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I’m finally almost finished with construction of a Panaxis AM100. I know it may not be the highest quality transmitter, I’m just trying to use it as a proof of concept so that I can buy something better for work. So far the only real problems were finding some of the components, and receiving surface mount items from Mouser. Luckily I’m clever, and I also had one of the items in my junk box. So where is all this going…..
Well, the instructions were a little unclear about the function of some parts of the transmitter. Specifically what the variable capacitors were doing. Are they adjusting the circuit to match the final push/pull amplifier? Or are they matching to the antenna?
If they match to the antenna, what will happen if I use a tuning coil on the antenna like the design on the SSTran site? I’m still leaning toward the SSTran AMT3000 as a more permanent solution, so I’ll probably want to build the antenna to meet it’s needs so that changing the TX out will be easier (while up on the tower). So can I change the variable caps to a fixed value (suggestions on values), or just tune things as best as I can?
I’ll probably have the power supply and a very short inside antenna on the AM100 during work Thursday, hopefully I haven’t made any mistakes (so it won’t blow up and let the magic smoke out). And then I just need to play with it for a few weeks while I wait for the snow to melt. Then I can start the on ground testing, and finally move it up to the top of the tower for final testing before the end of the semester in May.
Any help with the above questions would be great, thanks.
Total posts : 45366I have a scan of the entire manual, but the tuning and operations pages are probably what you want.
Page 11 is here Page 11
Page 12 is here Page 12
Be sure and resize the browser window and remebr to click the image max button if you’re using IE
If you’d like the entire thing I can put it up
Enjoy!
Experimental broadcasting for a better tomorrow!
Total posts : 45366I actually have the entire manual, it’s uploaded in the library here.
Running on an old failed computer power supply with +10 and -10 volts and a 3-4 foot antenna I’m getting about a 2 foot distance tuned up at around 1640Khz. My osc. scope is not happy with the RF on the signal, so it’s a little hard to pin down the frequency. The big thing is it’s working, and I didn’t let out the magic smoke.
ANtenna load doesn’t seem to effect the setting for the capacitors, but I’ll be playing with this a lot more in the coming days.
Total posts : 45366Tuning the antenna has little effect on the output voltage. Tine to make a field strength meter so that I can see what’s going on.
Total posts : 45366The unit needs + and – 15 volts! At 10 volts it is 1/3 too low and probably wont work right. I would get the proper voltages to it before going much further with your testing. I went through this with another transmitter that was only a few volts low,it killed the performance totally! Regards,Lee
Total posts : 45366Yeah, it’s just barely working with those voltages, and worse is that they aren’t balanced… it’s +11.5 and -10 which from reading the instructions is probably making a very odd bias on the push-pull section (final output). I’ve got some +15 volt Li-ion batteries that we use with our DV cameras, I’m just going to rig up a proper power supply from 2 of those to give a better test. Though I will say that even with this mismatched powersupply, it’s working fairly well. I’m hoping to get back to it today after I finish putting some new gear together for our remote kit. Brand new Telos One hybrid (modem case size) and Beringer headphone amp to mount in a rack case so our students can take it away for sporting events. Just using an old Mackie VLZ1402 mixer with the above.
I’m also a little concerned about mounting it on our tower in light of the recent fine for the 30 meter ground wire.
Total posts : 45366It works a little better with the batteries, but I’m still only able to get about 5 volts output at the antenna connection (with no antenna). I’m working on tuning the coil to see how close I can get back to those 5 volts. I wish I was seeeing the 12 or 16 volts with no antenna like the book says. I keep thinking the two inductors may be the wrong value to run at 1640Khz since that kit was really designed for up to 1500Khz, so I might drop the frequency down to around 800 and see what happens.
Total posts : 45366This project is officially dead!
Total posts : 45366If it’s like my projects, they’re never really dead! You just need time to regroup.
And the bonus is, you can always tell the spouse you have to work on that project right now!
Total posts : 45366I’m sending it to someone that will use it, I’m done trying to convince the other people in our department that there is another option. If they want to try sometime in the future, they can buy me an SSTran kit. It’s under $250 including all the materials for the antenna.
Total posts : 45366Never mind,I responded to the wrong AM-100 thread
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