ad: elecraft

need 48 states!

Discussion in 'SKED - QSO Scheduling' started by KE5RRH, Jan 24, 2008.

Thread Status:
Not open for further replies.
ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: Left-3
ad: Subscribe
ad: Left-2
ad: l-BCInc
  1. DL7GEM

    DL7GEM Ham Member QRZ Page

    Again, any comments/corrections by more experienced hams would be welcome.

    The SWR is a measure of how much of the output power is reflected
    back to the transmitter and of the impedance mismatch between
    the transmitter output and the feedline-antenna combination.
    An SWR of 3 means that 25% of the output power is reflected back to the
    transmitter, i.e. is not radiated through the antenna.
    Ideally, the SWR should be 1. As a rule of thumb anything below 1.5
    is fine, anything above 2 needs to be corrected.

    If I were in your place, I would not go ahead with replacing your
    dipole with a new antenna. You can certainly find a better use for
    that 40$. The fact that you can hear stations which are pretty far away
    and with good signals at that shows that your dipole is working. It might
    need a little bit of tweaking to make it into a good transmitting
    antenna. Alternatively, follow Jimmy's advice -- build a new one for a fraction of
    the cost.

    You should be able to get your dipole to a point where you do not
    need any antenna tuner as long as you are working on 20m only.
    You should probably ask one of the hams you know whether he owns an
    antenna analyzer and whether you can borrow that. (A grid dipper will
    also work). You'd connect the analyzer directly to the antenna and look for
    the frequency where the imaginary part of the impedance vanishes (or nearly
    so). For dipoles this coincides with the frequency having the minimum
    SWR. That frequency is the resonance frequency of your antenna. Four
    your purposes, that frequency should be somewhere near the centre of
    the 20m band. If your dipole has spent its previous life in a height
    greater than your current 15ft, you'll most likely notice that the
    resonance frequency is too low. This is because the ground forms a capacitive
    load on your antenna, which lowers its resonance frequency.
    Also note the impedance you get at the resonance frequency. Depending
    on the exact configuration, this will be significantly different
    from 50Ohm. The impedance of a dipole with both legs being parallel
    to ground and which is mounted in a height of half a wavelength is 75Ohm.
    If you decrease the height above ground, the impedance also decreases.
    Likewise, if you mount the dipole in an inverted v configuration, the
    impedance decreases with decreasing angle between the two legs of
    the dipole. For an inverted v having its feedpoint half a wavelength
    above ground, an angle of abt. 120deg will yield an impedance of
    50Ohm at resonance.

    For tuning the dipole you'd start by varying the height above ground
    of the feedpoint and the angle between the legs of the dipole in order
    to get as close to 50Ohms as possible. Then adjust the length of the legs
    of the dipole in small steps (1in or so), till you hit the desired
    resonance frequency.
    Following this process, you should be able to achieve an SWR of 1.5 or
    lower without needing an antenna tuner.

    For SSB, the output power is related to the strength of the
    modulating audio signal. The louder the audio, the higher the output
    power. However, there's a limit to the strength of the output
    signal. If you reach that limit, you will over-modulate the RF signal,
    which will generate splatter on both sides of your signal. The aim
    is to just reach 100% modulation. You reach this aim by adjusting
    the microphone gain on your rig. Refer to the section
    "Functions for Transmit --> Output power and mic gain" in the manual
    of your rig to learn how to adjust the mic gain.

    On a side node: what your are trying to do is rather ambitious. In
    order to reach that goal, you need efficient operating practice.
    Among other things, this means that you need to know how work the
    various bells and whistles of your rig in your sleep. Hook up the
    dummy load to your TRX (or switch your antenna tuner to dummy, if it's
    got a built-in dummy load) and play with your rig.

    Finally, 20m currently opens just after sunrise and closes down
    abt. an hour after sunset. About an hour before local sunset (i.e. around
    14:00Z) I can hear lots of US east coast stations.


    Marcus -- DL7GEM
  2. KE5RRH

    KE5RRH Guest

    thanks for the reply :) Looks like my antenna is not to bad after all, i made contact with k3ft in pennsylvania and ke7jgb in washington state this morning. :D but it was sked haha i heard pennsylvania really well but not so well with washington.

    edit. so now i have washington, pennsylvania, and Illinois , all the other states let me know when/if you can qso Thanks! 73s
    Last edited by a moderator: Jan 30, 2008
  3. KD7DCR

    KD7DCR Ham Member QRZ Page

    OK...let me think here...
    at 14242 in the afternoons you will be close to "Chris & Walt & others" from down south in the Islands with the "Parrots" et al. He is usually on 14240.. Sometimes George, the Voice of the Tropics, will set up on 14242... Late afternoon's you will find Masa JE1LET holding down 14247 - after the DX net clears off. 14260 may find George, see above, or even some Cuba or Brazil or other SA DX...up around 14280 you will find other SA and Mexico stations...but, sometimes they end up above 14320 or so...

    IF you can cut a wire for 40m Phone you should work most of the midwest and lower Eastern and Western side...wait for the band to "go long" around 2000 to 2100 hr GMT and you should get some more states beyond those done earlier...still on 40m. Try using 20m for your "outer ring" of states here in the Lower 48... just listen for AK stations - they are about 3 hours "behind" you - earlier in clock time...take them when you can, try around Noon their time and then around dinnertime or later...

    I am usually on 20m most afternoons from 2000hr till around 2330hr or so...hope to hear you and give you MONTANA...

    73, regards,
    de Mel
  4. WB5KHC

    WB5KHC Ham Member QRZ Page

    See what we got ...

    See what we got now that the CW requirement has been removed... Sheesh....

    To best thing is I'll never have to deal with his operating habits or lack thereof....:confused:
  5. KU0DM

    KU0DM Guest

    Uncalled for.

    Daniel, if you want I can give you KS. The path to TX hasn't been great these last few days, but we can certainly give it a shot!
  6. K0HWY

    K0HWY Ham Member QRZ Page

    If you're still needing North Carolina, let me know and I'll try to help you out. I probably won't be able to do anything before Monday night but after that, I should be available.
  7. KE5RRH

    KE5RRH Guest

    Sure, i so far have pennsylvania, washington state, maine, and Illinois. Got Mexico City this morning :p Oh now i can get onto 40m by the way. please email me for sked qso, or IM, aim = nvidiapwnsati, skype = danfwu, msn = email is Thanks and 73s!!
  8. KU0DM

    KU0DM Guest

    Several QSO parties today, snag any new ones in those?
  9. K5OP

    K5OP Ham Member QRZ Page

    You're not going to be able to get on 40 meters if all you have is a 20 meter antenna. What kind of antenna do you have? And I offered Mississippi to you but you still haven't taken my offer yet.
  10. K0HWY

    K0HWY Ham Member QRZ Page

    I'll AIM you early in the week then.

    73 from K0HWY
Thread Status:
Not open for further replies.

Share This Page