<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head>
<title></title>
<meta http-equiv="content-type" content="text/html;charset=utf-8"/>
<meta http-equiv="Content-Style-Type" content="text/css"/>
</head>
<body>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">I am somewhat confused here and I hope someone can help:</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">I am refurbishing an SB-200 for a friend. </span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">In this amp, C-27, the fixed 500 pfd 2 KV mica capacitor which is switched in parallel with
the loading capacitor C-28A/B on 80 meters where additional loading capacitance is
needed, especially on the low end of the band, had been replaced with a 525 pfd "door
knob" capacitor capable of at least 5 KV. This "door knob" is a large one and I think it is
actually either a 10KV or 25KV job.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">It checks out with my cap meter perfectly.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">While using this amp, with new finals, on the low end of 80 meters, I "run out" of loading
capacitor before achieving full load. I.e., the loading capacitor is up against the full-capacitance stop.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">The antenna is being fed through a home-brew antenna coupler, and the SWR between the
amplifier and the coupler is 1:1.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">I then paralleled that "door-knob" capacitor with a 500 pfd 2KV mica, and STILL run out of
loading capacitance on the low end of 80 meters.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">The amp works perfectly and properly on all other bands and frequencies.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">I then checked the bandswitch and every connection in the output tank and everything is
working exactly correctly.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">I then tried a different set of new finals, and got the same result.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">Anyone here have a clue as to what is going on?</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">Even with the amp acting this way, I can easily achieve at least 600 watts output with
around 50 watts of drive, and I am happy with that, but this still does not seem right to me.</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt"><br />
</span></font></div>
<div align="left"><font face="Arial" size="2"><span style=" font-size:10pt">Ken W7EKB</span></font></div>
</body>
</html>