Time to add a balun.


When I moved to the East coast from Ontario at the new QTH I purchased and installed an EndFed antenna and it worked great for me. It was a huge step up from the condo balcony mag loop antenna. The EndFed is a compromise-type antenna and does come with some issues. The main issue is (if you don't use a counterpoise) the coax shield is used as the counterpoise. This can cause some issues and an isolation balun is needed in the shack. I purchased a quality isolation balun from balun designs to take care of the feed line issues. In time I did install a counterpoise but it's not that effective when your Endfed goes from 10m-80m. 

I still had some RFI issues in the shack that ferrites did an excellent job in looking after. I still had some off-and-on issues with our electronic washing machine, the motion sensor light on the shed and some Google home devices. I then moved from the EndFed to a vertical antenna the Hustler 4BTV antenna. In the manual for the 4BTV, it is advised if you have any RFI issues due to the coax radiating RF place an isolation balun at the antenna. It seemed as time passed I was issue free. 

Drainage holes 1/16th

Now and then I started to notice while operating my Icom 7610 in CW mode I would have my N1MM contest program lock up. There was no rhyme or reason as to when this happened, what power level and what band I was on. I could make it through a CWops mini-test of an hour with no issues. The next CWops mini contest I had nothing but issues. I also noticed when using my VPN on the PC I would have the VPN disconnect and then reconnect messages coming up as I transmitted. I was reading online when coax radiates RF it can be very hit-and-miss as to when it happens and what is affected each time. This sounded like the issue I was having and I decided to place the isolation balun at the base of the 4BTV vertical. 

Once the isolation balun was installed I am RF free and have been for over a month now. My electronic washing machine, N1MM logger and VPN connection have no problems. 

Waterproof connections

I had to take into consideration some precautions when putting the isolation balun outdoors. It was recommended to drill 2 1/16 holes in the bottom so any condensation would not build up inside. Also around all PL-259 connections, I waterproofed them with self-amalgamating tape.

Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

4 Responses to “Time to add a balun.”

  • George VE3YV:

    Mike – good story and glad you’re on the air. Some thoughts:

    Use 2 RF-chokes (AKA “baluns”), one at the antenna feed point and the other at the rig (antenna switch or …). IIRC that was in TCA by an Ottawa ham many years ago. Using 2 reduces the RF-in-the-shack to manageable levels. As I understand it, the outside of the shield can pickup and conduct radiated RF, making matching much easier as the shield currents don’t create false SWR readings (with the second choke the shield is actually close to ground potential).
    I recommend visiting Jim’s, K9YC, excellent website for a great deal of practical information (very readable even for the non-engineering degreed folks like me) on taming RFI and building your own RF chokes. About 30″ of electric wire, a #31 toroid and you have a very effective choke for HF. In there you also learn why current chokes are preferred over voltage chokes and many other useful tips…
    GL 73, George VE3YV

  • Mike VE9KK:

    Good afternoon Geroge and thanks for stopping by and leaving a comment, I found his website and also some PDF documents from him as well on the internet. They will make good reading. I would much prefer to make my own as I contacted Balun Designs and they have a build-your-own for about 50.00 but the shipping is 50.00 as well. For me, that is just crazy!
    Thanks for the resource George and have yourself a great weekend,

  • George VE3YV:

    Mike – I made mine for approx. $20 each, the toroid with shipping (bought 10 and shared cost with a few locals), a 4x4x1″ hamfest Hammond plastic box, an SO239 from the misc parts cabinet and some household wire I already had from reno projects around the house and cottage. For the inside one, no box necessary unless you’re a purist.. HI
    In a row house in the centre of Toronto with roof mounted antennas, the chokes are critical to operating with all of the coupling from wiring, plumbing, etc and also to reduce noise pickup as the shield can act as a good antenna for all sorts of crud.
    For my Field Day kit, I always pack a couple of toroids along with an antenna analyzer as in a 8A-11 A club effort, somebody always has some RF issues to be dealt with.
    73 de VE3YV

  • Mike VE9KK:

    Good afternoon George, I am retired from 34 years working at Toronto Hydro and know very well what you are talking about when it comes to cramped housing conditions. I purchased 2 toroids from Mouser and they will be on the way soon. I will be in Toronto in the near future and will stop off at Radio World for SO-239’s and Sayal electronics for the enclosures. Oh, and I am 100% a purist 🙂

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