Westerbork, Dwingeloo and field day

Some photos made last week.

Close to one of the antenna’s in the Westerbork radio telescope array
Before Westerbork we had Dwingeloo, currently this dish is used by PI9CAM, see also http://www.camras.nl
Fieldday 8-apr-2017
40m elevated ground plane
This is the antenna I tested on the 8th of April and I call it an elevated ground plane for 40m. The essential part is the 9 meter of wire that you loosely wind around the mast. Use an antenna analyzer to tune it. The simplicity is that it works on a glass fiber mast without any guy wires, the tripod at the base is sufficient to keep it upright, secure the tripod with three tent pins. At 9 meter with 5 turns the antenna is resonant in the high part of the 40 meter band. The length of the radials is not critical, the box is a straight through, it has a SO-239 connector, center pin goes to the vertical and there are several bolts with butterfly nuts on which you attach as many radials as you carry, I always carry four of them. At the end of the radials I fix them with a tent pin. The transceiver is kept 20m away with a RG-58u 50 Ohm coax cable which is light and flexible which is ideal for field activities, the transmission line loss at 7100 kHz is negligible, we only run at most 80W on the transceiver and we avoid any tuner. The transceiver was a FT-991 running on a 3S lipo battery 5000 mAh. I got the mast at dx-wire and the batteries at CONRAD.

Last update: 9-April-2017

Field day 2-April-2017

Two blue sky Sundays on a row, so I had to go outdoor with the radio.

1:1 balun (diamond BU-50) mounted directly under the top mounting point of the guy wires, this prevents sagging of the glasfiber mast. Mounting it above this point is no success.
Purpose of the day was to tune the 40m dipole, in this setup it is an inverted V with the highest point approximately 8 meter above the ground. Within 3 iterations I had found an SWR below 1.3 for the entire 40 meter band. You don’t need any tuner.
The mast looks better I think than last weekend.
The 40 meter conditions were not splendid, and there was a SP DX contest, I just made 3 QSOs.

Last update: 2-April-2017

Field day 26-Mar-2017

The challenge is, arrange yourself in such a way that you can hike for several km, carry a GFK mast, a 100 Watt transceiver, batteries, cables, tuner, and all antenna material without the help of anyone. Today I came close to this, I had a suitcase and a separate bag, and a mast attached to a tripod. It is not comfortable hiking, but it worked.

20 meter antenna, 3 radials of 10 meter, and a MFJ 1979 vertical
GFK mast with an end-fed 40-20-10 meter
A bag, a suitcase and a mast+tripod
Blue skies, guy wires and antenna

Last update: 27-Mar-2017

The politics of ham

Can you say something about politics or religion as a ham over on the air? We had a change in the regulations, prior to 2008 it was certainly not appreciated, but since that time the official policy is that AT (our regulatory office) does not care about what you say, as long as it concerns matters of non-commercial interest that play on both part of the QSO. They do ask you to take care that your remarks don’t irritate anyone. Someone in a QSO mentioned nevertheless something about politics on the Rotterdam city repeater a while ago, and later at the club a member reminded me that this is not really appreciated. Legally it may be a different story, but a repeater manager can still say that certain topics are not appreciated on the repeater. It is his problem to enforce the house rules. So this is how much I know about the issue, now, can we as hams go political or religious on the repeater. The best answer is probably mostly no, and maybe a bit of yes. Do I want to say something about Rotterdam last Saturday night? Not as a ham over the air, no, please no, read the news and form your own opinion. I couldn’t see any traces of what happened on my Sunday morning hike, perhaps a broken window or a few rocks on the street and janitors cleaning up the mess. Read several newspapers today, the opinions vary between no foreign political assemblies in the Netherlands to, of course, this is democracy, the mayor should have allowed the assembly to happen. By the way, Wednesday there are elections, undoubtedly someone will benefit from the situation.

Your foreign license plate number?

For any amateur band above 20m this is the easiest solution in the field, a 5 meter whip antenna with a magnetic suction mount on the trunk of your car, it results in a SWR of 1.6 and you can tune it to anything above 20m by simply shortening the whip. MFJ makes these, the MFJ 1979 is the whip and the MFJ 336T is their magnetic suction mount. I haven’t tried this on the roof yet since I’m slightly worried about the thickness and the lack of anything that provides more stiffness. After posting these images on facebook the first reaction of my cousin was, are you now also carrying foreign license plate numbers? I rest my case about opinions in our country.

The MFJ 1979 and their 336T on the trunk of my car
The analyzer shows a SWR of 1.63, so that appears to be fine
16-Mar-2017, a field afternoon, the FT-991 was able to tune the whip between 14250 and 14350 kHz, I’m deliberating about a solution to move it more center 20m band.
Fieldday on March the 19th, notice the tuning stub at the end of the whip. Also, what you don’t see is that I added several radials to the magnetic suction mount. 3 radials of 10 meter each did the job.
It turns out that a 25cm tuning stub centers the resonance frequency in the 20m band.


Last update: 17-mar-2017