When is more than a few watts power needed?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N0PKG, Oct 27, 2015.

ad: l-rl
ad: abrind-2
ad: l-BCInc
ad: Left-3
ad: Left-2
ad: L-MFJ
ad: Subscribe
  1. N7GH

    N7GH Ham Member QRZ Page

    Get a better antenna or check your rig sensitivity and station grounding, the difference between 100 Watts and 1500 Watts between coast to coast USA is only 1 S unit. I work the world on 100 Watts and I do it with a 4BTV on the roof of my garage and I almost always get a 5/9 report.
  2. N7GH

    N7GH Ham Member QRZ Page

    Path to your desired receiver is the factor. Get out a map and see what is in the way and you'll quickly see you may need more than 5 Watts. How many concrete monsters do you have to bounce around to get our signal to the repeater, or canyons do you have bounce or forests you have to burn through.

    If you have a clear direct path 5 Watts will easily work stations 25 miles away under normal propagation conditions, but how often do you have a clear direct path when you are not working satellite?
  3. K9STH

    K9STH Ham Member QRZ Page


    The difference between 100-watts and 1500-watts is virtually 2 "S" units, not 1 "S" unit. The RMA, now EIA, standard "S" unit is 6 dB. Where power is concerned, it takes a 4-times increase in power to achieve 6 dB. Therefore, going from 100-watts to 400-watts will increase the signal 6 dB or 1 "S" unit. Then, going from 400-watts to 1600-watts is another 6 dB which is equal to 1 "S" unit. That makes a total of 2 "S" units by going from 100-watts to 1600-watts. Increasing power from 100-watts to 1500-watts results in slightly less than 12 dB or slightly less than 2 "S" units.

    Yes, it is possible to "work the world" with 100-watts into a trap vertical antenna. However, it is MUCH easier to work the world with 1500-watts and single band yagi antennas at 100-feet above ground.

    As for signal reports: There are quite a number of "S" meters that are not calibrated the the RMA / EIA "standard" of S-9 = 50 microvolts. I have measured a number of units with "S" meters that read S-9 with less than 10 microvolts applied and the "dB over" scales are no where near being accurate. Also, there are those operators who automatically give a "59" report even if their "S" meter is not reading an S-9.

    How much power an individual operator uses is their choice up to the full legal limit. There are those operators who just don't want to run high power, there are those operators who want to run higher power but cannot for a number of reasons including financial. And, there are those operators who do run higher power.

    As for antennas: Again there are those who are satisfied with mediocre antennas and there are those who are restricted in how good an antenna that they can have for any number of reasons including financial, spouse, CC&Rs, etc.

    When propagation is "just right", or with just plain luck, a 100-watt station may work DX in a hurry. However, in general, the 100-watt station is going to have to wait for a considerably longer time before working the DX station.

    Glen, K9STH
  4. KK4YWN

    KK4YWN Ham Member QRZ Page

    s units dont matter much. its the peak to peak amplitude of the modulation as its decoded at the receiver that matters. if the peak-to-peak amplitude of signal A is 1micorvolt and the peak-to-peak amplitude of signal B is 2 microvolts, B sounds louder than A. and ultimately, thats why so many people run amplifiers to talk regionally when 100w will do.

    the s meter doesn't tell us much.
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    When is more than a few watts needed you ask.....

    Well in our rag chew group we like to sit back and listen in comfort, that usually means the definition of QRP gets revised to include anything under 500W.

    I have to ask myself;
    Why is it we are encouraged to run as little power as possible on HF but if we are not Full quieting into the repeater people complain? :confused:
  6. K9STH

    K9STH Ham Member QRZ Page


    The truth be known, it is really the signal to noise ratio of the signal that really matters in how well a signal can be copied. When there is no QRM, and when the noise level is low, it doesn't take that much power for a signal to be easily copied. When there is QRM, then it takes a stronger signal to overcome that "man made noise" and when there is QRN, it takes a stronger signal to overcome that noise level as well.

    Glen, K9STH
    AF6LJ likes this.
  7. W9FTV

    W9FTV Ham Member QRZ Page

    I'm a new ham and I'd like to thank everyone for this thread. These are the conversations someone like me can learn a lot from.

    AF6LJ likes this.
  8. WA9SVD

    WA9SVD Ham Member QRZ Page

    It's not just a waste, it's discourteous, and not in keeping with "Good Amateur Practice." (Can you say "LID?")
  9. KC4YLV

    KC4YLV Ham Member QRZ Page

    there's no AGC noise reduction on FM, white noise is constant white noise. on HF you have the ducking effect from the AGC loop, bringing the average noise level at your ear down.

Share This Page