In this case, the cable was made from twisted shielded pairs. This was after one of the discussions on the K2 cables on this reflector. The cable I built also did not have the dogleg, just rig to K2.
I, too, had problems on 160 at one point in time... The base of my vertical, and max current, is still about 30 feet from the operating position. A new cable and better antenna interface cleared those problems up. Not sure if that would hold true if I ran an amp, sometimes LP/QRP is a real blessing. As I recall, I tied the drains together, but left them floating (no connection to pin 5 or the connector shell). I am sorry I didn't pick up a couple reels of CAT5 cable that were being auctioned at the lab, went really cheap. That was before I knew the benefit of the stuff in control applications. Oh well, live and learn. Pleased to say no RFI issues in the shack, even though it is on the second floor. Your documents have helped. 73, Julius Jim Brown-10 wrote: > > On Tue, 30 Jun 2009 11:15:50 -0700 (PDT), Julius Fazekas n2wn wrote: > >>My first attempts were OK, but laced with problems. Often I had to drop from >>5 watts to 2 to keep my logging computer from locking up in a key down > > The fundamental cause of this problem is the improperly designed serial > cable > for the K2. It uses parallel wires, and is shielded. A proper cable > designed > for RF immunity requires TWISTED PAIRS. > > I ran into exactly the same problem you did in Chicago, when my antenna > for > 80M and 160M was a long wire that ended in the shack and was fed against a > counterpoise. That put a current maxima in the station, right next to the > computer, and the associated magnetic field coupled into the serial cable > and > locked up the computer (in my case, at about 8 watts). > > The fix was quite simple. I replaced the parallel wire cable between the > K2 > and the computer with CAT5, using one pair for each signal circuit. I also > terminated the return of each pair to the SHELL of the DB9 rather than pin > 5, > fixing a pin 1 problem that also couples RFI. With that simple fix, I > could > run my K2 to my Ten Tec Titan at full power with no RFI. > > The wiring of a conventional serial cable is documented in > > http://audiosystemsgroup.com/HamInterfacing.pdf > > Note that the K2 serial cable is NOT a standard serial cable, so the > wiring in > the applications note applies only the wiring between the K2 and the > computer. > No change is required for the wiring between the K2 and KPA100. > > Note also that a cable shield provides NO magnetic shielding, only > ELECTRIC > shielding. Twisting is required to prevent magnetic coupling, and also > greatly > reduces electric field coupling. Nearly all coupling in the near field of > an > antenna is magnetic, except at higher HF frequencies. It would only be > necessary to shield this cable if you are using high power above 15MHz > with an > antenna that is within a few feet of the rig. > > 73, > > Jim Brown K9YC > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ----- Julius Fazekas N2WN Tennessee Contest Group http://www.k4ro.net/tcg/index.html Tennessee QSO Party http://www.tnqp.org/ Elecraft K2/100 #4455 Elecraft K3/100 #366 Elecraft K3 #1875 -- View this message in context: http://n2.nabble.com/RF-issues-with-logging-computer---internal-keyer-tp3184294p3190438.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
