business" radios and tranmitters. If having two-way radios in close proximity to their scanners were a problem, how could they do that?

Mark
 

W4KRR

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K5MAR said:
I've got two 780s in my truck, along with two 100 watt Motorola rigs, a VHF and a UHF. Other than feedback and desensing, I don't have any problems. Both Motorolas have a combination of ham and public safety/commercial freqs. Both 780s still work fine.

Consider: there are plenty of public safety vehicles that have scanners along with their "business" radios. There are also plenty of TV station vehicles that have scanners along with their various "business" radios and tranmitters. If having two-way radios in close proximity to their scanners were a problem, how could they do that?

Mark
What they're describing happened to me many years ago. I was in a vehicle with a 100 watt VHF low band radio, and an external scanner antenna connected to an old Regency HX1000 scanner. After transmitting, the scanner suddenly stopped receiving; it acted as if the sensitivity had gone bad. It had. I sent it in for service, and they replaced a diode in the front end. It worked fine after that.

Maybe it won't happen all the time, but it's possible. Sort of like getting struck by lightning!
 

K5MAR

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Statistically, anything can happen, given a large enough pool. But there are a lot of users out there that haven't had any problem. So, like being struck by lightning, your personal odds are pretty low. In the case of your scanner, ken, it could have been a defective diode to begin with.

The only scanner I've ever had fail was one I set up at the local Red Cross office. The only transmitters in the area were various cellphones, and the scanner didn't cover the 800 MHz band.

Heck, if I considered every possible thing that might happen to me each day, I'd never get out of bed. And do you know how many people my age and older die in bed? :D

Mark S.
 
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In retrospect, my original post should have included my factory-installed AM/FM radio (with its antenna embedded in rear window). Any thoughts on this or for these (or other, for that matter) radios with whip antennas? Anybody's AM/FM radio go kaput because of nearby high-powered transmitters? Just curious, not too worried about my AM/FM radio.

Peter
 

K5MAR

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Nope.

I have the following in my truck, in addition to a Panasonic AM/FM Stereo CD in the factory slot.

Motorola Syntor-X 100 watt VHF
Motorola Syntor-X 100 watt UHF
Alinco DR-610 VHF/UHF ham mobile
Alinco DR-135 VHF ham mobile (for APRS)
Alinco DR-M06 6m ham mobile
Motorola Mocat 40 ch. CB radio
Cingular cellphone hands-free cradle setup
Cingular cellular EDGE datacard (for mobile wireless Internet w/laptop)
Garmin II+ GPS w/ external active antenna
2 Uniden BC-780 XLT scanners
6" LCD color TV w/ external antenna

I've had this setup in my truck for several years, and to date I haven't had any radio fail. When traveling I use the DR-610 for repeaters, and the Moto VHF for 146.52 simplex. As you might imagine when using the Moto the Alinco desenses; and depending on the freqs selected the 780s occasionally give me some feedback. Other than that, no problems. So I wouldn't be overly concerned about using your ham rig while the scanner is on.

YMMV.
Mark S.
 

K3ONW

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I Have Knocked The Front End Out Of A Bc-780xlt And A
Pro-2067 Over The Years While Using A 50 Watt 2 Meter
Rig. In Both Cases, The Problem Was Caused By A Poor
Ground At The Base Of The 2 Meter Antenna. (rust &
Broken Shield)

Now, When I Change My Set-up, I Remove The Coax From The Scanner And Connect A Small Flashlight Bulb Or My
Rf Volt Meter Across The Scanner Antenna Connector And Make A Brief Transmission. If The Bulb Lights Or The
Meter Shows Rf, It's Time To Investigate.. Every Set-up
And Every Rig Is Different....
 

OpSec

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ILikeHatchChili said:
In retrospect, my original post should have included my factory-installed AM/FM radio (with its antenna embedded in rear window). Any thoughts on this or for these (or other, for that matter) radios with whip antennas? Anybody's AM/FM radio go kaput because of nearby high-powered transmitters? Just curious, not too worried about my AM/FM radio.

Peter

No issues. I had a 2002 Chevy Impala LS with the printed circuit antenna on the rear glass, and I had three 110w Motorola's with NMO antennas on the trunk with no ill effects to the AM/FM radio other than some desense in weak FM signal areas. The Moto's were transparent on AM stations.
 
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The only radios that I have that had "blown" front ends are a portable Sangean SW radio and a Sony ICF-2010 (also shortwave).

With the Sangean, I had noticed that the AM sensitivity had dropped drastically from one day to the next. I remember using the radio outdoors with a long wire antenna the day before the radio went bad. In New Mexico, especially in the winter, the air can be cold and very dry, and static electricity can be problem. I suspect that a static charge had gotten through the long wire and zapped the front end. I sent the radio back for repair; they said that the front end FET had blown.

WIth the Sony, I read once in the internet that you could check if that particular radio's sensitivity was down simply by tuning to a certain point in AM frequency where the loop antenna's job is taken over by the whip (somewhere around 2000 kHz or so). If you could NOT hear a discrete change in the noise level at that frequency transition, then the front-end FET was destroyed. Sure enough, I could not discern the noise level change. The article in the internet also told you how to replace the involved FET and how to add a back-to-back configuration of 1N914 diodes (all components from Radio Shack) at the antenna input. The diodes would short out any high voltage spikes (like static electric) and prevent them from destroying the FET. I did the repair and the radio has been fine since.

I imagine in cold, dry weather, and especially with a whip antenna (especially without a ball on the end of the whip), on a speeding car, static electricity build up and discharge through the antenna into the radio and destroy the receiver's front end if it was not protected with something like the diode configuration I described.
 

kb2vxa

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Hi Hatch and all,

Whether or not you realize it you have answered your own question. Please ignore this and all other answers, you are right and all else is superflous.
 
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