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=20
Recommendation:
=20
=20
My experience with several commercial amps has driven home one =
serious design weakness common to most brands. This is severe PA tank =
circuit resonance drift caused by heat instability in the fixed padder =
caps used to tune the tanks down to the low bands (most often 80 and 160 =
meters).
=20
Transmitting ceramics simply do not have the stability to be =
incorporated in this demanding application. During "heavy duty" =
operating, the heat given off by the PA tubes in the tank compartment =
causes violent drift in the ceramic caps. This in turn detunes the tank, =
causing more plate dissipation to occur which further heats the caps, =
and so on. In other words, a vicious, destructive cycle exists which is =
absolutely objectionable. I believe some heating is also internal to the =
caps themselves, generated by the dielectric in this high RF current =
service.
=20
I have had to replace all such caps in my amps with their stable =
counterparts: namely, xmitting micas. I realize they are hard to find =
and are expensive and take up more space. But they are absolutely =
necessary--unless the variables themselves are "big" enough to tune all =
the way to 160 meters. (Also not cheap, I know).
=20
We are willing to pay more; please refrain from using ceramics in =
the Titan II. And make known this good feature in your advertisements.
=20
Thanks & 73, Roy K6XK
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http-equiv=3DContent-Type><!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 =
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<DIV><FONT color=3D#000000 size=3D2> </FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 solid 2px; MARGIN-LEFT: 5px; PADDING-LEFT: =
5px">
<DIV><FONT face=3DArial =
size=3D2>Recommendation:<BR><BR></DIV></FONT>
<DIV><FONT color=3D#000000 size=3D2>My experience with several =
commercial=20
amps has driven home one serious design weakness common to =
most=20
brands. This is severe PA tank circuit resonance <U>drift</U> caused =
by heat=20
instability in the fixed padder caps used to tune the tanks down to =
the low=20
bands (most often 80 and 160 meters).</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>Transmitting <U>ceramics</U> =
simply do not=20
have the stability to be incorporated in this demanding application. =
During=20
"heavy duty" operating, the heat given off by the PA tubes =
in the=20
tank compartment causes violent drift in the ceramic caps. This in =
turn=20
detunes the tank, causing more plate dissipation to occur which =
further=20
heats the caps, and so on. In other words, a vicious, destructive =
cycle=20
exists which is absolutely objectionable. I believe some heating is =
also=20
internal to the caps themselves, generated by the dielectric in this =
high RF=20
current service.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>I have had to replace all such =
caps in my=20
amps with their stable counterparts: namely, xmitting micas. I =
realize they=20
are hard to find and are expensive and take up more space. But they =
are=20
absolutely necessary--unless the variables themselves are =
"big"=20
enough to tune all the way to 160 meters. (Also not cheap, I=20
know).</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>We are willing to pay more; =
please refrain=20
from using ceramics in the Titan II. And make known this good =
feature=20
in your advertisements.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>Thanks & =
73, =20
Roy =
K6XK</FONT></DIV></BLOCKQUOTE></BODY></HTML>
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