Back to the SARA Home Page

Next S.A.R.A. Meeting on Thursday, April 17th  at the Doylestown
Village hall.

This Month's Meeting will include:
Swearing...
in of officers

Most two meter FM transceivers are capable of operating on any frequency between 144 and 148 MHz.  Amateurs in the United States are also allowed by the FCC to operate anywhere between 144 and 148 MHz, however, the 2 Meter band must be shared among a great number of users.  The vast majority of the people that operate on 2 Meters use FM, but there are a surprising number of people that operate other modes, such as SSB and CW.  To prevent interfering with other amateurs (and to preserve your reputation as an intelligent operator) it is important that you carefully choose which frequencies you operate on. 

Because there are different uses for the 2 Meter band, a "bandplan"  has been agreed upon that allows an area for nearly every mode.  Table 1 shows the bandplan that is used on 2 meters in Ohio.  The basic bandplan is common over the entire United States, but some states use 20 KHz channel spacing on all FM allocations.

Channel Spacing

Notice the column in Table 1 marked Channel Spacing.  This refers to the increments that should be used when operating using FM.  Most radios will tune in 5KHz steps, meaning that if your radio is set on 146.520, the next frequency up is 146.525MHz.  The problem is that an FM signal is much wider than 5KHz.

Try this example:
Tune to a strong repeater, such as 147.390MHz.  While the repeater is being used, tune your radio to 147.395MHz.  You will still hear the repeater, and reasonably well!  Tune to 147.400MHz, and you will likely STILL hear the repeater, as shown in Figure 1.

147.390MHz is only the CENTER of the signal.  The actual signal goes from about 147.383 to 147.397MHz. To make matters worse, most FM receivers (such as HTs and mobiles) receive about 15KHz bandwidth.

You will find that if you tune your receiver to 147.405MHz, you probably will not hear the re

peater anymore.  It is not a coincidence that 147.405MHz is 15KHz away from 147.390MHz, and that 15KHz is the normal channel spacing for this part of the band!.

Selecting a Simplex Frequency
When selecting a frequency to use, ALWAYS follow the bandplan for your area.  Valid simplex frequencies are found in Table 3.  If a frequency is not listed in Table 3, you should not be using it as an FM simplex frequency.  There are also a few frequencies available between 145.500 and 145.600MHz, but these are considered general purpose experimentation frequencies.  For normal simplex QSO's, you should stick to the frequencies shown in Table 3.

Although your radio may have the ability to tune to frequencies in between the ones shown in Table 3, you should not use those "in-between" frequencies. Because of the width of an FM signal, if you tune in-between the recognized frequencies, you will actually be using two valid frequencies instead of one.

There are many people that will tell you that no one owns the band, and that they are licensed to use any frequency between 144 and 148 MHz.  Those people are correct, but they are also the first people to complain when their QSO is the one that is being interfered with.

If you use a frequency other than those shown in Table 3, the odds are very good that you will interfere with a repeater, a satellite, or someone using a weak signal mode such as SSB.  Believe it or not, if you transmit with an HT on the wrong frequency at the wrong time, you can make a passing amateur satellite unusable for the entire hemisphere!  With over 10 operational amateur radio satellites currently operating in orbit, the odds of interfering with one of them are very good.

By following the bandplan, everyone can enjoy the two meter band.  Next month, I'll cover the bandplan for the HF frequencies

Replacement of the Doylestown Water Tower

SARA has been informed by the Mayor of Doylestown that the village will be replacing it's main water tower at the Village Hall site with a new one.  Why is an amateur radio related newsletter publishing an article about a water tower?  Because the top of this water tower is the home for the antennas used by SARA's 147.390 and 442.275 repeaters.

The current water tower has a capacity of 100,000 gallons, and has problems including stress cracks in the tank, corrosion inside the tank, and lead based paint on the outside.  Doylestown's growth also will require more capacity than this tower can deliver.

The water tower that will replace the current unit is a newer "golf ball on a tee" style, and will have a capacity of 200,000 gallons.  SARA's Operations Manager, Bob, N8ZCC, also tried to convince the Mayor that the new tower should have 200 feet of additional tower on the top, but the Mayor didn't feel he could justify the cost.

The good news is that the Mayor has given SARA permission to install our antennas at the top of the new water tower when it is in place.  This will require a substantial effort on the part of SARA, because the newer style water towers do not offer as many places to bolt antennas to.  According to the Mayor, the new water tower will include a tunnel that will run from ground level up the center of the tower, and all the way to a hatch on the top.  At the top of the tower, there will be a small rail that can be used to attach antennas.

The hardline that is in place on the current water tower has been in service for at least 10 years, and has sustained several lightning strikes.  One of the primary ways that lightning can damage feedline is by creating small holes in the outside shield, changing the impedance and allowing water to enter the system.  The technical committee believes that this feedline is the source of many repeater problems that we have had in the past.  Installing the antenna on the new water tower will offer a chance to install an antenna system that has been engineered properly from the ground up.  The new installation will also include a more effective lightning protection system.

In case all this good news is making you suspicious, rest assured that not all of the news is good.  The process of removing the old water tower and installing the new one will begin sometime in September, 1997, and will require a minimum of 3 months to complete.  This means that our antennas will need to come off of the tower in August, and will not be re-installed until sometime in the spring of 1998. 

The process of selecting a temporary site to serve the SARA repeaters has already begun, and the technical committee has several good sites on the table.  The Mayor has even offered the top of Doylestown's second water tower (located in the Gates street park area) as an option.  Any temporary site that is selected will likely not have the profile of the current water tower (currently about 1,350 feet above sea level at the antenna) , but every effort will be made to get the antennas as high as possible.

Look for future updates on this subject here in the Salami Merchant as news develops.

The month of April is here already, and so is the occasional severe weather that goes with it.

The 147.390 repeater carries the Wayne county area Skywarn net during periods of severe weather, and the repeater occasionally makes some odd sounds in conjunction with Skywarn.  This article will fill you in on what the different sounds mean, and how you should react to them.

NOAA Weather Alert Tone: When NOAA Weather Radio (162.400 MHz) sounds it's severe weather tone, the 39 repeater will transmit an alert.  The alert sounds like this:
a long alert tone, followed by the DTMF digits 7 3 9, followed by a voice that says "N O A A Weather Alert".  You can use the 7 3 9 DTMF digits with the Coded Squelch features of some radios to "wake them up" when a severe weather alert is issued.  Please note that the National Weather Service tests the warning system on Wednesdays, around 11AM, and again around 7PM. 

6 Meter Backbone Monitor
New this year to the 39 repeater is a receive only link that monitors the 6 Meter Skywarn backbone.  The purpose of this receive-only link is to keep 39 listeners abreast of developing weather problems, and to allow statements issued by the National Weather Service to be directly heard over 147.390.
The link will be automatically activated when the repeater is put into the Standby Mode (see below).  In other situations, the link will manually be activated by the Skywarn Net Control station as required.  This 6 meter monitor is in the talkover mode, which means that any traffic on the 39 repeater will override the 6 meter link audio.  To help people determine where a signal came from, signals originating from 6 meters will have a separate and distinct courtesy tone, and will be at a slightly lower level than the normal 39 traffic.

Standby, Watch & Warning modes:
When severe weather  is possible or active in the area, the 39 repeater will be put into one of three modes:

Standby: You may continue to use the repeater for normal conversation, but be sure to leave long pauses between your transmissions.  The repeater will use a Morse code "S" (dit dit dit) for a courtesy tone, and there will be a long delay before the tone is heard.  WAIT FOR THE MORSE "S" TONE while using the repeater in this mode.  The repeater will also occasionally announce "Weather Watch Ready" as a tail message.

Watch:  The repeater will be put into the WATCH mode if a severe weather watch has been issued by the National Weather Service for Wayne County.  In the watch mode, the repeater will use a Morse "W" (dit dah dah)  for a courtesy tone.  You may still use the repeater at the discretion of the Skywarn Net Control.  Keep your transmissions short, and leave long pauses between transmissions.  The repeater will occasionally announce "Severe Weather Watch" as a tail message.

Warning: When a severe weather WARNING is issued by the National Weather Service for Wayne county, the repeater will be put into the Warning mode.  In the warning mode, the repeater will use a Morse "W" for a courtesy tone.  Use of the repeater is restricted to Skywarn Traffic in this mode, and the Skywarn Net Control station will advise what information is of interest.  The repeater will occasionally announce "Severe Weather Warning" as a tail message.

Listen to Skywarn Net Control
The best way to know what to do during severe weather is to listen.  The Skywarn Net Control station will occasionally announce what information is of interest, and will advise listeners of the current state of the watch or warning.

Where to Report
If you need to report severe weather information, you should do so on the Skywarn net that covers the area you are currently in.  For example, if you are visiting a friend in Summit county, you should report severe conditions to the 146.640 repeater, NOT the 39 machine.  If you are in Wayne county, you should report severe weather on the 147.390 repeater.  NEVER report severe weather on the 6 meter backbone unless you have been designated as the 6 meter liaison by the Skywarn Net Control station for this event.

Have a safe season!