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FT8 Power, how much ????

Discussion in 'Working Different Modes' started by K4EM, Nov 12, 2017.

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  1. K6BRN

    K6BRN XML Subscriber QRZ Page


    Wow! Great "Trolling Attack" Rege! Do they give out awards for those (at east in the "basket case" weight class)?

    BTW, I'm VERY impressed with your knowledge of "spinning electrons". You've made my day. No better way than to start out the morning than with a good joke.

    Brian - K6BRN
  2. VE3GZB

    VE3GZB Ham Member QRZ Page

    I'm relatively new to FT8 and now that I've gotten the bugs worked out, most contacts I work across the Atlantic on FT8 don't require much more than 30 watts output, measured in the Coax feed. Some contacts I've been able to work with 15 or 20 watts output.

    I have worked New Zealand and Australia a few times on FT8 and in those circumstances I need 80 to 90 watts output as my antenna is a fixed stealth wire antenna hidden in the trees and therefore cannot be aimed.

    73s, VE3GZB
    4X1ST and K2NCC like this.
  3. HS1LCI

    HS1LCI Ham Member QRZ Page

    I normally run not more than 20W to drive my linear amp for approximately 150W out if necessarily to compromise the good sake of all.

    73 Dave HS1LCI-W1LCI
    Last edited: Nov 17, 2018
  4. K8BZ

    K8BZ Ham Member QRZ Page

    As someone said earlier, a weak signal is better defined at the receiving end of the QSO and not the transmitting end. To make decisions on how much power in general you should run on FT8 by a signal report you receive in a 30 second QSO with a specific station in a fixed location with its own unique propagation path between you is nonsense.

    Yes, it can be possible to have QSO's at very great distances with very low power on FT8. And FT8 overall has a greater advantage than most other modes in completing a QSO between to given stations when only very weak signals can be received.

    It is also the case in very poor propagation conditions very high power levels may be required to complete an FT8 QSO.

    All of the WSJT modes were engineered to make contacts possible with very low power. But that doesn't mean that using anything but low power is unacceptable. If your interest is just working new grids in the continental US on FT8 then a few watts will do just fine. You are not necessarily trying to work a specific station in a specific location with very poor propagation between you that may be drifting between poor and no propagation. You just want to work someone, somewhere.

    If on the other hand you are trying to work that All Time New One (ATNO) DXpedition that comes along once every other leap year, on the last hour of the last day of the expedition and propagation between you is poor at best, it's not a crime to increase your power to what ever will get the job done, as long as your signal is clean.

    These examples are the extreme at ether end of the spectrum of possible situations with an unlimited number of in-betweens. Use common sense, operate within the rules, keep your signal as clean as possible.
  5. N2SUB

    N2SUB Premium Subscriber QRZ Page

    Fine, I understand all of that. I believe, however, that the JT/FT modes were designed because the majority of hams do not have a 40 tower with a 5 element yagi and a full legal limit linear. Many are working with 100 watts and a wire, or less. FT/JT was a way to level the playing field and let those ops make contacts that they normally would not be able to make using other modes. But since I wrote that, I've given up the fight. Now you can hear me running 1.5kw to a set of stacked monoband yagis, one for each band (of course) on a series of 100 foot towers. I'm sure I'm not bothering anyone though, because there's always plenty of space on the waterfall around my signal.

    I am, of course, being sarcastic. I just plain gave up and moved on. ;)
    ND6M and G0JUR like this.
  6. VA3VF

    VA3VF Ham Member QRZ Page

    Wow...26 pages.

    An 'encore', with corrections, from page 1 for the new 'arrivals':

    "Use as much power as is necessary to complete the QSO, up to the max allowed for your license, and that your equipment can safely handle. The only requirement is a 'clean' signal. FT8 is not necessarily a low power mode.

    As for the unspoken rules, they are unspoken, and they are not rules. Gentlemen's agreement at best. As for ethical mode rules, nothing specific, the same as for all other modes (listen/view first, no DQRM, etc.). Common sense, something that is not common at all these days, still applies. :D"
  7. G0JUR

    G0JUR Ham Member QRZ Page

    I like to crack nuts with a sledge hammer as well. :p
  8. K8BZ

    K8BZ Ham Member QRZ Page

    I understand your point and don't necessarily disagree with most of what you said. And I'm not trying to criticize anyone's position on this. The modes original intent was for weak signal PROPAGATION modes such as EME, Meteor Scatter, and VHF/UHF operation in general. That isn't necessarily the same thing as QRP. The fact that the modes became popular on HF is understandable. I am monitoring 7.074 FT8 at this very minute. At this time my S meter is not falling below 15db over S-9 and is reaching a little above 20 over on some transmissions. The signal you see in the attached screen print with transmission periods at 1500 is a +4 signal is a little broad and probably is being over driven in the ALC range or may have left the speech compressor on. But it's still not preventing me from decoding the signal at 1620 that is -16. If the operator checked his audio and made proper adjustments there wouldn't even be a potential of interference. I don't know if the +4 station is running 1 KW or 100 mW or likewise the station with the -16 signal. If the proper level of unprocessed audio is applied, a high power FT8 signal will not interfere with others on the waterfall. Stations that are very broad and interfering over a large part of the water fall have not properly adjusted their transmitting station. Cruddy signals on the FT8 waterfall that are interfering with other QSO's are not the result of higher power, properly adjusted FT8 stations.

    If the problem is that someone running higher power will have an unfair advantage as far as getting more responses to CQ calls or making contact with a desirable DX station then all I can say is, as I said before, use common sense, operate within the rules and keep your signal as clean as possible. If you are doing so, then how you operate within the rules is a matter of choice.

  9. G8KHF

    G8KHF XML Subscriber QRZ Page

    As usual a simple question ends up with the 3 camps arguing.
    Camp 1. Anything over a few watts is a sin and its great fun calling cq for hours on end just to get the odd qso.
    Camp 2. More interested in the technical analysis of the purity of their and everybody elses signal. Rather spend hours screen shotting waterfalls than communicating
    Camp 3. Its ham radio, lets have a qso.

    Taking cover :)
  10. AA4PB

    AA4PB Ham Member QRZ Page

    I'd say many modern transceivers can handle full 100W output power for 12.6 sec key down followed by 17.4 sec of Rx. Many of them are rated for full power output on RTTY and FM. AM ratings are lower because the total AM power consists of the carrier plus two sidebands. A 100W average AM power is actually 150W PEP because of the sidebands, thus the need for reduced power on AM. My Elecraft KPA500 amp, for example is rated for 500W for 10 minutes key down and 5 minutes standby. It easily handles FT8.

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