I decided to to build a End Fed HF Dipole Antenna in April 2020 during Covid19 Lockdown. The antenna known as the ZS6U Mini Shack Special Antenna with a 9:1 Magnetic Longwire Balun/Unun. The article relating to this antenna is available HERE.
I recently decided to take the antenna down to refurbish the balun as it has now been up in die sea air for 5 years and I was sure corrosion was "eating up" the balun. After taking it down I was quite surprised to see that the balun was still in a very good condition (outside and inside). See images. The only part I replaced was the eye bolt and nut. The bolt was lightly rusted and could have lasted another 5 years, however I decided to replace the eye bolt. The only other part that I replaced was a nut that came loose on one of the connecting bolts to which the counter poise was connected. The lock washer did not lock and in turn the bolt would turn around when tightening the wing nut. I replaced the nut with a lock-nut and this solved that problem. I installed the new eye bolt and nut and the balun was ready to be put up again.
The red cabinet has a watertight seal that keeps rain water out but I again sealed the unit with silicon to keep it water tight.
I also decided to measure the "SWR and Impedance" of the 9:1 Balun with my NanoVNA. Although this is not the correct way to do it, it gives me some indication that the Balun is working. Let's call the measurement a fault finding mission. I used a 270 Ohm resistor accross the connecting points and obtained the readings as depicted in the images.
Finally: This QRP balun served me well since 2020 and is now ready to use for another 5 years.
Images: Click on images for larger view.
