Don B. Thanks for that information - it adds credibility to that method along with a good dose of common sense.
Don W. W3FPR > -----Original Message----- > > Hi Don and All > > I have used this method on 3 or 4 of the K2's I have built. I use > a 1pF or > 2pF NPO cap to lower the bottom end of the range to get it to > meet the spec. > I agree with you on pulling the crystal much with this method. I > would not > recommend cap values above maybe 3 or 4 pF. I have never needed > more than 1 > pf. Padding C173 and C174 is a better method if the radio needs > more than 1 > or 2 pf. I believe this method was suggested by Gary at Elecraft > some time > back. At any rate it is a little easier to do than the padding or > change out > of C174 and C173 > > > The other Don > > Don Brown > KD5NDB > > > > ----- Original Message ----- > From: "Don Wilhelm" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[email protected]> > Sent: Thursday, December 08, 2005 5:03 PM > Subject: RE: RE: [Elecraft] K2 BFO Test > > > > Sverre, > > > > I have not tried that small capacitor from the junction of the crystals > > and > > L33 so I cannot comment on it from that standpoint. > > > > What I would like to state is that when one pulls a crystal by > any method, > > the stability becomes worse as the amount of pulling becomes > greater. One > > should be aware of this and related facts when modifying any > circuit in a > > way that is not 'approved and tested'. Also due to the nature of > > crystals, > > something that happens to work in one situation may not work > the same for > > all cases. Remember that I am only bringing up cautions here, I am not > > makeing a firm statement about the operation one way or another. > > > > It certainly would be nice if someone (or better yet, several someones) > > with > > access to suitable instrumentation could try this or any other mod and > > report the results. The fact that it worked on a sample of one does not > > create a statement that it will work in other cases - that is simple > > statistical knowledge - I would like to see something that says > it works > > in > > at least 5 or 10 trials before drawing any firm conclusions. > > > > So, yes I think it should be left on your website, but you may > want to put > > a > > "Use at your own peril" disclaimer on all those that are not > 'approved by > > Elecraft' or otherwise adequately tested (and I invite you to > add any of > > my > > mods to that group as well, even though I have absolute > confidence in my > > own > > work). > > > > 73, > > Don W3FPR > > > > > -----Original Message----- > > > > > > > > The preferred method of padding the BFO capacitors is to > > > > maintain the ratio between C173 and C174 by paralleling them > > > > with capacitors. A single capacitor from the junction to > > > > ground will be in parallel with the series combination of > > > > C173 and the varactor D38 and could make the BFO less stable > > > > than it should be. > > > > > > > > > > Don, > > > > > > How about a single capacitor (1-4 pF) from the junction of the > > > crystals and > > > the L33 inductor as in > > > http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html? > > Does that create potential stability problems also? > > > > I've got this link on my K2 mods page and just wanted to make sure I can > > recommend it and keep it there. I have never had any problems > > with BFO range > > myself so I have no personal experience with this myself. > > > > 73 > > > > Sverre > > LA3ZA > > http://www.qslnet.de/la3za/ > > > > _______________________________________________ > 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 > -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.13.13/197 - Release Date: 12/9/2005 _______________________________________________ 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
