[Elecraft] RE: K1 - Mystery of missing C78

[Morrow, Michael A.]

Tony wrote:

> In the K1 Rev. F manual, C78 is said to be an electrolytic
> supplied with the 80 metre filter module.
> 
> However I could not find the electrolytic for this in the
> 80 module pack, and the manual for the 2-band filter is
> silent on C78.

Then I wrote:

> There was no C78 in my 80m filter board component pack
> (received 07/02) either.  The K1 Upgrade application 
> note also fails to mention installation of C78 in older K1s.

I'm sure Gary Surrency won't mind my sharing with the list the info that he
promptly sent to me:

> All 80m kits for the KFL1-2 board SHOULD come with a 10uF 
> 16VDC to 25VDC electrolytic cap. If you have such a cap,
> or even a tantalum cap (better), then install it if you
> operate on 80m. 
>
> The cap just insures stable operation of the Driver on 80m, 
> particularly when the KAT1 operates.
>
> On older K1's, the cap goes across the 12V feed to Q6 and
> ground. You can find this on the bottom of the PCB, just to
> the left of the mounting screw for Q6.
>
> On later K1's with rev. E RF PCBs, there are pads for C78.

This enhancement is easy to miss, since it does *NOT* appear in the K1 rev.
D to rev. E RF-PCB upgrade instructions at
http://www.elecraft.com/Apps/K1%20upgrade%20instructions_3f.pdf .

73,
Mike / KK5F