I got the bug again. I ordered the sstran 5k on tues with the 2 day shipping. im hoping to see it arrive this weekend. I popped by the local surplus shops (weirdstuff.com and halted.com) and grabbed some "stuff" to build my new station. I managed to find some really awesome old health kit meters, a nice nematode weatherproof box, a 102" steel whip, and various components, ic's, pots ...
my plan is to build myself an audiO console. It should LOOK retro, but inside it has a few tl072's, and a raspberry pi.
If the build of the console and transmitter goes well, I have 2 friends who will let me stick transmitters and raspberry pis on their roofs and leech off the electric and Internet..
im using voscast.com for streaming, sending my studio output to voscast, then pulling it back down twitch the r-pi's, which then feed the transmitters.
Until I get the sstran, I won't know if I'm gonna need to stick a little amp in there or not.. I expect I will. Good thing I bought spare tl072's 🙂
im mostly posting because I'm waiting for the transmitter, and I'm bored. Yep.
I'm glad you were bored, mir, that is, I'm glad you posted.
Many of us will find the details of your construction to be very interesting, and I am especially pleased you are doing it with an AMT5000, a great transmitter. I am listening to mine right now.
I just noticed the title was "Strange" - thats what my ipad converted sstran to 🙂
Woot! My new amt5000 has shipped. This means I need to get some fire under my butt and get the audio console built. Hopefully, the console will work well, and I'll put the schematics up here. Maybe I should get them off the napkin and into a something more useful, then you guys can poke and prod and maybe we'll end up with something totally cool?
Ok - got the new transmitter, and last night I got through the resisters, IC Sockets, and Caps. I expect to finish this tonight.. easy peasy. Although, for me, trying to see the yellow on the resisters.. ugh.
It is all built and boxed in a waterproof housing.
I'm getting the mounting bracket "tooled" and the grounding done... maybe (maybe maybe) I can have it up and running today....
I will say; not being the mega-electronics genius that you guys are.. tuning the amt-5000 is a little daunting for me. Maybe I'm reading too much into the instructions.. but.. its really hard for me 🙂
During the first time tuning of the AMT5000 for someone new to the experience it takes time and patience to go over the instructions and become familiar with the process. This is typical of very professional serious-business transmitters, and the reason why not just anybody can be let loose with a station's transmitter knobs and meters.
I went through the tuning many times before I was confident about what I was doing.
I still get out the manual and re-read the many pages that describe the circuit, the tuning, and all the other guidelines. The jumpers get checked and double-checked.
After a few months of operation I tested to see whether the tuning had drifted and needed to be re-adjusted, and it was right on the mark, perfectly optimized, and did not need re-doing.
Sometimes I turn the power level down to minimum, which is about 56mW into the final RF stage, and I can still hear it everywhere I need to go.
Once, for a sneaky moment, I went to maximum power, which is about 356mW into the final RF stage, and found that the coverage was about the same as at 100mW, so I don't do that anymore.
Hmm.. so I have about 100 feet of Cat5E that I run from the tx to the house.
I know the thing is transmitting, because when I turn off the power, we go from hum to static.
However, I hear no audio that I am playing into the thing.
Also: The wall wart is getting REALLY hot. I know "use a real power supply" yadda.. whatever; I'm just trying to get tested before going final.
Any ideas?
The two things that need to get out to the transmitter are audio and power.
To comment on your audio situation, I would need to hear a description of what you are doing....
Are you sending audio on the Cat5E cable? I am only guessing, but I think Cat5E cable is like balanced telephone or data cable. To send audio on it the audio would need to be balanced: +, -, gnd.
If you send unbalanced audio 100-feet you would need shielded cable, but at that length you might suffer high end roll-off, which might not matter for AM.
And at the transmitter end you would need to convert from balanced-back-to-unbalanced to feed the transmitter with audio.
But all that is guess work because I don't know what you have.
As for power, all three of my SSTran transmitters have worked perfectly with their original wall-wart power supplies. And right now I'm going to go over and see how hot they are. I'll be right back.
O.k., I'm back. The wall-warts are all nearly cool, just slightly warmish. So you might have a power problem. Let's get to work solving it.
Question No. 2. Is your power also being sent on Cat5E cable? If so, you would have two Cat5E cables. Let me know.
Ugh.. soooo close. This is killing me. I have the whole sha-bang up and mostly working, i either get a horrendous hummmmmmm and no music, or very little music and no hum, or some combo of those things. I had my wife sitting in her truck about 1/4 mile away so we can get the fine tuning (or any tuning really).. and no luck.
Also.. as mentioned before; the wall wart is really hot.. like.. I had to hot-potato it once it was unplugged.
mir, I think you posted at the same time I did. Check No. 9
I use cat5 cause its what I have a lot of.. im not married to it.
I have about 60' from "studio" to TX. I am using a single CAT5e to get power and audio since the CAT5E is 8 pair. I use 2 for audio and 2 for power.
I am more than happy to go to OSH or Lowes and pick up whatever wire you suggest.
Here is my test setup:
Computer -> Powered Speakers (acting like a very low power amp) -> CAT5 -> TX
Wall Wart -> CAT5 -> TX
The antenna is the standard 102" steel whip from the local HAM shop
I am using pretty heavy guage wire from the ANT screw down to the antenna slug
Same for the GND
Grounding is using the power company ground for now, I have a couple of ground rods, and more heavy guage grounding wire I will use later.
This whole thing is on my roof (1 story house), on a 5' mast that is mounted to the crapper vent..
To use CAT5, Carl is correct, you are going to need some audio 1:1 transformers at each end or some type of balanced to unbalanced adapter.
A quick though more expensive way to accomplish this is to buy a couple audio ground loop isolators which contain the transformers.
The reason is, as Carl stated, you are using a balanced line but the powered speaker output and the transmitter input are both probably unbalanced in/outputs.
Most likely this is where the HUMMMMMMM is getting into the audio chain.
Otherwise, shielded coaxial audio cable might work.
Hi,
The walwart should not be hot, even barely warm. I have a feeling the AMT5K is drawing too much power. Check the orientation of the 4 silicon diodes in the power supply section. Make sure the bar/line on the diodes are in the right position. If one of them is backwards, you could end up with a half wave rectifier and a short during the other half ware.
Also measure the voltage on the board. You should have 5V and 12V. Is the voltage and current at the test points within the range in the manual ?
Andre
Things to do:
1) Check Diodes.
- while I'm at it, triple check the whole board.
2) Change the power and audio wire to ?? (rotor? 2 coax? Any particular ohm rating?)