No. The Tesla Coil produces exactly the sort of QRN that the noise blanker is NOT designed to suppress. It is as close to the random racket we call "band QRN" as you can get: the effect of millions of discharges of varying intensity and duration all overlapping in time.
The noise blanker is designed to suppress repetitive high-amplitude pulses such as you get from a *controlled* spark gap, like an automobile ignition, or a controlled impulse generator like a cheap lamp dimmer. These impulses are especially annoying because they have very, very high amplitude coupled with very short duration, so the average level is quite low, comparatively. Your "S" meter may say the noise is S7 or S9, but the actual peaks are far, far stronger than your S-meter is reporting. The KNB2 is excellent for suppressing them by anticipating the pulse and actually shutting off the signal path for an instant while it passes. If it tried to do that with the sort of QRN you get from the Tesla Coil it'd simply turn the receiver off completely <G>. As an aside, it is fortunate for me that the sort of noise produced by a Tesla Coil is indistinguishable from common QRN. Many years ago I fired up my prototype 8-foot tall Tesla Coil, excited by a spark gap wired to the A-C mains, and wiped out "I Love Lucy" on TV's for blocks around. My neighbors knew all about the "Ham Kid" in area but they didn't equate a TV screen filled with "snow" with the sort of thing they were used to seeing from my QTH, nor did I feel compelled to enlighten them. Ron AC7AC -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Skinner Sent: Friday, February 17, 2006 1:48 PM To: 'Elecraft' Subject: [Elecraft] Inoperable KNB2 Hello Group, Well, you can add me to the list of folks who think their noise blanker is not working. Now I don't have a lot of noise problems, but do hear the occasional light dimmer or neighborhood power tool. I have tried the scratch test, but results were inconclusive. Today I brought home a 75,000 volt Tesla coil and lit it off across the room. As expected, the noise level jumped from S1 to a bit over S9. The noise blanker has absolutely no noticeable effect in any position. I have re-inspected the placement of every component and confirmed every solder joint. The preps on the RF board were done correctly. I checked the two diodes and they appear to be neither open nor shorted. The Tesla coil is probably overkill, but if the noise blanker is working shouldn't it have SOME effect? I really don't know what to check next - any suggestions? TIA es 72/73, Tom, KJ3D K2 # 4991 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
