RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Topic Specific Forums > Antennas and Associated Hardware > Scanner / Receiver Antennas

Scanner / Receiver Antennas For discussion of any type of receiving antenna used by a scanner or receiver base, mobile or handheld.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 08-04-2014, 10:25 AM
Member
   
Join Date: Nov 2012
Posts: 38
Default Scanner antenna VHF only vs multiband

I'm going to be installing my BC355N scanner in my vehicle. All but one of the frequencies I will be monitoring are in the 151-162 MHz range. One frequency will be in the 800 MHz range. Would I be better off getting a multiband antenna like the Larsen NMO 150/450/800 or just a VHF whip antenna since I only will be receiving one 800 MHz frequency.
Reply With Quote
Sponsored links
  #2 (permalink)  
Old 08-04-2014, 10:43 AM
N8IAA's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2002
Location: Fortunately, GA
Posts: 5,181
Default

Quote:
Originally Posted by billyfromhill View Post
I'm going to be installing my BC355N scanner in my vehicle. All but one of the frequencies I will be monitoring are in the 151-162 MHz range. One frequency will be in the 800 MHz range. Would I be better off getting a multiband antenna like the Larsen NMO 150/450/800 or just a VHF whip antenna since I only will be receiving one 800 MHz frequency.
First, what is the size of the antenna? Is it a quarter wave? Length approximately 18"? Or, is it a 5/8 antenna, approximately 3' in length?
I have the Larsen tri-band antenna and it works maybe a bit better than a Larsen uncut quarter wave on 800MHz.
I'm sure all the antenna purists out there will tell you to have an antenna cut to length to receive. But, the Larsen uncut antenna is resonant at 800MHz.
It's really up to you to make the final decision.
Larry
__________________
Digital/Analog scanning and hamming
Reply With Quote
  #3 (permalink)  
Old 08-04-2014, 10:47 AM
Member
   
Join Date: Nov 2012
Posts: 38
Default

The VHF antenna would be 1/4 wave and be around 21". The multiband antenna is around 16.5" long.
Reply With Quote
  #4 (permalink)  
Old 08-04-2014, 11:26 PM
N8IAA's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2002
Location: Fortunately, GA
Posts: 5,181
Default

Go with the one you think will work. I was using the uncut 1/4 wave mostly for VHF air and VHF hi. 800 was just a lucky by product
Larry
__________________
Digital/Analog scanning and hamming
Reply With Quote
  #5 (permalink)  
Old 08-05-2014, 7:01 PM
Member
   
Join Date: Nov 2012
Posts: 38
Default

I think I'm going to go with the Larsen NMO 150/450/800. Does anybody know what the bulge is halfway up on the antenna?

Reply With Quote
Sponsored links
  #6 (permalink)  
Old 08-05-2014, 8:27 PM
Member
  Amateur Radio Operator
Amateur Radio
 
Join Date: Jul 2007
Location: NW Ohio
Posts: 1,346
Default

Not sure if it is a coil, a capacitor or a trap. In short, it electrically cuts off the part of the antenna above it on higher frequencies.
Reply With Quote
  #7 (permalink)  
Old 08-05-2014, 10:03 PM
Halfpint's Avatar
Member
  Premium Subscriber
Premium Subscriber
 
Join Date: Apr 2004
Location: Slightly NE of the People's Republic of Firestone high atop the redwoods of Venus!
Posts: 975
Default

Quote:
Originally Posted by billyfromhill View Post
I think I'm going to go with the Larsen NMO 150/450/800. Does anybody know what the bulge is halfway up on the antenna?

Well... If it is like the one I had that bulge is a coil that is supposed to be making the upper part resonant at the higher frequencies. I discovered that it was a coil after I managed to break it whilst herding some horses back onto our property. (Apparently I misjudged just how much clearance I had when I chased them through one of the groves of trees along our SW section of fence line. Though, up until then I'd driven through them before and hadn't had any problems. {GRIMACE!}) When we sold that pickup I warned the new owner to be very careful about making clearance calculations. {VB GRIN!}
__________________
Doleo ergo sum,
Halfpint
Show me a piano falling down a mineshaft and I'll show you A-flat miner.

Reply With Quote
  #8 (permalink)  
Old 08-07-2014, 10:16 PM
Member
   
Join Date: Nov 2012
Posts: 38
Default

Does this antenna also have a spring in the base or is there only the one spring on the whip?
Reply With Quote
  #9 (permalink)  
Old 08-07-2014, 10:31 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: SNCZCA01
Posts: 2,732
Default

No spring on the base, but you can purchase them separately. You just need to shorten the antenna (from the bottom up) to compensate for the extra length.
Honestly, though, the Larsen antennas I've had with the same base are pretty flexible without the spring. Unless you have frequent meetings with low tree branches and angry parking garages, you might not need it.
Reply With Quote
Sponsored links
  #10 (permalink)  
Old 08-07-2014, 10:33 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: SNCZCA01
Posts: 2,732
Default

But if you wanted to:
http://www.theantennafarm.com/catalo...ingb-3878.html
Matching color and everything.
Reply With Quote
  #11 (permalink)  
Old 08-07-2014, 10:45 PM
ronhl's Avatar
Member
   
Join Date: Jun 2003
Location: Live Free or Die St.
Posts: 115
Default

I've used the Larsen NMO 150/450/800 for yrs with a mag mount and is an excellent choice for the 3 bands specified. There is no spring, its short ab 20" so really no need.
__________________
Started back in the '70s...so there's been many others over the yrs.
BC-780XLT, BCD396T, BCD996T
IC-R20,IC-R2500,IC-2820H
PRO-64, PRO-95,PRO-96,PRO-2096,PRO-197,PRO-106
Reply With Quote
  #12 (permalink)  
Old 08-07-2014, 10:45 PM
Member
   
Join Date: Nov 2012
Posts: 38
Default

I was more asking if there was a loading spring/coil in the base in addition to the spring/coil halfway up the antenna. Larsen does rate the antenna up to 100 watts.

I have that exact same spring on my Larsen NMO27C antenna for my CB.

Could I use my NMO27C whip and spring on the NMO150/450/800 base?
Reply With Quote
  #13 (permalink)  
Old 08-07-2014, 10:52 PM
jhooten's Avatar
Member
   
Join Date: Mar 2004
Location: Paige, Republic of Texas
Posts: 1,277
Default

I use a Motorola 16" SS wire NMO vhf quarter wave for my mobile scanner antenna. It works fine on vhf high, uhf, and 800. vhf low is weak but readable.
__________________
Jerry

I read it on the internet, so it must be true.
Reply With Quote
  #14 (permalink)  
Old 08-11-2014, 3:25 PM
Member
   
Join Date: Nov 2012
Posts: 38
Default

How well does the NMO 150/450/800 work with VHF if it's only 16.5" long? 16" seems rather short for high-VHF
Reply With Quote
  #15 (permalink)  
Old 08-11-2014, 4:41 PM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: SNCZCA01
Posts: 2,732
Default

Not really. The coil adds some length. 17.5 inches is right about 160MHz. 16.5 with the center load isn't that much of a stretch for 1/4 wave on VHF.
Reply With Quote
Sponsored links
  #16 (permalink)  
Old 08-12-2014, 8:54 AM
Member
   
Join Date: Nov 2012
Posts: 38
Default

I though the coil only helps when transmitting. Does it add length when receiving also?
Reply With Quote
  #17 (permalink)  
Old 08-12-2014, 9:49 AM
mmckenna's Avatar
Member
   
Join Date: Jul 2005
Location: SNCZCA01
Posts: 2,732
Default

Yep, in the "electrical" sense.
Reply With Quote
  #18 (permalink)  
Old 08-12-2014, 10:19 AM
N8IAA's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2002
Location: Fortunately, GA
Posts: 5,181
Default

Quote:
Originally Posted by billyfromhill View Post
I though the coil only helps when transmitting. Does it add length when receiving also?
I hope that you don't plan on transmitting on the ham bands with this antenna. It is not tuned there.
The coil is just to make the antenna, as pointed out, "electrically" correct in length.
Just as the spring and coil on the Larsen shorty dual band antenna.
There is no spring on the Tri-band antenna.
Larry
__________________
Digital/Analog scanning and hamming
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 8:31 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2011 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions