[Lowfer] UWL station pics and measurements

[Eric Smith]

Jay,

Thanks for all this ... this is going to be very helpful to me.  I
will give a full reply later tonight with answers to your questions,
details about what I have already done in the past, and a couple more
questions of my own.

Thanks again,
Eric KD5UWL / WD2XFX


On Feb 11, 2011, at 8:28 AM, "jrusgrove at comcast.net"
<jrusgrove at comcast.net> wrote:

> No slings and arrows ... just constructive comments. You probably know most of the following already
> ...
>
> While it may be possible to get lucky and hit resonance with a few taps and no moveable variometer
> coil it's not likely (at least I've never been that lucky). A decent loading coil will be of high
> enough Q that tuning will be very sharp. One would have to hit the correct tap position - probably
> within an 1/8 of a turn or less! That's one reason why there needs to be some form of adjustment.
> Also, water, ice and changes in the immediate environment will shift the resonant point. Since the
> moveable variometer coil is much smaller than the main coil it provides the fine adjustment that's
> needed. I'd suggest reinstalling the one you have.
>
> For tuning, start with the variometer at a 45 degree angle (coils series aiding - not opposing) and
> check for resonance using one of your existing fixed taps. One simple and quick way to find
> resonance is to replace the transmitter with a general coverage receiver (IIRC you have an R-75?)
> and spin the dial noticing at what frequency the background noise peaks. That's resonance. By
> observing the resonant frequency using other existing taps on the main coil you should be able to
> predict (roughly) the correct position of the tap for your desired transmit frequency. The correct
> tap point is where the receiver noise peaks at your desired frequency and the moveable variometer
> coil is at roughly 45 degrees (series aiding - not opposing).
>
> Once the antenna is at resonance the next step is to couple power to the antenna. It looks like
> there might be a link coil wrapped around the bottom of the main coil ... if not, what method of
> feeding power to the antenna are you using?
>
> Jay
>
>
>
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