Category Archives: Featured

This category is for featured articles that we want to include in the sidebars and other areas on our website.

Education and Training, Featured, General, Homebrewing, Newsletter

Rig Audio Interfacing and Low Cost PC Headsets

April 27, 2016 Nashua Area Radio Society

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.

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

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

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.

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

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

Activities, Featured, General, Newsletter, On The Air

Saint-Gaudens NHS – Mobile HF Trial Run For Our NPOTA Activation

April 23, 2016 Fred Kemmerer 1 Comment

National Park Service Anniversary Mobile HF - Aron W1AKI and Merle W1MSI At Saint-Gardens NHS — Aron W1AKI and Merle W1MSI At Saint-Gardens NHS

The Nation Parks On The Air (NPOTA) program was created by the ARRL to commemorate the National Park Service Anniversary (100th). Aron W1AKI, Merle W1MSI and Fred AB1OC made a trip to Saint-Gaudens National Historic Site in NH this past week. Our goals were to seek permission for a Club National Parks On The Air (NPOTA) Activation at the park as well as to see the site and do a brief trial activation. I am happy to report that we achieved all of these goals and also activate the park using our Mobile HF station!

National Park Service Anniversary - N1FD NPOTA Presentation — N1FD NPOTA Presentation (click on the picture to see our presentation)

Aron and Fred put together a presentation which we shared with the head ranger, Greg Schwarz at the park. Our goal was to create an understanding of who we were, why we want to Activate Saint-Gaudens NHS, what our activation would involve and how we would relate to the National Park Service Anniversary celebration this year. We had a very good meeting with Greg and we secured permission for multiple activations of the park over the summer months. We will share more about what we are planning to do and the dates for our activations at our next club meeting.

National Park Service anniversary - Aspen House, Built abut 1817 — Aspet House, Built About 1817

The park grounds are very beautiful and will be absolutely stunning in the summer time!

National Park Service Anniversary - Garden With Bronze Monument — Garden With Bronze Monument

Saint-Gaudens was one of America’s greatest sculptors and some of his works and their history are nicely set in the building and gardens which make up the park. There is plenty to see and do in the park.

National Park Service Anniversary - Open Meadow In The Park — Open Meadow In The Park

The park has a large, open meadow which is surrounded by trees. The meadow is partly used for overflow parking and should offer a good area for us to use a mobile station plus a portable station when our club activates the park. We will be allowed to use a small generator and put up a small screened shelter to protect us from sun or rain while we operate. We were also invited to set up a table to share information about our club and about Amateur Radio in the area of the park which is frequented by visitors. The park hosts open air concerts most Sundays during the summer months. Greg indicated that about 200-400 visitors attend the summer concerts. He felt that this would be a good time for us to activate the park as there would be many visitors in the park for these concerts.

Mobile HF - N1FD On The Air In NS-60 — N1FD On The Air In NS-60

Greg also allowed us to park in the meadow and activate the park as part of the National Park Service Anniversary celebration. Aron W1AKI, Merle W1MSI and Fred AB1OC did a brief trial activation to get an idea of what propagation would be like in the park. We used Fred’s Mobile HF Station for the activation and we operated as N1FD on the 20m and 40m bands for about 45 minutes. If the trial run is any indication, we are going to have a lot of fun when our club does the real activation in the summer. In 45 minutes of operating, we gave 80+ happy Amateurs NPOTA NS-60 on a combination of the 20m and 40m bands. We were easily able to work stations in all regions of the US and we put 29 states and 4 DXCC’s into the log during our brief activation. We had folks in Alaska, Portugal, Poland and Canada call in and we had a good pileup for the entire time that we operated. We were using a paper log for the trial run and we had a hard time writing fast enough to get the QSOs into the log!

We hope that you’ll join us for one of our Saint-Gaudens activations during the summer!

Aron, W1AKI
Merle, W1MSI
Fred, AB1OC

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