421
Huh? / Re: If anyone is looking for a radio show idea...
« on: October 04, 2019, 0554 UTC »
Facebook.
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Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night
We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations.
Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.
Since when was the government interested in saving money?
..Just a thought.
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Nope, tradition high level PWM with phase modulated carrier drive. All the pre-correction is done in the exciter. The old transmitter was linear all the way from 0dBm to 400W carrier, at about 30% efficiency. I'm trying to get away from that...
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Sorry for the late reply. My PA is designed to look into a 50 ohm balanced load. The output transformer's only job is to convert the 50 ohm unbalanced load to something the PA can use. electrically, it is configured just like the last picture you posted showing a BLF188XR or similar pallet with a 4:1 output transformer. One of the benefits of CMCD, like class E is the voltage multiplication of the PA; peak output volts 3-3.5x supply volts. This makes a 1:1 output transformation practical with the high voltage devices we have now.
I would guess the reason behind the split 4:1 output balun topology used on all the CMCD guy's stuff is the ease of construction. I think it would have practical benfits too when dealing with higher currents encountered at power with large impedance transformations. The more ferrite in the system, the less likely it is to saturate and cause problems. FWIW, I did notice the output transformer in my transmitter running warmer when I converted it to a standard transformer output topology. This is most likely because there is now twice as much voltage across the windings as before, since I reconfigured the transformer to voltage mode from current mode.
When deriving your PA voltage supply from the AC mains, there is no longer a safe signal ground. All signals going into and out of the PA have to be isolated from ground. This is the next step in my design evolution and adding isolation to the PA output is one of those steps. It also means that the modulator and RF drive will also have to be transformer coupled or more likely, optically coupled through the use of photocouplers.
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422
The RF Workbench / Re: Stretchyman 40w GaN TX is sick
« on: October 03, 2019, 2126 UTC »
These modern transmitters have a lot in common with switching supplies...both operate in switch mode (class D or E) and the waveforms feeding the power devices have to be right or the smoke comes out. I too spent a few years working on SMPS's exclusively and the first thing you did before bringing up the mains was testing the drive waveforms. If they don't look right, your mosfets won't last long.
I understand the frustration, but you need the have the tools and know-how to work on these things. Its not like the tube days when you could swap a tube or two and see what happens. More often than not in solid state, you're greeted with pops, bangs, and puffs of smoke.
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I understand the frustration, but you need the have the tools and know-how to work on these things. Its not like the tube days when you could swap a tube or two and see what happens. More often than not in solid state, you're greeted with pops, bangs, and puffs of smoke.
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423
For Sale / Wanted / Barter / Re: Wanted TPA3116D2 Amplifiers
« on: September 30, 2019, 1829 UTC »
Your first mistake was designing something around a third party board from the orient... One-off are the way those folks roll, usually around someone else' design. At this point your choices are either drill new holes in the case to accept a different board, or roll your own and move on.
Simple!
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Simple!
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424
For Sale / Wanted / Barter / Re: Wanted TPA3116D2 Amplifiers
« on: September 30, 2019, 0636 UTC »
Why don't you just roll your own? A slack handful of parts and the IC is all you need. The datasheet provides the application circuit. You would even build it into your existing exciter board.
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425
Shortwave Broadcast / Re: Voice of Korea - transmitters
« on: September 28, 2019, 0812 UTC »
an I/Q recording would be helpful in determining the nature of said beast. AMSS might sound similar to this as well.
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426
Shortwave Broadcast / Re: Voice of Korea - transmitters
« on: September 27, 2019, 0444 UTC »
Do you actually see carrier frequency shift on the waterfall or spectral display? It sounds to me like slow speed data, or background noise in their audio chain.
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427
General Radio Discussion / Re: Proposed Termination of USCG Medium Frequency NAVTEX
« on: September 27, 2019, 0433 UTC »".....perhaps they could increase efficiency in the tx and antenna system to save money if that was the priority? Of course, new, higher efficiency equipment's going to take money too."
Since when was the government interested in saving money?
..Just a thought.
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428
The RF Workbench / Re: I need some help writing some arduino code for RS232
« on: September 22, 2019, 1820 UTC »
The control point and transmitter will be separated by some distance, and a RS232 link exists between those points.
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429
North American Shortwave Pirate / Re: XFM 6275 AM 0115 UTC 22 Sep 2019
« on: September 22, 2019, 0212 UTC »
I wish 60 meters was possible, but I only have the 48/43M antenna here tonight.
Band switch will be happening soon, but with the amount of storm noise out there tonight, 73M might be unlistenable anyway.
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Band switch will be happening soon, but with the amount of storm noise out there tonight, 73M might be unlistenable anyway.
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430
The RF Workbench / Re: Class D output match
« on: September 16, 2019, 2018 UTC »Oh for Cwuam surely a DtoA and a linear...?
Nope, tradition high level PWM with phase modulated carrier drive. All the pre-correction is done in the exciter. The old transmitter was linear all the way from 0dBm to 400W carrier, at about 30% efficiency. I'm trying to get away from that...
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431
The RF Workbench / Re: Class D output match
« on: September 16, 2019, 1938 UTC »
Until it can do cquam or other modes, no thanks.
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432
The RF Workbench / Re: I need some help writing some arduino code for RS232
« on: September 16, 2019, 1440 UTC »
A couple of people sent me some links that were helpful, and I'm also working with another guy on here to further develop some of the transmitter control system.
Thanks all,
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Thanks all,
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433
The RF Workbench / Re: Class D output match
« on: September 16, 2019, 1438 UTC »I think 1:1 is probably fine. It looks like you have the output balun as your only matching. I don't know if that's true or not. I'm not an electrical engineer so I don't understand the "isolated output line derived B+" part.
I see some amplifiers that do the matching with one balun as you do, but I've seen others (especially VHF amps) that use three baluns. One for each side of the amp and then one final on the output. Is there an advantage to this?
Really all I am trying to do is get my efficiency up above 5 MHz. Everything on my PCB has been optimized (no long traces, plenty of caps, good groundplane, good waveforms). I've narrowed the problem to the output match and I think it is the fact that I'm using wire on my output balun instead of coax. I'll try what you did first, redhat, with the coax because that shouldn't be hard. Then Ill try a T200 if it still doesn't work.
Sorry for the late reply. My PA is designed to look into a 50 ohm balanced load. The output transformer's only job is to convert the 50 ohm unbalanced load to something the PA can use. electrically, it is configured just like the last picture you posted showing a BLF188XR or similar pallet with a 4:1 output transformer. One of the benefits of CMCD, like class E is the voltage multiplication of the PA; peak output volts 3-3.5x supply volts. This makes a 1:1 output transformation practical with the high voltage devices we have now.
I would guess the reason behind the split 4:1 output balun topology used on all the CMCD guy's stuff is the ease of construction. I think it would have practical benfits too when dealing with higher currents encountered at power with large impedance transformations. The more ferrite in the system, the less likely it is to saturate and cause problems. FWIW, I did notice the output transformer in my transmitter running warmer when I converted it to a standard transformer output topology. This is most likely because there is now twice as much voltage across the windings as before, since I reconfigured the transformer to voltage mode from current mode.
When deriving your PA voltage supply from the AC mains, there is no longer a safe signal ground. All signals going into and out of the PA have to be isolated from ground. This is the next step in my design evolution and adding isolation to the PA output is one of those steps. It also means that the modulator and RF drive will also have to be transformer coupled or more likely, optically coupled through the use of photocouplers.
+-RH
434
North American Shortwave Pirate / Re: Wolverine Radio / WDDR 6935 USB 2341 UTC 14 SEP 2019
« on: September 15, 2019, 0130 UTC »
9/15/2019 6935KHz USB 4KHz audio. Tuned in at 0124z to hear 'Heavy Low' by We Hunt Buffalo...I really like the grove in that tune! WDDR ID by OM @ 0130z, about S9 on the loop and the WinRadio G31DDC.
The Old Professor wants to hear 'Hurdy Gurdy Man' by Donovan.
Thanks bud!!
0206 Rush 'Working man' Love It!
0220 B52's 'Deadbeat Club' very nice!
0237 Rod Stewart 'Dirty Old Town' requested by Skipmuck
0240 WDDR on the mic. Into Jackie Wilson Said by Van Morrison. Signal has been pretty stable over the last hour, just some minor shallow fades with peak approaching S9+10dB on the loop.
0311 The Who 'Eminence Front'
0321 Rolling Stones 'Gimme Shelter' I have to run out for a bit and feed the furries, but I'll post an aircheck here if your gone by the time I get back.
I've been feeling some Genesis...'Tonight Tonight Tonight'
Aircheck https://drive.google.com/open?id=14zV-u3SntrbTBr01oRyarz_ZRSRoIWdK
Thank You for the show!
+-RH
The Old Professor wants to hear 'Hurdy Gurdy Man' by Donovan.
Thanks bud!!
0206 Rush 'Working man' Love It!
0220 B52's 'Deadbeat Club' very nice!
0237 Rod Stewart 'Dirty Old Town' requested by Skipmuck
0240 WDDR on the mic. Into Jackie Wilson Said by Van Morrison. Signal has been pretty stable over the last hour, just some minor shallow fades with peak approaching S9+10dB on the loop.
0311 The Who 'Eminence Front'
0321 Rolling Stones 'Gimme Shelter' I have to run out for a bit and feed the furries, but I'll post an aircheck here if your gone by the time I get back.
I've been feeling some Genesis...'Tonight Tonight Tonight'
Aircheck https://drive.google.com/open?id=14zV-u3SntrbTBr01oRyarz_ZRSRoIWdK
Thank You for the show!
+-RH
435
Equipment / Re: Test Equipment for First Time Build
« on: September 13, 2019, 0601 UTC »
In the beginning, I wouldn't bother with a spectrum analyzer. They are easily damaged (done it) and for most of the stuff your interested in will be overkill. An SDR with sufficient padding will serve you needs fine for now. A VNA is great for filter tuning and antenna design, I don't leave for a show without one now.
For the beginner, a Weller or Hakko basic station is all you'll need. The Hakko is probably better for SMD work with the right tips. I've had Metcal irons in the past and used them professionally as well. Used, they don't seem to hold up well. The tips are also very expensive, and second hands ones are of dubious quality. Hakkos are cheap, and amazon has all the tip choices your likely to need.
A function generator is worth having. I have the DG1022 from Righol. It produces beautiful AM waveforms for calibration, which is actually how I calibrate modulation monitors now. I also use it in the field as my carrier source on the HF transmitter until I get a DDS one built.
+-RH
For the beginner, a Weller or Hakko basic station is all you'll need. The Hakko is probably better for SMD work with the right tips. I've had Metcal irons in the past and used them professionally as well. Used, they don't seem to hold up well. The tips are also very expensive, and second hands ones are of dubious quality. Hakkos are cheap, and amazon has all the tip choices your likely to need.
A function generator is worth having. I have the DG1022 from Righol. It produces beautiful AM waveforms for calibration, which is actually how I calibrate modulation monitors now. I also use it in the field as my carrier source on the HF transmitter until I get a DDS one built.
+-RH