[Lowfer] UWL station pics and measurements

[jrusgrove at comcast.net]

Eric

Thanks for the measurements.

The power input to your final amplifier appears to be 12.37 X .038 = 0.47 watts ... a bit more than 
3 dB down from the allowable 1 watt. While 3 dB may not sound like that big a deal, in the lowfer 
world it's huge. Looking at signals on an Argo screen near the 'visual' noise floor 3 dB is the 
difference between imperceptible and painting solid white lines.

A couple questions for starters. From the pix there doesn't appear to be a variometer associated 
with the loading coil ... so I wonder if there is one out of view or if you use some other means to 
bring the antenna system to resonance? Also, what type of final amplifier are you're running ... the 
usual 'class D' arrangement or some other type?

Any additional info will be useful.

Jay





----- Original Message ----- 
From: "Eric Smith" <esmithmail at gmail.com>
To: "Discussion of the Lowfer (US, European, &amp,UK) and MedFer bands" <lowfer at mailman.qth.net>
Sent: Thursday, February 10, 2011 11:22 PM
Subject: [Lowfer] UWL station pics and measurements


> Ok.  I have the numbers, perhaps you can help me interpret them.  Most of
> you know when it comes to analog what I don't know would fill volumes.  I do
> have fine success building and programming digital projects since anyone
> with a third grade education can do that.  But certain aspects of real
> electronics have always escaped my understanding.  So please bear with me:
>
> I took this picture of UWL today at noon:
> http://www.nutstreet.net/images/lowfer/UWL-daytime.jpg
>
> The final is covered by snow and located inside the void of that brick the
> loading coil is on.  The solar panel is not resting on the ground, there is
> actually a red brick under it but it is hidden by snow.  I didn't have time
> to take measurements then but I wanted to get the picture at that time
> knowing it would be dark by the time I could actually take the readings.
>
> Here is a picture of the input voltage to the final during key down -- shows
> 12.37 VDC:  http://www.nutstreet.net/images/lowfer/UWL-voltage.jpg
>
> Here is a picture of the final current during key down -- shows 0.038 A:
> http://www.nutstreet.net/images/lowfer/UWL-current.jpg
>
> The reason I have the meter on that scale is an open fuse on the uA/mA scale
> :(
>
> Inside the final enclosure and in-line with the DC feed is a non-inductive
> 0.1 ohm resistor of fair precision that I use to compute output power in
> watts.  But it would be difficult and disruptive to open up right now to get
> my probes on that.
>
> So what do you think?  I'm interested in any and all feedback, good and bad
> (Bill, please be nice :)
>
> Eric  KD5UWL / WD2XFX
> -- UWL is on 185302 Hz, QRSS30, at EM15gp
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