FT8 Power, how much ????

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

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  1. KP4SX

    KP4SX Premium Subscriber QRZ Page

    I think we all agree that for 13 seconds my gear has to be up to the task. That means my power supply, my rig, the DC wiring mainly. If it can't do that at a minimum then the rest of the debate is moot.
    The next 15 seconds or so it rests and supposedly cools off. That is a concern as big as the previous one. Does it have adequate ventilation, etc?
    If that is compromised then the ambient temperature rise is going to begin accumulating.
    Most hams know that and provide adequate ventilation but I see pictures of so many shacks where the gear is all crammed together. Maybe they get away with it for a while but all bets are off.
    At that point Duty Cycle doesn't mean squat.
  2. WA9FZB

    WA9FZB XML Subscriber QRZ Page

    In a practical sense, it also seems to make a difference how long you plan to operate at that "duty cycle." I note that with my Kenwood TS-590S and then the SG, that the rigs are rated at 100 watts RTTY, which would seem to be a 100% duty cycle mode. If so, then the rating must accept the fact that the cooling fans will run. . . a lot.

    When I run FT8, I can run any power level for the first 10 minutes or so, then the heat builds up. The KW's chassis is just a massive heat sink, but it cannot dissipate the heat of FT operation without the fans running. After heavy use for 10-15 minutes, the fans come on for a few minutes. Once the heat sink is properly cooled, they go off until the temperature once again reaches the trigger level. If I reduce power to 25-30 watts, the fans never run. . . but then hardly any DX hears me with my vertical (with just a small number or radials on a city lot).

    So, I can run the full 100 watts for a while, then the fans are needed. The KW tech I spoke with about this just said, "That's what the fans are for."
    KA9JLM and KP4SX like this.
  3. KC9VFO

    KC9VFO XML Subscriber QRZ Page

    I run a 100 watts on an Icom 7300 all the time and the temp meter barely rises.
  4. PA5COR

    PA5COR Ham Member QRZ Page

    FT991a 100 watts to 10 watts whatever is needed to get the job done.
  5. K2WH

    K2WH Premium Subscriber QRZ Page

    Not at all and if I did, I'd run 1500 watts.
    N3RYB likes this.
  6. K5BDH

    K5BDH Premium Subscriber QRZ Page

    10 to 50 watts gets the job done here.
    KP4SX likes this.
  7. KD0KZE

    KD0KZE Ham Member QRZ Page

    I don't (currently) have an amplifier, so 100 watts is my upper limit. Mainly I'm trying to get targeted stations for DXCC or a WAS band endorsement, so I check pskreporter.info a lot. If the area I'm trying to reach is showing me at like -15 dB or less I run higher power. If it's showing 5-10+, I dial it back. If I'm just throwing out a CQ to North America, then you can get by with a lot less than 100 watts on most bands + conditions.

    73, KD0KZE / Paul
    K5GHM likes this.
  8. NQ4T

    NQ4T XML Subscriber QRZ Page

    I'll start out somewhere at around 25 watts...depending on band conditions. If I really want a contact, I'll start cranking it up. Like I really needed SD for mixed WAS the other night...so when I saw them on 40m FT8; radio went right up to 100 watts. But like someone else mentioned with their 7300, my 7100 can really pump it out, kick the fans on, but the temp meter barely rises. My fan ran the entire time yesterday during NAQP RTTY...which I ran at 75 to 100 watts at all times; occasionally it'd get louder while transmitting...but the temp meter held pretty much solid and the rig just kept doing what it's supposed to be doing.
  9. N6YWU

    N6YWU Ham Member QRZ Page

    So even though some here consider kiloWatt QRO perfectly consistent with operating a weak signal mode and CFR 97.313(a), what if one wanted to test the actual minimum power necessary from the opposite direction?

    How many FT8 DX contacts might be possible at milliWatt QRPp or QRP power levels?

    What's the most miles per milliWatt that anyone here has logged for an FT8 QSO?
  10. WD4ELG

    WD4ELG Ham Member QRZ Page

    I have a bunch of QSO's on 20 with 500 milliwatts FT8 on my FT817 into EU. The best is probably 4K miles away so that's 8K miles per watt. Not too hard to do if the band is not overcrowded.

    I think I had a few on 40 last winter also.

    Now, would I try that on 80? Not on your life. I almost always turn on the amp on 80 and ALWAYS turn on the amp on 160 for FT8 QSO's. They're not going to hear me over the noise if I don't.
    N6YWU and N3RYB like this.

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