• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

Larsen NMO cutting chart

Status
Not open for further replies.
Joined
Feb 12, 2017
Messages
50
They have 27 to 30 MHz in .5 increments...

I've got a roof mount NMO antenna connected to a Uniden Pro510xl radio. Which is the proper MHz for that radio? I thought these base loaded whips were only supposed to be for Cb?
 

chief21

Member
Premium Subscriber
Joined
Mar 2, 2004
Messages
1,453
Location
Summer - Western NC; Winter - Tampa Bay FL
They have 27 to 30 MHz in .5 increments...

I've got a roof mount NMO antenna connected to a Uniden Pro510xl radio. Which is the proper MHz for that radio? I thought these base loaded whips were only supposed to be for Cb?
Those whips could also be used for amateur 10 meter band or certain commercial services around 30 MHz.

For CB use, you would want to tune the antenna to the middle of the band (ch20 - 27.205 MHz). You would then check the SWR on ch1 and ch40 to see if they are roughly the same.

John
 

jaspence

Member
Premium Subscriber
Joined
Mar 21, 2008
Messages
2,405
Location
Michigan
Cutting chart

If your reception is satisfactory, I would leave the antenna alone. A small mistake can turn an antenna into just another piece of wire. Many of the antennas I have used have a set screw on the coil to adjust the whip length, and you can make adjustments without worrying about cutting too much off.
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
13,254
Location
VA
For CB use, you would want to tune the antenna to the middle of the band (ch20 - 27.205 MHz).
The actual center of the band is channel 19, 27.185MHz, due to gaps in the CB channel lineup.
 

FiveFilter

Member
Joined
Jan 1, 2016
Messages
268
I have several mag-mount antennas of various lengths that I use on several vehicles. Since I only use them to monitor and report problems on the road, channel 19 is my frequency of interest. I stop cutting my antennas when I get to 1.5 or below on 19. This sometimes leaves me at an SWR of around 2.0 or so on channel 40, but I don't care since I don't talk on the higher channels anyway. Leaving the antenna a little long allows me more flexibility on vehicles and antenna placement locations. I can always cut more, but adding more no-can-do.
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
15,207
Location
SNCZCA01DS0
The Larsen NMO-27 is designed to cover a span of frequencies depending on the length of the whip. They are not just for CB, although they do make good CB antennas.

I have one that I use. I used my antenna analyzer from work to tune it. I achieved 1.03:1 SWR on Channel 19, center of the band, and 1.3 or so on channels 1 and 40.
46 7/16" is the length of mine from the base of the cone (where it screws onto the coil) to the top of the whip.

That is for my specific setup and location on permanent NMO mount. Your exact length will vary slightly depending on your exact installation.

I agree with prcguy, leave it a bit long and trim the whip using a proper SWR meter to get it correct for your installation.
 
Status
Not open for further replies.
Top