AB4UG Radioblog

Tested out the 6m dipole with a nice QSO with W4QYV (who happened to be pretty close by) up at 52.525 MHz (FM) and it worked out pretty well except for towards the end when I mysteriously stopped receiving/transmitting anything. The noise was still there, but apparently W4QYV wasn’t hearing me. Very weird.

I was also checking out the JT-65 activity at 50.276 and noticed that the signals there look a lot stronger with the ZS6BKW antenna than they do with the 6m dipole. The ZS6BKW is a good deal higher though and doesn’t have a bunch of houses in the way.

At any rate, I know that it can reach out at least a mile from the house. I was getting a bit concerned after tuning around the band and hearing nothing but noise. Now to decide if I want to leave it up at the house permanently or keep it handy to go portable with. Then again, I have enough wire around, so I could always make another one.

 

Built myself a 6m dipole using a dipole center and some of the hamfest wire I picked up back in February. As it’s also Towel Day, I had mine handy just in case.

I wanted my antenna to be resonant at 51 MHz. Using l = 149.35/f ¹ gave me a length of 2.96m, so I cut a 3m length of wire and then cut that in half. I soldered some stranded wire to one end of each wire to connect to the dipole center and attached a couple of ceramic insulators to the end. One end got tied off against the house and the other end to my PVC mast propped up against a ladder.

The first look with my antenna analyzer showed the antenna resonating around 49.3 MHz with an SWR of 1.0 (wires a bit on the long side). A bit of math (49.3MHz/51MHz = 0.97) told me the antenna needed to be 2.9m long (3.0 * 0.97) so I trimmed 5 cm off each end and got 1.0 SWR right at 51 MHz.

With the dipole connected to the radio, the receive is definitely louder than the ZS6BKW on 6m. I wasn’t able to pick up any other stations, but there was a lot of electronic noise. In the fldigi waterfall, there were lots of periodically spaced vertical lines all across the band. I’ll have to give a listen later when it cools down a bit and people turn off their AC units. Maybe it’ll get better then.

At 2.9m long, it’s small enough to be very easily portable. I’ll need to get a much shorter length of coax to use with it to minimize losses (it’s connected to the radio using about 23m of coax) and something to hold it up in the air. Could be neat to carry this around and break it out when a 6m opening pops up.

1. Take l = 490/f, which gives you the length in feet when f is in MHz, and multiply by 0.3048 to convert to meters. Metric is how I roll.