Friday, February 27, 2015

Amateur Radio Mobile Endeavours

                                             Backroading in Banff Park

Recently I built a new specialized 30 meter antenna induction coil for my multiband monobander antenna system, and this new coil will be used while operating my new HF APRS system.
 After I was finished with building this 30 meter coil and with it mounted in place on my mobile, I discovered that the shunt-coil that resides at the base of my HF antenna mount would not allow me to operate on 30 meters with this new antenna coil.

The problem was that the impedance at the feed-point of the antenna was not in the range required for 30 meters.
After spending time attempting to adjust the shunt-coil, I decided to build a new and improved model to replace the existing one with the capability to handle 30 meters as well as all the other bands that I operate on.

The shunt-coils that I build have to be well sealed to keep the weather out, as they are mounted beneath the back cargo-bay of my mobile.
The other necessity is to then make sure that the weather yucky's are kept out of the PL-259 connectors that couple the shunt-coil in place in the coax.
To do that I use a combination of the components described here.

The NYK-77 compound is a specialty formulated non-conductive sealant and corrosion preventative that once applied to the threads of the PL-259 connectors before screwing in place on the shunt-coil tee, provides sealing against intrusion of dirt and moisture.

I then wrap the fittings with Silicone tape made of specially formulated silicone rubber.
The tape has no adhesive, but chemically bonds to itself upon contact.
Once wrapped the silicone tape forms a permanent seal within 24 hours that is airtight and waterproof.
This silicone tape is an amazing product that every ham should have in his tool kit.
It may be used to insulate electrical connections, repair damaged wires, and it can even stop a pressurized leak.
I don't leave home without a roll of silicone tape in my tool bag.
If you have to remove it for whatever reason, its as simple as slicing it open with a razor knife, and then pulling it away from the connectors.

The tube of Carbon conductive grease shown in my photo is another product that I don't do without.
Although it wasn't required for this job, I thought I would mention it, as I use it everywhere I need to assemble a connection that needs to be conductive without the chance of the weather getting in and allowing for corrosion to start.
I'll bet that you have all had to deal with antennas that over time begin to give problems with the SWR going south due to corrosion setting in.
Comet dual band antennas with their many connections and set-screws that corrode and you cannot get them apart anymore are a prime example.
Before I install any antennas on my mobile, I disassemble them completely and I apply carbon conductive grease to all of the fittings and set-screws before reassembling them.
Not only are they protected against the weather, but the antennas actually perform better.
This is especially true for my HF antennas that I demand maximum performance from when driving 200 watts through them.

Also pictured in the photo is a roll of canvas tape that you might know better as hockey tape.
I love this tape and use it everywhere, some reasons being cosmetic and for other reasons as well.
One of these places is up on my roof of my house where I have weather station devices mounted in place.
The weather station that I built has a lot of electrical connections in place, and to keep the weather at bay, I wrap the connections with either electrical tape or on the past I have used 3M rubber tape.
This tape will deteriorate from the sun rays after a time.
To stop this from happening, I wrap the electrical or rubber tape with this canvas tape, and this prevents deterioration to take place.
I mentioned cosmetic reasons for using this tape, and that is one of my favorite reasons to use black canvas tape.
Canvas tape is easy to apply and looks terrific once applied. If it gets ratty looking it is easily removed for replacing, and does not leave any sticky residue behind if you wish to go without it.
I have used canvas tape to wrap camera tripod legs, the gimbal head that I mount long lens on, handles of various devices, the mount post for the radio stack in my mobile, the lid of my netbook that was way to bright in its silver paint, as well a numerous other reasons that I use it for.
Its a terrific product that I enthusiastically endorse and don't leave home without.

All of these products can be purchased at your favorite electronics supply outlet, although you may need to visit a hockey stick supply store for the canvas tape.
They even carry it in colors other than black.
Oh, I forgot to mention that the shunt-coil  on the right in the above photo has been mounted in the coax beneath my mobile for going on 3 years.
Expand the photo by clicking on it and you can see the fittings are still shiny and bright after 3 winters.

Note...all photo expand.....

For more info on my ham radio endeavors visit my website

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