• 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.

Pulse Larsen NMO-27 antenna plot

Status
Not open for further replies.

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,747
Location
SNCZCA01DS0
We hear a lot of people talk about the consumer grade CB antennas. We see a lot of people (me included) strongly recommend the Larsen NMO-27 antenna.

There are good reasons for both types, but here's some actual proof of what you get.

This is a 20 year old (at least) Larsen NMO-27 on a permanent mount NMO on the roof of a 2011 Ford F-150 crew cab. The NMO mount is near the back of the cab roof. Not the ideal position, but the center of the cab is reserved for my work radio antennas.

Plots were generated by an Agilent N9342C spectrum analyzer with a built in tracking generator.

First plot shows the 26.000MHz to 28.000MHz range.
Marker 1 is set to CB channel 1 26.965MHz
Marker 2 is set to CB channel 19 27.185MHz - center of the CB band.
Marker 3 is set to CB channel 40 27.405MHz
SWR readings are:
Channel 1 = 1.33:1
Channel 19 = 1.05:1
Channel 40 = 1.33:1




Second plot show just the CB band. 26.965MHz to 27.405MHz range.
Markers are set as above. 1 on Channel 1. 2 on Channel 19. 3 on channel 40.
SWR numbers are a bit different due to narrowing the sweep gives me better control of their placement.




I don't have any 3/8x24 mounts or any of the consumer grade antennas to compare. But at least here's proof that these are excellent antennas when set up correctly.
 

krokus

Member
Premium Subscriber
Joined
Jun 9, 2006
Messages
4,747
Location
Southeastern Michigan
Very nice. A similar plot for antennas like the Wilson 1000, K40, and Firestik, would be interesting.

Sent via Tapatalk
 

JayMojave

Member
Joined
Dec 13, 2007
Messages
695
Location
Mojave Ca
Hello mmckenna: Very good even WOW! Very impressive taking the SWR / S11 measurements, even more impressive is posting them. Thank you.

We all see and read many postings saying something about SWR, insertion loss, and even harmonics and such with opinion's and never backed up with real world measurements. And some do have the measurements but because of there cost and time investment, and what they show or indicate, they are not shared! And for good reason. Allowing one to set there like a coiled snake with the measured data in his notes only, allowing one to see who's says something different.

Yes making a S21 / Field Strength comparison test would be great of the different antennas.

Jay in the Great Mojave Desert
 

RRR

What?
Premium Subscriber
Joined
Dec 6, 2005
Messages
1,775
A no-gainer "Unity" antenna.....
 

kayn1n32008

ØÆSØ
Joined
Sep 20, 2008
Messages
6,267
Location
Sector 001
A no-gainer "Unity" antenna.....
Actually, it likely exhibits negative gain because it is a loaded 1/4 wave. regardless, it is better than most CB antennas, does not weigh much and is low drag, unlike most CB antennas on the market.

Try mounting a firestic on your roof, and then go 110km/h down a highway...
 

n3obl

Ø
Database Admin
Joined
Dec 19, 2002
Messages
1,137
Location
PA
I've used those on personal vehicles and few police cars that still have em. Works very well and the scope just proves it.
 
Joined
Jun 16, 2013
Messages
3,583
Location
Texas
Actually, it likely exhibits negative gain because it is a loaded 1/4 wave. regardless, it is better than most CB antennas, does not weigh much and is low drag, unlike most CB antennas on the market.



Try mounting a firestic on your roof, and then go 110km/h down a highway...


Just because it's a loaded 1/4 wave antenna doesn't mean it exhibits negative gain. With antenna design there are three trade-offs; size, bandwidth and efficiency but you can only pick two. Optimize for size and efficiency, bandwidth goes to hell (great example are atomic clocks). Optimize for efficiency and bandwidth, size becomes larger.

Yes it's a smaller antenna but when it was designed, a great receiver was considered 12 dB SINAD at .3 μV (-117.5 dBm). I'd be willing to stake any of Larsen's gain claims against say…Firestik's 6 dB gain claim.


Sent from my iPhone using Tapatalk
 

mmckenna

I ♥ Ø
Joined
Jul 27, 2005
Messages
14,747
Location
SNCZCA01DS0
Well, either way, I'm not putting a 108" tall whip on top of my truck. I don't have any expectations of gain and I don't expect it to work as well as a 108" whip.

The NMO-27 is about as tall as I'm willing to go, even on the highway.

As for the Firesticks, Wilson, anything else, I'd love to do a side by side comparison, however I'm not going to install a 3/8x24 mount on my truck as I have zero use for that.
 
Status
Not open for further replies.
Top