CB's & Scanners

[gcoleman]

Hey all, seeking some advice from the forum once again. My apologies for being absent from here lately, been busier than H.E. you know what with work and school. Anyhow Im upgrading my CB's in my truck to the NMO antennas (browning BR140 or Laird C27 models depending on funding) and a BR800 or MaxRad scanner antenna on an NMO as well. I was thinking of spacing each antenna 12" apart, starting on the roof 8" away from my third brake light to avoid static interference when the lights are on (in line down the center of the roof). The whips come stock at 49" for the CB's but Im trimming them down some according to the online tuning chart. I was curious if they would be too close to one another and interfere. My cbs currently stay on a different channel each (one usually on CH6 and one on CH30) and I plan on upgrading to a uniden BCT8 scanner to work with all the local police/EMS in my area (nobodys digital yet) coupled with the browning BR800 (if itll work) or the maxrad scanner antenna. Thoughts? I know its alot of information and possibly an effort in futility buutt if I can make it work, I will.
Thanks guys - Glen

 

[bnolte]

If I remember back in the day, the truckers mounted their antennas on the mirrors, as they were close to 8 feet apart. This is about 1/4 wavelength on 27 Mhz, or as we hams nickname it, the 11 meter band. This will give the array directionality forward and backwards, a useful property when on the road.

As far as choice of a scanner antenna, it depends on the frequencies they use. Up here around the big city, most are either on trunked systems up in the 800 Mhz band, some of the outlying areas and maritime interests use VHF, between 148 and 174 Mhz, but a few backwoods areas still use VHF low band (30-50 Mhz). This band is more subject to interference from skip and atmospheric noise than the higher bands. Interesting if you are looking for DX, not so good when you want predictable performance. Its tough to make specific recommendations, wideband scanner antennas tend to perform poorly compared to antennas purpose built for a particular frequency. If your important scanner frequencies are in the VHF or UHF part of the spectrum, you shouldn't see too much interference from CB, just don't program your scanner to CB frequencies.

73 and good luck,

Bruce N3LSY

 

[gcoleman]

Bruce, I actually just sold my co-phase antenna set up to a friend of mine who's implementing it on his jeep for offroading. The BR800 antenna is base loaded and tuned for 800MHZ frequency fields but its a trancieving antenna, most scanner antennas are receive only, so Im probably going to go with the antennas built for scanners (kindof a no brainer I know but theyre more expensive and if I can get the same effect with a cheaper antenna, I will lol)

In cop speak, Im 10-42 for now, Ill be 10-8 later.