That's too bad - I was hoping that mine might just be an aberration.
I was told that the modulation section was redesigned and now works perfectly. We'll see. My third should be arriving in another week or so.
I wouldn't hold my breath. I informed the builder of my distortion problem with my 2nd transmitter just 2 days ago, and he didn't say ANYTHING about a re-designed modulation circuit. I got the same old song & dance: He says: "I tested it with a portable CD player and it sounded fine. I don't understand what could be wrong. Maybe it was damaged in shipping." Bull s***! The box has been barely bumped. Besides --- Are we to believe all 5 of the transmitters (that we know of!) were damaged in shipping exactly the same way?
To send it back again for "repair" would only cost me another $15+, and cause me to wait another month for another distortion box to arrive. So I'm not doing that. I could send it back for a refund, but that would also be another $15+ I've put into it, bringing shipping money spent to $47. The whole transmitter only cost 60.
I've concluded that the builder is "distortion deaf". The equivalent of an off-key singer being "tone deaf". The singer simply cannot hear that he's off key, so he can't correct it. And our builder simply cannot hear the distortion in his transmitters, so he can't fix it.
I have therefore also concluded that the best route to getting this transmitter fixed, would be to send it to someone who could take a look and see what's going on. Whoever could figure this out, could report their findings and their fix to this forum, and our whole group would benefit.
I could sent my unit to you today. I'm in no rush to get it back, as long as I get it back eventually. It already has the xtal for 13.560 installed, and puts a nice, clean carrier on that frequency....until you feed it audio.
I simply want what's best for the whole Pt. 15 SW movement. Any takers?
Yeah, I'm not holding out much hope.
But we'll see.
It is very tempting to me to say, "Ya, send them here! I'll poke around and figure something out!"
But I am very close after many years to actually being slightly smart: I am not the best for the job.
The "Big Talker" shortwave transmitter that was designed by members of part15.us and built by some of us, was mostly not designed by me. The true transmitter stages were designed by several other top radio engineers that you know from seeing their posts from time to time.
The only real contribution I made was to find, through trial and error experimentation, a modulation transformer that worked best for this particular transmitter.
Maybe there is some wise advice in life which says, "Don't invite packages from people only known casually," I don't know. Wisdom is a whole other story.
What I hope for is that one of the REAL engineers will cave in and dig around with this strange case of the ISM transmitters.
(What is "ISM?")
Well, you can throw my name onto the list of people who have had to send the transmitter back for the exact same reasons as the others here have.
I'm gonna go with rlkocher's 'distortion deaf' theory and just leave it at that. I now know based on what I just read here that when I get my repacement unit back, it will just be more of the same. So, I'll take it as another life lesson learned and move on.
When I saw a part 15 SW transmitter for only $60, I should have known. You know the old saying, if it looks too good to be true...
If I was in this poiition, I would take the board out of the
box and get it running into a dummy load so that every thing
is the same as it was.
Then I would get an audio signal generator and
put the ground output on a ground somewhere
on the circuit board.
Then I would take a probe with the audio
signal on it, and touch it to various places
on the underside of the board. You might
be able to get a signal somewhere in there that would
work, and you could vary the amplitude
any way you wanted to try to get the
desired effect. I suppose an isolation cap
would be a good thing to have at the audio
source lead.
If all else is lost, that's what I would try.
Will it do any good? Maybe yes,
maybe no.
Bruce, The Dog Radio Group
What is "ISM?"...Carl Blare
Abbreviation for "Industrial, Scientific and Medical" bands defined by the FCC and the International Telcommunication Union.
So I got my replacement unit...same problem.
There was also a rattling noise whenever I moved the unit around so I decided to pop it open to see what's going on in there. Well...let's just say I was less than impressed with what I saw. The board was just loose in there, free to bounce around and the way components were soldered over top of one another, I'm surprsed nothing hasn't shorted out. If I knew that that was all there was to this thing, I would have just built it myself.
Perhaps when things slow down in the summertime, I'll tinker around with it some more.
But to anyone thinking of getting one of these, just know that it isn't what I would consider to be a finished product.
That's a terrible discovery, Mr. 1580. A bunch of loose shoddilly connected parts.... that sounds like one of my failed experiments in the 1970s.
Uh!
We must press forward and improve something. We cannot give up.
Third time's the charm!
The last transmitter that I was sent with the redesigned modulator circuit works perfectly. And it sounds great! I tried it out at 12 volts with a portable CD player. Next up is hooking it up to my computer but I've misplaced my stereo 1/8 plug to mono RCA cable - when I find it I'll report on those findings as well.
I haven't done any range testing yet, but it now sure looks promising.
Thank you Artisan Radio for bringing hopes back up for this very curious shortwave transmitter from somewhere else.
If it truly succeeds we will all be very happy.
I have done some further experimentation with the new and improved radio.
While it worked with my portable CD player, the modulation control had to be cranked up the way up to hear it. I just plugged in my computer feed - the one I use for broadcasting over the Canadian equivalent of Part 15 FM - and it worked even better. This radio has obviously been designed to use computer sound cards (properly this time) as the primary source - I could crank the modulation all the way up and the signal got louder (with no distortion); it was also more solid than with the CD player with the modulation control at maximum. I could also crank it down and the signal got progressively weaker until it disappeared.
So now on to the next step - range testing, and attempting to ensure that I stay within the maximum field strength allowed on 13.560.
Good stuff!
We need good news, and this is it!
Upon hearing of Artisan's good luck with his third transmitter from Turkey, I have decided to give the builder another chance to make good with my transmitter also. I've been in contact with the builder, who says he "remembers what I did" with Artisan's transmitter, and promises to make the same modification to mine.
I will post results of my testing next month after I get it back. Wish us luck!
I was sure the 3rd time I got a transmitter from Turkey -- that this one would be distortion free. Especially since Artisan's 3rd transmitter came back sounding fine, and I asked the builder to make the same modification to mine.
No such luck. Distortion is as bad as ever no matter what I feed into it. I'm giving up --- it goes back for a refund.
What about the other 3 transmitters (that I know of) that were purchased by you guys on this forum, that also sound terrible? Have you sent yours back for a refund? Are you just eating them? Or what? I'd hate to be the only buyer demanding a refund, knowing there are other bum units out there. Apparently the only one that works right is Artisan's! So what's everybody doing?