In 2004, when Scott Tilley (VE7TIL) and myself, decided to combine forces and equipment in order to participate in the upcoming Trans-Pacific LF DX Test, we could not decide whose call letters to use for our station. Since it was to be a joint effort, we decided to obtain a dedicated call sign that would be used specifically for our combined LF on-air activities. A quick perusal of IC's 'available callsigns' list revealed that the perfect call was still up-for-grabs and 'VA7LF' became the call sign for our LF outings.
The April'06 Trans-Pacific LF Test
The most recent DX Test was held on the nights of April 3-5 at the previously used site on South Pender Island, B.C. Last year's participants, Martin McGregor (VE7MM), who owns the property on Pender, Scott Tilley (VE7TIL) and myself, were joined by fellow LF enthusiast John Gibbs (VE7BDQ). Our last effort at Pender had been a huge learning experience as it was the first time using the Pender Island site as well as the first time we had used a large antenna system. The new site along with the large antenna had allowed us to finally push a signal to the team 'down under' as we were finally reported 'heard' by the boys at Quartz Hill. The ultimate goal of the T-P DX Tests is to complete the first two-way contact between New Zealand and North America on 2200m. Our latest outing saw another huge leap forward in accumulated knowledge as well as bringing us a major step closer to reaching our ultimate goal of a valid two-way QSO with ZM2E.
The two main improvements to our latest expedition were the inauguration of our newly constructed LF transmitter, the 'MOALFA' (Mother of All...) and the resurrection of Martin's British Army pneumatic tower which would be used as the base section of our top-loaded vertical.
When fully pumped up, the aluminum tower is 40' in height and solid as a rock. Before extending the tower, all sections had to be bonded to ensure good rf conductivity as well as to prevent arcing. This was a major job and took the better part of the first day and a half at the site. Now that it has been done, all cables and straps are ready to go for the next time and raising the tower will be a much quicker job.
Two 20' aluminum sections were added to the top section of the tower as well as a large (150') two wire top hat, spaced 10' apart. In addition to this, another 25' of wire was extended from the base of the antenna, out and over the cliffside and terminated just above the beach (where it was matched and fed with 50 ohm coax) for a total of 105'.
The entire antenna system was brought into resonance on 137 KHz with the homebrew loading coil shown below. Inside the loading coil, a variometer allows fine tuning of the system. The big vertical required 1.9mH of inductance to bring it down to 2200m.
As well as transmitting on the vertical, we used it to receive also since the dead quiet location allowed the big antenna to really shine. One receiver was kept on the 10' air core loop as well. In one instance, just at dawn, the loop produced copy that the vertical did not.
The new homebrew transmitter was burned-in for three solid nights without the slightest whimper. It consists of four separate dual-FET push-pull amplifiers fed into a four-port Wilkinson power combiner. Running Class D at 38 volts, the amplifier can, if required, pump out over 2KW all night long. The top section houses the power combiner while the four (W34NB20 switching FETs) P-P amplifier modules are in the center, behind the fans. Power supplies are housed at the bottom.
At one point, while testing, a large Canadian Navy frigate (the HMCS CALGARY) was noted at full speed in the middle of Haro Strait when it suddenly altered course, turned to directly face the transmittting site and came to a near dead stop in front of the antenna system. Knowing that the Navy is the primary user of the 2200m band, we pondered the significance of this sudden arrival. Perhaps some of their sensitive electronic countermeasure equipment had alerted them to the strong nearby VA7LF field in their path. After observing for a few minutes and much to our relief, the ship resumed course!
On Wednesday evening, we spent one hour working several CW stations via the crossband mode, 160m - 2200m. It was certainly a lot of fun and is something that we would like to do more of during our next outing. This time, I promise to give more notice of our crossband schedule. Many thanks to those that tuned in to our "CQ QSX 1815KHz" CW and gave us a call. Several stations in Oregon, Washington and B.C. were worked and will receive a special QSL card for their effort. John, VE7BDQ, an ex- Coast Guard radio operator, is shown here busily working our crossband callers.
The VA7LF group is shown below.
In spite of the dreadful propagation conditions, we had much better success than our last outing. Both stations heard each other on all three nights. Just before dawn on the third and final night of scheduling, ZM2E's signal suddenly rose 25db out of the noise and acknowledged our beacon signal, indicating an "O" (perfect copy). In our predetermined QSO protocol, this was also an invitation to exchange calls signs. Unfortunately the sun was almost over the horizon on Pender Island and our path to ZL vanished as suddenly as it had appeared. Hopefully the propagation will be better next time out!
