Tag Archives: Digital

Getting On The Air – Your First Station

Class Grad with Her CSCE
Class Grad with Her CSCE

So you’ve gotten your Technician License or your General upgrade – how do you get a station on the air? This was the topic of our recent Tech Night. The following are some thoughts to get you started. If you are a new Technician, the first thing to ask is – “What do I really want to do on the air and where will I be doing it?” Here are some common answers to this question:

  • I spend a lot of time commuting in my car or truck and I’d like to pass the time talking with other HAMs
  • I will mostly be operating from my home and I want to rag chew (chat with other HAMs) and check-in to emergency, ARES and/or other nets
  • My plans are mostly be doing parade and other HAM activities in the field and I need something that is portable

Approaches for Tech Operators

In all of these scenarios, you will be using a combination of FM Simplex and Repeater operation on the 2 m and 70 cm bands.

Mobile 2m/70cm FM Radio in a Vehicle
Mobile 2 m/70 cm FM Radio in a Vehicle

If the first case is you, then you’ll want to install an FM mobile rig and antenna in your car or truck. You’ll also probably want to permanently mount a simple  2 m/70 cm antenna on your vehicle.

Base 2 m/70 cm Radio with APRS Display
Base 2 m/70 cm Radio with APRS Display

If the second case is your prime operating scenario, then your choices in radios probably are along two main paths.  A 2 m/70 cm radio or a dual purpose HF and 2 m/70 cm capable “all in one” radio. You might take the second approach if you already have or are planning to get your General Class or Extra Class license.  A 2 m/70 cm ground plane style vertical antenna that you can mount outside or perhaps in your attic would be a good choice. You might also want to consider a radio that does D-STAR or another Digital Voice mode. There are some large worldwide nets that use digital plus internet linking to reach a large population of HAMs.

HT with Improved Antenna
HT with Improved Antenna

If the third case is you main operating mode, then you probably want a quality HT with a good antenna. The rubber duck antenna that comes with most HTs will provide relatively weak performance. A quality 5/8 wavelength antenna and a spare battery for your HT will be a good way to go.

Approaches for General  Operators

First Station - OCF Dipole and a 2 m/70 cm Antennas
OCF Dipole and a 2 m/70 cm Antennas

If you’ve received your General Class license and want to do HF, your biggest decision will your antenna antenna. This topic is pretty broad and we’ll cover it in more detail at our Tech Night. I usually recommend a simple wire antenna to get started. A 20m dipole mounted either horizontally or vertically is often a good first choice. It’s inexpensive and can be put up at most QTHs in a day or less.

Moving up from here, a 40m delta loop or a multi-band OCF dipole also make great starter antennas depending on your space and what you want to do. If you cannot mount an antenna outside, you may be able to mount a modest dipole in your attic or use a portable antenna system like the Buddipole that you can set up to operate and then take down.

First Station - Basic HF Station with PC
Basic HF Station with PC

Radio choice is also a broad topic which we will cover at our Tech Night. I would recommend a starter HF radio or a good used one (with help from an experienced HAM to select and check out). Your radio should be a 100W unit and cover all of the HF bands from 80 m – 10 m at a minimum. QRP radios (5 – 10W) are usually not a good choice for a first station. Making contacts at this power level with simple antennas can be challenging. It’s also good to have a radio which can do 6 m if that works out for you.

I highly recommend that you include digital mode capability in your first HF station. Digital modes such as PSK and RTTY provide a great way to learn to make contacts on the HF bands. Also,  these modes work very well for making DX contacts with 100W and simple wire antennas.

I hope that this will get you started thinking about how to set your first station. Please come to our next Tech Night session to learn more. You can ask questions and get the benefit of experienced folks in our club. We can help you with these choices. We can also help with installing radios, antennas and getting on the air.

Fred, AB1OC

Rig Audio Interfacing and Low Cost PC Headsets

First I want to promote some excellent papers on rig interfacing and grounding produced by Jim Brown K9YC.  There is a wealth of information there, produced by a very talented and experienced engineer.

Now…on to the topic of interfacing PC headset to ham rigs…

Heil Headsets get a lot of support and advertising in the amateur community.  But they are expensive.  The W2SZ VHF/UHF contest group that I belong to uses mostly Heil headsets, so I have a lot of experience with them.  The problem is that a lot of them are broken.  We only use them two weekends a year for about 36 hours but they fail in a variety of ways.

I don’t own a Heil headset (I’m too cheap), but wanted a more reliable headset for my own use on the mountain.  In this case, reliable means I can bring several for a reasonable price.  So, this led to a series of experiments with PC headsets that are available for prices that range from about $13 to $50.

PC headsets and Heil headsets operate differently.  Heil headsets use a dynamic microphone and cannot tolerate any DC current through the microphone.  PC headsets require a DC bias voltage to operate their electret microphone.

The diagrams below (copied from a great presentation on rig interfacing by AudioSystemGroup)  shows the two ways a PC puts electret bias on the ring terminal of the 3.5 mm microphone jack.

Rig Audio Interface Schematic

All PC headsets have the ring terminal for bias…that is the key to this design.

Rig Audio Interface Schematic

The box below takes 8 volts from the ICOM microphone connector and uses it to power the PC headset.  The circuit has…

  • 3.5 mm (1/8th inch phone) jack for the microphone
  • 0.47 uFd series cap on the microphone, pass audio and block DC
  • 2.2K resistor to pass DC from the 8V pin to the ring terminal
  • 1/4 inch phone jack for rig keying
  • Cable and ICOM microphone plug

Rig Audio Interface Circuit

Rig Audio Interface Circuit

It was important to ensure the Heil headset doesn’t see any DC if plugged into the microphone jack of this adapter.  The design put bias on the ring terminal to feed the PC headset.  But, the Heil microphone connector does not have a ring terminal so it simply grounds the bias voltage… so, no bias gets to the Heil.   The dynamic microphone in the Heil couples audio through the series cap.

Here’s another design.  This one has two 3.5 mm connectors, one jack, one plug plus a battery.  The battery supplies power to the PC headset without the need for power from the transceiver.  This also supplies power to the ring terminal and block DC to the microphone on the tip terminal.  This took about 5 minutes, the components are under the tape.

Rig Audio Interface Circuit

One of our W2SZ members, Tom Price KC2PSC, designed of a PC board to implement this idea.

  • RJ-45 connector for rig microphone interface
  • Converts to 3.5 mm microphone and line out
  • Converts 1/4 inch phone for rig keying
  • Includes option for battery

Rig Audio Interface Circuit

There are a number of web sites that discuss the same thing

Field Day IT Test – Stations, Network and Logging Computers

Dave Merchant K1DLM, our Field Day chairman, is bringing some 21st Century radio and computer technology to our Field Day setup this year. There are several aspects to this new component of our Field Day plans and the associated IT Test including –

  • Two Flex-6700 Software Defined Radios running over a network  for our new Digital and enhanced GOTA Stations
  • An on-site WiFi Network to enable using the N1MM+ Logger in network mode for sharing of log information, station activity, real-time scores, and messages
  • A central Score Board and Club Information Computer in our public information tent
2017 Field Day Site - Upper Field Layout
2017 Field Day Site – Upper Field Layout

We will again be holding our 2017 Field Day operation at the Hollis-Brookline High School in Hollis, NH. We are planning on using the upper baseball field area as our main operating location. We have decided to add a third tower this year and locate it on a soccer practice field which is situated several hundred feet away from our main operating area. All of our antennas and equipment will lie within the required 1000′ circle but the third tower would situate those operating at that location away from the rest of our group. Dave’s solution to this problem was to set up a network and operate two Software Defined Radios (SDRs) at the lower site remotely from our location on the upper field.

Dave has enlisted club member Piece Fortin, K1FOP to be our IT Chairman for Field Day this year. Pierce has been instrumental, along with Dave, in the planning and testing of all of this new technology. Pierce and Dave have a great deal of networking and IT experience and knowledge and we could not have put together what is described here without them.

Dave K1DLM, Pierce, Hamilton K1HMS, Mike Ryan K1WVO, Anita AB1QB, and I have gotten together multiple times to set up and test all of this new technology. I wanted to share some more about the equipment and the associated testing (which has been staged in the kitchen at our QTH – thank you, Anita!).

We began the testing process by setting up our 20m CW station.

IT Test - 20m CW Station Test
20m CW Station Test

This station uses an Elecraft K3S Transceiver, a K1EL WinKeyer and the N1MM+ Logger running on a Windows 10 Laptop PC. We used this station to get our basic N1MM+ setup including our Field Day CW keying macros right.

IT Test - 40m SSB Station Test
40m SSB Station Test

Next came our 40m SSB station. This setup uses an Icom IC-7300 Transceiver and allowed us to set up and test N1MM+ on the fly audio macro recording and playback. All three of our SSB stations will have on the fly recording and playback capability which will allow each of our SSB operators to record and use a custom set of audio macros.

IT Test - Digital Station Test
Digital Station Test

Next came our Digital Station. This station uses one of the two remote Flex-6700 SDRs.

IT Test - Remote Flex-6700 SDRs and Antenna Switch
Remote Flex-6700 SDRs and Antenna Switch

Dave, K1DLM put together a really nice package for the two Flex-6700 SDRs and associated equipment which will be located on the lower field. He used a rack system to mount the two SDRs, power supplies, a three-band Tri-plexor, a set of bandpass filters for 80m, 40m, 20m, 15m, and 10m and a 403A 8×2 networked antenna switch. This setup allows either of the two SDRs to share the tri-band yagi or the 40m and 80m Inverted-V antennas on the tower on the lower field and operate on any of the 5 available HF bands. Antenna and filter switching automatically track the frequencies of the two SDRs making the setup simple to use.

Digital Station Second Display - SmartSDR & More N1MM+
Digital Station Second Display – SmartSDR & More N1MM+

The Digital Station’s remote SDR will be operated using a SmartSDR client running on the Digital Station laptop PC. This station will have a second monitor to better accommodate all of the windows associated with it.

IT Test - Digital Station Main Display - N1MM+
Digital Station Main Display – N1MM+

The main display associated with the Digital Station will run decoders for all PSK and RTTY modes. The ability to decode multiple PSK signals simultaneously and multiple RTTY decoders are available. The Digital station also acts as the N1MM+ master station in our Field Day setup for all of the other stations which use N1MM+.

IT Test - Satellite Station Test
Satellite Station Test

Our Satellite Station 2.0 was also added to the test setup. It uses a MacBook Air laptop running MacDoppler to control the antenna rotators and the Icom IC-9100 Transceiver which are part of our Satellite Station. A Windows 10 Surface Pro computer is included which runs N1MM+ and provides logging and other network functionality for our Satellite Station.

IT Test - GOTA Station
GOTA Station Test

We also tested our GOTA station which uses the second Flex-6700 SDR and a FlexRadio Maestro to provide a more conventional “buttons and knobs” interface for our GOTA operators to use. This station will also have a laptop PC running N1MM+ for logging.

IT Test - Scoreboard Computer
Scoreboard Computer

We also build and tested a Scoreboard PC. This computer will be located in the Public Information tent at Field Day and will be connected to a large display. It will show our real-time score, QSOs being logged as they are made and other useful information about our Field Day operations. This computer will also continuously play videos from our Club Video Collection and will provide access to IP video cameras which monitor the tower and equipment on the lower field.

IT Test - Pierce, K1FOP and Hamilton, K1HMS Testing CW Stations
Pierce, K1FOP and Hamilton, K1HMS Testing CW Stations

Our networked N1MM+ test bed contained at least one station of each type (CW, SSB, Digital, Satellite, and GOTA) that will be part of our Field Day setup this year. The Station Masters for the additional CW and SSB stations came by to test their setups using the test bed.

IT Test - Field Day Networking System
Field Day Networking System

The networking system which Dave and Pierce built is central to all of the technology described here. All of the gear is mounted in a single rack which will be located on the upper field during Field Day. The setup includes a Firewall/DHCP server, a commercial grade outdoor WiFi access point, a 4G LTE modem for Internet access, an Ethernet Switch, and a UPS power supply.

IT Test - MoCA Data Link Cable
MoCA Data Link Cable

The upper and lower fields at our Field Day site are separated by several hundred feet. A thick line of trees between the two locations raised concerns about connecting the upper and lower sites using WiFi. Pierce came up with a great solution to this problem – we will be using MoCA Data Modems and RG6 Quad Shield 75 ohm Coax Cable to provide a 10 Mbps data link between the two sites. We tested the MoCA link using a much longer run of coax cable then we will need to use at Field Day and confirmed full 10 Mbps throughput.

N1MM+ Talk Window
N1MM+ Talk Window

Our networked N1MM+ setup will allow any station in our setup to send messages to everyone who is operating at Field Day. We can use this capability for important communications like “lunch is ready!” or “I need help from Pierce (our IT chairman) on the 40m SSB station”, or “The 6m band is wide open!”.

Our GOTA and Digital stations will be located together in the same tent and will provide our Field Day 2017 visitors to see and use 21st-century Amateur Radio technology to make contacts. We are expecting young people who participated in our club’s High-Altitude Balloon project and from other local schools where we have done Amateur Radio activities to attend. In additional to being a learning opportunity for all of us in the Nashua Area Radio Club, we hope that the state of the art technology that we are using will generate interest among our visitors.

Fred, AB1OC

Hashtags: #ARRLFD #N1FD

Quicker-Turnaround Digital Modes in Experimental Stage for WSJT-X Suite

WSJT-X developer Joe Taylor, K1JT, weighed in to express his appreciation to all who shared their ideas and experiences using JT9 and JT65 modes during recent multi-hop E-skip openings on 6 meters.

“We are very much aware that a mode with most of the excellent characteristics of JT65, but with faster turnaround time, would be a big winner in such situations,” Taylor commented on behalf of the WSJT-X development team. “We are experimenting with several such possibilities. Tentative goals include 15-second T/R sequences, sensitivity around S/N = –20 dB, occupied bandwidth less than that of JT65, and capability to decode as many as 10 or 20 signals in a 2-kHz bandwidth.”…

Source: Quicker-Turnaround Digital Modes in Experimental Stage for WSJT-X Suite

This is something to follow if you are interested in the JT modes for HF and VHF communications. Our experience is that a new JT variant that would trade S/N margin for a faster QSO segment speed would be just the ticket on many of the HF bands as well as 6m.

Fred, AB1OC