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Gary,<br>
I am forwarding your reply to the AMRAD LF reflector<br>
73<br>
André<br>
<br>
-------- Original Message --------
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<th valign="baseline" align="right" nowrap="nowrap">Subject: </th>
<td>Re: [Lf] [Fwd: LF: No US Ham Band]</td>
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<td>Sat, 17 May 2003 18:54:46 -0600</td>
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<th valign="baseline" align="right" nowrap="nowrap">From: </th>
<td>"Gary Peterson" <a class="moz-txt-link-rfc2396E" href="mailto:glpeterson@tfcbooks.com"><glpeterson@tfcbooks.com></a></td>
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<th valign="baseline" align="right" nowrap="nowrap">To: </th>
<td><a class="moz-txt-link-rfc2396E" href="mailto:andre.kesteloot@ieee.org"><andre.kesteloot@ieee.org></a></td>
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<th valign="baseline" align="right" nowrap="nowrap">References: </th>
<td><a class="moz-txt-link-rfc2396E" href="mailto:3EC304BF.1000903@verizon.net"><3EC304BF.1000903@verizon.net></a><050201c31c90$87a1c4a0$040ac1d8@hppav>
<a class="moz-txt-link-rfc2396E" href="mailto:3EC6979E.1030508@verizon.net"><3EC6979E.1030508@verizon.net></a></td>
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<div>Hi André,</div>
<div><font size="2"></font> </div>
<div>You wrote:</div>
<blockquote dir="ltr" style="margin-right: 0px;">
<div>The problems of radiating any kind of power at all at 73 kHz are
a good deal worse than at 136 kHz, and I would not see any advantage to
that band. </div>
</blockquote>
<div>I wish to study the characteristics of a poorly described LF surface-wave
and the apparatus for its production. The launching structure, which has
been called a grounded antenna, consists of a very well grounded, high aspect
ratio helical resonator connected with a short vertical conductor to an
elevated armature of large surface area and radius of curvature. Antenna
excitation is by means of a few primary windings in more or less close proximity
to the lower part of the resonator. I've read the propagation efficiency
of this surface wave improves with a lowering of frequency, making the 73
kHz band preferable to me. I've also read this wave is not a major contributor
to the field produced by base-loaded monopole LF antennas, another potential
area of inquiry.</div>
<div><font size="2"></font> </div>
<div>The receiving apparatus for this purported surface wave includes a matched
helical resonator grounded at the lower terminal and the upper terminal
connected to an elevated armature. See <a
href="http://www.tfcbooks.com/special/images/system.gif">http://www.tfcbooks.com/special/images/system.gif</a> for
an old sketch of the entire system.</div>
<div><font size="2"></font> </div>
<div>73</div>
<div>Gary KB0DEB</div>
<blockquote
style="border-left: 2px solid rgb(0,0,0); padding-right: 0px; padding-left: 5px; margin-left: 5px; margin-right: 0px;">
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3">----- Original Message ----- </font></div>
<div
style="background: rgb(228,228,228) none repeat scroll 0%; font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3"><b>From:</b> </font><a title="andre.kesteloot@verizon.net"
href="mailto:andre.kesteloot@verizon.net"><font size="3">Andre Kesteloot</font></a><font
size="3"> </font></div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3"><b>To:</b> </font><a title="glpeterson@tfcbooks.com"
href="mailto:glpeterson@tfcbooks.com"><font size="3">Gary Peterson</font></a><font
size="3"> </font></div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3"><b>Cc:</b> </font><a title="tacos@amrad.org"
href="mailto:tacos@amrad.org"><font size="3">AMRAD Tacos</font></a><font
size="3"> ; </font><a title="lf@amrad.org" href="mailto:lf@amrad.org"><font
size="3">lf-amrad</font></a><font size="3"> </font></div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3"><b>Sent:</b> Saturday, May 17, 2003 2:12 PM</font></div>
<div
style="font-family: arial; font-style: normal; font-variant: normal; font-weight: normal; font-size: 10pt; line-height: normal; font-stretch: normal; font-size-adjust: none;"><font
size="3"><b>Subject:</b> Re: [Lf] [Fwd: LF: No US Ham Band]</font></div>
<div><font size="2"></font><br>
</div>
<br>
<br>
<p> </p>
<hr>
<p></p>
Gary Peterson wrote:<br>
<blockquote cite="mid050201c31c90$87a1c4a0$040ac1d8@hppav" type="cite">
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<div>I understand that at one point a 73 kHz shared allocation was being
talked about and that UK hams were authorized to use that band for
a while, back in 1996. Do you think the ARRL would consider petitioning
the FCC for ham privileges between 71.6-74.4 kHz?</div>
<div><font size="2"></font> </div>
<div>I know some fixed European stations have frequency allocations in
that area. Are there PLC concerns associated with that portion of the
spectrum as well? </div>
<div><font size="2"></font> </div>
</blockquote>
Hello Gary,<br>
Yes the 73 kHz band is still in use in the UK but, as I understand it,
is due to be phased out in the near future. As far as I know, no new user
may be authorized to use that band in the UK.<br>
One of the early advantages of 73 kHz was that one could use regular high
power Hi-Fi audio amplifiers whose bandwidth would easily extend that
high. <br>
Now that we better control the problem of building transmitters with cheap
Power MosFETs, that advantage has really disappeared.<br>
The problems of radiating any kind of power at all at 73 kHz are a good
deal worse than at 136 kHz, and I would not see any advantage to that
band. One of the challenges that motivated us was the idea of trans-atlantic
QSOs on 136 kHz. That has now been effectively killed by our dear FCC
wizards. <br>
As far as the PLCs are concerned, you understand, I am sure, that they
do not have any privilege on 136 either. They are secondary users. I
have no idea whether they have equipment on 73, as they would not even
tell us the frequencies they use on the LF band <br>
73<br>
André N4ICK<br>
<p> </p>
<hr>
<p></p>
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