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Post by Deleted on Feb 28, 2017 1:35:46 GMT
Big Talker Link Now In ServiceThank you for your patience. The Big Talker Page has now been brought over from our old website and installed in our new Private Server from deep inside the Internet Building. KDX Big Talker Shortwave Transmitter
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Post by Deleted on Feb 28, 2017 20:08:21 GMT
Part 9 - KDX AM Carrier Current
With LPB equipment obtained by auction KDX began carrier current experimentation several years ago, I'd have to look it up, maybe 2010.
An LPB AM 2-20 Transmitter, adjustable from 2 to 20 Watts together with an LPB TCU-30 Coupler got us on the frequency for which the transmitter was tuned, something like 540 kHz.
At first trying the standard arrangement of feeding into the 240 VAC line did not do well... the standing wave was dangerously high and refused to adjust lower.
The second try employed the neutral injection method and tuned perfectly, but we were directly adjacent to a local station and needed to re-locate to a frequency with better clearance.
970 kHz ended up being the magic number which required changing the output capacitors and re-winding the toroid donuts, putting us on the air with a strong clear signal which covered almost the exact same area as the SSTran AMT5000 with its antenna.
As happens, one day the transmitter was limp and refused to fire up which has been traced to a burned-out diode probably due to a bad electrolytic somewhere in the voltage path.
Like everything on our priority list at Worldround Radio the repair is moving slowly.
We spent a week preparing a purchase order to replace every electrolytic and need only to place the order.
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Post by Boomer on Mar 22, 2017 1:10:01 GMT
That seems like it will be a good size project to replace all the capacitors, but it does get warm inside those. I have the TX-5 and keep the cover off. My power diodes run hot too, on the board.
Let us know how it goes. Carrier current is such a forgotten technology that I love it!
Boomer
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Post by Deleted on Mar 22, 2017 1:25:27 GMT
Hey Boomer
Ever since you have been posting good results with the Greek AM Carrier Current Transmitter I have been thinking about getting one, even though I could just fix these LPB transmitters.
I'd like to keep my CC station reliably up and operating so that mystery listeners can find it more than every few years.
Your job is to talk me into it or out of it. It's up to you.
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Post by Boomer on Mar 22, 2017 11:40:31 GMT
Ah, but that's Dood, the real carrier current guy, I'm the cheapskate with LPB's TX-5, 5 watt transmitter with the crystal, the old school technology, literally, it's from SEMO college. I wish I had the Greek unit, it seems like a Cadillac.
In my opinion, I'd start with what you have and go with that, just to get on the air, then think about an upgrade if you think you need it. LPB is out of business, but I think their transmitters are great!
I like to use mysterious ways to get the signal out, like carrier current, it's kind of fun to think that the electrical lines are being energized by your radio signal. It's stealth too, you look down the street and everything looks ordinary, no antennas to be seen, yet a high frequency AM signal is piggybacking on every line you see and trickling into homes. With all of the equipment inside the house, I think it's safer too, no outdoor antenna to weather, to pick up static electricity or get zapped by lightning.
Boomer
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Post by End80 on Mar 22, 2017 12:26:11 GMT
I wish cc was as clear cut to comprehend and install as free radiating is. Although I get the concept, actually putting experimentation into action is as vague to me as what's in a Twinkie.
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