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

[Don Wilhelm-3]

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.
> >

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[Don Brown-4]

Hi

These S-meter settings sound like the readings when T7 is reversed. I have
seen this several times and it makes the AGC and S-meter flaky as well as
the sensitivity low. However you can make the radio appear to work although
it just seems not quite right. The red wire winding should be closest to the
IC U12 and the green winding should be closest to the jumper W3. Looking at
another way the red winding should be in pads marked 3 and 4 and the green
in 1 and 2. This may not be your problem but it is worth a look.

Don Brown

KD5NDB


----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Elecraft reflector" <[hidden email]>
Sent: Saturday, February 18, 2006 10:15 PM
Subject: FW: [Elecraft] Inoperable S-Meter - Now works and new question
aboutalignment

>
>
> > 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.
> >

SNIP

> > Don W3FPR
> >
> > > -----Original Message-----
> > >
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