[Amps] Building or Buying a Tuned Input Network

[Paul Hewitt]

Hi Bob
The reason I don't supply caps or wire for the kit is simple, money!!  The
number of mica caps I would have to keep in stock would run me into the
thousands.  Every time you move the board farther from the cathode, change
tube choice, change blocking cap, or change tube socket wiring/layout, the
values change.  The silver mica caps are getting expensive and for me to
hit/guess YOUR needs exactly the first try would be very difficult and
costly.  As for wire, there aren't to many builders on this list that don't
have some sort of stash of magnet wire.  Most of us (cheap) hams would
rather supply/measure there own wire than pay me to do it.
73, Paul

PAUL HEWITT
WD7S PRODUCTIONS
QRO HOMEBREW COMPONENTS
http://home.earthlink.net/~wd7s



----- Original Message -----
From: "Bob Selbrede, K6ZZ" <k6zz at ccis.com>
To: <amps at contesting.com>
Sent: Sunday, January 22, 2006 8:45 PM
Subject: Re: [Amps] Building or Buying a Tuned Input Network


> Thank you Tony (and others) for the pointer to WD7S's web
> page.  That's the kind of web site I was hoping to find!
> I'm interested in doing a power supply filter cap upgrade,
> soft start mod and grid protection mod and he appears to
> have all that covered.
>
> While the tuned input board looks nice, I'm puzzled as to
> why he doesn't supply it with the mica caps and inductor
> wire if the application is known at the time of order.
> Without variable inductors, how would you go about tuning
> the system in-circuit?  I guess you would need to tune it
> out of the amp by simulating the tube drive impedance and
> play around with various combinations of L and C until you
> get a match; install it, and hope for the best?  Time for a
> call to WD7S.
>
> Thanks, Bob
>
> ----- Original Message Follows -----
> From: Bill Turner <dezrat1242 at ispwest.com>
> To: Tony King - W4ZT <amps080605 at w4zt.com>,
> amps at contesting.com
> Subject: Re: [Amps] Building or Buying a Tuned Input Network
> Date: Sun, 22 Jan 2006 20:14:34 -0800
>
> > ORIGINAL MESSAGE:
> >
> > At 07:14 PM 1/22/2006, Tony King - W4ZT wrote:
> >
> > >Take a look at Paul's (WD7S) tuned input board:
> > ><http://home.earthlink.net/%7Ewd7s/TU-6B.htm>
> > >
> > >73, Tony W4ZT
> >
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > I considered that board but decided against it because
> > nothing is  adjustable except by soldering and unsoldering
> > capacitors, or by  adding/removing turns from the toroids.
> >
> > Tony, have you used this board? What are the instructions
> > regarding  tuning? Does it have a chart of suggested
> > values for the silver mica  caps? How close did it come to
> > reality?
> >
> > Bill, W6WRT
> > _______________________________________________
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