Differences between PL-259, SO-239 and UHF Connector

There are a lot of confusion rise from the term use to describe UHF connector, commonly associated with Amateur Radio rigs.

Actually both PL-259 and SO-239 are collectively known as UHF connector.

PL 259 UHF Connector

Pictured above is commonly called the UHF male connector. Usually come in two version, one for lighter cable like RG-58, and another for heavier braid coax RG-8, RG-213.

SO-239 UHF Connector

Also known as UHF female. If you bought a mobile or base amateur radio rig, yours are likely to have this kind of connector.

Both PL-259 connector and SO-239 fits together and is collectivly called the UHF type connection.

So hope that would clear up confusion associated with SO-239, PL-259 connector. Both of them are known as UHF connector but with different names for male/female jack. That’s all for today folks!

10dBi – 6 Element OWA Yagi Antenna for 2 Meter band plan

Here is a 6 element yagi my friend and I have built for experimenting with directional antenna. Theoritically the antenna has about 10dBi gain in its main lobe and a good Front-to-Back ratio, a perfect substitute if you don’t have means to get the popular V24 Silverthunder antenna.

6 Element OWA Yagi for 2 Meter Band

Radiation Pattern Lobes
OWA 6 element 2 meter band

Dimensions (in inches)
Element, Length, Space from Reflector

Reflector – 40.52, —-
Driver – 39.96, 10.13
Director 1 – 37.38, 14.32
Director 2 – 36.31 25.93
Director 3 – 36.31, 37.28
Director 4 – 34.96 , 54.22

Calculated Center of gravity 23.87 inches

Dimensions (in cm)
Element, Length, Space from Reflector

Reflector – 102.92, —-
Driver – 101.50, 25.73
Director 1 – 94.95, 36.37
Director 2 – 92.23, 65.86
Director 3 – 92.23, 94.69
Director 4 – 88.80 , 137.72

Calculated Center of gravity :60.66 cm

The plan for the antenna has been taken from LB Cebik website. More article will follow that covers our construction of this Yagi antenna along with our reports of its improvement.

OWA 4 Element Yagi for 2 Meter – Great F/B ratio

I would like to share with you a compact 4 Element Yagi-Uda antenna design for 2 meter amateur radio band. This antenna has great front-to-back ratio and is optimized for wide range of frequency, a bargain for its compact design (about 76 centimeter long).

Although this antenna has almost the same gain as any simple 3 element yagi antenna (7-8dBi), this design has a significantly improved Front-to-Back ratio which is great for blanking noises and foxhunting purposes

Here how the antenna would look like
Optimized 4 Element Yagi 2 Meter

Front-Back Ratio Gain
Optimized 4 Element Yagi 2 Meter

VSWR from 143.000 MHz to 148.000 MHz

Antenna dimensions
Element, Length, Space from Reflector (all in cm unit)

  • Reflector – 103.0, 0.00
  • Driver – 95.0, 26.0
  • Director 1 – 92.0, 39.0
  • Director 2 – 83.0, 76.0

Calculated Center of Gravity – 35.0 cm

This antenna has been modelled using YagiMAX 3.0 software by K4VX

Please leave comments if you have sucessfully built this antenna. I would like to hear your experiences.

YagiMAX: The best Yagi Uda antenna modelling software

Today I want to share with you a great Yagi Uda Antenna modeling software for amateur radio operator and enthusiast.

The most interesting part of the software is, it can help you to improve your design by projecting the antenna radiation pattern and estimating the radiation resistance (impudence) at any given frequency.

The application is created for the venerable DOS environment, thus some of the operating system might not be able to run it natively. However I found out that I can run the application successfully using DOSBox DOS emulator software under Ubuntu Linux. For your information, DOSBox is also available for Windows operating system too.

YagiMAX Screenshots

Here’s a couple of YagiMAX screenshot taken from my computer (running Linux, Ubuntu Gutsy). The antenna shown here is a 6 Element OWA Yagi for 2 Meter amateur radio band, scaled from its 6 meter counterpart, the design was taken from L.B Cebik website

yagimax yagi software model

yagimax yagi software model

Download YagiMAX

Here is a download link to YagiMAX 3.11. Hope that will help you in your work !

2 Meter Amateur Radio Slim Jim Plan

Here are the plan I use for constructing and experimenting with Slim Jim antenna on 2 Meter VHF Amateur band. The measurement used are designed to center around 144-148 MHz radio frequency, which is used by amateur radio world wide.

FYI this is the plan that I use to construct my first ham radio antenna using PVC pipe and aluminium tube.

2 Meter Slim Jim Plan

Credit to Pak Halim and Azmeer for giving this plan and showing me how to construct a proper antenna.

2 Meter Slim Jim using 300 Ohm tv cable (Ribbon Antenna)
Here’s the plan that I use for constructing Slim Jim antenna for portable radio (ICOM V8).

ham radio 2 meter slim jim ribbon antenna

Both design are meant to be fed with 50-Ohm impedance coax feed line (RG-58/RG-8/RG-213) to obtain the most optimized results

2 Meter Amateur Radio Slim Jim Project

Hi there, sorry for being quiet for a while, but rest assured I was on some knowledge discovery mission to learn about building Slim Jim antenna for two way radio communication (specifically for Amateur radio band).

slim jim mypapit

slim jim papit

This antenna is specifically built to resonates within 2 meter amateur radio band (144-148MHz). This antenna has been build with the help of my friend, Amet who is a trained electrician.

Slim Jim Plan that we use
Please refer to 2 Meter Amateur Radio Slim Jim Plan post for more information

Among the items used to construct the antenna are :

  1. Aluminium tube 8mm diameter, sold in 10 feet (can be obtained from hardware store, 10feet, RM10)
  2. U PVC Pipe (15mm-20mm) for holding with T junction, RM4
  3. SO-239 connector (for mobile rig), RM10
  4. Coax Cable (either RG-8 RM7/m or RG-58 RM2/m, quality varies

Tools that we used are (included with cost if you want to buy them):

  1. Bosch hand drill for drilling pipes and aluminium tube ( RM100)
  2. Rivet / Riveter for attaching coax cable to antenna (RM 20)
  3. Bender (RM 30)
  4. some wire cutter
  5. Hack saw for cutting pipes and aluminum (RM 3)
  6. and oh yes, we *dont use* any torch welder for this one

As you already might guess, the cost for constructing the antenna alone cost slightly less than RM30 (~USD 10, except cable and tool cost), the Slim Jim is mounted on the roof of my house with ordinary TV antenna bracket, with the height of close to 40 feet from the ground.

Why build your own antenna? It is a way for me to better understand about radio wave resonance and to learn more about how to build a radio antenna to tune in to specific frequency, something that commercial antenna lacks, because it is built to tune to a wider range of frequency due to market demand.

This antenna is said to have a gain of 3.2dBi, though I don’t have confirmation about this information.

SWR Reading

Here’s the reading I’ve obtained from Diamond SX-200 SWR meter, using 20 watt output power :

  • 144 Mhz – 1.2
  • 146 Mhz – 1.3
  • 148 Mhz – 1.5

The reading is kinda bit off from the center of frequency :p, I know. this is due to my poor handling with aluminium bender. I’ve made it almost an inch longer, so that kinda explains the SWR reading is kinda centered on the lower frequency.

However this is way cheaper than buying a commercial antenna which cost me a lot of bucks, and I surely have more fun!

What can be improved?

Supposed if you want the antenna to resonate better, you could replace aluminum tubing with copper or brass tube and replace RG-58 coax cable with a low loss cable such as RG-213 or RG-8 which was used in this experiment.

What’s next ?

Next I’ll try to construct a ribbon antenna (?), which is a a very flexible antenna to be used with a portable handy radio, when you are traveling and gives you about 3dBi gain when positioned carefully.


Going for Amateur Radio Examination

I haven’t attended paper based examination for quite some time now, especially when it involve me answering hundreds of objective questions. To be honest, I’m not that confident with this examination.

Don’t get me wrong. it is not that I doubt my electronic and radio communication skills, but its more to my self doubt when confronted with a bunch of objective questions, especially when I studied a lot of questions (but with confusing answers) regarding the examination tomorrow.

examination hall

I’ve been preparing for a couple of weeks for this exam, it will be attended by a lot of candidates, and I suspect that the venue would be filled with amateur radio old-timers or ham radio rig sellers that would try to persuade candidates to buy them.

For those who are new to this, amateur radio examination is a must for those who are interested to operate an amateur radio station. The examination will determine if you are qualified to earn a license to communicate with other amateur radio operator (hams).

ham radio operator

Although radio communication is considered an “old fashioned” way to communicate since we already have internet and mobile phones, ham radio is still favored by enthusiast as a way to meet new friends and organise activities over the radio. Currently, Malaysia has at least 4,000 licensed ham radio operator across the country.

Please refer to wikipedia page for more information about Amateur Radio in general, and MARTS website for Malaysian ham radio-specific information.

p/s: Ham radio operator is not a paid job, its a hobby. Any body can participate as long as they are licensed.