[AMPS] tuned inputs

[2]

>
>
>From: "Jim Thomson" <Jim.Thomson@telus.com>
>Subject: RE: [AMPS] Input circuit
>Date: Fri, 6 Jul 2001 11:59:22 -0600
>
>
>
>
>#####   Rick,   pse  forward  this  on  to whoever.
>
>
>****   For  a  PI-net,   use  the   excellent  spreadsheet  on  G3SEK's
>website,  or  the  spreadsheet  on   Rich Measures (AG6K)   website.   Both
>these  fellows  post  regularly  on  'amps'   at    contesting.com.
>
>
>****  Use  a ckt  Q  of   3-3.5  (This  equates  to  a  individual  Q  of  2
>for  the  C1  cap.  IE: 100ohms/Q-2   =XC of   50 ohms   on  ALL  bands.
>C1  cap  will  have  50  ohms  of Xc  on  all  bands

/\   Most radios havee an output z of 50-ohms.  Thus, for a c. Q of 2, 
Xc1 =50/2 = 25-ohms.  In practice, this will give a Q of a bit over 2.
>
>**** If  Q  is  too  low, solid  state  rigs   will  not  like  it.
>Complete  info  on  AG6K's  website.
>
>***   There  is  no  commercial  source of  a  ready  made  tuned  input.
>If  you  are  planning  to  use   separate  tuned  inputs   for  each  band,
>most  fellows  use  small  torroids   for  the   coil,   and  ARCO
>compression  trimmers   for  the  C1  +   C2   caps.    The  input  Z  of  a
>4-1000  is   aprx   100  ohms.   The  coils  can  be  tweaked  by
>compressing  or  spreading  the  turns  on  each  torroid.  or   tuned
>slugs  can  be  used.
>
>***  avoid  using  fixed  caps,   unless  you  test  with  air  variables
>1st,  then  measure  the  value  of  the  variables,  and  then  substitute
>fixed   silver  mica's.   On   160,  and  maybe   80M,   most  fellows  pad
>the  arco's   with  silver  micas. 
>
>****  To  test  ur tuned  inputs put  a   100  ohm 1/4w   carbon
>composition  resistor  across  the  output  of  the  pi-net  in   question,
>and   put  a  MFJ-259/B  on  the  input.   Simply  tweak  both  caps   for
>flat  swr  on  mfj.   repeat  for  all  other  tuned  inputs. 
>
>
>****  Another  method  is  to  use two  broadcast  variables  and  a  tapped
>coil.   I  use  this  method  on  my   3000A7  tube.   It's  also  been
>used  on   2  x  4-1000  amps.
>
>****  You  can  see  pix  of  all  this  on  Larry  Molitor's   (W7IUV)
>homebrew  amp  pix  page. 
>
>***  still  another  method  that  is  used  with   4-1000's  is just  one
>cap  and  one   coil  in  parallel,   bottom   end  to  chassis,  and  top
>end  facing   cathode/exciter.  W6RU  uses  this  method  often.   Pix  of
>his   amps   are  also  on  Molitor's   website.  Everytime  some  new  pix
>shows  up,  it's  posted  on  'amps'.
>
>Cul......Jim    VE7RF   (ex-VE7RQ)  
>
>
>
>
>
>-----Original Message-----
>From: rick rosner [mailto:rar@uniserve.com]
>Sent: Friday, July 06, 2001 10:23
>To: jim.thomson@telus.com
>Subject: Fw: [AMPS] Input circuit
>
>
>
>----- Original Message ----- 
>From: "Peter" <pb0aiu@pi4cc.nl>
>To: <amps@contesting.com>
>Sent: Friday, July 06, 2001 3:16 AM
>Subject: [AMPS] Input circuit
>
>
>> 
>> Hello world,
>> 
>> Is there any source for a input circuit for a 4-1000 @ the hf bands? A
>> layout of a print circuit with components is also welcome.
>> 
>> Peter
>> 
>> Internet DX-cluster telnet://213.10.48.91
>> DX-cluster info http://www.pi4cc.nl/dxcluster
>> 
>> 
>> 
>> --
>> FAQ on WWW:               http://www.contesting.com/FAQ/amps
>> Submissions:              amps@contesting.com
>> Administrative requests:  amps-REQUEST@contesting.com
>> Problems:                 owner-amps@contesting.com
>> 
>
>


-  R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.  
end


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