Posted by
G3TCT on
Aug 28, 2010; 3:49pm
URL: http://elecraft.85.s1.nabble.com/Need-K3-dB-Measurements-on-new-160M-Antenna-tp5468244p5472974.html
Jim
Afraid I can't help with listening on 160, but an interesting topic, and
a measurement technique applicable to other situations. My observation
is that the mental averaging will be rather tricky, especially if the
QSB is slow and unpredictable. What we need is something (software?)
which will record the strength seen by the K3 over a minute or 3, and
then provide a statistical analysis. You would then get a picture of the
average, peak, trough and distribution of strengths.
I wonder if something like this exists already - or could be included in
P3 s/w?
Graham
On 19:59, Jim Brown wrote:
> Crew,
>
> I've put up a pair of new antennas for 160M that are predicted to have
> about 3dB of gain over my existing vertical. Without going into a lot of
> detail, each antenna is a wire sloping off of my 120 ft tower, one going
> east, one going west. The tower acts as a reflector. The tower and each
> wire have 4 elevated radials. The antenna is working -- I've made four QSOs
> with VK, one with FK8, and one with FO in about two hours -- but I need to
> figure out if it's working better than my existing omni vertical.
>
> By doing a lot of listening, I can clearly confirm the predicted 6dB or so
> of front to back, but QSB makes it hard to get a handle on gain, and I'm
> only expecting 2-3dB. That's where the dB meter in the K3 comes in handy.
>
> My method is to key down on one antenna for a while, let you get a reading,
> switch to the other and do the same, then back and forth between them,
> again for long enough for you to get a good reading. There IS a lot of QSB
> on the band, so you'll need to do a lot of mental averaging. Please let me
> know, OFFF THE LIST, if this is something that you would like to help me
> with. I need reports from stations that are between about 30 degrees
> azimuth and 120 degrees azimuth of my QTH south of San Francisco. In other
> words, my antenna is aimed at about 75 degrees (ENE), and I need reports
> that are within 50 degrees of being on axis. I could also use measurements
> from KH6 of the antenna that goes in that direction.
>
> BTW -- to access the dB meter in the K3, you need to hit the Display button
> once, then rotate the second VFO knob clockwise until you see a reading in
> mV. Let the knob in that position for about 15 seconds, then rotate it one
> more position clockwise. Now, the dB reading will be relative to whatever
> the average IF output was when the knob was in the mV position. Note also
> that the reading goes plus and minus.
>
> 73, Jim K9YC
>
>
>
>
>
>
>
>
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