This has little to do with PHP other than the fact that something being done with PHP is bringing in content with a contradictory meta tag. This is probably an include() or an include like function.
This block of code (highlighted and truncated) from the PHP page (seen by using the browser's 'view source' while viewing the page):
<div class="header" style="background-image: url(../../../../images/header_resources.jpg); background-repeat:none;"><a href="../../../../index.php"></a></div>
<div class="content-blog">
<div class="maintext">
<div class="maintext-content" align="justify">
<div class="maintext-title"><a href="http://davidfranklin.net/davids-blog">David's Blog</a></div>
<!DOCTYPE html>
<html dir="ltr" lang="en-US">
<head>
<meta charset="UTF-8" />
<title></title>
<link rel="profile" href="http://gmpg.org/xfn/11" />
<link rel="stylesheet" type="text/css" media="all" href="http://davidfranklin.net/davids-blog/wp-content/themes/twentyten/style.css" />
<link rel="pingback" href="http://davidfranklin.net/davids-blog/xmlrpc.php" />
<link rel="alternate" type="applica . . .
. . . title="Semantic Personal Publishing Platform" rel="generator">
Proudly powered by WordPress. </a>
</div><!-- #site-generator -->
</div><!-- #colophon -->
</div><!-- #footer -->
</div><!-- #wrapper -->
</body>
</html>
</div>
<div class="sidebar-content">
<div class="sidebar-title"><a href="http://www.davidfranklin.net/davids-blog">Resources</a></div>
<div class="sidebar-link" style="padding-bottom:15px; border-bottom:1px solid gray;">
David's Blog<br />
is probably an include of some sort and has the (red) meta tag that changes the character encoding. That's probably the problem.
Fortunately this block of code is probably a separate file that you can edit. Ideally you would get rid of:
<!DOCTYPE html>
<html dir="ltr" lang="en-US">
<head>
<meta charset="UTF-8" />
<title></title>
and:
</body>
</html>
from that file. But just getting rid of:
<meta charset="UTF-8" />
should fix this problem.
It's possible that the page that has that tag on it is also including other content or getting it from a database, so finding it might be a little tricky.
Good luck!