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Posted: 10/27/2010 11:58:09 AM EST
can I have a scanner, CB, and HAM antennas..... all on the same mast?
Link Posted: 10/27/2010 12:28:39 PM EST
[#1]
You can have them mounted to each other if you want.



I have a discone and a windom in the attic only a few feet apart and, besides the HF swamping the 2 meter rig, I've had no problems.  It's very doubtful you'll be transmitting on the Ham and CB at the same time, so it probably won't be a problem.
Link Posted: 10/27/2010 1:29:58 PM EST
[#2]
they DOOO affect one another.. its called parasitic coupling..

the rule of thumb is 1/4 wave space between the lowest freq you are listening or transmitting..  if that is not possible then seperation in elevation and space works too..

if that doesnt work then just run a test meter on your sticks before transmitting..
Link Posted: 10/27/2010 1:52:34 PM EST
[#3]
Without sufficient isolation, in-band amateur radio transmissions (6m, 2m, 440) can toast the front end of a scanner. Probably not from a 5w handheld but a 50w mobile can. ICE makes a protector to prevent that.

Vertical separation is the best way to get isolation, if the mast is tall enough.  Put the antennas absolutely in-line, one on top of the other.  The CB antenna can go anywhere provided you're talking about VHF/UHF amateur antennas.

Aside from RF effects on the equipment, you will get some pattern distortion with antennas side by side.  Avoiding resonant distances between the antennas on any frequency that is used will help minimize distortions.
Link Posted: 10/27/2010 1:52:39 PM EST
[#4]
I doubt that I'd be transmitting at the same time.....but the issue may be monitoring.

will having the antennas in such close proximity (2 ft) cut down on the recieving ability?

I was thinking of making a "Y" shaped topper for my mast.....and on the end of each point.....having a different antenna.

I will have them all insulated from the mast pole.

How should I route my cables?......twisted around the pole or straight run?

Thanks for all your help folks.....I'm sorry for all the novice questions.....but this is the best resource I've found for my mind set.
Link Posted: 10/27/2010 2:01:39 PM EST
[#5]
Quoted:
I doubt that I'd be transmitting at the same time.....but the issue may be monitoring.

will having the antennas in such close proximity (2 ft) cut down on the recieving ability?

We were posting about the same time... reference my previous post, would recommend horizontal spacing that avoids resonant distances (any 1/4 wave multiple) between the antennas on any frequency that is in use, and as far as is practical.  Would suggest at least 5/8 wave on 2m/VHF high band (~50 inches) as an example.

I was thinking of making a "Y" shaped topper for my mast.....and on the end of each point.....having a different antenna.

I will have them all insulated from the mast pole.

Why?  A bad idea for grounding.

How should I route my cables?......twisted around the pole or straight run?

Twisting is irrelevant... install them however works best for you.

Thanks for all your help folks.....I'm sorry for all the novice questions.....but this is the best resource I've found for my mind set.


Link Posted: 10/27/2010 2:03:26 PM EST
[#6]
What frequencies are you talking about for the amateur antenna?
Link Posted: 10/27/2010 2:56:54 PM EST
[#7]
it's a IC-718

When you say horizontial spacing.....would you recommend 2 masts?

I had it in my head from my buddies CB set up.....it was grounded.....but at the base. The antenna itself was insulated from the mast....30ft+/-
Link Posted: 10/27/2010 5:54:51 PM EST
[#8]
Quoted:
it's a IC-718

HF antennas are probably a whole 'nother ball of wax here.  What kind of antenna are you putting up for that... dipole?  Other than just to avoid physical contact between the elements you shouldn't have problems between HF and scanner antenna.

If you have a 5/8 wave CB antenna you could mount it at the top of the mast and use it with a tuner for all the higher HF bands except maybe 12.  My recommendation would be to tune it for 10m and sell your CB.
Link Posted: 10/28/2010 3:19:20 AM EST
[#9]

Chart detailing the separation needed and at what frequency. You really don't want to transmit watts into a receiver designed for milliwatts.
Link Posted: 10/28/2010 5:26:43 AM EST
[#10]
Quoted:
http://Www.repeater-builder.com/antenna/images/vertsep.jpg
Chart detailing the separation needed and at what frequency. You really don't want to transmit watts into a receiver designed for milliwatts.


A little distance would be a good thing...

Thanks for the help guys.
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