tag:blogger.com,1999:blog-1592992209402300549.post3368366640616560219..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: Heh Heh HehSiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-1592992209402300549.post-90972989223356197432023-06-18T18:46:35.335-04:002023-06-18T18:46:35.335-04:004 plus decades ago I worked in a Florida power pla...4 plus decades ago I worked in a Florida power plant that was built in 1927, and being torn down and repowered from steam only into a combined cycle mode with large gas turbines. The old (abandoned) generator metering and relay house was from that era was abandoned but still standing and was pure Frankenstein era. Oh how I wish I could have rescued the switchboard instruments and knife switches and copper buswork. All was bulldozed. However I managed to grab many wood cased test instruments of the era, meters and such. Remarkably they remain as accurate as a modern Simpson 260, even today. Fladavenoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-75131865208509083922018-01-16T20:10:03.499-05:002018-01-16T20:10:03.499-05:00Ah-h ... first-pass success. Sounds like fun. And ...Ah-h ... first-pass success. Sounds like fun. And I bet you didn't need to first run it through a Design Review Committee and get permission from Procurement.<br /><br />QAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-86317844565810431382018-01-16T18:45:56.781-05:002018-01-16T18:45:56.781-05:00Oh....duh! For some reason I had it stuck in the b...Oh....duh! For some reason I had it stuck in the brain this was some kind of small, low-noise 160M antenna.<br /><br />When I lived in my apartment and had the run of the nice, flat roof, I experimented with various loops and random wires, all fed by my SGC. Got some pretty good results with a bottom apex fed "squished delta loop" that was about 70' across the top, which was about 25' above the roof of a two-story commercial building. drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-68212104743248506462018-01-16T17:58:03.503-05:002018-01-16T17:58:03.503-05:00It’s not really electrically short. My loop is 22...It’s not really electrically short. My loop is 22’ around, which is just a little short of a quarter wave on 10.1. Gary’s original design was between 1/8 and 1/4 wave on 1.8 MHz; I scaled that to 7 MHz. 1/4 wave on 40m is 33’, so I’m between 1/8 and 1/4, just like Gary’s. Heck, my vertical is close to 1/8 wave on 80 (physically) and it works better. SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-4568995978139616772018-01-16T16:00:43.597-05:002018-01-16T16:00:43.597-05:00This is a "compact" antenna, right?
In ...This is a "compact" antenna, right?<br /><br />In all my years of playing with antennas, "compact" antennas have never worked as well as full-size ones. They can can get damn close, but due to the laws of Physics, they'll always be a bit behind...drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-81326579081368325752018-01-16T15:58:49.848-05:002018-01-16T15:58:49.848-05:001" thick slate back panels with BIG knife swi...1" thick slate back panels with BIG knife switches, BIG meters, and BIG knobs to turn.<br /><br />Oh, and don't forget to add a couple of spark gaps "just because"....drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-48991382737032365932018-01-16T10:54:29.764-05:002018-01-16T10:54:29.764-05:00Way back (over 50 years ago) working on large scal...Way back (over 50 years ago) working on large scale computers with vacuum tubes on method we used to test our "live" circuits was to vary the voltages to possibly induce failure. Failing circuits were pulled and sent to the repair lab where the common fix was to put in a fresh vacuum tube. The theory was that in a large (60,000 vacuum tubes) integrated electronic device that if the tubes were allowed to fail it was possible that so many of them would fail at the same time that the system wouldn't even be able to power up and thus it would be impossible to find which individual circuits were failing. So this proactive "marginal testing" method was developed. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-46402487681730575132018-01-16T08:48:25.815-05:002018-01-16T08:48:25.815-05:00Picture the big panels used in the 1930s movie Fra...Picture the big panels used in the 1930s movie Frankenstein. Huge wheels and dials that adjust the high voltage to bring the monster to life. The variac kinda has that vibe to it. The digital meter brings Frankenstein into the digital age. <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-67597603587911805032018-01-16T07:30:55.803-05:002018-01-16T07:30:55.803-05:00Sharp looking project.
And the digital display i...Sharp looking project. <br /><br />And the digital display in combination with the large dial of the variac looks oddly pleasing. John in Phillyhttps://www.blogger.com/profile/16196033252818387245noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-17897482879151011882018-01-15T22:47:21.953-05:002018-01-15T22:47:21.953-05:00It's actually pretty comparable - when the rig...It's actually pretty comparable - when the rig's preamp is on. It probably simply needs a bit more gain. SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-75912180726795007382018-01-15T22:44:17.145-05:002018-01-15T22:44:17.145-05:00Although they use non-radar terms in the descripti...Although they use non-radar terms in the description, I'm going to assume they're just using weird analogies. Radar works on reflecting back signals from a transmitter. <br /><br />The wave reflected back is going to vary with the shape and surface geometry of the object. Let's say you have a pocket pistol and you make a Faraday cage for it out of something like aluminum foil. You'll change the details of the reflection, but you don't make the metallic reflection go away. If you're carrying a polymer pistol, you'll increase the amount of reflection. If the aluminum was really form fitting, it would take on the shape of all the features on the surface and would be really recognizable. <br /><br />So let's say you had something like a Sneaky Pete holster - a rectangular box that completely hides the shape of what you're carrying. If you completely lined it with metal, it could be a good Faraday cage. It would still reflect, but the reflection now looks like a rectangular box and not "gun-shaped". <br /><br />They could decide that they search any big reflection or they could decide they only go after people when the radar box says, "Gun detected". <br /><br />That said, there's so much wrong with both the company's website and the Wired article that it's pretty disgusting. Too much emphasis on "concealed weapons", and the Vegas guy's "I have a concealed carry permit myself. But,..." When the big But shows up, you know it's a sham. More targeting the innocent and not doing anything about the bad guys. <br /><br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-42268396773566625252018-01-15T22:40:31.912-05:002018-01-15T22:40:31.912-05:00Yup....tubes can shrug off an enormous amount of a...Yup....tubes can shrug off an enormous amount of abuse.<br /><br />How does the noise level compare between the two antennas? Loops have a reputation for being "quieter", but perhaps that's only valid on higher frequencies.drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-34176513671585761172018-01-15T21:03:22.458-05:002018-01-15T21:03:22.458-05:00Off topic, but if I were legally carrying a firear...Off topic, but if I were legally carrying a firearm and wanted to defeat the technology in the link below, would some sort of faraday cage work? <br /><br />https://www.wired.com/story/the-las-vegas-resort-using-microwaves-to-keep-guns-out-of-its-casino/Divemedichttps://www.blogger.com/profile/14583007051962299381noreply@blogger.com