RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Commercial, Professional Radio and Personal Radio > Commercial Radio Antennas


Commercial Radio Antennas - Please keep discussion related to professional, commercially used antennas and antenna systems for the two-way radio industry. Topics for the use of these antennas on amateur bands are accepted here.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 01-21-2018, 3:14 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default Scanner/VHF/CB Antenna Solutions

Hello Everyone,
I am currently waiting on my 2007 Ford Crown Victoria P71 to be shipped to me. I just purchased a console for it and will get started on the installation once it arrives. I plan to install a BCD536HP, Harris/MACOM M7100 VHF (100watt) radio and a Uniden PRO520XL 4watt CB. I am having trouble thinking of antenna solutions.
I'm wanting to install the NMO CB antenna in the center of the trunk, the NMO 1/4 VHF antenna centered on the roof and a window mount antenna at the very top centered back window. The problem with the window mount is that the window is tinted and well, glass mount antenna's are garbage. I wouldn't be against taking the vehicle to the my local window tinting shop and having them cut a square out of the tint to mount the antenna if that's possible. I was also thinking of doing a trunk lip mount for the scanner, but am unsure about the antenna spacing between the scanner antenna and the CB antenna.
As far as the scanner goes, I am wanting to scan VHF/UHF (Aviation & Public Safety) as well as 800Mhz. Does anyone have any advise or solutions?
__________________
John Longoria
KG5HHS
Reply With Quote
Sponsored links
  #2 (permalink)  
Old 01-21-2018, 3:20 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

I just came across this duplexer (https://www.theantennafarm.com/catal...t-cf-360a-1640) Band1 being 1.3-30MHz and Band2 being 49-470MHz. Would something like this work? If so, I will place this on the Trunk NMO antenna, and put a NMO scanner antenna on the roof.
__________________
John Longoria
KG5HHS
Reply With Quote
  #3 (permalink)  
Old 01-22-2018, 2:32 AM
madrabbitt's Avatar
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Apr 2004
Location: NM
Posts: 521
Default

Use the duplexer on the NMO CB antenna, and feed the scanner with it, and put a NMO on the roof, center mounted for the VHF if you plan on transmitting with it.

You're not going to be scanning anything under 30 mhz, a long whip makes an excellent all band scanner antenna, and 4 watts from a CB isnt going to cause any issues into a commercial radio like the harris.

I would be slightly concerned with 100 watts of RF coming off the VHF into the scanner. The duplexer will help cut it down a bit, but its still possible to overload the scanner.
Reply With Quote
  #4 (permalink)  
Old 01-22-2018, 3:12 AM
jonwienke's Avatar
Member
   
Join Date: Jul 2014
Location: PA
Posts: 8,884
Default

Quote:
Originally Posted by madrabbitt View Post
a long whip makes an excellent all band scanner antenna
Not once it gets longer than 3/4-wave; the gain pattern goes vertical rather than horizontal. It will work OK for 6-meter and maybe FM broadcast, but not anything above that, especially UHF/800.

Quote:
I would be slightly concerned with 100 watts of RF coming off the VHF into the scanner. The duplexer will help cut it down a bit, but its still possible to overload the scanner.
No "slightly" about it; you run a major risk of frying the scanner. The duplexer won't offer any protection, given that VHF is in its passband. I have 500mW feeding into my scanner coax when I key up a 25-watt radio, and a 100W radio could feed 2W or more into your scanner's front end. That is an excellent way to fry it.

Before cennecting your scanner, hook up a decent watt meter to the scanner coax, and key up the 100W radio at full power to see how much power feeds into the scanner coax. You'll probably be surprised.
__________________
Gone camping.
Reply With Quote
  #5 (permalink)  
Old 01-23-2018, 10:39 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

Quote:
Originally Posted by jonwienke View Post
No "slightly" about it; you run a major risk of frying the scanner. The duplexer won't offer any protection, given that VHF is in its passband. I have 500mW feeding into my scanner coax when I key up a 25-watt radio, and a 100W radio could feed 2W or more into your scanner's front end. That is an excellent way to fry it.
So the distance between the trunk (VHF Antenna) and the roof (Scanner Antenna) is not enough distance? If that is the case would buying an antenna switch solve the problem? Could I connect the scanner to a watt meter, then from there to an antenna switch that would switch between the scanner antenna on the roof and a dummy load? That way then I need to transmit on the VHF radio I could switch the scanner to a dummy load.
__________________
John Longoria
KG5HHS
Reply With Quote
Sponsored links
  #6 (permalink)  
Old 01-25-2018, 9:30 AM
BC_Scan's Avatar
Member
   
Join Date: Aug 2006
Location: Vancouver BC
Posts: 359
Default

For Scanner this is my go to preference in a mobile environment, every vehicle from service to personal I have put one of these on and for me it works like a hot damm.I have used it exclusively for close call and picked up from AM all the way to 800 mhz, I have driven thru my Province and and across the Country with it. Its low profile , you could mount wherever there is space.
https://www.wearecb.com/bmaxscan1000...r-antenna.html
Reply With Quote
  #7 (permalink)  
Old 01-25-2018, 10:41 AM
Member
   
Join Date: Nov 2005
Location: JoCo, KS (SoDak native)
Posts: 308
Default scanner/cb

a couple of comments

the duplexer is a possible solution, but.... If the MNO CB antenna has a grounded coil (most do), it will be very deaf above 27 mhz.... on the other hand, if it is a whip with elevated coil, then you may be OK.....

I would just use a trunk lip mount for the scanner. I have done that on several vehicles, the CB doesn't put out enough RF to damage the scanner input.

Just a note, the P71's had non metal trunk lids for several years.....

$.02
Reply With Quote
  #8 (permalink)  
Old 01-25-2018, 2:31 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

Quote:
Originally Posted by byndhlptom View Post
a couple of comments

the duplexer is a possible solution, but.... If the MNO CB antenna has a grounded coil (most do), it will be very deaf above 27 mhz.... on the other hand, if it is a whip with elevated coil, then you may be OK.....

I would just use a trunk lip mount for the scanner. I have done that on several vehicles, the CB doesn't put out enough RF to damage the scanner input.

Just a note, the P71's had non metal trunk lids for several years.....

$.02
Thank you for the reply,

This is the antenna I plan on using (https://www.theantennafarm.com/catal...logies-c27-690) from what I can see it does not have a grounded coil.

My concern is not the CB putting out to much RF, its the 100watt radio putting out to much RF that I am worried about.
__________________
John Longoria
KG5HHS
Reply With Quote
  #9 (permalink)  
Old 01-25-2018, 3:37 PM
Member
   
Join Date: Nov 2005
Location: JoCo, KS (SoDak native)
Posts: 308
Default cb/scanner

the antenna you referenced is a DC grounded antennas. it is in the description......

you will not see much isolation on a vehicle if the only separation is horizontal. Putting the scanner antenna on the trunk gives "some" isolation, but at 100watts VHF you will at minimum see desense on the scanner. Whether it does damage is to be determined.....

Do you really need 100watts?

$.02
Reply With Quote
  #10 (permalink)  
Old 01-25-2018, 3:40 PM
Member
   
Join Date: Sep 2006
Location: Southern California
Posts: 152
Default

Quote:
Originally Posted by KG5HHS View Post
... and well, glass mount antenna's are garbage....
Not necessarily. I had an Antenna Specialists 2 meter glass mount antenna and it worked just fine. It lasted about 10 years until the dual sided tape and silicone chaulking started to go bad. I simply cleaned the surfaces with denatured alcohol and reattached it with 3M external grade, dual sided "tape". Lasted many more years.
__________________
No man has a good enough memory to be a successful liar. -- Abraham Lincoln
Reply With Quote
  #11 (permalink)  
Old 01-25-2018, 4:56 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

Quote:
Originally Posted by byndhlptom View Post
the antenna you referenced is a DC grounded antennas. it is in the description......

you will not see much isolation on a vehicle if the only separation is horizontal. Putting the scanner antenna on the trunk gives "some" isolation, but at 100watts VHF you will at minimum see desense on the scanner. Whether it does damage is to be determined.....

Do you really need 100watts?

$.02
Wow... First thing in the description box. Totally looked right over that. As far as needing 100watts, I wont need it most of the time, I could get away with 50. One of the counties I work in is 3000 sq mi, so there will be times where 100watts will be required.

How far apart would the scanner antenna need to be from the radio antenna?
__________________
John Longoria
KG5HHS
Reply With Quote
  #12 (permalink)  
Old 01-25-2018, 5:54 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

Just came across this from another thread (https://forums.radioreference.com/ge...nearby-rf.html). The ICE LTD RF Limiter / receiver protector Model 199 (Limiter / Arrestor, VHF / UHF 30-500MHz). Would a device like this work? (Receive Only Processing Equipment)
__________________
John Longoria
KG5HHS
Reply With Quote
  #13 (permalink)  
Old 01-25-2018, 7:56 PM
Member
   
Join Date: Jun 2013
Location: Texas
Posts: 3,094
Default

Quote:
Originally Posted by byndhlptom View Post
a couple of comments

the duplexer is a possible solution, but.... If the MNO CB antenna has a grounded coil (most do), it will be very deaf above 27 mhz.... on the other hand, if it is a whip with elevated coil, then you may be OK.....

I would just use a trunk lip mount for the scanner. I have done that on several vehicles, the CB doesn't put out enough RF to damage the scanner input.

Just a note, the P71's had non metal trunk lids for several years.....

$.02
Non-metal? State your source please. It's a well known fact that P71's had aluminum trunk lids for select model years but this is the first I've heard of fiberglass trunk lids.

Sent from my SM-T713 using Tapatalk
Reply With Quote
  #14 (permalink)  
Old 01-26-2018, 2:26 PM
Member
   
Join Date: Nov 2005
Location: JoCo, KS (SoDak native)
Posts: 308
Default P71

oops, my error, you are correct, they were aluminum, not fiberglass. Just remember that mag mounts didn't work very well on them.... ;<)

$.02
Reply With Quote
  #15 (permalink)  
Old 01-26-2018, 2:30 PM
Member
   
Join Date: Nov 2005
Location: JoCo, KS (SoDak native)
Posts: 308
Default scanner antenna

Since on a car, horizontal separation differences of 3-6 feet are practically the same, it really doesn't make much difference. if you have a short scanner antenna, the roof of car will provide "some" shielding for tthe 100w tx, just don't expect miracles....

$.02
Reply With Quote
  #16 (permalink)  
Old 01-26-2018, 4:23 PM
Member
   
Join Date: Mar 2003
Location: Chicago area
Posts: 1,027
Default

Quote:
Originally Posted by byndhlptom View Post
a couple of comments

the duplexer is a possible solution, but.... If the MNO CB antenna has a grounded coil (most do), it will be very deaf above 27 mhz.... on the other hand, if it is a whip with elevated coil, then you may be OK.....

I would just use a trunk lip mount for the scanner. I have done that on several vehicles, the CB doesn't put out enough RF to damage the scanner input.

Just a note, the P71's had non metal trunk lids for several years.....

$.02
Ford PI has not had a aluminum trunk lid since 1997
Reply With Quote
  #17 (permalink)  
Old 02-09-2018, 1:18 AM
bwca44's Avatar
Member
   
Join Date: Nov 2009
Posts: 304
Default

Quote:
Originally Posted by bb911 View Post
Not necessarily. I had an Antenna Specialists 2 meter glass mount antenna and it worked just fine. It lasted about 10 years until the dual sided tape and silicone chaulking started to go bad. I simply cleaned the surfaces with denatured alcohol and reattached it with 3M external grade, dual sided "tape". Lasted many more years.
I had an antenna specialists cellular band antenna years ago... I had to replace it every few months it just kept falling off.
Reply With Quote
  #18 (permalink)  
Old 03-15-2018, 10:01 PM
KG5HHS's Avatar
Member
  Shack Photos
Shack photos
Amateur Radio Operator
Amateur Radio
 
Join Date: May 2015
Location: San Angelo, TX
Posts: 426
Default

I have decided not to put a CB in my vehicle. The console I have does not have room for it. Plus, with putting a scanner in, I will still be able to at least monitor the CB Band. I decided to go with the Larson NMO150/450/800 antenna (https://www.theantennafarm.com/catal...0-450-800-1050) for the scanner that will go on the roof of my crown vic. I also decided to go with the Laird QWB144 (https://www.theantennafarm.com/catal...ies-qwb144-719) that will be mounted in the center of the trunk for my VHF P25 radio. 95% of the time I will be only monitoring 144-160mhz. When I do transmit, I will mostly transmit in the 2M amateur band at 50watts, but will occasionally need the 100 watts and will occasionally also be transmitting in the 155-158mhz area also at 50 watts , 100watts depending on how far out I am.

I went to go order the ICE RF Protector (model 199) but found that they no longer make it. I have found several different makes and models from protection from 0.5mhz-150mhz, but that is not high enough for the RF Protection I need to the scanner. Can someone point me in the right direction as to where I can find something to protection my scanners front end for RF overload from my VHF radio when I transmit. Everything will be in a console so I wont be able to just disconnect the scanners antenna when I transmit.
__________________
John Longoria
KG5HHS
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 12:53 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2015 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions