Skip to main content

VHF Frequency Confusion

Tom Kamlowsky of Salt Lake City, Utah, asks:"While sailing in San Francisco Bay last month, I contacted the Coast Guard on VHF channel 16. On receiving my call, the Coast Guard radio operator asked me to change frequency to channel 22. I changed both my Icom M304 and M34 radios to channel 22 and quickly found that I could not use the M34 because of interference from a
  • Author:
  • Updated:
    Original:

Tom Kamlowsky of Salt Lake City, Utah, asks:

"While sailing in San Francisco Bay last month, I contacted the Coast Guard on VHF channel 16. On receiving my call, the Coast Guard radio operator asked me to change frequency to channel 22. I changed both my Icom M304 and M34 radios to channel 22 and quickly found that I could not use the M34 because of interference from a local FM station broadcasting on 106.9 Mhz.

I switched off the M34, finished the Coast Guard call on the M304, and later determined that channel 22 on the M34 can’t be used in San Francisco because of the FM broadcast interference. I suspect an IMD problem with the radio. Other channels could be affected, but I don’t have any way to test them. Now I worry the radio might not work properly in other ports of call because of additional, yet to be discovered interference issues with local FM stations. Other than replacing the radio, which is out of warranty, is there something I can do to resolve the problem?"

Gordon West replies:

I may have an easy answer to this problem. IMD (intermodulation distortion) can’t be the culprit; it’s too far a spread from 106.9 MHz to 157.100 MHz. So let’s do some math: 157.100 MHz (coast guard output and your input) + 4.600 MHz (international duplex VHF channel 22, receive). This adds up to 161.700 MHz, which is assigned by the FCC to FM and TV audio remote links.

Your Icom M34 radio is in international mode, where our U.S. “A” channels are domestic simplex mode, transmitting and receiving on the same frequency. The coast guard transmission on 22 alpha was simplex, domestic receive, not international duplex receive on 4.6 MHz and up.

Put your Icom M34 radio in “domestic” or “USA” mode. Then you will hear the coast guard on channel 22A, not the FM remote link on 22 international at 161.7 MHz!

Related

Alexforbes Archangel1-1 (14)

Cape2Rio Draws to a Close

With just four boats still on their way, it has been a long road to Rio for the fleet competing in this year’s Cape2Rio. Larry Folsom’s American-flagged Balance 526 Nohri took line honors and a win in the MORCA fleet, finishing with a corrected time of 18 days, 20 hours, and 42 ...read more

_01-Steve-and-Irene-1

Close Encounters: A Star to Steer By

I first met Steve and Irene Macek in the proper way—in an anchorage full of bluewater cruising boats. This was in St. Georges, Bermuda, in the spring of 2019. Theirs, without doubt, was the most distinctive boat there—an immaculate, three-masted, double-ended Marco Polo schooner ...read more

14_01_230123_TOR_JOF_0414-2048x

The Ocean Race Leg 2 Kicks Off

After a trial by fire start to the race and only a brief stop for limited fixes, the five IMOCA 60 crews in The Ocean Race set off for Cape Town, South Africa, early on January 25. Despite arriving somewhat battered in Cabo Verde, an African island nation west of Senegal, the ...read more

Lead

Cruising: Smitten with a Wooden Boat

I was sailing down the inner channel of Marina del Rey under a beautiful red sunset when Nills, one of the crew members on my boat, pointed out an unusual and unique-looking 40-foot gaff-rigged wooden cutter tied to the end of a dock. Its classic appearance was a stark contrast ...read more

Screen-Shot-2023-01-23-at-12.03.19-PM

Racing Recap: Leg One of The Ocean Race

New to spectating The Ocean Race? Managing Editor Lydia Mullan breaks down everything you need to know to get started. ...read more

image00001

From the Editor: Keeping the Hands in Hands-On

SAIL Editor-in-Chief Wendy Mitman Clarke enjoys a sunny autumn cruise in her Peterson 34 on the Chesapeake Bay. It was late afternoon just after the U.S. Sailboat Show in Annapolis when I climbed aboard the last boat on the schedule. I and others who review and sail boats for ...read more

P1580711

B&G Announces New Zeus S Chartplotter

B&G has long been putting out top-of-the-line electronics, but the new Zeus S Chartplotter is a new take on the best way to give sailors the exact information they need, when they need it. “So many more people sail shorthanded these days, whether as a couple or when they’re ...read more

00-LEAD-DSCF1601

Charter: Mission to Mars

In the wake of the pandemic, many sailors are seeking adventure and grabbing onto a vision of their best lives. For some, that may mean sailing across the Atlantic with the ARC (Atlantic Rally for Cruisers) while for others, it could be a yacht charter in the Caribbean. The ...read more