[Amps] placement of RF choke bypass cap.

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Mon, 22 Mar 2010 14:54:33 -0400, "David J Windisch"
<davidjw at cinci.rr.com> wrote:

>
>Replacing the choke with p/n RFC-3 from rfparts.com, and putting the bypass right at the cold end, made several differences in circuit operation.  The tank setting for max-power-out, Ip-min, and Ig-max on 15M and up coincide, and there is more power out on 12M.  My guess is that the choke and resistor were dissipating significant r-f power.

REPLY:

Glad you got it working, David. 

I have used that RFC-3 choke in five different homebrew amps so far
and I am quite impressed with it. Designing a choke that will cover
all ham bands from 1.8 to 30 MHz  including WARC with no resonances is
not easy, as even the commercial amp makers have found out. 

A word of caution to anyone who might try to copy the RFC-3:  Be sure
you get the same wire diameter, the same type of insulation and the
same insulation thickness. Change any one or more of those and you
have a different choke. 

The usual disclaimers apply - no connection to RF Parts except as a
satisfied customer. 

73, Bill W6WRT