All posts by Nashua Area Radio Society

Webmaster for the Nashua Area Radio Society
Featured, General, Newsletter, On The Air, Space

Huh? 2 meter QSO into Canada!

2 Comments

Ok, this is slightly misleading but it’s true.  I had a QSO with a Canadian station over 200 miles away on 2 meters. From my car none the less!

You may wonder how this was done. I had some help from above that’s how. I discovered that on the International Space Station (ISS) is this cool thing called a digipeater.  Now I’m no pro at this but I will attempt to explain in hopes that someone else can enjoy getting their toes wet in Amateur Satellite opportunities.

To start, here is an eQSL card of my from my first QSO of this nature:

ISS Packet Contact QSL

Note the mode on this card. It’s packet. The digipeater on the ISS relays APRS messages.  This was all foreign to me prior to this contact. I discovered all of this by accident while I was monitoring the ISS frequencies for voice and SSTV. APRS transmissions were pouring out of my radio. Curiosity got me to research the sounds and ultimately steered me towards giving it a go.

Although I already had all the parts and pieces to start my way I lacked the knowledge of what to do. It took some figuring out, but I now have a simple and relatively low-cost way of working some satellites. Unlike voice mode, you do not need a directional antenna to do packet through the ISS. I use my mobile radio in my car, an omnidirectional antenna, a USB SignaLink sound card and an inexpensive Windows tablet pc. I downloaded UISS and AGW packet engine (both are free).  I think I blew a brain fuse or two figuring out how it all goes together, but in the end, it works.

The uplink and downlink frequency for this is the same: 145.825

Go ahead, tune in and listen while the ISS is over your location.  There are many websites and smart phone apps to give you the pass schedule.

If you are interested in this and want help getting started on this for yourself then feel free to shoot me an e-mail [email protected]

Hope to hear you on the air!

Curtis (KB1RTQ)

CW and QRP, Featured, General, Newsletter, On The Air

6M Propagation to Europe on JT65.

Wow, six meters was wide open this morning to Europe. I started playing on CW, but the signals were so steady that I decided to go to JT65 so I could see where I was being heard. I have included a pskreporter.info map filtered for my station for the previous 6 hours. The snapshot was taken at 2016-06-13 at 18:05 UTC. Beam was between 45 and 60 degrees. The USA stations were all off the back of a 3 element Yagi. Running 70 watts. The rig was my Flex-5000.

The ARRL VHF contest this weekend also had great openings, primarily state side, although I did work an EA8.

This is the time of year to get on 6 meters.

73,
Bill
NJ1H

Education and Training, Featured, General, Homebrewing, Newsletter

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

Radio Amateurs Developing Skills Worldwide