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Post by jimhenry2000 on May 6, 2017 3:43:19 GMT
This may not be the most recent thread about this, but the enclosure and transmitter are still on my bench. The AMT-5000 is installed via Velcro in the enclosure and the Cat5E STP (150 feet) is wired to J5 on the xmtr. The 102" whip is mounted to the enclosure and wired to the xmtr. If I get the time Saturday I will connect the other end of the STP to the PC output. If it works then I will peak the RF output again and re-mount the xmtr outside on my 25 foot telescoping fiberglass tower. Previously at its best I got about a mile of good coverage when running through 150 ft. of coax so I am hoping for much better results getting rid of that coax. This is the enclosure I plan on using.
Drill holes to feed the power and audio cable, those entries aren't exactly weatherproof on the Rangemaster either, but those holes are located on the underside so there's little chance of rain or anything getting in there anyway. I suppose you could use silicone to seal it after you run the wires.. but I never did and have not experienced any ill effects in years of use. Besides, it seems the little bit of ventilation the holes provide is probably a good thing.
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Post by Deleted on May 6, 2017 13:17:25 GMT
Incomplete Description
JH said: "the Cat5E STP (150 feet) is wired to J5 on the xmtr."
The J5 has two different attachments... power voltage and mono audio (balanced). Which one of those is your Cat5E STP attached to?
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Post by jimhenry2000 on May 6, 2017 22:24:49 GMT
Mono audio. At least I think so. The PC output is going to the last 2 contacts on the right of J5, with the STP cable's shield connected to the ground terminal (3rd contact from the right). If that doesn't work I'll connect the output to the consumer audio input jacks. If neither the connections to either the consumer audio inputs or J5 won't work coming straight from the PC then I'll have to figure out to use that amp you suggested, and find a power supply for it. Incomplete DescriptionJH said: " the Cat5E STP (150 feet) is wired to J5 on the xmtr." The J5 has two different attachments... power voltage and mono audio (balanced). Which one of those is your Cat5E STP attached to?
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Post by Deleted on May 6, 2017 22:51:29 GMT
Audio Connections From PC to AMT5000
The audio output of the computer is stereo, consisting of two unbalance audio lines with a shared shield.
If you connect that the J5, which is a mono BALANCED input, there will be no harm, but very little audio because the left and right channels will go out of phase with each other and cancel.
The stereo unbalanced lines from the computer should go to the AMT5000 RCA jacks which provides a built-in mixer to convert stereo to mono.
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Post by jimhenry2000 on May 6, 2017 23:04:07 GMT
OK then but why does it (the 5000) expect two inputs from a mono source? Audio Connections From PC to AMT5000The audio output of the computer is stereo, consisting of two unbalance audio lines with a shared shield. If you connect that the J5, which is a mono BALANCED input, there will be no harm, but very little audio because the left and right channels will go out of phase with each other and cancel. The stereo unbalanced lines from the computer should go to the AMT5000 RCA jacks which provides a built-in mixer to convert stereo to mono.
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Post by jimhenry2000 on May 6, 2017 23:09:18 GMT
Disregard that but I just remembered I have a cable that might convert the stereo to mono. OK then but why does it (the 5000) expect two inputs from a mono source? Audio Connections From PC to AMT5000The audio output of the computer is stereo, consisting of two unbalance audio lines with a shared shield. If you connect that the J5, which is a mono BALANCED input, there will be no harm, but very little audio because the left and right channels will go out of phase with each other and cancel. The stereo unbalanced lines from the computer should go to the AMT5000 RCA jacks which provides a built-in mixer to convert stereo to mono.
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Post by jimhenry2000 on May 7, 2017 21:49:22 GMT
Attached are two photos of the cable plus RCA adapter I mentioned last night. Both ends of the cable are the same, a 3.5mm phone plug with 3 contacts. The RCA adapter plugs onto the 3.5 mm phone plug. I bought this at Radio Shack. I had one end plugged into the stereo output of a neat little FM radio tuner/MP3 player and the other end, with the RCA adapter, plugged into the auxiliary input of an antique console radio that of course did not cover FM. It seemed to work fine for that purpose. I was hoping to use it to combine the stereo output of the PC so I could use the balanced mono inputs on J5 (Aud+, Aud-, GND) but the RCA adapter obviously has just two conductors in the output. If I fed that into the STP cable and used the STPs ground (shield) lead connected to the GND contact, do you think that might work? Disregard that but I just remembered I have a cable that might convert the stereo to mono. OK then but why does it (the 5000) expect two inputs from a mono source?
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Post by Deleted on May 7, 2017 22:16:18 GMT
Following the Progress
Jim, this line you wrote is an example of why I'm not always sure of whether you understand some of the information you are given: "so I could use the balanced mono inputs on J5 (Aud+, Aud-, GND)"
So, what's the problem with your description? You are referring to "inputs" in a plural way, but the J5 offers ONE balanced mono input.
Another thing in this latest post about your alleged "stereo-to-mono cable", there is no way the two photographs convey any information about how the cable is actually designed... if it is simply a "Y" cable that combines two cables into one it is not a true stereo to mono mixer... but, if somewhere in the middle there are two isolation resistors (usually of 47k apiece, then it is a mixer, or, in other language, a "combiner".
IF the resulting mono is not distorted from shorting 2 low impedance lines into each other, the level is already too low to work properly with J5, which needs +4 db, fully 14 dB more level than the consumer outputs provide, which may give you a very low modulation level from the AMT5000.
Can you connect an unbalanced line to a balanced input? Sometimes adding a wire from the (-) audio terminal to ground will unbalance the input... but in other circuit designs you would simply attach the shield to ground and the center conductor to (+), but I'm not sure which way you'd do it with the AMT5000.
Safety tip: have the transmitter turned OFF when connecting long wires to it's terminals... long wires can carry a static buildup that may potentially damage solid state devices.
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Post by jimhenry2000 on May 7, 2017 23:19:07 GMT
Carl, Perhaps I should have said TERMINALS instead of INPUTS. According to my manual it says: "A Professional Audio Mono source can be connected via standard shielded twisted pa(i)r cable to three adjacent screw terminals labeled GND + AUD - on connector block J5 on the board." Later on in the paragraph it says this input is "suitable for long audio cable runs of hundreds of feet". So, while I'm really not confused about the input to the transmitter, I guess I am confused in that it makes no mention of the need for an amplifier at the PC end or that this input requires +4 dB to drive it, at least I don't see it mentioned in this section of the manual. I don't doubt you at all, just explaining why I thought I'd try it without the amplifier first. Also you are right about not enough info in the photos. The 1st contact of the phone plug connects to the center contact of the RCA adapter. The 3rd contact of the phone plug connects to the outer contact of the RCA adapter, and the 2nd contact of the phone plug connects to nothing on the RCA adapter. The resistance of the connections from the 1st and third contacts on the phone plug to their corresponding contacts on the RCA adapter is each 0.8 ohms, so now I understand that it won't work for this purpose. I had no problems with it connecting the FM tuner/MP3 player to the antique console radio because I don't listen to music, just news, talk, and audio books. Following the ProgressJim, this line you wrote is an example of why I'm not always sure of whether you understand some of the information you are given: " so I could use the balanced mono inputs on J5 (Aud+, Aud-, GND)" So, what's the problem with your description? You are referring to "inputs" in a plural way, but the J5 offers ONE balanced mono input. Another thing in this latest post about your alleged "stereo-to-mono cable", there is no way the two photographs convey any information about how the cable is actually designed... if it is simply a "Y" cable that combines two cables into one it is not a true stereo to mono mixer... but, if somewhere in the middle there are two isolation resistors (usually of 47k apiece, then it is a mixer, or, in other language, a "combiner". IF the resulting mono is not distorted from shorting 2 low impedance lines into each other, the level is already too low to work properly with J5, which needs +4 db, fully 14 dB more level than the consumer outputs provide, which may give you a very low modulation level from the AMT5000. Can you connect an unbalanced line to a balanced input? Sometimes adding a wire from the (-) audio terminal to ground will unbalance the input... but in other circuit designs you would simply attach the shield to ground and the center conductor to (+), but I'm not sure which way you'd do it with the AMT5000. Safety tip: have the transmitter turned OFF when connecting long wires to it's terminals... long wires can carry a static buildup that may potentially damage solid state devices.
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Post by Deleted on May 8, 2017 0:21:29 GMT
Manual Specifications
The AMT5000 Manual page 40 Specifications --
Audio Input Level: Consumer Audio: -10 dBV, 0.316 Vrms;
Pro Audio: +4 dBu, 1.228 Vrms
The author (PhilB), by mentioning "Pro Audio" is speaking to the professional audio engineer who can be assumed to know how to achieve the necessary level. PhilB did not write a tutorial for the non-engineer who is trying to feed consumer signals into this input (J5).
For example, a typical professional might be coming out of a studio audio board or a rack mounted audio processor, all of which use +4 dB standard balanced audio.
The use of the Amplifier is my own recommendation since you are making the jump from a computer consumer audio source.
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Post by jimhenry2000 on May 9, 2017 1:59:33 GMT
Carl, OK I get it now. Thanks as always for your help and guidance. At this point I just have a few questions about cabling of the mixer circuit. From your previous instructions: Step 1: In a small mini-box build a stereo-to-monaural mixer (circuit will be identical to that employed within the AMT5000, except that we want it to exist at the computer end of the line, not at the transmitter end). a. using a stereo female 3.5MM phone plug (all metal construction preferred). We've already established this should be a male plug.b. cut a length of 3-conductor shielded audio cable to about 1'; So, is this a cable that is three conductors PLUS the shield, or TWO conductors plus the shield to = 3-conductor audio cable. If the latter I would think I could just use the cable I posted photos of last night, and cut the 3.5mm 3-conductor plug off one end of the cable, and solder the left and right cables to the 10k resistors. What do you think?C. connect one end of 1' audio cable to the stereo male plug: tip = left signal; ring = right signal; ground tab = shield; Understood.E. To the left conductor of the 1' audio cable attach 1-end of a 10K 1/4 watt resistor; to the right conductor of the 1' audio cable attach a 10K 1/4 watt resistor; connect the other ends of both 10K resistors together, (stereo to mono mix is thus achieved); Understood.F. Cut a 1' piece of 2-conductor audio cable. Attach the center conductor to the junction of the 2 10K resistors; attach the shield of this audio 1' audio cable to the shield from the 1' 3-conductor audio cable from Step A; pass the 1' 1-conductor audio cable through a hole in the small project box and attach it to the RDL Line Amplifier linked in the next step; This might be the most confusing for me. Remember as I have admitted that I am not and have never been an audiophile. What is 2-conductor audio cable? Is it what is commonly known as "speaker wire"? From your description it sounds like that it has just a center conductor and a shield conductor. Is that correct and if so what might it likely be called at a store? Finally, you reference a 1-conductor audio cable? Is that actually the two conductor audio cable you referenced earlier?
If you can answer these that will at least get me started. If I should have to change from the included wall-wart supply via the outdoor 120vac line, to POE, well I have a bunch of POE power supplies on hand, in addition to various wall warts that I could use to feed power over the other 2 pair on the STP cable, so I'm sure I could come up with something but for now I'd like to try the 120vac line I ran and just power the 5000's wall wart INSIDE my outdoor enclosure. Additionally I will read the specs on the RDL line amp and determine if I can use a power supply that I already own, or purchase one from the manufacturer. Again, thanks so much for your help. Jim
Manual SpecificationsThe AMT5000 Manual page 40 Specifications -- Audio Input Level: Consumer Audio: -10 dBV, 0.316 Vrms; Pro Audio: +4 dBu, 1.228 VrmsThe author (PhilB), by mentioning "Pro Audio" is speaking to the professional audio engineer who can be assumed to know how to achieve the necessary level. PhilB did not write a tutorial for the non-engineer who is trying to feed consumer signals into this input (J5). For example, a typical professional might be coming out of a studio audio board or a rack mounted audio processor, all of which use +4 dB standard balanced audio. The use of the Amplifier is my own recommendation since you are making the jump from a computer consumer audio source.
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Post by Deleted on May 9, 2017 11:24:31 GMT
Response to Jim's Giant Questionaire with Red Colored Questions
Today Jim I will draw a diagram which will make it easier to communicate than words, but of course there will also be words and arrows pointing to the illustrations.
Keep your eye on this Outdoor Enclosures thread for the diagram!
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Post by Deleted on May 9, 2017 21:46:54 GMT
Getting OrganizedThat's strange, I would have sworn my scanner did legal size pages, but it's slightly short by a couple inches. Anyway, most of my drawing fits and I added the other end of the page so it can be cut together. SCHEMATIC DRAWING HOOKING UP LINE AMPAND... the power supply for the RDL Line Amp is here RDL Power SupplyI anticipate being asked why the resistors in the mixer circuit are different than the 10k resistors used in the AMT5000 mixer. The AMT5000 mixer circuit consists of more than those 2 resistors which further isolates the AMT5000 inputs from loading the input sources. Our mixer is simpler, and the line amp gain will absolutely make up for the change. You can order the power supply from markertek.com
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Post by jimhenry2000 on May 10, 2017 2:54:05 GMT
Carl, Thanks again. I have ordered the PS and printed the drawing. I'm not really surprised at the change from 10k to 47k resistors as I read 47k in some other thread somewhere. In any case I should have plenty of each in my parts drawers for restoring antique radios. I'll probably use 1/2w resistors instead since that's generally what I use and I'm sure you know that's not an issue. In the drawing I see no references to "2-conductor" and "1-conductor" audio cable as per your initial instructions, just 3-conductor. Am I reading that right? My vision sucks and I could easily miss stuff. Jim Getting OrganizedThat's strange, I would have sworn my scanner did legal size pages, but it's slightly short by a couple inches. Anyway, most of my drawing fits and I added the other end of the page so it can be cut together. SCHEMATIC DRAWING HOOKING UP LINE AMPAND... the power supply for the RDL Line Amp is here RDL Power SupplyI anticipate being asked why the resistors in the mixer circuit are different than the 10k resistors used in the AMT5000 mixer. The AMT5000 mixer circuit consists of more than those 2 resistors which further isolates the AMT5000 inputs from loading the input sources. Our mixer is simpler, and the line amp gain will absolutely make up for the change. You can order the power supply from markertek.com
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Post by Deleted on May 10, 2017 3:03:52 GMT
Number of Conductors
The question: "In the drawing I see no references to "2-conductor" and "1-conductor" audio cable as per your initial instructions, just 3-conductor."
I suspect that I have not used consistent language to describe the number of conductors in each of my posts.
There are center conductors and the shield is a conductor.
In the short unbalanced line from the computer to the mixer there are "two cables in one" since the left and right channel each have a center conductor sharing a common ground-shield conductor; 3-total conductors.
From the mixer to the Line Amp is a mono cable with 1 center conductor and the ground-shield conductor; 2-total conductors.
From the balanced output of the Line Amp is a two-center conductor (+)(-) mono balanced with ground-shield for a total of 3-conductors.
If that's confusing I'll be out of town for about 3-years, all my calls will be taken by End 80 or Mark.
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