The 'Best' AM Transmitter

ArtisanRadio · 2024-05-14T01:26:46Z

I just read a discussion elsewhere about the supposed 'best' AM transmitter. Use of the term best is very misleading. What is best to one person and application may not be so good to another. It is a highly qualitative judgement, and I'd rather deal with specifics. In the case I referenced, the author was actually referring to the fact that in a comparison test between AM transmitters conducted multiple years ago, the Hamilton Rangemaster had the highest field strength. But even that statement needs an asterisk, as the comparison was flawed in many aspects - I'm not going to rehash those flaws here but they can be found in historical posts. Now, Artisan Radio hasn't always used FM. Back in the early to mid 2010s, we broadcast on AM 1570, and used/experimented with a number of transmitters, including the aforementioned Rangemaster, the Procaster, the Talking House and the Talking Sign (precursor to the ProCaster). I wouldn't have the necessary hubris to label any one of these as the 'best'. What I would say is that all of them have strengths and weaknesses and all can be used for various specific Part 15 broadcasting applications. The best for your application is really up to you. I thought I'd ruminate on these transmitters, giving newcomers at least a starting point in their investigations if they are looking at broadcasting, and dispel some of the misinformation that is out there. I'll be looking at field strength, but also such factors as cost, sound quality, reliability and ease of use. First, let's talk about the elephant in the room, field strength. I actually consider that to be the least important when considering an AM transmitter. There are so many other things that affect range more - where you've installed the transmitter/antenna, ground conductivity, the quality of your transmitter ground, buildings and other obstructions, electrical noise, even the weather. All of these transmitters will give you range of a mile or more under ideal conditions. All will suck and you'll be lucky to get 1/4 mile range if, say, you have poor ground conductivity in your area, or lots of concrete buildings. But with that being said, and if those extra few feet matter to you, the Rangemaster will be able to give you them, as you can manually tune it to deliver exactly 100 milliwatts to the final amplifier. All the others have non adjustable power, usually a bit less than the allowed maximum to allow for manufacturing variability. The Rangemaster would be followed by the ProCaster, then the Talking Sign and finally the Talking House. But those extra few feet have a cost in ease of use. The Rangemaster takes a while to set up and tune if you're going to do it right (i.e., manually), requiring taking internal measurements with a multimeter. It does have accessories to supposedly let you know when you're tuned, but I never found they worked all that well. If that turns you off, and you want plug and play, all the other transmitters fit the bill. As I said, there are no power adjustments on any of them, and even the antenna tuning is automatic on the Talking House. With the ProCaster and the Talking Sign, it's just a matter of turning a knob and peaking a meter to tune the antenna. Sound is something that is important to most broadcasters, although the quality of your source material plays a large role. Music would require better sound; voice, not as much, and for historical recordings such as OTR, it matters the least. Both the Rangemaster and the ProCaster have high quality sound. The Talking House has mediocre sound at best, and the Talking Sign is somewhere in between. I should note that there is a version of the Talking House that has better audio, but it's more expensive. The older models can be modded, but that's outside the scope of this discussion. All except the ProCaster require external audio processing if that is desired; the ProCaster has built in limiting and compression, making it more of an all in one solution. Moving on to installation, the Rangemaster and ProCaster were designed to be installed outdoors with whip antennas (the ProCaster supplies this as well). Both are fed power and audio through interfaces located indoors. The Talking Sign and Talking House come with wire antennas, and are meant for indoor installation. Outdoor installation normally is recommended for the best range, as it gets the antenna away from your house wiring and any interfering outside walls. It is possible, however, to run the wire antennas from these transmitters outside and up over the roof, and that is exactly what I did with my Talking Sign install. With that configuration, range was in the ballpark of an outdoor ground-mounted Rangemaster or ProCaster. Now let's talk about reliability. The only transmitter I ever had issues with was the Talking House. I've owned many, and I'd say that approximately half had issues, and/or didn't get much range at all (i.e., only a few feet). Most of the pro...

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RichPowers

(@richpowers)

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I think Sausalito is still using 5 or 6 of the crystal Rangemasters linked with the help of barix boxes. I'm not real clear on the installations. I actually tried one time using google street veiw to find some of the transmitter. Didn't find any, but didn't really try that hard.

You know Radio Sausilto celebrated their 20th anniversary long ago. No other part 15 station has ever got as much mass media coverage, with exception to some college campus stations in the past.

This post was modified 2 years ago 2 times by RichPowers

Posted : 15/10/2024 2:42 pm

Rugster

(@rugster)

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@richpowers I think part of the reason for their longevity and success is the involvement of a sizable group of people, who all produce programming for the station. It's not just a one-person operation, like many Part 15 setups. It's the closest thing I've seen to a real community station in the Part 15 world.

Posted : 15/10/2024 2:51 pm

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