FW: [Elecraft] Inoperable S-Meter - Now works and new question about alignment

[Don Wilhelm]

This bounced the first time for me because of the extra spaces in the
subject made it look like spam.
I thought this may be of general interest, so I am re-sending it, see below.
73, Don W3FPR


> Rich,
>
> Your S-meter settings of 191 and 009 are a bit more broad than I
> usually experience, but the AGC Threshold setting has a lot to do
> with the final settings too - the 3 settings do interact a bit.
> I usually end up with 185 to 189 for the low setting and 16 to 19
> for the high - but that is after optimizing the AGC Threshold
> voltage to produce no noticable change when switching from AGC ON
> to AGC OFF with no antenna connected (I usually end up with an
> AGC Threshold voltage between 3.65 and 3.75 volts).  I also
> strive to place a 50 uV signal on 40 meters (with preamp off) at
> S-9 on the S-meter, so that is a bit more 'fussing' with the AGC
> Threshold and CAL S LO and CAL S HI.
>
> On your transmit vs. receive bandpass filter alignment question -
> yes the transmit alignment is the 'fine tuning' for the initial
> receive alignment.  It is just easier to observe the peak in
> transmit than it is to hear a slight change in signal strength in recieve.
>
> Even though the bandpass settings appear to be 'touchy', that is
> not an indication of the stability of adjustment - no need for
> any 'fixatives', the settings will not change even with
> substantial vibration.  In fact on K2s that have not had the
> trinmmers and inductors changed in some time, there is a bit of
> initial resistance when the settings are initially moved during a
> realignment - testimony to the fact that the adjustments will
> indeed 'stay put'.
>
> If you want to check the locations that should have 68 pf caps, I
> suggest you download the .pdf copy of the manual - the FIND
> function in Adobe Reader will find all occurrances of '68'
> easily, so you can check each one individually.  The parts list
> also shows the proper locations for each capacitor value - on the
> RF Board, C221 should be a 39 pF cap and you should have a 68 pF
> cap in C88, C153, C104 and C214 locations.
>
> 73,
> Don W3FPR
>
> > -----Original Message-----
> >
> > No Ron, the meter is pegged all the time.   Well, maybe I need to
> > recalibrate the S-Meter alignment after readjusting the AGC threshold.
> >
> > Duh, that's just what the instructions on page 47 say.  Now I get
> > an S-meter
> > working! Don't tell me there's nothing wrong with it!  I went
> nuts poking
> > around with my scope trying to figure out what was wrong with the
> > mixer.  At
> > first I thought it was the crystal because I didn't see it
> > oscillating, but
> > the I was expecting a 5v signal instead of the whimpy signal this
> > thing puts
> > out; too much time looking at digital circuits.  Well, I guess I always
> > wanted to see how this circuit worked.  Maybe it was a weak
> battery in my
> > voltmeter all along.  I get 191 for the low value and 009 for the high
> > value.  Sound about right?  I'll have to double check the other
> > calibration
> > values to see if something else is high.
> >
> > How can I tell if my AGC is working right?  I think I'm all set
> > but I'd like
> > to double check this before I button things up.
> >
> > When I was finished construction, I was short a 39pf cap and had
> > a 68pf cap
> > left over.  One would thing there's probably a 39pf cap installed
> > somewhere
> > that a 68pf cap belongs, but no such luck.  This is pretty amazing since
> > there must be several thousand parts to kit.  Anyone know how
> > many?  I don't
> > know who Chistine is, but she's not human.  Nobody can possibly be that
> > accurate.  I've got four 10pf caps in there where the 39pf cap belongs.
> > That's the best I could come up with from my parts bin.  Still has me
> > thinking it's my fault, but I can't find the cap.  I suppose
> 68pf and 39pf
> > are probably close enough for most stuff so I guess there's no
> harm.  The
> > righ certainly performs well enough.  Earlier this evening, I
> figured I'd
> > compare the performance of my shiny new K2 next to my TS-2000.  I
> > dialed in
> > WWV just to see how I receive.  The TS-2000 had trouble tuning in WWV
> > because the signal was weak.  This rig just came back from Kenwood for
> > service yesterday.  They repaired and realigned the rig. No matter what
> > settings I chose, I could barely copy.  Propagation being what it
> > is lately,
> > this doesn't surprise me.  The K2 on the other hand pulled the
> station in
> > clear without the pre-amp.  Even my wife was impressed. I expected some
> > marginal difference based on what I've heard and read, but this
> > is night and
> > day!  I didn't build this thing because I need a new rig.  I
> > think this will
> > become my favorite however.
> >
> > One last thing.  I followed the alignment directions carefully.
> > I had poor
> > success aligning the receiver, so I skipped over and aligned the
> > transmitter.  If I understand this, that's all I need to do.  If
> > you do the
> > transmitter, the receiver gets aligned too because they share the same
> > filters.  I found the alignment to be very sensitive.  A slight
> > movement of
> > the adjustments would drop the power output level.  This has me
> > wondering if
> > I should put some kind of wax or something on the adjustments
> to keep them
> > from moving.  Anyone out there have thoughts or suggestions?
> >
> >
> > Thanks for all the help guys.
> >