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Date: Thu, 18 Nov 2004 19:12:39 -0600
From: WE0H Mike <we0h@genesiswireless.us>
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References: <01C4CCB4.3A7963B0.actalbot@southsurf.com> <002401c4cdc7$94613100$80457ad5@jgtdiynm>
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Subject: Re: LF: Loading Coils
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I was working on a Cisco router yesterday and found a bad surface mount
ferrite. I asked the other guy in my department if he could look on a
parts board for a ferrite bead and he returned later to say there isn't
any on the other boards. I said hmmm, let me look. Sure enough it
wasn't labeled FB whatever but Z1 or something and I had to explain to
him that in radio talk that Z means impedance and ferrite beads are a
resistance to RF hence the Z labeling. I guess us amateur radio
operators have an edge against the new people coming out of college
thinking they know lots about electronics. Oh well...<br>
<br>
Mike<br>
<br>
James Moritz wrote:<br>
<blockquote cite="mid002401c4cdc7$94613100$80457ad5@jgtdiynm"
type="cite">
<pre wrap="">Dear Andy, LF Group,
----- Original Message -----
From: Andy <>
To: <a class="moz-txt-link-rfc2396E" href="mailto:rsgb_lf_group@blacksheep.org"><rsgb_lf_group@blacksheep.org></a>
Sent: Wednesday, November 17, 2004 2:46 PM
Subject: RE: LF: Loading Coils
</pre>
<blockquote type="cite">
<blockquote type="cite">
<pre wrap="">I share my office with some young electronics engineers and was
surprised that they know very little about RF inductors or Q factor.
It must be a dying art !
</pre>
</blockquote>
</blockquote>
<pre wrap=""><!---->
</pre>
<blockquote type="cite">
<pre wrap="">Its not just young electronics engineers who know nothing about inductors.
</pre>
</blockquote>
<pre wrap=""><!---->I
</pre>
<blockquote type="cite">
<pre wrap="">work with a number of middle aged ones (well, 30 - 50 anyway) who also
</pre>
</blockquote>
<pre wrap=""><!---->know
</pre>
<blockquote type="cite">
<pre wrap="">next to nothing about inductors, wire antennas, or even radio
</pre>
</blockquote>
<pre wrap=""><!---->communications.
Actually, there is quite a lot of interest in academic and engineering
circles about inductor Q at the moment - but this is about inductors on
ICs - little planar spirals of several nH that occupy quite a lot of space
on most "system on a chip" ICs containing RF transceivers for "Bluetooth",
"WiFi" and so on. A state-of-the-art Q for one of these is about 5 - 10 ...
even with lousy Q like this, circuit designers find they can't live without
them for amplifiers and oscillators and the like, despite spending half a
century inventing circuits to try and get rid of inductors!
</pre>
<blockquote type="cite">
<pre wrap="">some graduates can't even apply ohms law to a practical
situation.
</pre>
</blockquote>
<pre wrap=""><!---->
As someone who occasionally has to help undergraduates do this, I'm afraid I
have to agree. V = I x R they can usually cope with, but I = V/R is a bit
more challenging, involving division as it does ... any mention of kilohms,
microamps etc. and all bets are off!
Cheers, Jim Moritz
73 de M0BMU
</pre>
</blockquote>
<br>
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