Messages

376

The RF Workbench / Re: 3kw pep solid state amp 1.8-54 mhz

« on: February 12, 2018, 1728 UTC »

   Yes, still amazing solid state gear if you have the skill to complete it and the power supply, plus a driver. Not sure how much drive. Generally a fan helps the sink get that time down for broadcasting service

377

The RF Workbench / Re: Amplifier Topologies and Classes

« on: February 12, 2018, 1459 UTC »

 How much drive does the BLF 188 xr require? I note complete soldered on PC board units without driver and harmonic filter or power supply.
Thanks , just curious. Much amazing stuff available these days in RF

378

The RF Workbench / 3kw pep solid state amp 1.8-54 mhz

« on: February 12, 2018, 0154 UTC »

   When I was a boy I WAS IGNORANT in many ways, but could make an AM transmitter and in fact almost killed myself a number of times, HV KILLS.
But, here is a solid state 3 kw pep amp, which would need cooling fan, but with some amount of carrier in 41 meter band, and we would also need harmonic filter would make a 700 watt am transmitter. You figure which class D amp you want to series modulate or use the Heising method? Did I spell that right.
Its work for a technical person in a lab to complete the unit. Now, question was asked about class C vs E vs bipolar vs FETS.
I can't quite price everything here, but 3 kw pep would make a lethal rig driven with a ssb exciter.
Oh, naughty.. but there are many ways to make a transmitter work.. its a matter of choice, your needs, your skill level and pocket book. My gut feeling here is home brewing a kw am transmitter with class E, would be by far least expensive, but its also needs higher skill levels and lab equipment to adjust.

https://www.ebay.com/itm/3000-Watt-PEP-LDMOS-RF-Power-Amplifier-1-8-54-MHz-HF/222707564979?hash=item33da67c1b3:g:wjQAAOSwNNdZ1ToL

379

The RF Workbench / Re: Xtal Replacement

« on: February 11, 2018, 2234 UTC »

 Streach, if you have the PC board for the 100 whiskey transmitter, that's a real plus. Now please say you did not plan on 20 dollar FETS because somewhere there will BE smoke..

380

The RF Workbench / Re: Amplifier Topologies and Classes

« on: February 11, 2018, 2229 UTC »

  Mate, I am an engineer retired, wondering this myself. If you go single FET (YES its very doable) you have less peripheral toroids et-al. You will more than likely spend 10 USA dollars for a FET. It will in all likelihood need more power to drive than a modest push pull arrangement. The FET will not like much less than 50 volts Drain voltage as a single ended. Also the famous push and pull centered taped output network, reduces second harmonic way down. However, that said Fourier mathematics says a square wave (you won't see a perfect one) is ODD harmonics. In a way when you do a LPfilter having images at odd harminics gives you a LOWER Q. Well, that's as much take as I have at this point, but if I make it past my next car payment, I'll have a scope and a little lab before end of year. BTW not to worry mate, 48 volt switching supplies are cheap and easily available,

381

The RF Workbench / Re: Xtal Replacement

« on: February 11, 2018, 1611 UTC »

  calm yourself mate.. we are just speculating here. Now, I used to own a tube 100 watt am rig.. it was BIG, heavy had 807 modulators, a modulation transformer and pair of 6146 finals. Yes, on 80 meters it worked very well circa 1965. later as a dumb fu..k kid of 16 bought a 500 watts Tx with 810 modulators. now that busted the band.

I guess my point is we broadcasters want pro gear. It needs be reliable, not freaking be such a smoke pyre that G..od damn FCC comes into the scope sites. Now, that's the reality. I personally think a good 100 watt  DDS Class E with maybe two FETS (cheap ones) and a fancy pwm mod that could look pretty, sound like a PRO, maybe better than that. Size, is small better, but should have the correct audio and RF connectors. At 100 watts, HF a cheap PL259 female makes the grade.
I do think we do not want a government massacre day as took place 20 years ago. Do I think given sad condition of Federal Budget, plus really nobody to BITCH we are NOT likely going that way?
No, mate, but keep OUR freakin heads DOWN.
What the hell would be the point of a bust, unless something designers like you get Fucked up. And a spur ends up on a military channel.
So goal here buy good scope work bench and dummy loads watt meters and so on and start test tubing to get up to 100 watts class E. That much smoke needs be handled with care although its just a little light bulb.

So we Pirates that want to keep our art and science going have to watch the back side. If you understand.. and many of us Streach are former legal engineers in broadcasting. So, NO JUNK, look good, smell good.. be good..

382

North American Shortwave Pirate / Re: Dr. Detroit 5060 AM 1515 UTC 11 Feb 2018

« on: February 11, 2018, 1545 UTC »

   Just noise here on Cherokee Mountain, but every now and then I hear music (or should I say a beat)

383

North American Shortwave Pirate / Re: UNID 6950 USB 0143 UTC 11 Feb 2018

« on: February 11, 2018, 1515 UTC »

  I did hear this transmission, just barely above the noise , and could hear echo on the modulation. But, copy was really 1222

384

North American Shortwave Pirate / Re: UNID 6925 AM 1323 UTC 11 Feb 2018

« on: February 11, 2018, 1357 UTC »

   Nice 454 signal in Cherokee Mt.
Lots of memories from George.
Went to breakfast and found another transmission. This one was 555!
Also some SSTV that I wasn't  ready to decode.

Nice choice of MUzac will be here next Sunday for a show. Please show!

385

The RF Workbench / Re: Xtal Replacement

« on: February 11, 2018, 0133 UTC »

  Ok, Streachy I understand you point of view. Wanted to say since AM pretty much went out in 1960's little effort to design a class C output with 100 watts or more and modulate it as you will.
The disadvantages, more drive power, you more than likely will pay more for real linear RF transistors.
The FETS are pretty much dirt cheap. They of course work well in class D or E mode.
Circuit considerations are different, but just slightly so. I wonder if any company ever marketed a class C transistor am trans.
I know AM transmitters unless they are from moth ball attics with tubes are damn difficult to locate for anything outside of the BC band .. I.E 1700 kHz. Medium Wave

386

North American Shortwave Pirate / Re: Wolverine Radio 6955 USB 0039 UTC 11 FEB 2018

« on: February 11, 2018, 0044 UTC »

  blues at 0044 signal 555
SDR showing useable sideband out to 3.7 kHz.
Old Devil Moon @ 0047
Nice motif of Devil Songs
I switched to FT900 where I see an s meter reading of to 9 plus 25 db !
I can see the band is far from closed.
Starting a death plunge here in Cherokee country at about 0138. Lots of deep fading.

387

The RF Workbench / Re: Xtal Replacement

« on: February 10, 2018, 1455 UTC »

   Just thinking as a sell point, could you grab about 50 watts carrier. That number catches eyes more than 40. Also, not to push you, but there are those who always want the best. Maybe price two models, 50 watts and 100 watts. I am looking at experimenting with a conventional push pull for 40 meters at 100 watts, but no ideas on modulator. Lots of working stuff complete with cheap FETS that could do. But, although I , a grey hair engineer, its my first experiment with class E. Reading up on theory etc. Now, if you make a very high quality modulator the Yankee AM ers (hams)  will jump on it because many are using museum AM rigs such as Viking 2, DX 100 and so on.
So you get a very real market for your box.  But the sell part with hams might be more than one band, full VFO and yes, that Magic number 100 watts!

Also yes, compact is the way. Good idea. Now you may need change that logo, no offense because the hams will be putting in orders and yes FCC will stay down as long as its a kit with something the buyer must compete, even if it just plugging in a transformer. My deal rig is a compact, but fitted with meters, RF forward/Rev and audio level VU with a FRONT PANEL that could be rack mounted into a pro studio looking operation. Also make the thing able to do 50 watts, its just a better selling number.

388

North American Shortwave Pirate / Peskie Music 6930 LSB 0038 UTC 10 FEB 2018

« on: February 10, 2018, 0039 UTC »

  Seem to be playing music and speaking in a group. Obviously some kind of free banding!

389

North American Shortwave Pirate / Re: UNID 6945 USB 2341 UTC 9 Feb 2018

« on: February 10, 2018, 0004 UTC »

  MUF has caused band to drop big time, but hearing station at 0003utc.
   344
     
 Band seems to have folded at 0008utc

390

The RF Workbench / Re: Xtal Replacement

« on: February 09, 2018, 1939 UTC »

  To be honest Streachy, 50 watts is probably enough fire. Generally were not wanting International Radio Cops calling.
I am looking at the transmitter that I posted a while back. Its NOT PWM, uses a DDS, and a fet driver and single ended FET for that final. Problem, it needs to be made PROFESSIONAL with at least VU meter and a couple of knobs to twist.
I think its fine to try in the lab for higher power, but used as a freedom radio, its tail will always be up in air.
FCC here if they want to bust:
1. look for a strong signal
2. look for some idiot always on same frequency
3. look for a predictable schedule of operations

But, current the black hole is busy devouring little American FM banders.
But.. that could change, however the 41 meter band here has just nothing there except illegals using fish radios and CB sets.
 

Also to legally market the Tx in USA, do this:
1. extend DDS to 7.325, reason AM ham window top of 40 meters to 7.3 mhz.
2. sell as a kit not as a product factory finished. Reason FCC will require type acceptance if you sell more than one.
This means make something not quite finished. Probably something easy to finished, just qualifies as a KIT

Also pro Female studio audio  connector and either a resistive attenuator, could just be cheap POT. But NO preamp! The hams want to connect a mic direct, broadcasters already have high level processed audio to input! We do nOT want distortion from non linearity or add our own attenuators. This is a pain in the ass with ham ssb transmitters. It also creates HUM
The answer may be just include a high and LOW level audio input!