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Man!
All I have done was to reconfigure the output tank. The Pi filter has =
actually better
harmonic rejection than a "T" . In terms of cost and reliability ( from =
the HAMs point of view), this mod is much better as it gets rid of the =
external tuner, this less components prone to failure, less components =
to tune. Just think about it!
Alex
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
If we can accept the notion that GUNS are
the killers and not the people, why is it that
we can not accept the idea that CARS are
the speeders and not the drivers?
Alex, trying to understand the world around.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D.
----- Original Message -----=20
From: "Peter Chadwick" <Peter.Chadwick@zarlink.com>
To: "2" <2@vc.net>; <jukka.kulha@nokia.com>; "AMPS" =
<amps@contesting.com>; "'alex'" <alex@sandlabs.com>
Sent: Monday, December 17, 2001 2:44 AM
Subject: RE: [AMPS] SB-200 & 10MHz++
> Alex said:
>=20
> >I have modified several amps by replacing the conventional=20
> >Switch/PlateCap/Inductor/Load Cap with a simple Pi filter.
>=20
> How do you meet FCC Part 97.307(d) with such an arangement?
>=20
> In a class AB amplifier, the second harmonic component of plate =
current
> is 6dB down on fundamental, so you need another 34dB out of the tank =
circuit at
> the second harmonic, which the sums suggest you won't get without an
> embarassingly high Q.
>=20
> In view of the costs of tank circuit components, I don't believe
> manufacturers would have gone to pi-L networks unless they had to.
>=20
> If the Radio Regulations on Spurious Emissions are to be followed, =
even
> 40dB is not enough attenuation. Fortunately, despite Administrations =
signing up
> to the regs, they've quietly forgotten about implementing them.
>=20
> 73
>=20
> Peter G3RZP
>=20
>=20
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<DIV><FONT face=3DArial>Man!</FONT></DIV>
<DIV><FONT face=3DArial>All I have done was to reconfigure the output =
tank. The Pi=20
filter has actually better</FONT></DIV>
<DIV><FONT face=3DArial>harmonic rejection than a "T" . In terms of cost =
and=20
reliability ( <FONT size=3D4><STRONG>from the HAMs point of =
view</STRONG></FONT>),=20
this mod is much better as it gets rid of the external tuner, this less=20
components prone to failure, less components to tune. Just think about=20
it!</FONT></DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial>Alex</FONT></DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT =
face=3DArial>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D<BR>If we can accept=20
the notion that GUNS are<BR>the killers and not the people, why is it =
that<BR>we=20
can not accept the idea that CARS are<BR>the speeders and not the=20
drivers?</FONT></DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT face=3DArial>Alex, trying to understand the world =
around.</FONT></DIV>
<DIV><FONT face=3DArial></FONT> </DIV>
<DIV><FONT =
face=3DArial>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D.<BR></FONT></DIV>
<DIV><FONT face=3DArial>----- Original Message ----- </FONT>
<DIV><FONT face=3DArial>From: "Peter Chadwick" <</FONT><A=20
href=3D"mailto:Peter.Chadwick@zarlink.com";><FONT=20
face=3DArial>Peter.Chadwick@zarlink.com</FONT></A><FONT=20
face=3DArial>></FONT></DIV>
<DIV><FONT face=3DArial>To: "2" <</FONT><A =
href=3D"mailto:2@vc.net";><FONT=20
face=3DArial>2@vc.net</FONT></A><FONT face=3DArial>>; <</FONT><A=20
href=3D"mailto:jukka.kulha@nokia.com";><FONT=20
face=3DArial>jukka.kulha@nokia.com</FONT></A><FONT face=3DArial>>; =
"AMPS"=20
<</FONT><A href=3D"mailto:amps@contesting.com";><FONT=20
face=3DArial>amps@contesting.com</FONT></A><FONT face=3DArial>>; =
"'alex'"=20
<</FONT><A href=3D"mailto:alex@sandlabs.com";><FONT=20
face=3DArial>alex@sandlabs.com</FONT></A><FONT =
face=3DArial>></FONT></DIV>
<DIV><FONT face=3DArial>Sent: Monday, December 17, 2001 2:44 =
AM</FONT></DIV>
<DIV><FONT face=3DArial>Subject: RE: [AMPS] SB-200 &=20
10MHz++</FONT></DIV></DIV>
<DIV><FONT face=3DArial><BR></FONT></DIV><FONT face=3DArial>> Alex =
said:<BR>>=20
<BR>> >I have modified several amps by replacing the =
conventional=20
<BR>> >Switch/PlateCap/Inductor/Load Cap with a simple Pi =
filter.<BR>>=20
<BR>> How do you meet FCC Part 97.307(d) with such an =
arangement?<BR>>=20
<BR>> In a class AB amplifier, the second harmonic component of plate =
current<BR>> is 6dB down on fundamental, so you need another 34dB out =
of the=20
tank circuit at<BR>> the second harmonic, which the sums suggest you =
won't=20
get without an<BR>> embarassingly high Q.<BR>> <BR>> In view of =
the=20
costs of tank circuit components, I don't believe<BR>> manufacturers =
would=20
have gone to pi-L networks unless they had to.<BR>> <BR>> If the =
Radio=20
Regulations on Spurious Emissions are to be followed, even<BR>> 40dB =
is not=20
enough attenuation. Fortunately, despite Administrations signing =
up<BR>> to=20
the regs, they've quietly forgotten about implementing them.<BR>> =
<BR>>=20
73<BR>> <BR>> Peter G3RZP<BR>> <BR>> </FONT></BODY></HTML>
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