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AR15.COM
10/25/2008 8:42:29 PM EDT
So I have a seperate VHF mobile and UHF mobile radio. I also have seperate base station antennas for each radio. My question is can I mount both of them to the same mast, side by side so to speak or will I run into problems. Obviously when receiving there would not be a problem but what about transmitting having two antennas that close?
10/25/2008 8:53:35 PM EDT
[#1]

Quoted:


So I have a seperate VHF mobile and UHF mobile radio. I also have seperate base station antennas for each radio. My question is can I mount both of them to the same mast, side by side so to speak or will I run into problems. Obviously when receiving there would not be a problem but what about transmitting having two antennas that close?


mike,



ideally, you would mount them one above the other; this will significantly reduce crosstalk between the two radios.  however, this is not always practical.  that said, whether or not transmitting causes problems depends on a few things.  for example, what type (manufacturer and model) radios are these?  what type of antennas are you using?



ar-jedi
 
10/25/2008 9:42:09 PM EDT
[#2]


Both of the mobiles are Kenwoods. The antennas are copper J-poles

10/25/2008 9:44:14 PM EDT
[#3]

Quoted:



Both of the mobiles are Kenwoods.



commercial or amateur?



ar-jedi
 
10/25/2008 9:54:50 PM EDT
[#4]
J Poles - how far apart are you thinking?  Would you be using both base stations simultaneously?
10/26/2008 7:05:43 AM EDT
[#5]
Both radios are commercial and the antennas would only be inches apart on the same mast. I would not be transmitting with both radios at the same time, only receiving and only transmitting with one at a time.
10/26/2008 7:30:10 AM EDT
[#6]


i think you could end up damaging one radio or the other with that setup.  

is there any way you can get the antennas one above the other?



ar-jedi


10/26/2008 7:51:20 AM EDT
[#7]


Quoted:



i think you could end up damaging one radio or the other with that setup.

is there any way you can get the antennas one above the other?



ar-jedi





Yes that should not be a problem. Would it work ok if one was above the other?
10/26/2008 7:56:06 AM EDT
[#8]

Quoted:




Yes that should not be a problem. Would it work ok if one was above the other?


yes, that is the ideal way to do it.  



ar-jedi



 
10/26/2008 9:52:21 AM EDT
[#9]

Quoted:



Quoted:



Yes that should not be a problem. Would it work ok if one was above the other
yes, that is the ideal way to do it.  



ar-jedi

 
Yep.  Try to get them as close to directly vertical if possible, and with a little separation in height.  I agree that the "inches apart" would probably lead to radio problems (if not damage) as well as antenna performance issues.





 
10/26/2008 2:17:58 PM EDT
[#10]
Ideally, you would want them a little more than 1 meter apart (1/2 wavelength).  Closer than that they will cause issues.  You could also construct a beam to push each jpole out from the tower on each side and get some separation, but over/under is preferred.