[Amps] High C out

[Dennis12Amplify at aol.com]

Will,
 
 I believe Chris is talking about converting from a PI network to  a Pi-L 
network. The Pi-L having two levels of impedance matching, and a little  more 
harmonic suppression, than the original Pi network.
 Thus the original Tune C becomes the middle capacitor of the Pi-L,  allowing 
for a larger value of C, and the plate C is now the new Tune C.
 Also, If his tune cap is already backed all the way out, he needs  LESS 
inductance in the tank to tune it, not more... Therefore he would be  SPREADING 
the coil turns apart, or removing a turn, or moving the tap towards  less turns, 
any of which would result in less inductance in the tank  circuit....
 
Regards,
 
Dennis O.
 
 
 
 
In a message dated 1/21/05 11:49:21 AM Central Standard Time,  
craxd1 at ezwv.com writes:

A 300 nH  coil (0.3 uH) is not very much. Assuming this would be the tank   
coil, the 10 meter end being the largest in size, one might just  squeeze  
the coils together to raise the inductance enough to bring  it in tune. If  
not, adding 1 to 2 turns of the same size wire, and  same diameter would  
most likely do it. A dip meter would be easier  to use to find the exact  
placing of the tap on the coil if it has  taps. According to the way the  
tube is ran and tube type, some at a  higher frequencies dont need a tune C  
in order to tune correctly  because the tubes output C is high enough and  
takes care of it. In  the amps I've seen this way, a load C was all that  
was  used.

Will


On Fri, 21 Jan 2005 09:00:56 -0800, Chris  <rfcrazy at cox.net> wrote:

> Can anyone tell me what size wire  and dimensions to use for a 300 nH
> coil? I don't have an inductance  calculator.  I am having a problem with
> a 3cpx5000 that has high  C Out.  The tune vacuum cap is a backed all the
> way out in order  to tune. I read on web site that you can use a 300 nH
> coil from anode  to C1 to rectify this.
> Thanks for the help,
>  Chris