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. > > _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
