Posted on QRZ Forum  By Dr. Bob Heil, K9EID January 3, 2024

Amplitude Modulation has been the method used between Amateur Radio voice transmissions since the late 1920’s. In 1947 Wes Schum, W9DYV created the first Amateur Radio SSB transmitter with his Central Electronics 10A. In the mid to late 50’s things began to ‘heat up’ between the ‘died in the wool’ AM operators and the new voice mode of Single Sideband. Things evolved into a sit-down face to face meeting between major SSB operators and the long time AM operators. They each agreed to a ‘Gentlemen’s Agreement’. On 75 meters, the AM operators observe 3.870MHz to 3.890MHz. On 40 meters 7.290MHz. to 7.295MHz. 14.268MHz. These ‘windows’ were promoted by the ARRL and strongly observed by the AM operators for several decades, but as new SSB transceivers and newly licensed operators came upon the scene in the late 80’s through the turn of the century, the ‘Gentlemen’s Agreement’ was not promoted well and has slowly faded.

During the 1980’s and 1990’s AM operations had declined but in 2015 with the introduction of new technology from the iCOM iC7300, Yaesu FT101DX, Kenwood TS890, Flex Radio systems, the K7DYY,Apache Labs, Anon and other new transmitters each producing great sounding AM signals, the voice mode of Amplitude Modulation has grown exponentially. Many have discovered how much fun the AM mode can be.

Many of the present-day operators are not aware of the ‘Gentlemen’s Agreement’ and operate anywhere within the F.C.C. band plan of their respective license, which have once again caused some minor rages between the AM and SSB operators. No one ‘owns’ a frequency. It is good practice to check your frequency, making sure it is clear and not in use by others regardless of mode keeping in mind that many AM Operators are crystal controlled and not able to move frequencies. Thus, AM operators stay within the ‘windows’ to not cause interference to SSB operators. SSB transmitters all have built in VFOs and have the ability to freely move to frequencies outside of the ‘windows’. The solution to any disagreements would be to observe the AMATEUR’s CODE.


The Amateur is considerate, never knowingly operates in such a way to lessen the pleasure of others.


He offers his loyalty and encouragement to fellow amateurs.


Keeps his station efficient and well maintained. His operating practice is above reproach.


Offers kind assistance, cooperation and consideration for the interest of others.


Radio is his hobby. He never allows it to interfere with duties to his home or family.


His station is always ready for service of his country.

Adapted from the original Amateur’s Code, written by Paul M. Segal in 1928.

The increased popularity of AM has, at times, required its use outside of traditional AM Windows. As always, with any mode, asking if the frequency is in use, first, will help to alleviate many misunderstandings. I encourage everyone to join AMI., appreciate, and enjoy AM operation. Hopefully we can all be courteous to each other and share our frequencies.

73, Bob Heil, K9EID


My official view as AMI Executive Director on the whole AM window

 I do not take issue with what’s designated as an AM calling frequency. However, it’s not okay to be stuck operating in a “window”. AM operations should be and are allowed anywhere you can operate ssb i.e. phone parts of the bands period. So promoting windows for operating AM is not really a smart thing to do. Because it boxes AM operators in a certain slot of frequencies when in fact we have a right to operate anywhere we want in the phone bands according to the FCC and our lisc privileges. There is no slight of hand or grey area on this. So I do want to promote considerate operating on all modes but, I also want to say that AM operators consider operating in other places beyond the so called windows. This not to cause malicious qrm to someone, you would be fully expected to make sure your frequency you choose is clear just like you should do operating Digital, SSB, SSTV etc etc. 

As for the “gentlemans agreement”. It’s old news and it would be difficult to enforce such a thing that was never really enforced anyway because it was never a fcc thing it was a ARRL deal. AM windows or the idea of them are like a cage for you to operate in that area only. No, I am sorry we have the same right to operate anywhere in the phone bands period. 

John McGrath, N9AMI

AM International – Executive Director