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Post by Druid Hills Radio on Jun 25, 2018 12:16:38 GMT
It would be fun to see him actually fall of his chair.
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Post by Deleted on Jun 25, 2018 16:14:26 GMT
Are you referring to the Am Transmitter Challenge post?
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Post by Druid Hills Radio on Jun 25, 2018 17:05:46 GMT
Are you referring to the Am Transmitter Challenge post? Yup. :-)
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Post by Deleted on Jun 25, 2018 18:05:42 GMT
I wonder what set him off this time? I didn't see reference(s) to anything in the post.
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Post by thelegacy on Jun 25, 2018 19:24:58 GMT
Someone please clue me in as to what is actually said or what you were talking about?
If it can't be discussed here please head to the elite section of my sight and post it there. If you don't have the elite password once you sign up send me a message and I'll give it to you so that you can discuss it.
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Post by Deleted on Jun 25, 2018 19:32:05 GMT
Nothing untoward. The reference is to a post on Hobbybroadcaster, in which Bill DeFelice goes off on person or persons unknown for something to with his 2013 AM Transmitter Challenge.
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Post by Boomer on Jun 25, 2018 21:39:54 GMT
I've heard of that testing, it was posted at Radio Discussions I think. It took common off the shelf and kit transmitters of the time and tested them in a field to rate them.
They could update that testing, since the transmitter landscape has changed since 2013, with new models on the scene and a few old ones have left.
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Post by Druid Hills Radio on Jun 26, 2018 12:55:08 GMT
I wonder what set him off this time? I didn't see reference(s) to anything in the post. I think he is just stirring the mud. He could have an alcohol or drug problem.
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Post by Boomer on Jun 26, 2018 15:37:32 GMT
Could the ALPB do a new transmitter test, and how could it be done when we live in all different cities?
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Post by thelegacy on Jun 27, 2018 1:40:40 GMT
To do a real transmitter test one would have to have a lot of money. What you would do is you would test something like the rangemaster and check its range and audio quality.
You would have to know where the signal fades and if you have the Hotspot that you do have and if so where they are.
Next you would test a procaster in the exact same place. This means taking the rangemaster down completely and setting up the procaster with its antenna and grounded in the same way that you did with the rangemaster. Then you do a drive test and know how far it transmits. The best thing to do is to have a video where one can hear the actual signal showing the distance that you are traveling. This is very important during a transmitter test a video of the actual results.
Next you would test the Sean Cuthbert transmitter and no tits Quality Inn range. Remember that you would have to keep notes on the areas travel especially your dead spots in your hotspot.
Next you would do the SsTran 5000 and so on. Each time every transmitter would be set up in the exact same location. This is how you make a comparison but you have to make sure that you read the manuals of each transmitter and set them up in the way that they recommend having them set up.
This would take a broadcast engineer or somebody who has money along with donations and things of that nature. I think we could do it if our organization were big enough.
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Post by Boomer on Jun 27, 2018 5:43:36 GMT
Koko the gorilla's favorite transmitter
I'd have to think some hobbyist is out there who has every transmitter on the market, those who like to collect and try everything in an interest area, or engineers could work with their local engineering society to get enough transmitters and test equipment.
I'd be interested in testing for a lot more than range, also looking at features like audio quality, modulation capacity, audio distortion, frequency stability, and look for how much incidental FM is produced with modulation, harmonics, how easy is it to tune, and also what advanced features or refinements it might have, over just being a basic transmitter.
Onboard audio processing would be important to many, at least some kind of ALC to help keep levels up, with a jumper to bypass it for when you'd get a separate processor. What about GPS or master and slave sync, both low and high impedance outputs (as in the I-AM Talking House), and C-QUAM stereo broadcasting, some stations would want those features.
My idea is that range is one of the important things, but for day to day listening to your station, you might want the other qualities to be high too, depending on your tastes.
What about categories? I can see a couple right away, transmitters meant to be remotely mounted outside with whip antennas, like Rangemaster, Procaster and Grain, or indoors in your studio or with your stereo system, like the Cuthbert and Spitfire. The I-AM Radio can be ordered for both indoors and outdoors, and they might be coming out with the remote ATU again.
Outdoor transmitters typically built with lower loss tuning components, since they're more focused on signal levels than a transmitter for around the house and yard. Outdoor units also have protection components like static drain resistors and transient protection tubes that you don't see on indoor units.
Also, would you want to evaluate transmitters not currently on the market? Some might still be in use, but testing them might make people desire a product that doesn't really exist any longer, like for example Ramsey and the two models of SSTRAN, plus the Talking Sign. The Talking House line is easy to get, even though they seem to have been discontinued long ago, you can still find them easily on the used market.
I like your idea of using video with audio in range tests, for having a record of the tests for later review by the testing team and those interested in the results. That way you can hear or see for yourself what the tests brought in.
Boomer
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Post by timinbovey on Jun 29, 2018 18:53:42 GMT
As some of you may know or remember, I AM a broadcast engineer, and I have at my disposal all the necessary test equipment to do a far more complete test than was done back in 2013 at that other website.
A couple years ago I did actually do testing on a number of FM Part 15 transmitters. I have never bothered with testing AM. For one reason there are so many variables. With FM it's basically "what's the field strength at 3 meters, and what's the harmonic situation" Oh, and how well can you adjust the modulation so you're not way over the limits.
I have a suitable test field nearby where I can set up whatever I like.
Your "drive" test is unscientific. It would show range based on that cars particular radio and reception abilities. And have no accurate indication of field strength generated.
The only way to test this properly is with calibrated field strength metering, which I own and use regularly in my work.
I had several issues with that infamous 2013 test.
The ability to modulate to 100% or more makes quite a difference in range. This puts, say, a Rangemaster at a disadvantage to a Procaster, since the Rangemaster has no internal processing, and it's pretty easy to modulate a Procaster to 100 + % with no external devices. This would also require an accurate AM modulation meter. Again, it's right here in the shop.
You cannot use a range test to compare when shopping. Variables will make expectations invalid. A one mile range in one location may only be a half mile somewhere else even if the installs are identical.
With FM you simply measure for compliance with the rules at 3 meters. The same sort of thing should be done for AM. Since there is no field strength at a given distance rule for AM the distance could be chosen out of convenience. TEst field strength at 100 feet, for example. Obviously the transmitters with the most field strength at a given distance will have more range.
Further, any transmitters to be tested must be purchased at retail through normal means with no indication to the seller that they will be tested. You want to insure you're receiving a typical unit.
Audio quality can also be tested but not by ear, but with spectrum analyzers, distortion meters, etc. But that's getting pretty persnickety for AM. Audio quality cannot be tested by listening to a radio, as each radio will have it's own distortion and frequency response characteristics. You want to use equipment designed for the purpose that will not add their own quirks to the data.
Anyway, just tossing out random thoughts.
Many of you probably read my tests of various FM units. AM is a different ballgame.
Tim in Bovey
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Post by Boomer on Jun 30, 2018 13:35:12 GMT
Hi Tim in Bovey, I've seen your FM transmitter reports before, a thread about them a few years ago on P.15 US when I started to read there, and I somehow have a PDF with illustrated tests you did of some cheap transmitters out in a field and how much the power outputs vary between them.
There are so many variables with AM, even with a single installation the signals vary day to day, time of day and season to season.
My dream test results wouldn't emphasize range and field strength so much, maybe with some informal testing with listening quality out in the field, on a range of radios. If there's an extreme difference in signal it should be noticed quickly, then tracked down as why that might be happening.
I'd do listening tests at night, with interfering stations on the channel, as some transmitters have incidental FM along with their AM signal that can cause noise and distortion when another station is under it.
You can detect the transmitter FMing with a communications receiver and a BFO, but I'd like to hear the effect in the real world on a regular receiver too.
I'd want to know all about the audio and modulation qualities as you say, and an oscilloscope also works, it can be set up to test many of the qualities of modulation, headroom, linearity and frequency response.
I think a radio can give a general idea of audio quality, especially if you know the radio, like if it's your reference receiver, and you know how good and bad signals sound on it. True, it's not scientific and might be slower, but I've tuned up many transmitters with a radio alone for more casual use.
I'd like looking at the other features and accessories, as you mentioned with the Procaster and Rangemaster. The Procaster comes with its own extendable antenna, where you have to buy a CB whip for the Rangemaster and I-AM radio outdoor units, because the whip is too long to send economically, as I understand it.
I totally agree about buying a rig through channels that any other station would. I've read so many reviews of products where a company sent a demo unit in for evaluation, and wondered if they'd give it a full checkup before sending or even tweak it up.
What about the bias of a reviewer getting a radio to keep or to borrow for a while, especially when it results in a review they get paid for doing, lots of pressure there.
More ideas just tossed out there, and even if no one in the hobby does more transmitter testing any time soon, at least it could give some ideas of what to look for in a transmitter system.
Boomer
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Post by thelegacy on Jul 4, 2018 16:38:04 GMT
I like the idea of a transmitter test but I'd also like to hear a drive test (Youtube Video or service like Degoo). A tecsun PL 380 is $47 and has a DB meter So we'd know what the audio sounded like in comparison. This is important too as some stations transmit a genre that depends on Audio Quality (Album Rock is a High Demand Genre). Range to an Album Rocker doesn't matter if your audio sounds like your singing through a plugged nose like a Talking House transmitter without any audio processing.
I already know that the Procaster has an advantage and so does the Sean Cuthbert however both transmitters need to be tested in a range test. And yes I have my Sean Cuthbert outside on a pole with a short wire.
Comparing antenna broadcasting with neutral injection carrier current in an area with above ground power lines I'd like to see a test (Drive Test) of a neutral injection carrier current system in an area with above ground power lines to get a feel if I should work on this project for my station. I've read so much about this and it sounds so tempting here in Deltaville whereas we have only one power distribution system from Dominion. The lines start just before the Deltaville market. This should mean that if I inject a 20 Watt signal into the neutral line with a coupler and a 8 Ft ground rod for the return I'd get my 2 miles on each side and according to what I read about 262 Ft from the power line in outside range while the signal travels along the line.
If I get a schematic of a coupler my engineer is willing to try it and maybe get a suitable C-Quam AM Stereo transmitter capable of carrier current or modify my Sean Cuthbert for the 5-30 Watts needed. I only hope to do this so I can have a signal that covers my town and won't get to the big cities near my town. No jealousy would happen which means no issues.
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Post by Admin on Aug 31, 2018 19:21:24 GMT
He could have an alcohol or drug problem. "COULD??"
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