Well, I'm giving up on this device that I found on e-bay as an abject failure. I just received another transmitter that supposedly fixed the problem of terrible distortion (at any output volume level from a line level source, and at any setting of the device's modulation control) - it was supposed to have occurred because I got sent the wrong transmitter by mistake (that was set to take phono input).
To make a long story short, it didn't fix the distortion (at least with the output from my computer sound card). I'd like to hear if any other purchasers have received a 'fixed' transmitter that works, but I certainly can't recommend the product based on my experiences.
I'm not really knowledgeable enough to look at the circuit to fix it myself, so I'll try a few other things, such as attenuating the input signal, some other devices as input (such as a CD player) but I don't hold out much hope.
And just for a lark, I attempted hooking up a record player (yes I still have a few kicking around) to the inputs of the first transmitter I was sent, and it still had the distortion.
Live and learn.
Artisan, if you can show a schematic of the transmitter there are several here who have designed a shortwave transmitter, and also those who have designed transmitters in general.
We would love to size up the situation and post reactions.
Just add a notice that "This schematic is for professional educational consulting purposes only and cannot be distributed without permission of the copyright holder".
Thanks Carl. I didn't get a schematic from the manufacturer, but I might be able to cobble something together. I'd even be willing to send you one of the transmitters (or anyone else that would be interested) to look at to see what's going on.
However, right now, I'm too frustrated with this (and some other Part 15 things) to attempt to do the schematic now. Perhaps in the future. I know that several other people purchased this transmitter, and maybe they're more technically inclined on the electronics level to do that.
Thanks for the offer, though.
Here's some more info re my testing.
The thing still isn't working properly. The first one I got required the modulation control to be almost fully set to work, but it did work with a portable CD player (with horrible distortion).
The new one now has had its input desensitized, admittedly - but instead of getting rid of the distortion, now you don't get any signal at all from the CD player.
I hooked the transmitter up to a portable cassette player's line out - again, no signal. When I hooked it up to the headphone jack and cranked the volume, I got a signal, but it was distorted. However, if I reduced the output to where the transmitter was barely getting any output, I finally got a clean signal. But I could barely receive the signal a few feet from the antenna. To get any sort of range, you have to crank the volume, which gives you distortion. Catch 22.
I hope the others that are getting their 'new' transmitters have better results. The builder claimed to have tested out my transmitter with a CD player, but I doubt that was the case. This is hardly, at least in my eyes, a finished product. I suspect with a little more tweaking, it could be fixed, but I'm giving up for now.
What is the policy at eBay when the customer is totally dissatisfied?
Is it an "as is" sale, where you must keep whatever they send?
Since the transmitter does do something it seems like it could be "corrected" in some way, but it makes you wonder how someone could offer a product that cannot perform as expected.
First, being sent "the wrong version" seemed strange, although the exchange managed to delay things until now, when "the correct version" turns out to be no better.
I think there's a way to post complaints on eBay, for whatever that's worth.
There are probably other unhappy customers.
I suppose anyone who gets this transmitter "new"
out of the box should maybe try it with a dummy
load first.
I built one of the 13.560 MHz transmitters from Carl's
website. (The Big Talker.)
There were lots of instability and distortion problems
until I got it right. Just one little part or even the wrong
placement of that part could make a difference.
Anyway - all of the initial tests on my homemade rig were done with a dummy load.
Somewhere on a transmitting blog I remember somebody saying that what works
great on the test bench might be really messed up once you get it into the
transmitting shack and put it on an antenna. Also, I'm figuring the RF out on this
thing was designed to see 50 ohms. So maybe the antenna has to be a full
sized dipole. It probably shouldn't be that critical, but maybe it is.
Bruce, The Dog Radio Group
There are lots of ways to attempt to correct problems on e-bay. I'm just trying to figure out which way I want to go. I knew it was a gamble since this is a 'homebrew' type of product, but at least expected it to work somewhat.
Bruce, I'm using a 50 ohm antenna with about a 1.2:1 SWR, so I don't think it's the antenna's problem.
I'd just like to find out if anyone else here who bought the transmitter has had the same problem the 2nd time around. Perhaps I've just been unlucky. Twice.
This is disappointing. It would be nice to have another plug and play transmitter in our Part 15 arsenal but not yet.
This is one of those "gotta ask" questions: Are you sure it is not the receiver? Overloaded, mistuned, etc.
Things are tricky at this frequency which is 8 to 12 times that of the AM BCB and it may not be worth the effort to try to fix this, especially lacking a schematic. Your choice, but I would ask for a refund and return it.
Neil
Well, I can't fault the builder of the radio for effort.
He has just sent me ANOTHER transmitter, free of charge, with a redesigned modulator circuit. Obviously, I (and others) are helping him debug this thing, but I'm OK with that, as long as I eventually get something that works. Let's cross our fingers.
A product sold before it's time?
That's a new concept.
I am developing a wine, but so far all I have is water. Send your order and I'll catch up with you later.
Not intending to interfere with invention, but this is an interesting case.
Artisan must be credited with being a philanthropist for sponsering new development.
Stand by for the next episode.
If I had the money, I might do it, too.
To help this guy get the bugs out is
good for everybody.
Best Wishes and good luck. I'll be
crossing my fingers.
Bruce, The Dog radio Group
Well, I'm getting this next one for free. And overall, I haven't spent all that much money. It's just my darn orneriness - I want to see this thing thru and get something that works.
I'm one of the other purchasers. My 1st transmitter suffered from horendous distortion. I too, was promised a 2nd transmitter, since my first one was also "designed to work with a phono cartridge output and sent to me by mistake." I too was told that my new transmitter would be designed for a line-level audio source, and would be tested for proper operation before it leaves Turkey. (but couldn't be sent until I returned the 1st one) On 2/28 I retruned the 1st one. On 3/18 I recieved an e-mail stating that my "new" transmitter had been tested and shipped. I don't expect it to arrive until around 4/5.
Now I'm reading where even the new replacement transmitters have the same distortion problems! Bummer. Since it takes 2 1/2 weeks to send a package each way between here and Turkey -- I think the problem we're going to run into with E-bay, will be the amount of time that has past between the sale and our final dissatisfaction, while we send these things back and forth and try to get them working right.
Anyway, I will also post my results when transmitter #2 finally gets here. Good luck to all! Looks like we may need it!
It arrived sooner than I expected, but that's where the good news ends. My "new" transmitter suffers from exactly the same faults as Artisan's "new" one. No need to elaborate any further -- it's doing EXACTLY the same things Artisan's is doing, when I make all the adjustments to the input levels, and all the changing around to different audio sources. EXACTLY the same results. I guess I'll ask for a 3rd transmitter as well and see what happens before I complain to E-bay. At this point, I honestly don't believe the builder knows how to make AM modulation work in this transmitter. Seems he's grasping at straws. We'll see. 3 strikes -- Yer out! I'll try to write up a schematic while I wait, although I've never done that before.
Many thanks to rlkocher and Artisan for bringing this subject alive.
It seems that shortwave could be a splendid expansion ground for Part 15ers, if only the available technology would arrive.
The guy in Greece has the right idea, even if he's too soon on the market with an imperfect piece of work.
It would be great if this escapade can be followed all the way to a solution.
I looked for these transmitters on eBay and didn't see anything, so I guess the supply is spent.
In the U.S. (correct me if I'm wrong) we would not be allowed to sell fully built SW transmitters unless they were properly certified, the best we could do is offer kits, which I think might be a bigger effort than pre-building the equipment. Composing and printing manuals and including all the right parts takes a village (to borrow a phrase).
Would-be transmitter scofflaw.