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Messages - Dave Richards

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91
Part 15 AM and FM Station Operation / Re: Part 15 AM and FM
« on: April 11, 2020, 1627 UTC »
Thanks for the range information, it's interesting to learn how far Part 15 operations can get out!

Thanks Chris. Unfortunately, I'm in a relatively dense urban environment, which limits the evenness of the coverage. If I were able to locate the transmitter in an open lot, with several hundred feet of clear space around it, I think the coverage would be more even.


I still think it's pointless, may as well turn up the stereo or even shout, you're going to be heard at a greater distance and it's free.

Good luck with your part 15.

With don't have anything like that here thank goodness and can't say I'm bothered about it

At All.

Str.

My Part 15 doesn't have particularly spectacular coverage, but I get an easily listenable signal 1/4 mile away, and my stereo won't reach that far. I sure as heck can't shout that far either - at least, not without ruining my vocal chords  ;D

There's a Part 15 station not far from me, in Sausalito, CA. They're called, funnily enough, Radio Sausalito ;D  A few years ago, I did a write-up on the station, and went out to Sausalito to hear it.  I was surprised to find that, on walking along Bridgeway, the town's main drag, the signal was absolutely consistent for a mile. It may have been further than a mile, because I didn't investigate how far it went in the other direction. It wasn't a blowtorch signal by any means - it did sound a bit thin, but it was remarkably consistent in level for a whole mile. The station uses 6 Rangemasters. I don't know whether the carriers are synchronized or not, but I'm tempted to think that they are, due to the consistency of the signal over the part of the coverage area I walked. However, the signal did get a bit more shaky on walking inside buildings. Obviously, that can be a problem!

Radio Sausalito enjoys strong support from the city, and the local Chamber of Commerce. Their format, which is strictly jazz, streams on the internet as well. Jonathan, the station owner, told me that the majority of their listeners these days are online. The streaming fees are not insubstantial, but I'm thinking that Radio Sausalito is in an enviable position. Sausalito is a small, yet wealthy town, with strong income from tourism. I'm sure they're quite proud to have their own little radio station representing their town.

I only mention the above because, in my opinion. Radio Sausalito is a good example of how to run a successful Part 15 station. Many licensed LPFM's find that, after the initial enthusiasm of opening subsides, the hard graft of keeping it going sets in. That's when the automation systems kick in ;D  At least, with an LPFM, you have decent coverage over a small area. You barely get that with a Part 15. An internet stream really helps  - but then, there are the fees associated with that.

Anyway, for me, it's a hobby. I enjoy hearing my little well-processed AM signal in the neighborhood. I'm not trying to change the world, thank goodness.

92
Part 15 AM and FM Station Operation / Re: Part 15 AM and FM
« on: April 10, 2020, 1822 UTC »
I have a Rangemaster transmitter, fed by a Schlockwood 200 LPAM processor. Automation software is the free version of Zara Radio on a laptop, running through a Mackie mixer, so that I can do live programming. Occasionally when my best friend comes over, we go live on the air for fun. Mics are an EV RE27 N/D and Shure SM7 on boom arms.

I worked on the programming for several months, on a full-time basis. Zara Radio allows you to mark the exact segue point on each individual song file, if you're that detail-oriented (I am!) I download monthly 60 second featurettes from the US Census Bureau, and the Mayo Clinic (their Radio Health Minutes), which air regularly. I also scripted and recorded an "On This Day In History" feature for every day of the year. Free PSA's are available from several online outlets, and I air those also. The automation software airs the correct features for each day. While not a huge playlist, at 2427 songs, it's bigger than virtually all commercial stations. I also produced and voiced a bunch of ID's and jingles for the station, which is called "Ant Radio" in tribute to my best friend Ant (full name Antoinette). She is also a DJ, so is pretty chuffed that I named the station after her. The top of the hour ID contains the sound of our recently deceased neighborhood cat's loud meow. Mingus was a local legend.

All in all, I'm pretty proud of the station. In true Part 15 fashion, coverage is not even, and does interesting things. In one direction, reception falls off sharply in just a block. In other directions, it goes for about 1/4 mile before becoming unlistenable. On a very good day, I can just barely make it out above the noise a mile away. At various points in between, the signal will pop out of the noise, then disappear again. I think this is about normal for a compliant Part 15 setup. Of course, once dusk arrives, coverage suffers greatly.

93
I built this little beacon back in May of last year, but only just got around to mounting it permanently outside. It is powered by a small solar panel, with no battery. As a result, it operates during daylight hours only, coming on 30 minutes to an hour after sunrise, and going off-air 30-45 mins before local sunset. It works on bright and moderately bright cloudy days, but does struggle a bit when the clouds are particularly thick and dark. I've thought about adding another panel or even a battery but, for the time being, am considering the slightly quirkiness of it's operating hours as part of it's charm.

It sends the letter "BRS" at 10wpm, in honor of my neighbor's cat Boris. Power is a stunning 1mW to a half-wave dipole in a slightly bent configuration on a second floor balcony. With such low power and a compromise antenna, I'll be amazed if anyone hears it. The plan is to run it at 10wpm for a few months then, if it has not been heard, to change to QRSS.

The frequency is a nominal 13556.9 KHz, which varies up and down by a few 10's of Hz, depending on the ambient outside temperature.

I hope it's OK to post this link. There's some more info, and pics, here -

https://aa7ee.wordpress.com/2019/01/03/putting-the-hifer-brs-boris-beacon-on-the-air-finally/

94
Thanks for the info and encouragement Ed. Space for antennas is limited here, due to my living situation, but this beacon project has already taught me a few things. A couple of good lessons have already been learned, and I am currently leaning towards not putting it on the air. It will most likely be the subject of a blog post though. I will provide a link to it in this thread if and when that happens.

The two things I have learned so far are -

1) I am hopelessly behind the times in continuing to use 78L05 regulators. I had a small stash of them, so was blindly using them, without considering alternatives. However, the 4mA quiescent current and ~2V dropout voltage was a needless drain on a little beacon that only draws ~3mA on key-down and is intended to run solely from a small solar panel with no battery. I have finally put in an order for some more modern LP2950 regulators, which have a quiescent current of <0.1mA and much smaller voltage overhead of ~0.1V.

2) The ATtiny 85 which keys the oscillator was not starting up properly in the mornings when the sun came up. I think this was because I had the BOD (brown-out detection) set to 1.8V. At that low voltage level, the small panel wasn't supplying enough current to power the beacon properly. The remedy was to burn the fuses on the chip again and increase the BOD to 2.7V, which seems to have cured that problem. Another cure would be to simply include a battery in the circuit that is powered from the panel.

Anyway, I'll link to my blog post when this particular learning experience is over. Thank you for your help and comments.

95
Thanks for the input, Σ and Dag - and thanks for the kind words on my blog, Σ. This little beacon will probably get a write-up. I also built a little temperature beacon, which will get written up first. It's a neat little device that outputs the current temperature as Morse code on the HiFER band. I liked the circuit, and got to wondering if I could build it as a simple beacon. Dag - using QRSS speeds for both your FSK and CW is a good choice. Even at the maximum radiated field strength allowed on this band, we're still talking about very low power levels. I use 4.6mW into a dipole as my standard, as calculated by W1TAG.

I ran it into a 50 ohm resistor this afternoon and put it on the scope. Peak-peak voltage into 50 ohms is only around 0.6 - 0.7V, so it looks as if the RF power out is only about 1mW. This could turn out be more challenging than I had thought.

I think I'll start out using ~5wpm and go from there. It sure will be great when the sunspots return. Perhaps I should say "if", but I want to be optimistic about this. The thought of spending the rest of my life in a repeat of the Maunder Minimum isn't very inspiring!

96
Hello there, fellow HiFERs. I'm very happy to see a dedicated HiFER section on these forums.

I am scratch-building a little beacon that will put out about 2mW into a horizontal dipole on top of my property fence, at about 7 feet above ground. It will be a bit of a cloud-warmer, I think, but I'm interested to see how it will get out. It will be powered by a single small solar panel with no batteries, so will be operational during daylight hours only. I hope I won't be missing the valuable grey-line propagation time with this approach, but we'll see how it goes. It should be on the air sometime this week. As it sits on the bench, it is coming up on around 13556.91 or thereabouts.

My question to the group is what you think an ideal code speed is? I want it to be fast enough to be copyable to the ear, so no QRSS. I have a personal preference for something around 10 - 12wpm, as anything slower bores me somewhat. However, I want the decision to be driven by what is most likely to be copyable to listeners struggling with what will almost certainly be a very weak signal. The beacon's callsign will be BRS, in honor of my neighbor's cat Boris.

I'm thinking that a relatively high speed would maximize the chance of copying the entire callsign before any fading takes the signal out, so I'm veering towards around 10wpm. What do you guys think?

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