Ftdx1200 , no 100wt

Discussion in 'General Technical Questions and Answers' started by AE4MO, Jul 13, 2019 at 7:33 PM.

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  1. AE4MO

    AE4MO Ham Member QRZ Page

    ok this is my case, and I think others have it. I have a ftdx1200,, I can not get more than 60 watt, in ssb, , in cw have 100, if i Whistle 100, but when I speak no, and I have tried it with dunmyload, and it is the same, I have tested meny microphones and the same, What's the reason?
     
  2. N7WR

    N7WR Subscriber QRZ Page

    That is normal for SSB. The fact that in SSB mode it peaks at the advertised 100 watts indicates it is working as it should be.

    PEP is equal to steady carrier power, or radiotelegraph dot or dash average power, in a properly-formed CW transmission. PEP is also equal to average power in a steady FM, FSK, or RTTY transmission.

    Although average power is the same as PEP for complex modulation forms, such as FSK, the peak envelope power bears no particular ratio or mathematical relationship to longer-term average power in distorted envelopes, such as a CW waveform with power overshoot, or with amplitude modulated waveforms, such as SSB or AM voice transmissions. Typical average power of a SSB voice transmission, for example, is 10-20% of PEP. The percentage of longer term average power to PEP increases with processing, and commonly reaches ~50% with extreme speech processing.
     
    WG7X likes this.
  3. WG7X

    WG7X Premium Subscriber QRZ Page

    To add a bit more to what N7WR explained: it is just a metering problem. Assuming (for the sake of discussion) that you are either using the radio's built-in meter or a non-peak reading external meter; what you are seeing is normal as N7Wr explained.

    Most of the less expensive meters available simply cannot follow the peaks of the RF envelope generated during SSB operation. They normally show only an "average" reading. That is why when you are using a full carrier mode like CW, or whistling into the microphone on SSB you see 100 or nearly 100 watts out. Whistling into the mic mimics the CW tone. Personally, and this is just me, I find whistling into a microphone a poor way to determine proper SSB modulation or power out measurement.

    As you advance in your ham radio explorations, you will find that having good test equipment is vital to ham radio nirvana...
     
    K9ASE likes this.
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    In every SSB transmitter I have or have ever owned over five decades if a 100W PEP rated transmitter exhibits 60W of "displayed" output power on modulation voice peaks, something's wrong -- as it really should indicate about 30W.

    To force it up to 60W indicated, in my experience, demonstrates that something is cranked up way too high and is probably causing distortion.

    As stated, conventional power meters can't indicate PEP power (although special ones, all of which require DC power to indicate anything, can). An oscilloscope can, also, and is generally the best instrument to display SSB or AM modulation as it can display not only PEP power but also evidence of overdriving or poor ALC characteristics which result in "visible" distortion.
     
  5. WG7X

    WG7X Premium Subscriber QRZ Page

    Yeah, Steve is right. I forgot to mention that...
     
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    When calculating r.f. exposure, the FCC "assumes" that the average output from an SSB transmitter is 20% of the peak output power. With an average reading wattmeter, of which the vast majority of wattmeters actually are, between 20% and 25% of what the meter read when tuning the transmitter with a carrier, average with a very occasional peak to around 30% is perfectly normal.

    Any more power output and you are almost certainly over-driving the transmitter and that can produce all sorts of spurious emissions, "splatter", "buckshot", and so on, all of which cause problems to others operating on the same band.


    Glen, K9STH
     

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