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micky <NONONOmisc07@fmguy.com>: Jul 23 08:47PM -0400 In alt.home.repair, on Fri, 23 Jul 2021 12:30:09 -0400, Clare Snyder   >>Do cars with plastic bodies, like the Saturn, give bad radio reception? > What would prompt that question? What properties of Plastic, or the >behavior of radio waves????   Actually, it's that car radios have always given me better reception than house radios have. Is it the antenna, the ground plane? What?

Michael Trew <mt999999@ymail.com>: Jul 24 12:13AM -0400 On 7/23/2021 8:47 PM, micky wrote: > Actually, it's that car radios have always given me better reception > than house radios have. Is it the antenna, the ground plane? What?   Typically better reception in the car, yes, but that all depends on the antenna set up. You can have a very good antenna at home, but one with a fault in a car. I've owned both. I'd like to build an AM loop in my attic to get better AM reception at some point.   I am very into AM radio, especially long-distance AM stations at night. I've owned cars where they seem to put no thought into the AM radio band, and it shows (sounds). Dad had a Chevy Trailblazer (2006?) where you could always hear the transmission or something interfering with the AM reception.

Phil Allison <pallison49@gmail.com>: Jul 23 10:02PM -0700 micky wrote: ===========   > Actually, it's that car radios have always given me better reception > than house radios have. Is it the antenna, the ground plane? What?   ** Car radios rely on a tuned, vertical whip antenna that has a modest ground plane - the car body. This tends to work better than a small, ferrite loopstik - partly because the car antenna is normally *outdoors*.   Also, it is common for car radios to have a tuned RF stage prior to the frequency converter and IF. So three tuned circuits instead of the usual two.   FYI they normally used inductance tuning.     .... Phil

micky <NONONOmisc07@fmguy.com>: Jul 24 10:06AM -0400 In alt.home.repair, on Sat, 24 Jul 2021 00:13:18 -0400, Michael Trew >band, and it shows (sounds). Dad had a Chevy Trailblazer (2006?) where >you could always hear the transmission or something interfering with the >AM reception.   Wow.   The '72 Buick and then the '84 Chrysler and 88 Chrysler would get perfectly here in Baltimore WRC, 980AM, in Washington, DC, a station no indoor radio, even the fancy receiver, would get at all. (I've only lost interest in that station because it changed format.)   And for decades, one car radio after another, (maybe the Buick,) Chryler and Toyota, would get WAMU, 88.5FM, (American University in DC), perfectly, when only one inside radio would get it. Even now a much different Toyota radio gets WAMU usually perfectly, when the one inside radio no longer does as well. (For a while I was reporting to the WAMU engineer when reception was good or bad, and he got it good, but months later, it got weak again sometimes. (And like I say, that's the one radio that gets it at all.)   At one point a friend gave me a nice wood "box" designed to hold a car radio, an antenna, and a DC adapter, just for the sake of using a car radio indoors, but at the same time he told me that it didnt' work for him (which is why he was giving it to me). So it seems like the difference is the metal body on cars, all but a few cars.   The urls people have posted here (before electronics.repair was added) make clear that the ground plane in the car makes a difference, and that cars without one need a special antenna cable, but a) they're mostly pushed for CB radios, b) it's not at all clear that the special antenna is as good c) when shopping for an antenna, any with ground plane provision probably make note of it, but those without do not, afaik, warn people what is missing.

Ralph Mowery <rmowery42@charter.net>: Jul 24 10:21AM -0400 In article <q76ofg9e48u9nb1k4kpouknn7vdpr704ba@4ax.com>, NONONOmisc07 @fmguy.com says... > engineer when reception was good or bad, and he got it good, but months > later, it got weak again sometimes. (And like I say, that's the one > radio that gets it at all.)   One other thing about the radio in the house is that some homes have so much metal in them , especially the aluminum siding and foil reflecting insulation that the radio signals have a hard time getting in to the house.

Ralph Mowery <rmowery42@charter.net>: Jul 24 10:26AM -0400 In article <q76ofg9e48u9nb1k4kpouknn7vdpr704ba@4ax.com>, NONONOmisc07 @fmguy.com says... > is as good c) when shopping for an antenna, any with ground plane > provision probably make note of it, but those without do not, afaik, > warn people what is missing.   For AM radios in cars, the ground plane effect is almost nill. There is some capacitance coupling from the frame to the gound, but that plays very little in the AM band. The FM antennas are often built in the windshelds and the metal of the car does not com into play there either to ammount to anything.   To be much of a ground plane at the AM band you would need a plate of around 100 feet, 200 feet would be better. Just look at how tall the AM transmitter antennas are. Those antennas have about 120 wires as long as the antenna is tall burried in the ground.

Frank <"frank "@frank.net>: Jul 24 10:41AM -0400 On 7/24/2021 10:26 AM, Ralph Mowery wrote: > around 100 feet, 200 feet would be better. Just look at how tall the AM > transmitter antennas are. Those antennas have about 120 wires as long > as the antenna is tall burried in the ground.   This is the big difference in spectra that I looked at:   https://courses.lumenlearning.com/boundless-physics/chapter/the-electromagnetic-spectrum/     Shorter wavelengths penetrate better.

micky <NONONOmisc07@fmguy.com>: Jul 24 11:11AM -0400 In alt.home.repair, on Sat, 24 Jul 2021 10:21:07 -0400, Ralph Mowery >much metal in them , especially the aluminum siding and foil reflecting >insulation that the radio signals have a hard time getting in to the >house.   I have T1-11 siding, not alumininum As to foil clad insulation, I don't think so. I've been in the walls a little bit when I put a floodlight in the outside bedroom wall. House built in '79, not cheap but not the most expensive either. Plus there is a 6-foot wide window facing DC from the bedroom, where many of the radios have been, with aluminum window frames but the frames are not very big.

micky <NONONOmisc07@fmguy.com>: Jul 24 11:16AM -0400 In alt.home.repair, on Sat, 24 Jul 2021 10:26:38 -0400, Ralph Mowery >very little in the AM band. The FM antennas are often built in the >windshelds and the metal of the car does not com into play there either >to ammount to anything.   Only one car had the antenna in the windshield. A long time ago, I can't remember which. >around 100 feet, 200 feet would be better. Just look at how tall the AM >transmitter antennas are. Those antennas have about 120 wires as long >as the antenna is tall burried in the ground.   So what can I do to get reception inside as good as what I get in the car? Especially FM. In the past year, reception for WAMU, 88.5 and C-Span, 90.1, seems to have gone downhill.

Jeff Liebermann <jeffl@cruzio.com>: Jul 24 08:38AM -0700 On Sat, 24 Jul 2021 10:06:23 -0400, micky <NONONOmisc07@fmguy.com> wrote:   >is as good c) when shopping for an antenna, any with ground plane >provision probably make note of it, but those without do not, afaik, >warn people what is missing.   I beg to differ. Nobody seems to have mentioned the bane of all MF (medium frequency) reception, RF noise. A metal ground plane (car body) does a tolerable job of isolating the AM antenna from the noise generating ignition, black boxes, and gizmos. With a plastic body, the antenna will pickup more noise from the engine.   The typical car antenna is sometimes located as far away from the noisy engine as possible and connected to the AM receiver with RG-62/u 93 ohm low-capacitance coaxial cable. There is an adjustable capacitor between the antenna and the receiver input capacitance to resonate the antenna system. The coax cable capacitance and the receiver input capacitance act as a voltage divider. The more coax cable capacitance to ground, the less signal and noise arrive at the receiver. Choose your coax cable type and length carefully.   You can have a really sensitive AM receiver, and still not be able to hear much. The threshold of sensitivity is atmospheric and man-made noise. <https://en.wikipedia.org/wiki/Atmospheric_noise> Note the graph. At 1MHz, the RF noise (mostly from thunderstorms) is huge. <https://map.blitzortung.org/#3.91/39.62/-91.39> RF noise from neon signs, motors, sparking of any kind, etc just makes it worse. If you simply build a bigger antenna, or add an RF amplifier, you increase both the desired signal and the noise proportionally. If a receiver and antenna produce some SNR (signal to noise ratio), and I add more antenna gain, or more RF amplification, the resultant SNR will be the same. In other words, a bigger antenna or a "signal booster" don't buy you anything. The trick is to somehow improve the SNR, which is not easy. See various articles on the PA0RDT mini-whip antenna for clues: <https://www.google.com/search?q=pa0rdt+mini+whip>   Car AM radios tend to have the minimum sensitivity and RF front end gain needed to function in a strong signal environment. They're not made for digging signals out of the noise. That's NOT because AM car radios are made to be inexpensive. It's because the receiver is sitting next to a very noisy car engine. Were it designed to be as sensitive as an LF or HF receiver, all you would hear is engine noise. Try it. Build yourself a BCB (broadcast band) RF amplifier and attach it to your car radio antenna input. In most cases, you'll hear your engine, pump motors, and atmospherics quite well, but the distant AM stations will still be buried under the noise.   I don't have any suggestions to improve your mobile AM reception. Well, maybe the obvious suggestion to do what you can to eliminate, move, shield, or isolate sources of RF noise. If weak AM signals magically appear when you turn off the engine, the source of the noise is obvious. The problem is that you might do a wonderful job of noise reduction on your car, such as buy a diesel, but that does nothing if you're stuck in traffic and surrounded by other noisy vehicles. Notice that the ultimate noise generator, the all electric car, usually does not come with an AM radio. For example, Tesla will sell you an optional overpriced infotainment package that includes AM: <https://electrek.co/2020/10/28/tesla-brings-back-radio-infotainment-retrofit/>   Vendors used to sell rubber grounding straps, that discharge any static buildup on the car body. That should get rid of some noise. However, I believe carbon doped car tires have largely eliminated the need for those straps.   So, to answer your question, yes a plastic body gives lousy AM reception if your engine belches lots of RF noise and your receiver is reasonably sensitive. If your receiver is stone deaf, it doesn't matter.   Good luck.   -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

Ralph Mowery <rmowery42@charter.net>: Jul 24 11:57AM -0400 In article <lebofg5ovck64gg67ed1kmdvb0va3cug2n@4ax.com>, NONONOmisc07 @fmguy.com says...   > So what can I do to get reception inside as good as what I get in the > car? Especially FM. In the past year, reception for WAMU, 88.5 and > C-Span, 90.1, seems to have gone downhill.   For in the house put up an outside antenna and feed it with coax cable.

Jeroni Paul <JERONI.PAUL@terra.es>: Jul 24 06:26AM -0700 > BVM models can demand a fair bit of money. Not all CRTs are equal but > targeting gamers into that is an easy way to turn one into some amount of > $   Yes, for gaming I definitely prefer a CRT. There is something wrong in the LCD refresh or digital processing that makes the difference. Also most CRT PC monitors allow 50Hz refresh for European games. Playing a 50Hz game forced at its right speed by the emulator in a 60Hz LCD is a jerky experience.

Jeff Liebermann <jeffl@cruzio.com>: Jul 23 11:10AM -0700 On Fri, 23 Jul 2021 08:57:43 -0700 (PDT), "jurb...@gmail.com"   >In the meantime I will be uilding an XP PC but on a better board. It is going to be fast. Wil have the 4GB RAM of course, 2 SSDs.   XP can use more than 4GB RAM if the motherboard supports PAE: <https://itstillworks.com/how-to-enable-pae-on-a-32-bit-windows-xp-10155.html> <https://www.betaarchive.com/forum/viewtopic.php?t=36597>   An SSD will work on XP, but you will have problems unless you impliment some scheme to regularly run the "TRIM" command. The TRIM command or button is usually found in the various SSD managment software that comes with the SSD (e.g. Samsung Magician). I've had problems with TRIM when using a fairly new SSD and old software that's XP compatible.   [Q] What do you get when you put a jet engine in a Volkswagen? [A] It's still a Volkswagen.   >Has all the outputs for HDMI, DVI, It will have al kinds of cool >software on it that would cost many many thousands for the new version.   Or, you could get the FOSS or Linux versions for next to nothing.   >Everyone warn of virus and all tis sit, I don't have those problems.   The old viruses are still out there. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558

Jeroni Paul <JERONI.PAUL@terra.es>: Jul 24 05:54AM -0700 > In the meantime I will be uilding an XP PC but on a better board. It is going to be fast. Wil have the 4GB RAM of course, 2 SSDs. Has all the outputs for HDMI, DVI, It will have al kinds of cool software on it that would cost many many thousands for the new version.   If it has at least 2 cores, Windows 10 LTSB works great. Note I mean the LTSB version, not the mainstream Home version that comes overloaded of useless apps. I use the LTSB version in old computers like Intel Duo core with 2Gb of RAM and it works great and lets you install up to date software like Edge and Office 2019.

"ohg...@gmail.com" <ohger1s@gmail.com>: Jul 23 12:26PM -0700 > On the side, got a Tek 561A with delayed tie and dual trace, a 422 that will ont work on 12V, also a meter with nice big characters also wil only run on 12 volts. I got aa 12 volt backup thing fo a car, or newer batteries could be put in the scope and run them both.   > Already for sale are Tek 7603 and TDS-360, both need work.   > I'll still be around.   Good luck Jeff. Hope your health improves.   Regarding the 7603, most problems are the big honking Mallory caps in the power supply. Over the past 30 years, mine has gone down 4 times, three to bad caps (last time two months ago) and one bad IC in the horiz plug in. Symptoms of those bad caps are no display or a badly distorted display.

Trevor Wilson <trevor@rageaudio.com.au>: Jul 24 08:46AM +1000 > On the side, got a Tek 561A with delayed tie and dual trace, a 422 that will ont work on 12V, also a meter with nice big characters also wil only run on 12 volts. I got aa 12 volt backup thing fo a car, or newer batteries could be put in the scope and run them both.   > Already for sale are Tek 7603 and TDS-360, both need work.   > I'll still be around.   **Damn. Good luck for the future. Pity you're not nearby (I'm in Australia), I'd grab that 7603. Nice 'scope. I salvaged a 7A22 for use in a 7000 series, when one falls in my lap.

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