Contributed by Gary Gordon, K6KV, this is a picture of the Audible Transmitter Output monitor (ATOM): A box measuring 4 x 2 x 1 inches with SO239 connectors on the long sides. The top view shows the name plate, a speaker grill at the right and the on/off switch below it. Price: $90, contact

Audible Transmitter Output monitor (ATOM) model 200

Welcome to the ATOM200 page.

ATOM stands for Audible Transmitter Output Monitor. ATOM is a friendly device that produces an audible pitch related to how much power your transmitter is sending to your antenna.

When you first install your station, you'll probably want to borrow the help of someone using an SWR meter to check everything out. However once that's done, it's nice to know that each time you sit down to operate, you haven't inadvertently set some switch or knob incorrectly, or developed some rig or antenna problem that's preventing your signal from getting out.

ATOM provides an audible substitute for the visual power meter on your rig. You don't even need to connect it directly to your meter; you just connect it in series with the feedline coming out of the back of your rig. And although the expensive systems provide facilities to hear a power meter's reading, ATOM is dynamic in that you're instantly aware of a change without having to do anything but turn it on.

ATOM is very easy to use and doesn't even have any controls other than its power switch. What ATOM measures is the relative RF voltage across the feedline, which is proportional to the power on the feedline.

If ATOM's tone falls to zero, you'll know that for some reason your tuner cannot find a match, and there is no output. By listening to the pitch of its tone, you can follow the process of your automatic antenna tuner searching for a match.

As your tuner searches, the pitch will jump around, trending higher and higher. And when the pitch finally settles down, your tuner has finished, and your rig is now ready to put out full power.

ATOM works with rigs using both internal or external antenna tuners from 160 to 6 meters, and with any antenna an auto-tuner can match. It's conservatively rated at 200 watts PEP but could be used with power levels up to 500 watts if the feedline is matched with no VSWR. It can even be used with QRP rigs as it responds effectively to only 1 watt!

To hear what it sounds like, listen to the demo.

The device is built in a 4 x 2 x 1 (HWD) die-cast aluminum box. The top panel has a speaker grill on the right edge with an on-off switch below it. SO239 connectors are mounted on the side panels, and the unit can easily be installed between the RF output and feedline using a short coax jumper cable or the supplied PL259 coupler. PL259 to BNC couplers are also included.


To order this device or make inquiries, call 650-386-6286 or email Thank you.