[Elecraft] Wayback machine K2 SSB filter roll-off mod question

[Don Wilhelm]

Doug,

This is one of the problems with using info from the wayback machine.
That was one initial 'cure' that worked only marginally.
Elecraft released a mod kit that works well.  Put the parts from the kit 
in, and yes, C180 is to be removed in the process.
Go back to setting L34 for best S/N ratio as instructed in the K2 manual 
(even the old ones).

73,
Don W3FPR

On 9/21/2020 10:40 AM, Douglas Hagerman via Elecraft wrote:
> I am trying to install the mod described in "Application Note Eliminating the Frequency Roll-off of the K2 SSB Filter.” Instructions are from March 2001, kit is new. Radio serial number 875 with SSB and 160 meters and antenna tuner and digital I/O options.
> 
> The capacitor that is to be removed as part of the mod, C180, was already removed when I got the radio. Solder indicates it was in there originally. But the additional parts (transistor, caps, resistor) of the modification are not installed. I don’t see anything unusual on the SSB board, and I don’t see anything that looks like an FCO in other places on the RF board.
> 
> The application note says that one way (less desirable) to accomplish the filter change is to just screw out L34 a long way, but it doesn’t say anything about taking out C180.
> 
> I’m wondering if there was another version of the mod, maybe that came out before the 2001 version of the upgrade kit, where you took out C180 and then adjusted inductor L34. It does appear to be screwed pretty far out.
>