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AM or SSB, are there "windows?"

Discussion in 'Amateur Radio News' started by AA7BQ, Jan 3, 2024.

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  1. AA7BQ

    AA7BQ QRZ Founder QRZ HQ Staff QRZ Page

    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

    KZ2W, KZ3H, W7XLR and 59 others like this.
  2. WL7PM

    WL7PM Ham Member QRZ Page

    3890 has always been an AM watering hole, call freq around here.
    W7XLR, WH6LU, N3HOE and 3 others like this.
  3. KB2FMH

    KB2FMH Platinum Subscriber Platinum Subscriber QRZ Page

    Although first licensed in 1985 Fred, I preferred AM over SSB having transitioned from CB where AM was the popular mode even though many modern radios had the SSB feature. I liked the Sound of it and the fading of the voices as the signals traveled around the world. I had Drake twins at the time, 4 line B series, and the transmitter sounded great. I learned of the Windows by tuning around and talking to other AM enthusiasts.

    Today I am mostly on SSB chasing DX because no expedition uses AM as a rule as well as many other ops in the various countries on Earth. But, every now and then I will venture to AM when doing a POTA activation or special event operation and have even done it while on an expedition to some remote rock in the ocean somewhere, along with FM which can be interesting when prop is good. When I do that I am sure to be in the Right Place for AM / FM to not cause trouble for others. It is surprising how many try to respond in SSB due to hearing Me clearly while I cannot understand them, even when I say I am in AM - please change your mode so I can understand you. The nice thing is when someone does find how to get to me and says it is their first ever AM contact despite being a Ham for a number of years or decades.
    I'd like to believe I have inspired them to try it more often to help keep the mode alive in the world of solid state transceivers and newly minted ops we've seen since the Virus business brought many into our fine hobby.

    Thanks for putting this reminder from Bob up - hopefully many will read it and give AM a try.

    James, KB2FMH
    W7XLR, HB9EPC, K9EID and 18 others like this.
  4. W5ESE

    W5ESE Ham Member QRZ Page

    In my area, most 40 meter AM is around 7160 KHz.

    The 7290 Traffic Net has been meeting on that frequency since 1953.
    W7XLR, HB9EPC, W1PAA and 2 others like this.
  5. N9AMI

    N9AMI Ham Member QRZ Page

    Bob you hit the mark. As AM International Excutive Director, I feel the "gentlemans agreement" needs to be promoted again by the leauge. The west coast AMI net has lots of qrm from stations in Texas and Nevada ie 3870 and 3875. It has been going on for a long time. Another example: we used to have a very nice Satuday morning roundtable on 3870 for years suddenly it was met with ssb qrm and fighting so the guys decided to walk away from it. Thats not right the band plan is large enough for everyone. Friendly asks have gone out and gone on with either silence or nasty responses. There is in fact a group that operates on 3.888 just to interfere with AMers on 3885, I have heard the comments a number of times.

    Bottom line is this. Most AM operators still try to only operate in the window IE the "gentlemans agreement" and we could use the help of others like the league and "friendly" reminders of this agreement. The backing of the ARRL would go along way in this.

    John, N9AMI
    Excutive Director - AM International
    W7XLR, WA4KCN, K9EID and 22 others like this.
  6. KL7AJ

    KL7AJ Premium Subscriber QRZ Page

    For quite some time 10 meter AM has been semi-channelized, and it's worked fairly well. Of course, there's a lot more elbow room on 10 than on 80. It does make it a bit easier to FIND AM stations, however, without knowing ahead about the local watering holes.
    M0MNE, HB9EPC and N6SPP like this.
  7. K6CLS

    K6CLS Ham Member QRZ Page

    Please remember AM Rally every year, first weekend of February.

    Biggest trouble for making QSOs, the Old Buzzards that camp on the frequencies with 15 minute overs. Many of us with classic equipment are rockbound and just can't move.
    M0MNE, W7XLR, WA4KCN and 14 others like this.
  8. UT7UX

    UT7UX Premium Subscriber QRZ Page

    Towards AM, in my part of the world I rather hear 'freebanders' around 100m. Most of them have awful signals and, sure, they're pirates, so it's not my cup of tea. For me AM means broadcast-like signal to please other party's ears so the shack should rather appear a broadcast studio and one should be rather using water-cooled plates than those tiny legal limit linears. :)
    N3HOE likes this.
  9. WA3VJB

    WA3VJB Platinum Subscriber Platinum Subscriber QRZ Page

    Fred, I'm not sure whether the author of your posting is on AM that much, but it's nice to see the topic brought forward, thank you. He seems to be missing some current perspective on our part of the hobby, and I am stepping up to try to round it out. I am a little puzzled that he didn't post his article himself, and I hope he will respond by acknowledging this information that could be new to him.

    I believe this same writer has appeared in videos posted to, and if so, he's the same person I tried to discourage from his repetitive references to "windows," as if it was incumbent upon AMers to perpetuate the use of such areas.

    They remain in use, yes, but only because people are in the habit of being there. Today, and this is something overlooked in the perspective of the article, the use of AM on HF has far outgrown the limited areas that may have been adequate in the 1950s, or whenever the timeframe your writer seems to rely upon.

    It is true that SDR and other modern transceivers do a far better job on AM than the rigs your writer may have earlier had experience with. The result is high quality AM on both transmit and receive that encourages its use. In the old days, possibly respecting your writer's experience, AM on transceivers was an afterthought, or not included at all.

    Presently, at least in the eastern time zone of the U.S., there is a tremendous amount of activity "down low" in the 80 meter phone band, with stations on wholesome AM from 3695 through 3725. The Antique Wireless Association uses 3835 for its Sunday afternoon AM gathering that runs several hours and draws dozens of participants.

    A group in the lower midwest uses 3725 weeknights, and our Canadian counterparts have been using 3715 for AM nightly since long before our FCC expanded the phone bands back in 2006.

    On 40 meters, the consistently higher level of AM activity now finds roundtables and 1:1 QSOs from 7275 on up to the top of the band.

    It really is incumbent upon bystanders using incompatible modes to first check to see if a spot on the dial can support their late arrival near an AM QSO. Some education about the relative difference in passbands can go a long way toward avoiding being surprised when someone in the existing QSO questions why the newcomer has tried to come so close to a frequency that's in use.

    And while the concept of "AM windows" may once have been a leadership overture on our part to minimize friction with incompatible modes, our phone privileges are all we really need to warrant the same respect anyone on any activity can expect in a mixed-mode, non-channelized hobbyist communications venue.
    Last edited: Jan 3, 2024
    W7XLR, WZ5Q, KM5QS and 23 others like this.
  10. KD2BRM

    KD2BRM Ham Member QRZ Page

    I'll keep it respectful & simple. FCC Part 97 regulates what modes we can use & where depending on license class. As long as the mode you chose is within those limits & doesn't interfere with adjacent signals, you're good to go. No Gentleman's agreement is needed. If you can pass a test to achieve a specific license class, you should also possess the basic reading comprehension ability to understand the rules. Even if that means you memorized all the answers etc.
    M0MNE, K2JPV, WN8SCI and 24 others like this.
  11. AB2RA

    AB2RA Ham Member QRZ Page

    I had a 3 way QSO on 7160 with TX, NE, and SD a while back.
    But I heard activity and answered. I normally stick to the window near 7290, but when foreign BC ruins it, I will QSY lower.
    The 7290 SSB group is not heard well in the Northeast; and it rarely has traffic, just a roundtable, no reason it could not have been anywhere.
    KN4IDF, K4KYV, AC0OB and 1 other person like this.
  12. W1YW

    W1YW Ham Member QRZ Page

    I agree with KD2BRM: not sure what problem needs to be solved here. The frequency and mode allocations do not impute nor suggest any 'gentleman's agreement'.

    No one owns a given frequency. AMers can spin the knob just like everyone else. We run into major problems when groups of operator feel they DO 'own' a given frequency or a sub-band. For example: 14313...

    Are we reverting back to the days of N9OGL and "I was here first..."??

    OTOH, where, exactly, does one see clear and graphical representation of this 'gentleman's agreement'? Surely some of these issues are based on ignorance via lack of evidence.

    Chip W1YW
    M0MNE, W7DGJ, K5HFG and 8 others like this.
  13. AB2RA

    AB2RA Ham Member QRZ Page

    One solution is to stop calling them "windows" and start calling them "calling frequencies".
    Call there, then move off to a nearby frequency.
    This solves the problem with old buzzards flipping the "monologue" switch on for 15 minutes.
    It also recognizes that some of us would rather have a conversation rather than a 25 deep roundtable where your turn comes around every 90 minutes.
    That said, I often check into roundtables while I work at the bench on a project.
    M0MNE, HB9EPC, K9EID and 9 others like this.
  14. KK4JI

    KK4JI XML Subscriber QRZ Page

    Chip, this is not true much of the time. A lot of the older gear and converted stuff is running on crystals. So that's why some frequencies are sort of "agreed upon" as "AM windows". I started operating AM on the Amateur Bands in Texas in the early 2000s with vintage Collins, Johnson, and some HB gear. We would start up on 3880 at 0400 or 0430 in the mornings many times, and yet there was a group that pretty much always came up on 3878 LSB every morning right on top of us, essentially. No care in the world that the freq was already in use. 3880 has been a long-standing AM carrier freq, and of course, it also occupies both upper and lower sidebands at +/-3 or 4 kHz, so why these bozos chose that frequency is beyond reasonable logic. So we did the "Gentlemanly thing" and moved to 3885, since most folks that had 3880 crystals also had 3885. That also ended up poorly because of other groups using 3885 elsewhere in the country. So we moved to 3890 Naturally, then some New Mexico operator later decided it was a good idea to operate on 3892 LSB with west coast operators out in CA. That also didn't end well, as he often bragged about causing all kinds of problems with "those AM'ers". The "windows" should be respected, as the article suggests, but there is no other reason other than the crystal-bound radios to do so, to your point. I have operated AM down in the new Extra portion of 80m as well from time to time, just because a group of us had more frequency agile gear. So we did that to take some pressure off the already congested and very encroached upon traditional AM frequencies.

    EDIT: Here is an ARRL list of partial AM Carrier frequencies, keeping in mind the issues with it occupying 3-4 kHz above & below.
    K9EID, N3HOE, HB9EPC and 11 others like this.
  15. WB2GCR

    WB2GCR Ham Member QRZ Page

    Imho, more or less a non-issue.

    Nothing to debate or argue about.
    Given the relative paucity of AM activity, with the US Northeast arguable being the most active
    in North America, the need for more places for AMers to operate beyond wherever they often do
    show up, isn't there. (and no, not only in that 3885 nominal area...)

    MOST, not all SSB operators just leave the ~10kc between 3873 and 3885 open... as the rest of
    the band
    similarly has a paucity of activity.

    There is one oddball (imho) group that appears to have VFO problems, since they say they are
    a "39xxkHz. net" that shows up evenings, for no apparent reason - but they go away, and frankly
    there is a paucity of AM activity... lurkers, listeners, yeah.

    When the bands had much much much better propagation, and when I was a "jn" back in the 1960s,
    one could not find an open spot. It was a massive "cluster f***" and one masive tumult and heterodyne
    symphony. All day and all night... the times have changed and that is a dim, distant memory of the past.

    Ya wantz to do AM?
    One needs a good ANT, and a signal.
    Then maybe some properly modulated audio.

    As I said before, a non-issue.

    M0MNE, WZ5Q, KX1MAD and 4 others like this.

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