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amdx <amdx@knology.net>: Apr 26 07:52AM -0500 On 4/24/2021 6:02 PM, micky wrote:   > https://www.amazon.com/0-5-Fail-Safe-Long-Range-Transmitter/dp/B003FO4UHW/ref=sr_1_12_sspa > $120 Mine was cheaper, I guess because it had no RCA inputs, which I > have no use for.      I have the FM transmitter listed above. At one time it quit transmitting.   I could not find any info on the unit at that time.   Here's the schematic as I drew it on my unit manufactured in 2011. May or may not be correct or complete.   > https://www.dropbox.com/s/8sjv8u3xlsdsg3d/FM%20TRansmitter%20Schematic%20Updated%20schematic%20Latest.jpg?dl=0 Here's a picture of the PCB.   > https://www.dropbox.com/s/o1vuhbgjcyndo3b/FM%20Transmitter%20amp%20section..jpg?dl=0 F1 is the output transistor, it went defective on my unit.  I changed it and that fixed it. Check the voltages, at the output MosFet   If they don't match what I have on my schematic, it would be suspect. I used part # RDO1MUS1.   > https://www.mitsubishielectric.com/semiconductors/content/product/hf/sirfpowermosfet/siliconrfdiscrete/siliconrfdiscrete_lv4/rd01mus1.pdf You will also notice when it's working properly, that the 100 ohm resistor in the L/H power switching circuit runs hot, (I think in low power mode).   It is just poor design it is a 0.5 watt resistor dissipating 0.59 watts.   But 10 years of often hours of daily use and it is still fine. So you can ignore that.                                      Hope that helps, Mikek     -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

amdx <amdx@knology.net>: Apr 26 07:57AM -0500 On 4/26/2021 7:52 AM, amdx wrote:   > But 10 years of often hours of daily use and it is still fine. So you > can ignore that.   >                                    Hope that helps, Mikek   BTW, I bought one in 2011 and paid $114, I bought another in 2017 and paid $69.   The first one I repaired and is still working, the second one is working fine.                                                  Mikek         -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

"Peter W." <peterwieck33@gmail.com>: Apr 26 08:10AM -0700 First, I have a legacy Ramsey FM100B that I built from a kit almost 20 years ago. It has performed flawlessly throughout that time. Sadly, it is no longer made, although they do, occasionally, show up on eBay. Ramsey continues to support them.   Second, there is a LOT of Chinese Junque out there that is awfully cheap, and that is no better than it should be at the price. Those that I have come across have had nice extruded cases, and looked pretty simple. But have not performed anywhere as nicely as the Ramsey.   Third, I suspect that the unit you have that has failed has done so (in rank order) because of a connector failure (antenna, power or input), or because of a failed critical component - because, did I mention, they are cheap.   Fourth, you will notice that the Rangemaster is "FCC Certified". In the world of Part-15 FM transmitters, that does mean something.   You get what you pay for.   Peter Wieck Melrose Park, PA

whit3rd <whit3rd@gmail.com>: Apr 25 10:47PM -0700 On Saturday, April 24, 2021 at 8:15:17 PM UTC-7, Ed Vance wrote:   > I went through the Set Up procedure and had it scan the TV Channels > but the set still didn't let me see the Stations that I had been > able to watch before the Power failed that time.   Two odd possibilities, are that the station might have gone off-the-air during your scan, or that the TV has a restricted tuning range because its varactor bias supply has been misadjusted.   More likely, your antenna isn't picking up all the stations, and could use adjusting. If you still have a converter box, some of those have signal strength indicators (and you can see if the converter scans and finds the same stations, or a different subset. If a converter picks up more stations than the TV on the same antenna... then the TV might need an antenna booster amplifier.

Rheilly Phoull <rheilly@bigslong.com>: Apr 26 07:09AM +0800 On 25/04/2021 8:14 pm, Edward Hernandez wrote: >> the 3 groups in series or connecting 3 cells in series first to >> obtain 6 volts, 2amp per set and connecting the set in parallel?   > This question sounds suspiciously like a homework problem.   As do many :-(

Jason Bowers <jbbowersnospam@aol.com>: Apr 25 01:47PM -0400 The last time I did any serious HF radio adjustments I had a large and heavy 100 Mhz oscilloscope as well as an HP 1 Ghz spectrum analyzer. Due to finances and lack of interest, those items, along with several others, were sold about twenty years ago.   Recently, my interest has been rekindled somewhat and I am thinking about getting on 10 meters once the solar cycle begins to favor the upper HF more consistently. The problem is that my 10 meter radios have been in storage for about twenty years. Some were bought used and I have no idea how clean/ dirty transmitter/ receiver stages are not to mention transmitter output spectrum and modulation. I came across an HTX-100 recently, for example, where someone had removed the "do not adjust" sticker on the bandpass filter. Not good. So, being on a limited budget, I have been looking at these test equipment pieces:   https://www.amazon.com/Portable-TinySA-Spectrum-Frequency-Generator/dp/B08FB5XT7B?tag=worradfor-20   https://www.amazon.com/YEAPOOK-Handheld-Oscilloscope-Professional-Bandwidth/dp/B07XBL4BTL?tag=worradfor-20   I'm hoping that I would be able to check out and adjust spectrum output using the SA for anything up to 30 Mhz as well as checking out radio internals with the scope up to 30 Mhz (as well as viewing output SSB waveforms). So, I would appreciate any feedback on the above units. Thanks in advance.

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