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Post by part15engineer on Jun 13, 2018 12:42:01 GMT
I see a NOUO in this guys future since he was apparently written up in the local paper.
this is partly what got ken cartwright a visit and subsequent NOUO's.
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Post by Druid Hills Radio on Jun 13, 2018 12:45:05 GMT
I see a NOUO in this guys future since he was apparently written up in the local paper.
this is partly what got ken cartwright a visit and subsequent NOUO's.
Looks OK to me. |
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Post by part15engineer on Jun 13, 2018 12:47:20 GMT
he's got a TH inside the building with a long connecting coaxial lead to an elevated isotron.
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Post by Druid Hills Radio on Jun 13, 2018 14:28:06 GMT
he's got a TH inside the building with a long connecting coaxial lead to an elevated isotron. It was certified for use with an external antenna. (ATU) |
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Post by mighty1650 on Jun 13, 2018 17:47:57 GMT
he's got a TH inside the building with a long connecting coaxial lead to an elevated isotron. It was certified for use with an external antenna. (ATU) Ditto. Though I'm not 100% sure if it HAS to be the iAM ATU or if it can be any ATU. I doubt the FCC is going to bother this guy very much.
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Post by thelegacy on Jun 14, 2018 4:57:53 GMT
Better to use high power Bluetooth to get the Audio to the Transmitter and use a very short wire to the ATU. Longer coax means more lose.
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Post by Boomer on Jun 14, 2018 10:13:26 GMT
I wonder if acompliant could be a word, meaning not compliant, like asymmetrical is not symmetrical. It might be a good word to throw around sometime. Good setup there, a lot to make others drool, like I used to think about having a separate small building for my station. It's something like Bob's MRAM was set up, an I-AM transmitter, connected to a recording studio for local bands. Radio naturally goes together with a lot of things, if only people give it a little thinking. I like how KSMR's automation system is called Dead Beef..  Boomer |
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Post by Druid Hills Radio on Jun 14, 2018 12:24:34 GMT
Better to use high power Bluetooth to get the Audio to the Transmitter and use a very short wire to the ATU. Longer coax means more lose. Loss at the kHz frequencies is negligible. |
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Post by thelegacy on Jun 14, 2018 16:54:55 GMT
I use to think the same thing until my broadcast engineer friend showed me its NOT. When your dealing with mW's and mV's every little bit of juice matters. Lets take a look at a few different TX's and how there set up and some examples of range difference.
Lets start off by part 15 engineer's offer of the Talking Sign in a weatherproof box and its setup. If you look at the setup he is using a short wire (one that use to be the antenna for in the house operation. He cut and then stripped the end of the wire and screwed it to the threaded bolt used to screw in a CB whip antenna. By doing this his range would be better than simply making an ATU and then using the outside antenna port.
The Talking House used to have an ATU for its external antenna operation but they discontinued it. Instead they came up with a weatherproof box and again a short wire to the terminal for the CB whip antenna. Note that both of these antannas are stainless steel (Not as good as copper or aluminum for conductivity).
Part 15 engineer got some good range with the Talking Sign as compared with my Talking House connected to an ATU with about 25 feet of coax. So we see a range difference and no one has turned their power beyond the legal limit.
The Procaster has had better range results than the talking house WHY? Lets look at the antenna. The Procaster has an aluminum antenna (Not stainless steel) remember aluminum has a better electrical conductive characteristic compared to stainless steel. Look too at the Procaster's antenna mount the antenna screws right into the transmitter's chassis a direct contact design. Transmitter efficient circuits make the difference too.
The Rangemaster went further with their loading coil system and some folks have displayed far better range with the Rangemaster than the Procaster. So we start to see why these transmitter's are designed to go outside on a pole and not in the house.
RF Feedback Issues and the RF not going to the antenna due to the ground planing effect of audio cable
Again while my broadcast engineer friend set up the station for me we talked about the danger's of RF feeding back through your cables and back into your audio equipment. For one you can burn your stuff out if excessive RF feeds back. In Robert's system (My engineer friend) we use a Bluetooth Audio transmitter which has a little antenna on it. Its plugged into a USB power supply and has a standard headphone jack on it so we use a patch cord from the audio processor to the Bluetooth transmitter. This keeps all of the transmitter's power up at the antenna and not feeding back into my audio leads causing lose of range and harmful effects to my audio processor, and computer and in house electronics.
Some of the AM hum some of you experience is caused by cable inductance remember AM follows long cables. This is why if you were to ground your system to the utility pole in many cases your signal will have a piggy back effect and travel. Ground radials can sometimes help (or hurt) your range if in certain situations the signal gets sucked into the wrong direction where there is no audience. Sometimes you want a 360 pattern and not a beam pattern.
Low Power is fickle and does not always follow the same rules as Full Power transmitters
For an experiment we tried a CB ground plane design whereas we had a hot element and then several ground plane elements. You'd think the range would soar for MILES right? Wrong it sucked wind. I barely made it to the 7 11 and then the signal faded out and was unusable. Trust me Robert and I spend hours on this station before we got it right (for my location). As we saw the idea of multi ground plane elements did not in any way increase the range. Lots to learn from this as there went the CB ground plane design for increased range.
Monopole design did work better as the range was far better with aluminum than with galvanized steel as he first made the same antenna design out of. When we went back to the drawing board and used a monopole made of aluminum we saw the increased range with an Album Rock quality signal with the range I told you about.
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Post by Boomer on Jun 15, 2018 13:04:27 GMT
The Legacy's post just goes to show that radio engineering can be complicated, and you can't stop learning about it and trying different things.
I hope you get to do carrier current too, Legacy, possibly with a low band transmitter on the other end of the dial. Yeah, with your station expenses recently it might not be the time, but you could keep it in mind.
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Post by thelegacy on Jun 15, 2018 18:53:31 GMT
Yes I took a portable radio out to see what it would do. I used a Grundig 450dlx and I could hear the station one point three miles away although at one point three miles it was very faint you could still hear the song and know who was singing it but it would do far better on a car radio I guarantee that. Then I took it inside the building and I could not hear it at all at one point three miles.
Now if I were to do carrier current and neutral injection it might be heard inside the building on a regular portable radio like a Grundig or the sangean or Tecsun maybe the Radiosophy HD-100.
I may have to try and save up and do 2 transmitters one for part 15 Section 219 which is the one I've got and do another one for part 15 section 221 but do that somewhere else on the dial maybe down at the low end. Maybe the middle end somewhere to I don't know there's not that many blank frequencies on that part of the band. It may become a choice that I have to make either carrier current or antenna and leave it at that.
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