- What happened to Car Radio Antennas? - 14 Updates
- In Need of tone genertor/cable tracer - 2 Updates
- Tek 465 degree-of-difficulty repair - 6 Updates
| David Lesher <wb8foz@panix.com>: Aug 31 04:48PM >But most cars nowadays only have FM and DAB+ anyway. For some reason, Tesla's do not have an AM band. I can't imagine why that is... -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
| David Lesher <wb8foz@panix.com>: Aug 31 06:00PM >AM transmitters with over 50kW output are not used in the US at all. cough, cough.... WLW. It ran 500KW+ in the past, but regulators cut them back to the ordinary 50KW level in ~1940. The transmitter tubes had 3-phase filiments, if that gives you some idea of their size. There were multiple stories of farmers getting bit by their hot barbed wire fences, metal roofs that played WLW, etc. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
| Rob <nomail@example.com>: Aug 31 08:36PM +0200 >>But most cars nowadays only have FM and DAB+ anyway. > For some reason, Tesla's do not have an AM band. > I can't imagine why that is... You can't? Well I can! - not useful in large parts of the world - interference from motor control |
| Rob <nomail@example.com>: Aug 31 08:39PM +0200 > the ordinary 50KW level in ~1940. > The transmitter tubes had 3-phase filiments, if that gives you > some idea of their size. Actually it makes no sense to make an AM (MW) transmitter using tubes today. Designs using semiconductors and some switching mode are 3+ times more efficient (mains->antenna) and that is a big difference at those powerlevels. See e.g. Nautel NX https://www.nautel.com/products/am-transmitters/nx-series/ |
| Ralph Mowery <rmowery42@charter.net>: Aug 31 02:54PM -0400 In article <slrnsistli.nb4.nomail@xs9.xs4all.nl>, nomail@example.com says... > You can't? Well I can! > - not useful in large parts of the world > - interference from motor control Probably the interference from the other electronics in the car. Easy to eliminate if you just leave the receiver out of the radio. I just hope it is not like a friend that had a car about 40 years ago where he replaced the spark plug wires and spark plugs with the non resistor types. If you had an outside TV antenna which almost everyone did back then you could tell he was on the way from about 3 blocks away and when he got in the driveway you lost all of the TV station. |
| Phil Allison <pallison49@gmail.com>: Aug 31 03:11PM -0700 Rob the Imbecile wrote: ================== > > I can't imagine why that is... > You can't? Well I can! > - not useful in large parts of the world ** Choke, choke ??? WTF is this idiot on ? > - interference from motor control ** Obvious reason. AM radio simply does not work satisfactorily in their wacky contraptions. ..... Phil |
| Michael Terrell <terrell.michael.a@gmail.com>: Aug 31 08:29PM -0700 On Saturday, July 31, 2021 at 12:50:55 PM UTC-4, Brian Gregory wrote: > AM transmitters with over 50kW output are not used in the US at all. > (There were a handful of experimental ones at one stage in the past) > Yes in Europe higher powers were not uncommon, a few were as high as 1MW. There was one 500KW AM station, WLW. It was on 700KHz and it operated under an experimental license, and it was shut down in 1939. I saw the site 30 years later, along with the Bethany Ohio VOA site. http://j-hawkins.com/wlw.shtml Modern AM broadcast transmitters are a lot more efficient. All solid state, and no separate modulator which operates like a digital audio amplifier. It is built of plug in RF trays that can be hot swapped without shutting down the transmitter. The built in computer monitors the operation of each tray, and lets the staff know that a tray has failed, or can email the engineer if he is off site. Harris Broadcast introduced the first generation in the late '80s. Harris used to have white papers on their website. You might find them on the 'Wayback Machine' if you want more details. |
| David Lesher <wb8foz@panix.com>: Sep 01 02:29PM >> For some reason, Tesla's do not have an AM band. >> I can't imagine why that is... >You can't? Well I can! <https://www.merriam-webster.com/dictionary/satire> -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
| David Lesher <wb8foz@panix.com>: Sep 01 02:40PM >> some idea of their size. >Actually it makes no sense to make an AM (MW) transmitter using tubes >today. Designs using semiconductors and some switching mode are ^^^^^ >3+ times more efficient (mains->antenna) and that is a big difference >at those powerlevels. The transistor had not been invented when WLW's transmitter was built. It was decades later before high power FET's appeared. <https://youtu.be/CbHjcwIoTiY> -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
| David Lesher <wb8foz@panix.com>: Sep 01 02:46PM >> - interference from motor control >Probably the interference from the other electronics in the car. Easy >to eliminate if you just leave the receiver out of the radio. I assume you are pulling his leg. Think of the power levels involved in the drive motor electronics. (You might research what FCC regulations cover electric car RFI. You can be sure Musk did...) -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close.......................... Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433 |
| Rob <nomail@example.com>: Sep 01 05:05PM +0200 > in the drive motor electronics. > (You might research what FCC regulations cover electric car RFI. > You can be sure Musk did...) I would not at all be surprised when FCC regulations covering RFI specify maximum levels that are still way too high to allow reception of AM radio in the car itself. |
| Ralph Mowery <rmowery42@charter.net>: Sep 01 11:08AM -0400 In article <sgo3nb$j7o$2@reader1.panix.com>, wb8foz@panix.com says... > (You might research what FCC regulations cover electric car RFI. > You can be sure Musk did...) > -- No, not pulling a leg, just guessing. Many devices will interfere with AM radios. The FCC has a limit on how much is allowed. The car may just produce enough to affect the onboard AM radio, but not ones 50 feet away. People buying the electric cars probably do not listen to the AM stations anyway,but FM and the Sirus radio. |
| "Peter W." <peterwieck33@gmail.com>: Sep 01 08:19AM -0700 > I would not at all be surprised when FCC regulations covering RFI > specify maximum levels that are still way too high to allow reception > of AM radio in the car itself. Think it through: A vehicle is a rolling Faraday cage. Even the glass will be from about 0.2% to 0.8% iron, providing some shielding (and why many automobiles have passive cell-phone 'repeaters' for lack of a better word - antenna designed to take cell rF to outside the vehicle - both our Ford C-Max & our Subaru Forester are so-equipped). This suggests that a well-designed & shielded AM front-end and an external antenna should do the trick nicely. Yeah-but. That would make that AM front-end no longer a trivial 'extra chip' in an already trivial device. And put at least one more step in the glass manufacturing process. Not gonna happen. Note that it is not just the Tesla that has dropped AM - several other all-electric vehicles have done the same. Funny thing, however. The C-Max with a (depending on conditions) 15-35 all-electric range does fine in AM. Peter Wieck Melrose Park, PA |
| Rob <nomail@example.com>: Sep 01 06:17PM +0200 > Many devices will interfere with AM radios. The FCC has a limit on how > much is allowed. The car may just produce enough to affect the onboard > AM radio, but not ones 50 feet away. That is what I mean. To know the difference between RFI regulations and reasonable AM reception, just ask any radio amateur (as the previous poster probably is). The common levels of interference these days, likely emitted by fully compliant devices, overwhelm all but the strongest signals on frequencies below a couple of MHz. |
| Tim R <timothy42bach@gmail.com>: Sep 01 05:07AM -0700 On Monday, August 30, 2021 at 8:47:01 PM UTC-4, three_jeeps wrote: > I just bought an inexpensive one from one of the references. I'll use my flashlight arrangement as a backup. > I did learn something from Jeff about cable locators - TY. Will file that away as I may be doing some of that in the future. > J Yes, I agree, thanks much for that link. There was much in there that had not occurred to me, especially about other current sources coupling to underground lines. It seems just possible though maybe not likely that I can find an AM radio or other device that will buzz a bit close to the line, and that the effect is larger if it's carrying a good current, worth a try anyway. I'm pretty sure my line is shallow and maybe even DIY. |
| "Peter W." <peterwieck33@gmail.com>: Sep 01 06:45AM -0700 > Yes, I agree, thanks much for that link. There was much in there that had not occurred to me, especially about other current sources coupling to underground lines. It seems just possible though maybe not likely that I can find an AM radio or other device that will buzz a bit close to the line, and that the effect is larger if it's carrying a good current, worth a try anyway. I'm pretty sure my line is shallow and maybe even DIY. This might be possible for an acutely sensitive device - and most AM radios are not that. some basics, and a few assumptions first: a) The underground cable in question is either UF cable, or several conductors run in some sort of conduit. If the conduit is metallic, or otherwise shielded, the AM radio trick will not work. b) This cable is in the US, and so is single-phase, 240 V, and consists of two (2) hots, one (1) neutral and one (1) ground per present code. I will not speculate on Euro/Aussie codes or cables. We do know also from Phil that electricity has unusual properties down under. So, if the goal is to locate the cable so as not to dig through it, proof-of-concept would suggest that if the target radio were to be placed near to say.... an active AC line cord inside, it should buzz. And it should start buzzing within 18" or more, at least. Given that most ground is at least a little-bit-damp, and so will do some shielding, and the depth is unknown, this margin is needed. Just a few thoughts - considering that if it were that simple, an underground power cable tracer would be a trivial device vs. their actual cost. Peter Wieck Melrose Park, PA |
| "Eike Lantzsch, ZP6CGE" <eikelan@gmx.net>: Aug 31 05:48PM -0400 Chris K-Man wrote: > Where do you think I got my stash of spare TV remotes from? > If a bar's got a Sony on the wall, in Vivid mode, Im can whip out > my Sony remote, and at least put it in Standard mode. Thats the moment I secretly use my TV-B-Gone Kind regards, Eike |
| Phil Allison <pallison49@gmail.com>: Aug 31 03:54PM -0700 three_jeeps wrote: ------------------------------ > I second the motion to join & post on the TekScopes message board. > A lot of *very* knowledgeable ppl hang out there. ** Antique scope freaks ..... > A 465 is a very well-known and popular scope. > It was standard gear for DEC and IBM field circus back in the day, ** Had the use of the earlier & similar a Tek 463 for a couple of years. On loan, from a Sydney based IBM engineer - son of the man I worked for. Not very fond of it cos it lacked the one thing a good analogue scope needs. A sharply focused trace. The PDA ( post deflection acceleration ) tube was poor and you could see the blurring effect of the acceleration grid behind the face of the CRT all the time. It also had an external, lamp lit graticule - very clunky compared internal graticule tubes that most scope used from the 1980s onwards. ...... Phil |
| Phil Allison <pallison49@gmail.com>: Aug 31 06:43PM -0700 Phil Allison wrote: ----------------------- Correction: ** Had the use of the earlier & similar a Tek 453 for a couple of years. |
| Michael Terrell <terrell.michael.a@gmail.com>: Aug 31 09:09PM -0700 > ----------------------- > Correction: > ** Had the use of the earlier & similar a Tek 453 for a couple of years. I have a Tektronix 453A, which has a very sharp focus. The 453 was 50 MHz with Nuvistor inputs, the 453A is solid state and works to 65 MHz. It was built for Telex, for their field techs. I've had it since 1988, and it was well worth the $400 that I paid for it. I now have two Tektronix 2465A scopes. Four channel, 350 MHz. |
| Trevor Wilson <trevor@rageaudio.com.au>: Sep 01 02:26PM +1000 On 1/09/2021 11:43 am, Phil Allison wrote: > Correction: > ** Had the use of the earlier & similar a Tek 453 for a couple of years. **The 453 used Nuvistors in parts of the machine. It also had this horrible 'flyscreen' covering the CRT display. Like almost all Teks, mine worked flawlessly. |
| Phil Allison <pallison49@gmail.com>: Aug 31 09:58PM -0700 Trevor Wilson wrote: ================== Phil Allison wrote: > > ** Had the use of the earlier & similar a Tek 453 for a couple of years. > **The 453 used Nuvistors in parts of the machine. It also had this > horrible 'flyscreen' covering the CRT display. ** I'm sure that is a projection from the internal PDA mesh. Defocussing the trace made it really obvious. There was a plastic graticule over the CRT screen. My current scope has a mesh PDA mesh that is quite invisible. The CRT is by Matsushita - type 140CBG31 .... Phil |
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