Sunday, December 14, 2014

Low band preparations

PACC is still some time in the future but we decided to prepare our low band set-up. We will be working from a different location this time and we will be using a center fed dipole for 160m in stead of the end fed antenna we used last year.

We modeled the 160m dipole in a semi-inverted-v set-up with three supports (12m-18m-12m). It seemed to be a usable configuration in theory.

We were planning to use the center support pole to hold the inverted v's for 80m and 40m as well.

To check the practical feasibility of the plan and to be able to cut the 160m antenna to the right length before the contest, we planned a test run this morning.

We arrived around 9.30am at a small park just north of Arnhem. PG8M was accompanied by his station manager so that we had 4 people to set up the low band configuration. After some coffee to get us started we began setting up the support poles around 10 am.

18m pole on the ground, fully extended and full of wires
At the first try we extended the 18m center pole fully whilst it lay on the ground, added all support wires and antennes and tried to push it upright. Even with 4 people this plan was a failure. There were so many wires to keep from entangling while the top of the pole rocked back and forth. Spaghetti is the right word for the effect we gained.

Preparation of the first approach: putting a fully loaded 18m pole upright
We took the pole down, separated all the wires and tried a different approach by extending the pole bit by bit whilst keeping it vertical. This was a more manageable process but as the top still moved about, the antenna wires found a way to unite again. 

PG8M & PD7YY trying to get all the wires separated and clear off the bushes

These 2 hours have shown us that we are a reasonably good team as there was no shouting or physical violence involved. Even the fact the PG8M and PD7YY are both called Marcel - which is rather inconvenient when you try to communicate to each other what to do - did not disintegrate Ynomy.

With this experience we have concluded that running 3 dipoles from the one center support is a task that is just too daunting. We will therefore use one of the 12m supports for our 40m inverted v and run only the 160m and 80m dipoles from the center support.

Having learned all this it was time for PG8M and his better half to leave the site. PD7YY and PH0NO decided to focus on the 160m dipole to get it resonant on the desired frequency.

After a few cuts we got the resonant frequency to 1.890 Mhz, which suits us fine. The antenna is now very usable in a large part of the phone portion of the band and might need a little tuning in the bottom part of the CW portion.

A stable center pole for the 160m dipole 

Just for fun we tried to tune the enormous antenna to other bands with the antenna tuner I brought. There was a contest going on on 10m. We heard several stations among them PY2NY. Spelling our call two times (due to splatter) we were in the log. The tuner clearly does its job well.

The whole tuning process took another 2,5 hours including the breaking down of all the poles and wires.

There is still some testing to do of the combined 160/80m set-up but we are better prepared for the contest. Do not forget to give us a shout.