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I seem to remember the famous Ulrich Rohde publishing a small note in =
?Ham Radio using pad and compensating reactances to tame gg input with =
no switching bands.
Anybody got a lead on this?
73
end
Barry Kirkwood PhD ZL1DD
Signal Hill Homestay
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----=20
From: KG6DV@cs.com=20
To: amps@contesting.com=20
Sent: Tuesday, 09 October, 2001 11:49 AM
Subject: [AMPS] Tuned Input, what me worry
There is a lot of discussion lately on how to design a proper tuned =
input .... that topic and beer have dominated lately. 16 ways to figure =
the Q of the input circuit, 17 ways to tell a really fine beer. I can =
understand the value of passing on your knowledge of how to judge a =
really good beer, but a tuned input ....why bother.=20
I built way too many tuned input circuits till I gave it up ... too =
much work. I ended up borrowing an approach from the old timers (you =
here know who you are) remember swamping. A variation on the old method =
works for me. I use a T-PAD attenuator.=20
The great thing about a T-PAD attenuator is the fact that the load on =
the output side can swing a great deal while the input will stay put =
wonderfully. Does this sound like whats needed for an input circuit, it =
does to me. These transmitting tubes display a fairly large swing in =
load at different drive levels, not what your exciter needs to see.=20
I design the T-PAD for 1db attenuation, nobody needs to loose a lot of =
drive power.=20
I size the resistors (non inductive of course) in each of the three =
legs to handle the dissipation and ..... wallah, you have an input =
circuit that will show your exciter a nice consistent 50 ohm load. What =
could be simpler. Its worked for me for years.=20
Now we will all hear whats wrong with this approach .... or maybe just =
some more great beer theory. =20
Ron KH6DV=20
Kaneohe Hawaii=20
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<DIV><FONT size=3D2>I seem to remember the famous Ulrich Rohde =
publishing a small=20
note in ?Ham Radio using pad and compensating reactances to tame gg =
input with=20
no switching bands.</FONT></DIV>
<DIV><FONT size=3D2>Anybody got a lead on this?</FONT></DIV>
<DIV><FONT size=3D2>73</FONT></DIV>
<DIV>end<BR>Barry Kirkwood PhD ZL1DD<BR>Signal Hill Homestay<BR>66 Cory=20
Road<BR>Palm Beach<BR>Waiheke Island 1240<BR>NEW ZEALAND<BR><A=20
href=3D"http://www.waiheke.co.nz/signal.htm";>www.waiheke.co.nz/signal.htm=
</A></DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<A title=3DKG6DV@cs.com href=3D"mailto:KG6DV@cs.com";>KG6DV@cs.com</A> =
</DIV>
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Damps@contesting.com=20
href=3D"mailto:amps@contesting.com";>amps@contesting.com</A> </DIV>
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Tuesday, 09 October, 2001 =
11:49=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [AMPS] Tuned Input, =
what me=20
worry</DIV>
<DIV><BR></DIV><FONT face=3Darial,helvetica><FONT size=3D2>There is a =
lot of=20
discussion lately on how to design a proper tuned input .... that =
topic and=20
beer have dominated lately. 16 ways to figure the Q of the input =
circuit, 17 ways to tell a really fine beer. I can understand =
the value=20
of passing on your knowledge of how to judge a really good beer, but a =
tuned=20
input ....why bother. <BR><BR>I built way too many tuned input =
circuits till I=20
gave it up ... too much work. I ended up borrowing an approach =
from the=20
old timers (you here know who you are) remember swamping. A =
variation on=20
the old method works for me. I use a T-PAD attenuator. <BR>The =
great=20
thing about a T-PAD attenuator is the fact that the load on the output =
side=20
can swing a great deal while the input will stay put wonderfully. Does =
this=20
sound like whats needed for an input circuit, it does to me. =
These=20
transmitting tubes display a fairly large swing in load at different =
drive=20
levels, not what your exciter needs to see. <BR>I design the T-PAD for =
1db=20
attenuation, nobody needs to loose a lot of drive power. <BR>I size =
the=20
resistors (non inductive of course) in each of the three legs to =
handle the=20
dissipation and ..... wallah, you have an input circuit that will show =
your=20
exciter a nice consistent 50 ohm load. What could be simpler. =
Its worked=20
for me for years. <BR><BR>Now we will all hear whats wrong with this =
approach=20
.... or maybe just some more great beer theory. <BR><BR>Ron=20
KH6DV <BR>Kaneohe Hawaii=20
<BR></BLOCKQUOTE></FONT></FONT></BODY></HTML>
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