Station Log of WC2XSR/13

by W5JGV

October, 2002 - December 31, 2002

This is a copy of the Official Station Operating Log of Part 5 Experimental Radio Station WC2XSR/13.

It is presented here in reverse order, so that the latest log entry will appear at the top of this page. That way, you don't have to scroll through the whole thing to get to the new log entries. Since this log is transcribed from my notes, the wording tends to be a bit clipped at times, but, hopefully, the meaning will be clear.


31 DEC 2002 - Transmission continues.


26 DEC 2002 - Receiving tests completed; the transmitter has been placed back on the air at 1600 CST on 166.500 KC, at 400 watts TPO.

The modulation sequence is: The ID letters "XSR" are sent once in QRSS30 mode, then "XSR" is sent twice in QRSS10 mode, then "XSR" is sent three times in QRSS3 mode, then the following plain text is sent three times in 10 WPM CW, "DE WC2XSR/13 DE WC2XSR/13 QSL VIA W5JGV". The modulation sequence then repeats.


14 DEC 2002 - Transmitter off the air @ 1842 CST so that I can use the antenna for receiving tests.


09 DEC 2002 - Transmitter back on the air at 0421 CST on 166.500 KC, at 400 watts TPO.

The modulation sequence is: The ID letters "XSR" are sent once in QRSS30 mode, then "XSR" is sent twice in QRSS10 mode, then "XSR" is sent three times in QRSS3 mode, then the following plain text is sent three times in 10 WPM CW, "DE WC2XSR/13 DE WC2XSR/13 QSL VIA W5JGV". The modulation sequence then repeats.


06 DEC 2002 - Transmitter off the air @ 1457 CST so that I can use the antenna for receiving tests.


24 NOV 2002 - On-the-air testing between 1345 - 1400 CST to recalibrate antenna tuner.

Transmitter back on the air at 1402 CST on 166.500 KC, at 400 watts TPO.

The modulation sequence is: The ID letters "XSR" are sent once in QRSS30 mode, then "XSR" is sent twice in QRSS10 mode, then "XSR" is sent three times in QRSS3 mode, then the following plain text is sent three times in 10 WPM CW, "DE WC2XSR/13 DE WC2XSR/13 QSL VIA W5JGV". The modulation sequence then repeats.


18 NOV 2002 - The transmitter of WC2XSR/13 went off the air at 1815 CST today.

Have switched to listening mode to try to receive WC2XSR/11 on 166.550 KC.


9 NOV 2002 - Modulation returned to previous sequence at 1010 CST.

See log entry of 3 NOV 2002 for details.


8 NOV 2002 - Modulation changed to 10 WPM CW ID continuous loop at 2300 for propagation tests with WE0H.


3 NOV 2002 - The modulation on WC2XSR/13 has been changed.

The new modulation sequence is as follows: The ID letters "XSR" are sent once in QRSS30 mode, then "XSR" is sent twice in QRSS10 mode, then "XSR" is sent three times in QRSS3 mode, then the following plain text is sent three times in 10 WPM CW, "DE WC2XSR/13 DE WC2XSR/13 QSL VIA W5JGV". The modulation sequence then repeats.

The time required for a complete sequence is 33 minutes, 43 seconds.

This new modulation sequence allows listeners to try various reception methods.

Power is 400 watts to the antenna, frequency is 166.500 KHz.


2 NOV 2002 - Transmitter off the air at 1230 CST in order to change some of the antenna support lines.

The existing lines are made of Poly rope, but even though they are rated for sunlight exposure, they appear to be deteriorating a an excessively rapid rate after less than two months exposure to the elements. I will replace them with some braided Dacron lines which I know from experience, last in excess of fifteen years. I don't know why I mess with anything other than the good Dacron rope. Everything else either deteriorates too fast or stretches too much. The Dacron line tightens up like a wire, and lasts for years.

Antenna support line replacement successful; transmitter placed back on the air at 1315 CST.


31 OCT 2002 - Happy Halloween! Transmitter off the air at 1416 CST for antenna modifications. Time to chase some gremlins from the system!!

I have determined that there is an excessive amount of unwanted shunt capacity across the loading coil. This unwanted capacity is caused by the close proximity of the feed pipe running from the antenna tuning cabinet to the lower part of the antenna. The roof structure acts as though it were a large capacitor connected between the lower portion of the antenna and ground. Having this extra capacity causes the amount of loading coil required to tune the antenna to resonance to be smaller than it would otherwise need to be.

When it rains, the wet roof acts as an additional load and even more capacitance across the coil. resulting in shunting of the antenna and unloading the transmitter. The net result is that there is about a 3 dB power drop when it rains. Because the antenna RF ammeter is placed between the loading coil and the antenna feed pipe, the extra shunt capacity causes additional RF current to flow inside the loading coil - RF ammeter - shunt capacity circuit, even as the actual antenna current decreases. As a result of this, the reading on the RF ammeter stays nearly the same, even though the RF power from the transmitter has decreased by half.

In an attempt to reduce this shunt capacity, I removed the 9 foot horizontal section of the RF feed pipe, and cut off the lower 8 feet of the vertical antenna wire. I then attached the lower antenna insulator to the bottom of the now shortened antenna wire, and tied off the lower end of the insulator to the steel horizontal support pipe which is connected to the tower. This keeps the vertical antenna wire properly spaced from the tower. Next, I ran a length of #14 wire between the stub of the feed pipe attached to the antenna tuning cabinet and the lower end of the vertical antenna wire, which is now 8 feet above the roof.

After making these changes, I retuned the antenna. I found that I had to add an additional 10 turns of loading coil to achieve resonance. This is one tap on my loading coil adjustment switch. I also modified the input matching transformer, that is made from a single FT-193A-J core originally had a total of 21 turns of #14 THHN wire. The transmission line connects across the entire winding, and the input to the antenna tuner was originally connected to a tap on the auto-transformer at 16 turns from the ground end of the transformer winding. To improve the match, I add one turn to the total winding, and one turn to the tap, making the number of turns on the input and output connections 22 and 15 turns, respectively. This gives a good match for the transmitter and a good VSWR. Based on the turns ratio and transmitter loading, the overall antenna system load resistance is about 30 ohms. This is slightly reduced from the estimated 33 ohms before the changes made today.

System readings:

Before changes: RF amps = 2.6, DC amps = 20.1, Fwd Pwr = 425 W, Ref Pwr = 20 W

After changes: RF amps = 2.52, DC amps - 20.0, Fwd Pwr = 410 W, Ref Pwr = 10 W

Although this is slightly less RF amps then before the change, the actual RF field strength is now greater, indicating that more RF power is being radiated instead of being lost as heat in the loading coil and the garage roof.

Transmitter intermittently back on the air for antenna adjustments at 1455 CST.

Transmitter back on the air for normal beacon operation at 1524 CST. The carrier frequency is 166.500 KC @ 400 watts. Modulation is QRSS30, signing XSR, followed by a 10 WPM CW ID.


27 OCT 2002 - Antenna oddities abound!

Yesterday and today, I have been trying to determine what is causing the drastic swings in the transmitter PC current when it begins raining. I think I have traced the problem to the close proximity of the garage roof structure to the lower connection point of the vertical portion of the antenna wire. Apparently when the roof gets wet, it becomes conductive enough to detune the antenna system and affect the transmitter loading. I think it will be necessary to modify the lower connection point of the antenna. When I have the changes made, I will post a complete description and my findings on the web site.

The WC2XSR/13 transmitter has logged over 2,000 on-the-air hours since it was first placed on the air.

For the time being, transmissions continue with the carrier frequency at 166.500 KC @ 400 watts. Modulation is QRSS30, signing XSR, followed by a 10 WPM CW ID.


16 OCT 2002 - At about 1515 CDT, I changed the modulation of the transmitter to a 15 WPM CW ID followed by a 60 second carrier ON signal.

WA4LIP, Lewis Denton, (distance = 117 miles) noticed the change almost immediately, and promptly sent me a WAV file of my signals, in which the 15 WPM CW transmission was easy copy by ear. Thanks, Lewis!

This modulation change was made so that I could go out in the field and do some preliminary reference field strength measurements in preparation for some planned antenna changes. I need the reference readings so that I can figure out if the changes are effective or not.

At about 2100 CDT, I returned the transmitter modulation to the previous mode.

Frequency is 166.500 KC @ 400 watts. Modulation is QRSS30, signing XSR, followed by a 10 WPM CW ID.


12 OCT 2002 - Today I decided to see if connecting the LF ground system to the local city water pipe system would make any change in the antenna current.

I already had a short jumper using a length of #16 insulated copper wire connected between the ground side of the antenna tuner and the closest outside water faucet, which was located about fifteen feet away. With the wire connected, the antenna current read 2.60 amperes. With the wire disconnected, the antenna current dropped to 2.55 amperes.

I disconnected the jumper wire and ran two longer #14 stranded insulated copper wires from the antenna tuner ground connection. One wire ran around the left side of the house, and the other wire ran around the right side of the house. Where the wires met in the front of the house, both wires were connected to the main water line where it entered the house. With these wires in place, the antenna current went up to 2.60 amperes.

I replaced the original jumper between the rear-of-the-house water faucet and the antenna tuner. There was no change in the antenna current.

Since the original jumper wire was going to be less visible and less in the way, I decided to remove the two longer wires and replace the short jumper with a more permanent installation. I fabricated a heavy cable made from four lengths of #12 stranded silver-plated insulated wire. Using an electric drill, the four wires were twisted together to form one heavier length of wire.

After installation of this twisted wire ground cable, the antenna current rose to 2.65 amperes.

I think that the reason the addition of the two longer wires directly to the city water system did not make any noticeable improvement is that the plumbing under the slab of the house is made of copper. Since the pipe covers a larger area than the two added wires, the in-house pipe system acts as a better ground system than the thinner but longer wires.

Frequency is 166.500 KC @ 400 watts. Modulation is QRSS30, signing XSR, followed by a 10 WPM CW ID.


11 OCT 2002 - Transmitter off the air at 1600 CDT.

I had to lower the top loading wire in order to make modifications to the antenna support rope fasteners. The new ropes which were installed just before hurricane Isidore, had stretched enough so that the antenna current was affected slightly. I installed four new rope cleats - actually, a series of eight 5/16" x 3" long bolts - on which to fasten the hoisting lines for the antenna systems attached to the roof mast. I don't like the performance of the new rope, and I will replace it shortly when the new rope arrives.

Transmitter back on the air at 1640 CDT. Frequency is 166.500 KC @ 400 watts. Modulation is QRSS30, signing XSR, followed by a 10 WPM CW ID.


10 OCT 2002 - It has been busy around here since hurricane Lili blew through the area. Luckily, very little damage was done here, and the winds did not become strong enough to cause any serious damage to anything at this QTH. The lines holding the antennas stretched somewhat, but that was expected, and they can be easily retightened. The new steel guy lines came through fine, and no readjustment seems to be needed on them.

The transmitter remained on the air through the entire storm, and several reception reports of this station which were taken during the height of the storm were received several days ago. All indicate that the signal was unchanged during the hurricane.


73, Ralph W5JGV


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The entire contents of this web site are Copyright © 2002 by Ralph M. Hartwell II, all rights reserved.