[Elecraft] Re: 5.068 MHz signal (was: general coverage)

[Wayne Burdick]

Sverre,

The signal from the 5.068 MHz crystal is barely audible on my K2
modified to cover 60 meters. It's also well below the proposed 60-m band
edge (5.25 MHz). 

The 153 kHz "auxilliary" I.F. is not in the normal receive path, by the
way. It is only used for obtaining a clean, fast AGC response. The 153
kHz signal is amplified by CTRL-U1 and U2 to drive the AGC detector.
Because the frequency is so low, these gain stages need no shielding and
also do not introduce BFO leakage back into the I.F. strip. Such leakage
and the need for shielding are characteristic of receivers that attempt
to amplify the I.F. directly for AGC detector drive purposes. If the
shielding is left out in such a design, AF envelope modulation of the
AGC signal may result, compromising AGC performance.

73,
Wayne

Sverre Holm - LA3ZA wrote:
> 
> But, even today, how do you deal with the 5 MHz band and the 5.068 MHz
> crystal for the 153 kHz AGC IF, replace it with one on the other side of
> 4.915, i.e. 4.762? Just asking out of curiosity!
> 
> 73 Sverre LA3ZA
> www.qsl.net/la3za
> 
> > -----Original Message-----

> > > Let's just hope they don't move the proposed band to include 4.915
> > > MHz. The K2 will never be able to cover that frequency effectively
> > > (well, not without a modification far more extensive than planned),
> > > because it would be right on top of the IF.
> >
> > I'd like to believe that whoever dreamed up the proposed band
> > edge had the K2 in mind ;)
> >

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