Posted by
Tom Hammond-3 on
Oct 05, 2005; 11:15am
URL: http://elecraft.85.s1.nabble.com/Two-Band-Moxon-wire-beam-tp382311p382316.html
Hi Jerry:
>I guess I don't understand at all how to use the spot feature. For all I
>know my K2 may not even have it. I just listened to N0SS 2 different wav
>files and still can't figure out what I'm doing. When I hit the Spot
>button, same as Rit only held longer I get SE L 143. The number changes as
>I turn the main tuning dial but the tone completly wipes out the signal I'm
>listening to, no matter how loud it is. Maybe I need one of those LED Tuners
>I've been reading about. What am I doing wrong??
Invoking SPOT is NOT by pressing-holding RIT, but by pressing-holding the
PRE-ATT button!
If you press-hold RIT, you're invoking the PF1 user-programmable function,
which happens to default to the MENU | ST L (sidetone level) setting.
If your ST L value is currently set to 143, it's probably MUCH too loud for
90% of the spotting uses you'll use it for.
Try this...
1. Press-hold PF1 (RIT) to go to the ST L menu and then crank the VFO
knob DOWN to set ST L to a level of between 25 and 40. This should
give you a CW sidetone level which you can still hear adequately
while sending, but one which won't 'swamp' received signals when
you attempt to use it for zero beating.
Exit ST L by pressing MENU briefly.
2) Be sure you have your tuning RATE set to show the last two decimal
places in the frequency display.
3) Find a signal on the band... doesn't have to be a blindingly strong
signal but let's not start with a water-weak signal either. Maybe
find someone who is 569 to 589.
4) Press-hold SPOT (PRE-ATT) to turn on the SPOT tone.
This should allow you to hear both the SPOT sidetone AND the signal
from the other station.
5) Now, slowly crank the VFO knob until the tone of the received station
matches that of the SPOT tone.
As the two tones come closer together (esp. when within 30-40 Hz),
you will start to hear a secondary beat note between them (this is
the difference tone between the two higher-pitched tones). As you
continue to tune the VFO, this beat note should get slower and
slower until you can easily hear individual beats. At this same time,
the tone of the received station should 'disappear' behind the SPOT
tone (that's what I was trying to demonstrate in the WAV file you
played).
Once you have matched the two tones, such that the received signal
disappears behind (and within) the SPOT tone, you're zero beat with
the received signal.
One VERY IMPORTANT point of using the SPOT tone for zeroing in on a
received signal is to not have the SPOT tone so darn strong that it
completely swamps out the received signal. What you should try to do is to
find a SPOT tone level which more or less equals the volume of the tone
from the received signal. The closer the two tones are in level, the more
easily you can zero beat them and the more easily you should be able to
hear the beat note between the two signals.
Learning to properly zero beat a signal is not necessarily an instantaneous
success. It might take a bit of time to master it, but it is NOT difficult,
and once you 'get' it (the technique), you will never lost it again.
If I can help in any way, please drop me a note. Maybe I'll try to make a
better WAV file example of how to zero beat.
73,
Tom Hammond N0SS
_______________________________________________
Elecraft mailing list
Post to:
[hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help:
http://mailman.qth.net/subscribers.htmElecraft web page:
http://www.elecraft.com