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From: "J. B. Weazle McCreath" <weazle@hurontel.on.ca>
To: rsgb_lf_group@blacksheep.org
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Date: Sun, 22 May 2005 12:11:11 +0100
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Subject: LF: Re: Loop antenna problem W1TAG suggestion
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-- Original Message -----
From: "John Andrews" <w1tag@w1tag.com>
Sent: Saturday, May 21, 2005 10:45 PM
Subject: LF:Re: Loop antenna problem


> J.B.,
>
> There is another approach you might want to consider. Skip the single turn
> link altogether. Rather than the normal parallel tuning, series tune the
> loop into a transformer wound on a ferrite core. The turns ratio of the
> transformer will determine the Q of the loop. You might not want a really
> high Q setup with a loop of that size.
>
> I have been using a 10 turn (on the loop side) to 20 turn transformer to
> couple to a 50 ohm termination. This places a nominal 12.5 Ohms in series
> with the loop. A higher ratio would improve the Q, but this might be a
good
> starting point for you to play with. The core material in this case is
#77,
> but #43 or similar should be OK.
>
> The advantage of this arrangement is that the loop remains inherently
> balanced to ground, while giving you the flexibility of playing with the
> coupling. You may choose to put the preamp right at the transformer
> secondary, or run a coax line back to the shack. A short write-up on
> my arrangement is available at:
> http://www.w1tag.com/rxloop.htm
>
> John Andrews
>

Hello John, LFers,

Thanks for your suggestion on the series tuning setup.  Yesterday I tried a
simple non-shielded single turn pickup loop but it was no different than my
original shielded pickup.  I can't help but think that I'm getting led down
the garden path by something, but I'm amiss as to what!

Do you suppose that because I used #12 wire, rather than the #20 that
Steve, VE3SL, used on his loop that my Q is too high and therefore the
bandwidth is too narrow?  I think I'll wind a toroid transformer today
based on your info (I checked your website too) and see if I can get
better results.

Niels had suggested I try a capacitive divider, but my collection of caps
doesn't have anything close to the values he recommended.  I'll keep on
plugging away at it until I get it to work.