During this weekends World Wide CW contest weekend where you'd be forgiven in thinking that there has been a change to the band plan I decided to finish up tuning the vertical antenna that I installed a few weeks ago so I could operate from the portions of the bands that I prefer are at the lowest SWR and hence I have the best opportunity it getting some good DX contacts over the winter.
I'd preassembled the antenna with the recommended spacings between the various traps but had discovered that the SWR varied wildly across the bands and even with a tuner (And yes I do agree with the sentiment that a tuner only hides bad set ups, but in some cases it is essential) the SWR was hard to get down to acceptable levels. On checking the spacings last night I discovered that they had almost all reduced significantly so detuning the antenna.
??Why?
Over the past few weeks we've had some strong winds and this may have contributed but I'm not entirely convinced yet.
Solution
Re-tighten the bolts and check again in a few weeks. Perhaps some kind of nylon spacer needs to be made up rather than relying on friction if this is going to be a problem. Hacksaw anyone!
Apart from this issue I have been very pleased with the retuned SWR, very low across all the bands and it just goes to show that quality breeds quality.
What about using the counterpoise system. I would like to mount mine about 10 feet in the air. Do the counterpose wires have to come right off the base or can they be attached at the bottom of the metal pole that the antenna attaches too.
ReplyDeletelapipara@yahoo.com
I understand that they can be attached to the base of the pole. DX engineering do a clamp that goes round the base of the base pole that would give extra mounting points if you needs them. In fact DX engineering do just about every thing you'll need if you didn't want to make up the wires yourself. They'll need to be resonant lengths for elevated mounting and coming off at a 45 degree angle.
ReplyDeleteI would recommend that it's ground mounted and that you protect the feed screw threads as i have found that the mild steel female tread is corroded and it's hard to clean the threads out.
73's
Alex, g7kse