[Elecraft] K3 250Hz Filter gain maxed yet low

[Don Wilhelm]

Jim,

Your problem may be that you are centering the filters.  There was a 
post by Lyle Johnson a while back which explained that the filters are 
not operated at their center, but are used closer to the slope than 
center to take advantage of the better rejection provided.
I don't recall the exact circumstances, so you might want to look for 
that post in the archives.

73,
Don W3FPR

Jim Miller wrote:
> I spent a few minutes today checking the filter gain balance on K3
> 1210. I fed in a 1uv signal from my XG2 and qualitatively measured the
> audio out when switching (XFIL) between filters. I started by finding
> the XG2 signal and zero beating it using the CWT/SPOT features and
> then switched between filters.
>
> I have an 8 pole set as follows: FL2-2.8, FL3-1K, FL4-400, FL5-250.
>
> I have gains as follows: FL2-0db, FL3-0db, FL4-3db, FL5-8db.
>
> The audio is good with these settings except for FL5 which even though
> maxed out has a very noticeably lower output. By fiddling with the FL4
> setting and doing comparisons it appears that FL5 could use another
> 3db to bring the output up to equal that of the other filters.
>
> Just to make sure I was in the center of the 250hz filter I tuned
> around with the FINE setting and moving around made no improvements in
> the output only the expected decrease as I moved outside the filter
> BW.
>
> Is there any remedy for this?
>
> Should I send my 250hz/8pole back for replacement?
>
> tia
>
> jim ab3cv
>   
>