Tag Archives: Education and Training

NARS Winter Field Day Plans

Brian, W1XMM, has opened up his station for NARS members to operate Winter Field Day  (WFD) on Saturday and Sunday January 27th and 28th so that members can operate WFD with the club callsign, N1FD.  Brian’s station is in a great location, in Antrim, NH and should provide for some great operating.

What is Winter Field Day?

Winter Field Day is an annual event, sponsored by the Winter Field Day Association on the last full weekend in January to encourage development of emergency operating skills.  It is open to frequencies on the HF, VHF and UHF bands.  Here is a summary of the rules. The full rules can be found here.

  • All stations are limited to a maximum of 100 Watts PEP
  • QRP CW limit of 5 watts multiplier of 2
  • QRP Phone limit of 10 watts multiplier of 2
  • Each mode worked on each band counts as 1 multiplier
SteppIR DB18
SteppIR DB18 at W1XMM

W1XMM Station

The following stations and associated bands will be available at W1XMM:

  • SteppIR DB18 40/20/15/10/6m with an Elecraft K3S
  • SteppIR Vertical 80/40/20/15/10/6m with a Yaesu FT991a
  • Log Periodic 50MHz -1.2GHz
  • Inverted V: 80M and 160M (one cable out to both)
Log Periodic Antenna at W1XMM
Log Periodic Antenna at W1XMM

Great Opportunity for New and Experienced Hams!

This is a great opportunity for newly licensed or inactive amateurs to get some operating experience and a top-notch station.  Brian and other members will be available to coach those who are new to HF and VHF operating.

W1XMM Operating Equipment
W1XMM Operating Equipment

Emergency Communications

NARS member Jack Ciaccia, WM0G, who is also the ARRL New England Division Assistant Director for Emergency Communications and Public Service, is encouraging amateurs throughout New England to operate Winter Field Day to developer emergency operating skills.   

We have been challenged by the ARES group to also set up an NVIS antenna and communicate with other ARES operators at set times.  This would be both VHF/UHF and HF.  The ARES is going to use this opportunity to test their communication skills here in New England.

SteppIR Vertical Antenna at W1XMM
SteppIR Vertical Antenna at W1XMM

Join Us

Interested in joining us for Winter Field Day?  Please sign up by Thursday January 25th at 7:00 pm.  Here’s what you can do:

  • Sign up for operating times – See this Forum Post for the link to the sign-up sheet.
  • Join us on Thursday, January 25th  at 7:00 pm for our final Winter Field Day meeting.  See this Forum Post for the Zoom link.  Or contact Brian at [email protected] to get the details if you cannot make the meeting.
  • Show up at Brian’s QTH in Antrim before your operating slot.

 

Interpreting S-Meter Readings

Introduction

Most communication receivers and transceivers have S-meters, either analog or digital. We also know that there is a 50-ohm coaxial connector on the back of most receivers. What do S-meter readings mean in terms of the 50-ohm receiver input?

High Frequency (HF) < 30 MHz and Very High Frequency (VHF) > 30 MHz receivers work to different input signal level conventions. In other words, and to confuse matters, an S9 for HF is not the same as S9 for VHF.

Nearly 100 years ago, it was decided that S9 should be 50 uV at the receiver input. However, no input impedance was specified. A signal level of S9 was meaningless until the voltage level was standardized to 50 ohms by the International Amateur Radio Union (IARU) some 50 years later. Different voltage levels at the receiver inputs were adopted at that time for HF and VHF.

While S-meter readings are useful for signal reporting and logging, it is important to remember that S-meter readings are not perfectly linear, and linearity differs from receiver to receiver. It may depend a great deal upon receiver settings.

HF Receivers

Suppose that an HF receiver is displaying a signal of S9. We are told that this signal level is defined as a voltage of 50 uV (50 microvolts) at the 50-ohm receiver input connector. This does not tell us what the signal power is incident on the antenna because we do not know what the antenna gain is, what mismatches there are, and what any other gains or losses might be. We only know that a 50 uV signal is present at the receiver input and that the receiver is displaying S9. If we perform a little calculation, we arrive at the power level at the receiver input connector.

To convert this signal power to milliwatts (mW), we divide by 1E-03 or 0.001 since a mW is 1/1000 of a Watt.

There is another way to do this if we know that there are 1E+03 mW in a Watt. We can use dimensional analysis to arrive at the right answer.

We may now convert this value in mW to dBm.

So, a signal of S9 is equivalent to a signal power level of -73 dBm into a 50-ohm input.

Example 1

Bearing this in mind, what would the power level of a signal be for an S-meter reading of S1 in units of dBm?

The signal level at S1 is 8 S-units lower. If each S-unit adds or subtracts 6 dB by convention, a signal of S1 would be 48 dB lower than S9. Subtracting 48 dB, the signal at S1 would be -121 dBm.

Example 2

Suppose we are told that the signal input to the receiver reads S9+10 dB (10 dB over S9). What would the signal into the receiver be in units of uV?

We know that a signal voltage level of S9 is 50 uV into the 50-ohm receiver input. We already know that the signal power level of S9 is -73 dBm. Thus, if we add 10 dB, the signal power level would be -63 dBm (less negative). All that is left is to convert this power level back to uV.

Let’s convert this -63 dBm input signal level to mW. In order to do this, we must take the antilog of the input signal level.

Next, let’s convert mW to Watts by dividing by 1000

Finally, we convert to Volts using the formula

We can convert Volts to uV by multiplying by 1E+06

Since the impedance level for the 50 uV and the 158.3 uV input signals are both 50 ohms, we can check the result to see if it is 10 dB higher than our S9 signal of 50 uV. We notice that the 50-ohm impedance cancels when we take the ratio of the two power levels in

Example 3

What is the 50 uV signal in dBuV?

Receiver specifications are frequently written this way.

VHF Receivers

VHF uses a different standard for S9, notably –93 dBm (5 uV) into a 50-ohm receiver input. A value of 6 dB still represents 1 S-unit. All of the calculations are similar to those for HF receivers.

Example 4

Prove that 5 uV is equivalent to an input signal level of -93 dBm into a 50-ohm VHF receiver input.

Again, there are several ways to proceed. Let’s begin by converting 5 uV to Volts.

We can convert this to power

Convert to mW by multiplying by 1000

We convert to dBm using

Example 5

Convert the 5 uV signal to dBuV

Conclusions

The reference levels for S9 are defined differently for HF and VHF receivers. In this article, it has been shown how one would convert between voltage and power levels at 50-ohm receiver inputs.

When discussing S-units, some receivers are more linear than others, and linearity may depend upon receiver settings. Nonetheless, S-units are useful for signal reporting and logging because everyone agrees on the same standards.

Title Photo Credit: Photo of Ten-Tec Orion S Meter, author: Martin Ewing. Public Domain, https://commons.wikimedia.org/w/index.php?curid=1575140

 

 

 

 

Nashua Area Radio Society at HMS STEM Night on March 13th

Dan Pooler (AC1EN), a teacher at Hudson Memorial School in Hudson, NH, and a Nashua Area Radio Society member, worked with the school and other NARS members to present an exhibit to students and their families promoting HAM Radio and highlighting some of the activities of our club to them. Dan reported that “STEM Night at HMS was a big success.

HMS Steam Night
HMS Steam Night

We had over 100 5-8th graders attend the HMS STEM Night, with over 400 people attending the event. Students and their families could watch SubZero Ice Cream demonstrate how they created ice cream, learn how pickles are made, program robots, shoot off Alka Selzer Rockets, make math art, and play games with family and friends along with visiting the NARS booth.”

Lining up for HAB Exhibit
Lining up for HAB Exhibit

Fred Kemmerer (AB1OC): shown here explaining aspects of our High-Altitude Balloon activities to some students. Anita Kemmerer (AB1QB), Mackenzie Pooler (KE1NZY), and Sam Hergenhahn (KC1PVZ) also participated at the event .

HMS STEM Night
This big

Dan Pooler (on the left) at the High-Altitude Balloon exhibit.

Morse Code Exhibit
Morse Code Exhibit

NARS Exhibits at Hudson Memorial School STEM Night

Our exhibits included:

  • A Fox Hunting display
  • A remote HF Radio Station, where students heard amateur radio operators from Australia, Greece, Lebanon and other countries.
  • An ISS /Satellite exhibit including a Raspberry-Pi based video of the HMS ISS contact video,
  • A Morse Code display with keys and practice exercises.
  • A High-Altitude Balloon display
Remote HF Radio Station
Remote HF Radio Station

Special thanks and appreciation to NARS Vice President Jamey Finchum (AC1DC), who worked with Dan and the school to plan NARS’ participation in the event.. Thanks also to Fred (AB1OC) and Anita (AB1QB) Kemmerer, who graciously took the time to provide the displays and attend and share their love of the hobby with the students and their families.

HMS Principal Keith Bowen told me in an email after the event, “It was great having your group participate in our STEAM night. Students and families enjoyed their experiences.”

Hudson Memorial School will also be the location for NARS Summer Field Day 2023. Please check the forums on n1fd.org for updated info.

SUMMER FIELD DAY WEEKLY PLANNING MEETING THURSDAY NIGHTS AT 7:00 PM – Nashua Area Radio Society (n1fd.org)

Radio Amateurs Developing Skills Worldwide