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Volume 29, Number 7 - JULY 1999

JULY MEETING

Kurt Kiesow, KF6QNC will speak on APRS. 

We had a speaker on this topic a while ago, but it is time for a refresher. It works like this: Take one ham and attach him to a Geopositioning device, computer and a transceiver. Send the ham out running around in circles. Track the ham by way of the Internet and APRS software which displays the location of the ham on a map on your very own computer.

APRS WEB Sites:

aprs.rutgers.edu - Download site for APRS info and Software.
www.tapr.org
www.aprs.net
www.cave.org/aprs
The following web site is used to track someone with APRS where you know their callsign, like Andy Fu, AC6GN or Chris Verbil, N5CV.
maps.aprs.net/callsign (where callsign is the callsign of the person you want to track)
Information source: Howard, KE6PWH

 

WILKES LATE WITH NEWSLETTER AGAIN

Sorry about that, I got my weeks mixed up.  If I hadn't run into Arv at Haltek, this newsletter would have come out next week.
 
 

PRESIDENT'S CORNER

Field Day was a success after a lot of hard work by the few who participated.  We were sadly lacking in operators and loggers. 

The new transceiver has been installed at the club station and we encourage club members to get checked out and operate the station. 

We are going to be operating the club station in some of the other contests and the purpose of this is to train club members in the operation procedures during contests.  This will give you a chance to operate the club station and to learn about contesting. 

It is time for club members to start thinking about who you want as officers for next year.  We always come up to election time and have a difficult time finding those who are willing to help lead the club. 

Some members have served and served and really have done more than their share and it is time that those of you who haven't served to be willing to lend a hand.

Jack WA6YJR

 

CALENDAR

Livermore Swap Meet - 1st Sunday of each month at Las Positas College in Livermore, 7:00 AM to noon, all year. Talk in 147.045 from the west, 145.35 from the east. Contact Noel Anklam, KC6QZK, (510) 447-3857 eves. 

Foothill Flea Market - 2nd Saturday of each month from March to October at Foothill College, Los Altos Hills. FARS NET on 145.23 repeater Thursday nights at 8 PM. 

Jim, WE6V is running W1AW code practice sessions on the 145.23 repeater every Tuesday evening 8:00 to 8:30.
 
 

APPARENT S-METER ANOMALIES

The 145.230 repeater S-Meter has generated a lot of interest and controversy.  I recently heard some interesting S-meter reports. One person who was testing first got an S5 reading then on the next test he got S9.  This is an apparent 4 S unit change.  As each S unit is 6 dB, that would seem to be a 24 dB increase in power entering the repeater receiver.  If one were using a 2.5 watt HT, 24 dB up would mean the person was running an amplifier with 628 watts out.  While this IS possible, it is not likely. 

There are several other possible explanations.  Remember that while the repeater's S-meter is calibrated to respond to an analog input, the controller's output is digital.  One can envision this as a set of stairs going up, each step of which is 6 dB (one S unit).  Superimposed on this stairway is a smooth curve of the analog signal.  Ideally, the analog signal will touch the stairs at the corner of each step.  If the initial S5 reading were near the top of one step, say only 1/2 dB below, and the S9 were just above (say 1/2 dB above) the S9 stair step, then instead of a 24 dB increase, there would really be only a 13 dB (two steps at 6 dB each plus two 1/2 dB steps) change.  13 dB above 2.5 watts is ~= 49.9 watts.  50 Watt amplifiers are a lot more common on two-meters than 628 Watt amplifiers. 

One other logical explanation assumes that the S5 was obtained with an HT putting out only 200 milliWatts.  Some of the new shirt-pocket HTs have the capability to select a very low power output.  One 523 repeater user puts out only 50 mW into a good antenna which results in an almost complete quieting of the repeater receiver.  Assuming a true 24 dB change, 24 dB above 200 mW is ~ = 50 Watts which is well within the normal range of many amplifiers. 

Heard on the repeater recently, a mobile station at rest was testing using the S-meter. This station said that they varied the power setting on his radio from 5 Watts to 50 Watts and the S-meter gave the identical reading at both extremes and at several levels in between. His conclusion: "I guess the S-meter isn't working". What might have been happening there? OK, one could say that the S-meter was not working, but that response was thrown out by other stations testing and obtaining reasonable reports. There are several other possibilities, however. Just because one switches a radio from low to medium to high power does not mean that the radio is in fact changing power levels. I remember checking one HT which had multiple power settings with a through-line wattmeter connected to a good dummy load. Changing the power level switch had NO effect on power output Conclusion: the Power Level switch on the HT was not working. 

In a mobile installation there are other possibilities. With the engine off, a weak car battery will experience voltage drop as more current is taken from the battery. In this scenario, with the radio in the low power position, the battery voltage may be 12 volts. At the 50 Watt position, the 10 Amps or so drawn by the radio to put out that amount of power could cause a weak battery to output only 10.5 to 11 volts. Thus the radio is not really putting out 50 Watts even when the switch is in the 50 Watt position. 

A similar situation would exist if the car motor were running and a new car battery were installed, but the connection to the to the battery were though the cigarette lighter and/or there were even a small resistance contact somewhere between the battery and the DC going into the radio. At a current of 10 Amps, it would take only 0.1 Ohm resistance to drop one volt between the battery and the rig. Yet this could significantly affect the rig's power output. 

Keeping in mind the stair-step analogy above, switching from 5 Watts to 50 Watts should yield a 10 dB gain in signal strength, or one and two-thirds S units. But the controller does not report in thirds of an S unit. The signal has to at least be at or over the next step to read the next S unit. So, if everything were working properly, a change from 5 to 50 Watts output should cause a 1 S unit change in reading. How far would power have to drop not to hear any change? If we assume that at 5 Watts output, the signal at the repeater was just barely above the S5 level, the signal could rise 5.5 dB and still not read an S6. 5.5 dB above 5 watts is: 17.74 Watts. (17.74 / 5 = 3.548 and 10 x log 3.548 = 5.5 dB). 

There are other possible causes of apparent S-meter anomalies. Some examples: if one were using an HT to drive an amplifier and both were being powered from the cigarette lighter outlet, if the current taken by the amplifier were causing the voltage to the amplifier to be low, the voltage to the HT would also be low. Even if the HT is operating on internal batteries, how well is the internal battery holding up (over the duration of the test) at 5 Watts out of the HT? If one is using an HT to drive a Class C amplifier, but the HT is on low power, there may not be sufficient drive to the amplifier to have it produce full output. 

So what is the answer? For starters, IF the S-meter is not responding the way you expect, monitor the voltage actually going into the back of your rig, whether at home or in the car. (Beware of possible RF effects on any voltmeter using semiconductors. One may have to use an analog meter in series with an appropriate resistor to obtain an accurate reading in the presence of RF.) As we have seen above, even a small resistance somewhere between the power source and your radio could be the problem. Second, attach a power meter at the output of your rig and measure actual change in power output as the power level switch is changed for one level to the next. Chances are that if the S-meter is not changing S unit levels, that the rig is not putting out enough power to cause it to change.

De Rich, W6APZ


I did an Internet search for newsletter input and was pleased to find the above by one of our very own was the most interesting this month.

DW

 

Amateur Radio Newsline

Proposed APRS Satellite Some of the nations APRS leaders have been doing conceptual studies for a small nano satellite for relaying APRS status position packets from stations in remote areas and off shore. This, according to an internet posting by the father of the mode Bob Bruninga, WB4APR. According to Bruninga the biggest problem has been designing the system to be optimize for mobiles while mitigating the interfering signals from all the fixed operations on a given radio channel. But says WB4APR the job is not as difficult as first thought. This is because 90% of the North American population located on 20% of the land is already covered by the APRS infrastructure. This means that a dedicated APRS satellite need only supply coverage in the remote 80% land mass. This is because the remote 80% comprises only 10% of the population. This means interference is minimal where satellite relay is needed the most as the remote mobile will be hearing nothing else on the channel since he is far from any other stations. This means an almost 100% chance at hearing the downlink. Bob says that this makes a flying simplex digipeater operating a perfectly viable space satellite application for North America and surrounding off-shore areas. The satellite would be silent over the rest of the world if its operating frequency is not available in order to abide by international agreements. No firm plans for an APRS satellite are in place. It's only in the very beginnings of a discussion phase.

(AMSAT BBS, VHF Reflector)


Kids Day Follow Up The June 19h Kids Day operating event was a bigger success than anyone might have imagined. Hams around the nation heeded the call and gave many of the nations youngsters their first look at the magic world of Amateur Radio. And the world was listening in as we learn from Australia's Graham Kemp, VK4BB: Kids Day on June the 19th showed off Ham Radio to the next generation. Kids Day was started by Larry Tyree, N6TR under the auspices of the Boring Amateur Radio Club in Oregon. During a January running of Kids Day more 400 youngsters took part at a fun on the air event that has grown tremendously popular in the last few years. Much like JOTA, but open to all kids. World Radio editor Rick Mc Cusker, WF6O of Sacramento, California printed brochures about Kids Day and distributed them in his neighborhood. He then threw a barbeque to feed the kids when they stopped by to make some QSO's. And Rick Painter of Tennessee had a similar notion. He invited a church youth group for pizza, soda and ice cream, plus a chance to step up to the golden microphone at the Kids Day Radio Party. This was the last Kids Day of the 20th century. The next one is not that far away. It's slated for January, 2000.

(Q-News)


DX In DX, 6 meters continues to conjure up images of 20 meters on that bands very best DX days. For example, Ed Rodigez, WP4O in Puerto Rico reports that he now contacts Europeans on a regular basis. Some of the stations Ed worked on June 16th include G0JHC, EI5FK, F5JK and ON4ST. Ed says that he worked all of these and more running CW to a four element quad antenna up only fourteen feet. (VHF REflector) And even one of the Newsline staff is getting into the 6 meter DX craze. On Monday, June 14th, our producer Bill Pasternak was at work where they had just connected a newly installed 5 element Cushcraft 6 meter beam to the stations Kenwood TS 570 S transceiver. Bill gave a call on 50.125 MHZ and immediately made contact with N2ODU who gave his location as being about 50 miles South of Buffalo, New York. This took place at about 02:00 UTC with signals at 5 by 9 plus on two way SSB. (Newsline) So if we may editorialize to all the Technician and Technician Plus class hams sitting on repeaters and hoping that some day restructuring of Amateur Radio will permit them to chase DX on the high frequency bands. The DX is already there for you on 6 meters. Your current Tech license, a 6 meter radio and an antenna is all you need to bring that very special DX to you.That OTTER Radio Hunt And finally, we all know that here in the United States hidden transmitter hunts are often called Fox Hunts or even Bunny Hunts. But what about a hidden transmitter hunt that takes place on water? According to John Arsay, VK4QA, that's what the Dutch call an Otter Hunt. Here's John with more: Today one should be in the Netherlands for an fascinating experienced as VERON is organizing the fourteenth OTTER Hunt. We all know about fox hunts or, to use its proper name, radio direction finding games. The Dutch, of course, want to be different so they started the Otterhunt, It is held near the old Zuyderzee, now called IJssel Lake, in a place called Meppel. It is a pretty wet area and the fox, sorry, the otter can only be hunted by boat'. The hunters can chase an Otter on two meters or on eighty meters or, if 'they are really keen, can try to locate both otters, using two receivers at the same time. Various boats are available for hire if you don't own one yourself. These hire boats vary from a motorboat driven by an electric motor to one man canoes but they don't say how many rescue vessels there will be on the water! It will be a very busy period as one has to locate not one, but five hidden transmitters, each transmitter point having both a two meter and eighty meter unit. To make things morn interesting or, should I say, more difficult, extra points will be awarded to those hunters who manage to accurately indicate on their maps the location of the found otters.' And to make things more interesting again, a questionnaire must be completed covering the natural habitats of the area around the Otters! If you think that the Otter Hunt is different, how about a T-Hunt in the air. The Dutch are doing that too. That story, next week.

(Q-News)


The Amateur Radio Newsline web page is at: www.arnewsline.org. According to our Support Fund Administrator, Andy Jarema, Newsline has received only enough financial support to keep the service going though mid July. In other words, the bills from May have been paid, but now money has to be raised to keep from losing the phones and e-mail service in mid summer. We also need to raise an additional $1500 to cover our part of the expenses involved in administering and presenting the annual Young Ham of the Year Award.

picture

This was our site. The HF antenna is in the middle with the VHF antenna on top. The VHF station was in the screened canopy on the right. Behind the canopy was the truck with the HF station. The CW station and picnic area were across the field in the left background and the RTTY station was over the hill behind the CW station. 

Picture 

Some people worked very hard to make contacts. Virginia and her husband came down from Oregon just for Field Day. 

Picture 

So did some others (Note: Get placement fee from 7-UP). Here are Dennis and Charley at the Novice/Tech station. Goal for next year: Get some Novice CW operators. After going through the available voice contacts, there was nothing left except CW. 

Picture 

But then some other people.......... Just kidding. These people and others worked very hard to make Field Day a success. 

Paul, Jack, Martin, and Arv take a break after erecting towers (To Hell with the Telecommunications Act).
 
 

Missing Person

One of the Field Day activities I missed most was conversing with Father Wence. We lost him since last Field Day and none of the Fathers came over to talk with us. Father Wence was in China when the Japanese invaded during WW II. Everyone has a period of history and that was part of mine. How many other stories do the priests have?




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How to get to meetings:

(Visitors always welcome)

FARS meets at the Covington School District building, 201 Covington Road, Los Altos. Take the El Monte exit (The same exit as for the Foothill Fleamarket) off of I-280 and go East on El Monte. Cross Foothill Expressway and turn right at the next light on to Covington (Note Saint William church on corner). Stay to your left as the road forks. Just past the fork, turn left into the school parking lot. Walk through the center hallway and turn right. The meeting room is the first door on the left. Talk in on 145.23 or 145.27, negative offset, 100 PL.