++++++++++++++++++ Date: Sat, 20 Oct 2001 20:30:54 -0700 From: "Jerry T Dowell" Subject: [Elecraft] Tone burst: not the K2! Hi agn, The "tone burst" I was hearing every 20 sec apparently is not a K2 problem. Doug, W6JD, called me up and told me that he was also observing it with his K2, but that he was also hearing it on his other rig. He lives a few miles from me. I had checked with my two Drake receivers, a TR-7 and an R-7 , and had not heard it on any band with them. After Doug called me, I checked again, and discovered that I had the noise blankers on for both the TR-7 and R-7, but not on the K2. With the noise blankers off, the signal was strong on both the Drake receivers. Interestingly, with the K2, the signal was strong on all noise blanker positions: OFF, NB1 and NB2. The noise blankers in the TR-7 and R-7 are both in general far superior to those I have tried in Yaesu and Kenwood gear. The K2 blanker is VERY effective on all noise I have checked it on, excepting the mysterious "tone burst". It also appears to affect the dynamic range much less than the Drake blankers. It will be interesting to investigate the time signature of this signal and to assess the reason for the differing performances. In the meantime, it looks like we have a problem in this area. We have a lot of suspects to choose from since the area is electromagnetically highly populated: The Stanford Linear Accelerator, the Stanford RadioPhysics setup on the hill overlooking our QTHs, a jillion radar setups, yuppie modems, computers and burglar alarms, and last but not least, the cheap COSTCO "atomic clock" with UHF link external temperature sensing! Something to keep busy hands and minds occupied while waiting for the KPA-100 !! 73 de Jerry AI6L K2 #1113 +++++++++++++++++++ Date: Sun, 21 Oct 2001 16:29:30 -0700 From: "Douglas Westover" Subject: [Elecraft] Mystery "pulses" I promise I won't take up any more reflector bandwidth on this, but enough people have contacted me privtely about this that mailing to the list may make sense. With a little more detective work I've determined that what this is, is in fact a swept frequency signal which starts at 2 MHz and stops at 20 MHz so just listening at a fixed frequency makes it sound like a pulse. You can easily verify that it's sweeping by listening on two receivers separated in frequency. Or using 1 receiver, changing frequency, and noting the difference in ABSOLUTE seconds that the signal occurs at each frequency. My conclusion is that this is a swept frequency ionospheric sounder (like a C-3) running at a roughly 1 MHz/sec sweep rate. There have been a variety of such sounders operated at the Stanford field sites over the years. I'll see if I can find out who's running this one and how long they plan to run it. Unfortunately these sounders are perfectly legal as far as the FCC is concerned. More if I find out anything else. 73, Doug W6JD +++++++++++++++++++++ Date: Mon, 22 Oct 2001 15:15:42 -0700 From: "Douglas Westover" Subject: [Elecraft] You're Welcome The "mystery pulses" are now QRT, at least you won't be hearing them every 20 seconds. Don't ask don't tell. 73, Doug W6JD ++++++++++++++++++