Tag Archives: Digital

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.  Heils 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.

Screenshot from 2016-04-26 22-42-16

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

Screenshot from 2016-04-26 22-35-38

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

20160426_222121

20160426_222213

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 has 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.

20160426_222402

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

20160426_222551

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

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
  • I will mostly be doing parade and other HAM activities in the field and I need something that is portable

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 (many radios for mobile or vehicle applications will be good choices) 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 for you in this case. You might also want to consider a radio that does D-STAR or another Digital Voice mode as 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 similar antenna and a spare battery or two for your HT will be a good way to go.

OCF Dipole and a 2 m/70 cm Antennas
OCF Dipole and a 2 m/70 cm Antennas

If you’ve just received your General Class license and want to get on HF, your biggest decision will be what to use for an 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. Its 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.

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 that you consider 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 good choice for a first station as 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 how to make contacts on the HF bands and 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, ask questions and get the benefit of experienced folks in our club on these choices and all that goes along with installing radios, antennas and getting on the air.

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 will be the topic of our next 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
  • I will mostly be doing parade and other HAM activities in the field and I need something that is portable

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

Mobile 2m/70cm FM Radio in a Vehicle
Mobile 2m/70cm 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 2m/70cm antenna on your vehicle.

Base 2m/70cm Radio with APRS Display
Base 2m/70cm 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 2m/70cm radio (many radios for mobile or vehicle applications will be good choices) or a dual purpose HF and 2m/70cm 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 2m/70cm ground plane style vertical antenna that you can mount outside or perhaps in your attic would be a good choice for you in this case. You might also want to consider a radio that does D-STAR or another Digital Voice mode as 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 similar antenna and a spare battery or two for your HT will be a good way to go.

OCF Dipole and a 2m/70cm Antennas
OCF Dipole and a 2m/70cm Antennas

If you’ve just received your General Class license and want to get on HF, your biggest decision will be what to use for an 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. Its 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.

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 that you consider 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 80m – 10m at a minimum. QRP radios (5 – 10W) are usually not good choice for a first station as making contacts at this power level with simple antennas can be challenging. It’s also good to have a radio which can do 6m 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 how to make contacts on the HF bands and 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, ask questions and get the benefit of experienced folks in our club on these choices and all that goes along with installing radios, antennas and getting on the air.

73,