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How To Build A 2 Meter Antenna For Bicycle Mobile

Perhaps the biggest problem with taking your HT bicycling is coming up with a decent antenna on your bicycle. This is because the bike doesn’t provide much of a ground plane. I found an article in the ARRL’s Hints and Kinks written by Charlie Lofgren , W6JJZ, titled “The Bike ‘n Hike Special”. Below are the plans for the antenna for bicycle mobile he described in the article.

This antenna is a 1/2 wave vertical dipole made out of RG-58/U coax. The beauty of this design is that it is cheap, simple, and easy to make with readily available materials. The radiator should be 39 inches long for 2 meter operation. What I use for the radiator, is the center conductor of the RG-58/U coax. I start out with a 12 foot piece of coax. Then there is enough left so it can be run up to the radio. I keep my radio in my handlebar bag.

First measure how long the radiator is to be, then trim off the outer sheath, and shield. Next, on the other end of the coax, I cut off a piece of coax that is going to be the shorting stub. The proper length is dependent on the velocity factor of the coax used (see table below). In all cases, I always make the lengths to the long side. This way the antenna can be trimmed in to the desired frequency with a SWR bridge.

Short the center conductor to the shield of the coax at point C

The dimensions for the matching section are dependent on the velocity factor of the coax used.

Dimension	Vel. Factor 0.66	Vel. Factor 0.80
A to B	11.25 in	13.5 in.
B to C	1.63 in.	2.0 in.

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How To Construct a J-Pole Antenna for the 70cm Ham Band

Here is an inexpensive J-pole antenna that is easy to construct. In about an hours time, and about $10 worth of materials, you can have a great performing omnidirectional j-pole antenna. This antenna is based on the same ideas as my 2 Meter J-Pole construction plans. The j-pole antenna is basically an end fed half wave dipole that uses a 1/4 wave shorted matching stub as an impedance transformer. The j-pole antenna will yield slightly less than 3 DB of gain omnidirectionally.

The material I chose to build the j-pole antenna was 1/2 inch copper pipe used for plumbing. Here are the plans:

The above dimensions for the J-pole are in inches, and aren’t typical for a 440 mHz. J-pole antenna. This is what it took for me to get the SWR low. Measurements on overall length, and stub length are from the centerline of the separation pipe (horizontal) to the top of the antenna. The Connect at measurement is 1 1/2 inches from the top of the horizontal member to the point of connection. The distance between the main element of the j-pole centerline and the tuning stub centerline is 0.75″.

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How to Run Winkeyer on a Raspberry Pi computer

Being a Ham Radio operator that likes CW (Morse code) and contesting, it helps to have a programmable keyer that will get text from a computer. In my search, I found the Winkeyer USB by K1EL Systems. There are several variants of the Winkeyer that include kits as well as fully assembled keyers. In this post, I will show you how to run Winkeyer on a Raspberry Pi computer.

Most logging programs have some way to send a pre-set string of characters to your rig, such as “CQ CQ CQ FD DE WB8ERJ WB8ERJ FD AR”. which is fine however when running CW at any speed faster than say 13 WPM, the computer is prone to timing problems and your CW comes out like you have terrible CW skills. This is because sending Morse Code that is generated by the computer has timing problems – especially in a Windows environment!

So by using the Winkeyer instead of the computer to key the transmitter, the task of actually generating the Morse Code is off-loaded from your computer, and your Morse Code is sent perfectly.

I have used Winkeyer with N3 FJP‘s contest logging software and it works just fine with that logging software, and I am sure many others. But there is a problem, I rarely run Windows computers and usually run Linux on a Raspberry P i computer. Specifically an install package by Jason, KM4ACK. Now this particular install package is targeted to portable / off-grid Ham Radio Operations. Since I have been doing POTA acvitations, Jason’s setup works great, and I highly recommend it.

So I needed a way to run Winkeyer in the Raspberry pi. On K1EL’s site there is this page that mentions winkeydaemon. Which is the answer to the problem. However not being completely fluent in the world of Linux, the task was a bit daunting. Maybe its just me and my lack of Linux knowledge, but I found the documentation to be rather difficult to follow.

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Programming Your Radio For The ISS Crossband Repeater With Chirp

As of September 2, 2020, the new FM ISS Crossband repeater on board the International Space Station is activated. This is great news as it has been quite a while since anything significant has happened with Ham radio on board the ISS. Early reports indicate that the receiver is quite sensitive and can be used with just an handheld such as a Baofeng.

If you have never done any space communications via ham radio, there are some things to get acquainted with. The most important one is Doppler Shift. This can be a bit tricky. What is happening is that as ISS is moving and transmitting, you have to have to adjust your receive/downlink frequency. It is the same phenomenon as a passing train blowing its whistle, and you hear the tone of the whistle drop as it passes by you. In the case of the ISS, what you have to do is to listen a little bit higher when it is coming at you. As it is more overhead, you will hear it become noisy in your receiver. Just tune down 5 kHz, and you wil hear it. As the ISS moves away from you, you will have to tune down another 5 kHz.

The new crossband repeater on the ISS has an uplink frequency of 145.990 mHz and a downlink frequency of 437.800 mHz. In order to access the crossband repeater, it requires a 67 Hz tone on your radio. Also this is an FM repeater.

The best way to handle doppler is to pre-program the frequencies into your radio. I use the Chirp program. Its free and open source. This is what I use for my Yaesu FT-857D as well as my various handhelds like my Baofeng radios. You can download Chirp here if you don’t already have it.

Below is a screenshot of a portion of my chirp file for my FT-857. I have programmed 5 channels for the ISS Crossband Repeater. This allows me to easily adjust for doppler as things get quite busy when working the ISS Crossband repeater.

Programming your radio for the ISS crossband repeater with Chirp

Some items to note, I gave each channel a specific name. Obviously it starts with ISS so I know what satellite I am dealing with. In addition I also added RP for Repeater. The reason for this is that there are other ham radio rigs on board the ISS such as APRS and I didn’t want to get confused. Additionally I added a lower case letter at the end.

So at the beginning of the ISS pass, I start out on the channel labeled ISS RPa and listen. Sometimes on a low pass I will toggle between ISS RPa and ISS RPb since the affect of Doppler isn’t as pronounced on a low pass as it is on a more overhead pass.

Speaking of listening, its best to run your radio unsquelched. In the past I have missed passes of other satellites because I had my radio squelched. Even though unsquelched can be annoying, it does give you the best chance for success in working the ISS crossband repeater.

Once your radio is programmed, the next problem is knowing when the ISS is visible. There are several satellite tracking programs available for download. Being a Linux guy, I use gpredict. Its free and open source. There are other windows and MAC based satellite tracking programs as well. Doing a google search and you will find several for whatever computer you are using.

Another option if you don’t want to download and install software is to use N2YO’s Satellite page for the ISS. There are also apps for android and iPhone to tracking satellites as well.

One thing I do when working the ISS crossband repeater is record the pass. This helps with logging as it is very fast paced and its quite easy to mis-write a call.

Hope to catch you on the ISS repeater someday!

This article was originally posted on www.mikestechblog.com Any reproduction on any other site is prohibited and a violation of copyright laws

How to Build a DIY 2 Meter J-pole Antenna

If you are looking for an inexpensive, and easy to construct antenna, the J-pole antenna is a great one! In about an hours time, and about $15 worth of materials, you can have a great performing omnidirectional j-pole antenna.
The j-pole antenna is basically an end fed half wave dipole that uses a 1/4 wave shorted matching stub as an impedance transformer. The j-pole antenna will yield slightly less than 3 DB of gain omnidirectionally.

The material I chose to build the j-pole antenna was 3/4 inch copper pipe used for plumbing. Here are the plans to build a 2 meter J-pole antenna:

The above dimensions for the J-pole are in inches. Measurements on overall length, and stub length are from the centerline of the separation pipe (horizontal) to the top of the antenna. The Connect at measurement is 2 1/4 inches from the top of the horizontal member to the point of connection. The distance between the main element of the j-pole centerline and the tuning stub centerline is 2″. I cut a length of RG-8X foam coax to a length of 67″ for the feedline, and coil up 4 turns (as small as you can get it) just below the horizontal part of the matching section. This will de-couple the feedline from the j-pole antenna, and help provide some lightning protection. Connect the center conductor of the coax to the main element, and the shield to the tuning stub of the j-pole.

In all of the above dimensions, they are to be considered starting points for constructing a j-pole. I temporarily attach the coax using 1 inch hose clamps, and adjust the coax connection first to the lowest SWR. From there, I adjust the length of the main element of the J-pole. Then I start over by re-adjusting the coax connection.

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Stop EMI / RFI Interference in Off Grid Solar PV Systems

Stop EMI Interference from Off Grid Solar Being a Ham radio operator, I am quite aware of EMI and RFI radiation interfering with my radios. Recently I added an Off Grid Solar PV system to my ham radio station. Using solar panels is great for ham radio, especially for emergency communications when the grid is down, I am still able to operate. However it was producing a lot of EMI /RFI interference on my lowband rig.

What I did was purchase a 100 watt off-grid Solar PV kit on Amazon, similar to the one to the one on the right. (Why yes I am an Amazon Afilliate) Solar PV kits such as this one comes with everything you need. The photo above shows the solar panel mounted on my ham radio tower. One thing on my installation, I had to come up with my own brackets to mount the solar panel to my tower. So if you are thinking of doing a similar set up, you will need to figure out your own tower mounting arrangement. The Solar PV system works great charging my deep cycle batteries that run my Ham radio station. The problem however is the charge controller, which is a PWM type charge controller, generates a lot of EMI interference. The particular charge controller that came with my solar PV kit, is a WindyNation P30 Charge Controller, which is typical of all the other inexpensive PWM type of solar charge controllers.

Track Down The EMI / RFI Source

Before I tell you how I resolved my EMI / RFI interference, I would like to tell you how I was able to track down the source of my EMI noise. I have a small portable AM/FM radio that clips on to your arm. All I do is switch to the AM band and tune around. Usually EMI interference is a harmonic of its fundamental frequency, so just tune around until you hear a strong EMI noise. Then its a matter of walking around until you hear the noise the loudest.

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