The AM Forum
March 29, 2024, 07:03:35 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 ... 3 [4] 5 6   Go Down
  Print  
Author Topic: How much peak power can a class C 6146B put out?  (Read 114488 times)
0 Members and 1 Guest are viewing this topic.
N2DTS
Contributing
Member
*
Offline Offline

Posts: 2307


« Reply #75 on: January 29, 2014, 08:00:53 AM »

Very tight building, lots of stuff in a small box.
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #76 on: February 17, 2014, 07:50:35 PM »

After a lot of work, problems and modifications, the  the "Dual Quads" 6146B / 6LF6 PDM rig is working well.

Since my last post, I blew up five $45 IGBT PDM switchers one by one - they all died from thermal runaway at only 1100V.  I went back to the 6LF6 sweep tubes.  The rig will now handle  1800V at  300 w carrier out, 1500 w pep out - without one crap out so far, since the mods. I love tubes!

I ran out of modification room, so split the PDM switcher and RF deck into two separate cabinets.  Also, I discovered that the original PDM filter, wound on toroids, was 1/10 the inductance it should be. Space-out! That was one of the main problems that I finally figured out when I got an L/C meter... duhhhh.   Now I'm using my old 4-1000A air wound PDM filter coils for the time being. Overkill. They are thousands of turns on 5 gallon PVC pails.  I tapped them to give the perfect 12mH  / 16 mH  inductances for a 1,000 ohm RF load.

The audio sweep tests look flawless with 10, 100 and 1000 Hz triangle waves looking textbook. I added a fan to each set of quad tubes blowing air directly down on them. After a transmission, they are cool enough to lay fingers on without discomfort.  And I am really hitting them hard at 1500w pep.  Without air flow, my laser temp gun shows a bulb temp approaching 300 degrees  F.  With air, they are usually about 110 degrees F. The tubes are mounted on plates, so air can go underneath for the bottom seals too. I can't stress enough the importance of aggressive cooling, even for these smaller convection-style tubes like 6146Bs and so forth.  With great cooling, these tubes will last a long time, especially at maximum operating parameters that are based on no air.

I had it on 75M last night and the locals thought it sounded FB. Rob /AEX and Steve/ QIX both sent me recordings which I felt were decent sounding to my ear.

The rig will sweep from 1 Hz to 9 Khz before the PDM filter starts to roll off.  I will be controlling the audio bandwidth from low level.  I still need to do some analog compensation of the switch tubes. It will modulate down to about -94% and I have seen 160% positive when at 250 watts carrier, according to Steve's mod monitor file.

The RF finals run a hefty -110V grid bias, which is very heavily into class C.  The switch tubes are probably in the 90% efficiency area.  There is very little heat coming out of the cabinets after a long key down.  


All in all, I am very happy with this rig's performance and expect it will be a nice little medium power rig to fill in the gaps.  It's working so well that I'm designing up a much larger tube PDM rig  - but we'll have to see if my ambition holds. This project was a real b-buster ... Grin

Here's a bunch of pics showing the latest progress.

T


* DSCF0006.JPG (322.95 KB, 1280x960 - viewed 756 times.)

* DSCF0010.JPG (319.83 KB, 1280x960 - viewed 719 times.)

* DSCF0008.JPG (332.35 KB, 1280x960 - viewed 688 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #77 on: February 17, 2014, 07:52:38 PM »

More shots. Check out the 4X1 PDM coils....


All HV points are protected by Plexiglas or the cabinets.


Notice the little castor wheels to allow easy servicing access.


The blue cabinet on the second shelf holds the 2200VDC  1.5A supply, (with a step start)

Notice the PDM generator in the silver box on the right - 2nd pic.


* DSCF0009.JPG (323.76 KB, 1280x960 - viewed 758 times.)

* DSCF0003.JPG (319.48 KB, 1280x960 - viewed 685 times.)

* DSCF0005.JPG (333.8 KB, 960x1280 - viewed 734 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #78 on: February 17, 2014, 07:54:12 PM »

Station shots:  Fabio I, Fabio II, Mr. Clean, Rico Suave, Dr Love -


* DSCF0017.JPG (325.02 KB, 1280x960 - viewed 697 times.)

* DSCF0016.JPG (336.28 KB, 960x1280 - viewed 712 times.)

* DSCF0015.JPG (338.67 KB, 960x1280 - viewed 733 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #79 on: February 17, 2014, 07:55:11 PM »

This RF deck has been thru a lot of changes in the last two months.

Notice that both the RF deck and PDM units have SO-239 jacks on the front panel for PDM in - PDM out access. This will allow any PDM filter to be added without tearing things up.  Eventually I will wind up smaller coils that fit inside one another.  They will reside with short leads between the two units.

Thanks to Frank / WA1GFZ for his help via email to help me solve the many issues I came across with this project!

T


* DSCF0007.JPG (328.58 KB, 1280x960 - viewed 702 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
W2NBC
Contributing
Member
*
Offline Offline

Posts: 327



« Reply #80 on: February 17, 2014, 08:29:57 PM »

Good looking transmitters Mr. T! Congrats on the "dual quads".. Looks great! I am wondering if the blue and white color scheme might just be your thang..

Oh yea.. Guess it is!


* jj-mobile.jpg (205.05 KB, 1000x749 - viewed 717 times.)
Logged

Vintage Radio Pages- http://www.dealamerica.com
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #81 on: February 17, 2014, 08:38:14 PM »

Heheheh - pretty funny!     Just imagine driving around in that Fabio car. I wonder how long it would be before you got dragged out and beat senseless?   


OK, now all eyes are on you. When is that new ??  pill mawl gonna hit the airwaves?


T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #82 on: February 17, 2014, 10:04:06 PM »

more power in oil?  amazing. 70W carrier..

Don't wear out all the 6146's. I just gave up all my 807's to help restore a working museum piece computer in the UK. 807's are used as row or column resets in that. It has many many 807's.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
N2DTS
Contributing
Member
*
Offline Offline

Posts: 2307


« Reply #83 on: February 17, 2014, 10:18:54 PM »

Wow, that sounds like it was a LOT of work.

Buckets?
Is there RF on the buckets?

I think that is crazy, bucket coils in the shack behind glass!

Could you not make something small on a toroid or something?
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #84 on: February 18, 2014, 01:21:46 AM »

Wow, that sounds like it was a LOT of work.

Buckets?
Is there RF on the buckets?

I think that is crazy, bucket coils in the shack behind glass!

Could you not make something small on a toroid or something?



Those are PDM filter coils handling 170 KHz square wave pulses.  They were originally wound for my KW   4-1000A PDM rig.  They are being used temporarily cuz my small toroidal filter was wound at 1/10th the proper inductance by error.  Actually, a filter like I'm using doesn't get any better than that. Less inter-turn capacitance than a toroidal based filter means better filter isolation.   Some designs use an air core as the first inductor and toroids afterwards.

The plan is to try winding compact coils one inside the other, all air core.The filter will mount between the two cabinets with short coaxial leads.

T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
W3RSW
Contributing
Member
*
Offline Offline

Posts: 3308


Rick & "Roosevelt"


« Reply #85 on: February 18, 2014, 07:51:17 AM »

My thoughts on those PDM coils too.  Shades of Tesla; with a one or two turn pulsed primary you could stand some serious wig on end.  Grin

Where's that classic charlie Chaplin pix?

Seriously, love those blue and white, plexiglass cabs too.  very nice.
Logged

RICK  *W3RSW*
W2PFY
Contributing
Member
*
Offline Offline

Posts: 13312



« Reply #86 on: February 18, 2014, 10:56:16 AM »

What would happen if you stuck your head in a filter like that when modulating?

Very nice work Tom...........
Logged

The secrecy of my job prevents me from knowing what I am doing.
N2DTS
Contributing
Member
*
Offline Offline

Posts: 2307


« Reply #87 on: February 18, 2014, 02:34:00 PM »

Could you keep your coffee warm in the buckets?
Could you turn them into bug zappers?
Logged
W3GMS
Contributing
Member
*
Offline Offline

Posts: 3063



« Reply #88 on: February 18, 2014, 04:38:39 PM »

Tom,

Its been great following both your progress and set backs.  Personally I am thrilled that you went back to the tube PDM and if you had not, you probably would have never found were the problems were.   So now you know the good, bad and ugly! 

So now try and get on the air since others would like to hear the rig that has put you through the hurdles of hell! 

Oh, it does feel good when the issues are concurred and the results speak for themselves.

Joe, GMS 
Logged

Simplicity is the Elegance of Design---W3GMS
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #89 on: February 18, 2014, 08:35:17 PM »

Tom,

Its been great following both your progress and set backs.  Personally I am thrilled that you went back to the tube PDM and if you had not, you probably would have never found were the problems were.   So now you know the good, bad and ugly!  

So now try and get on the air since others would like to hear the rig that has put you through the hurdles of hell!  

Oh, it does feel good when the issues are concurred and the results speak for themselves.

Joe, GMS  

I appreciate the comments Joe and all!

You make a good point about following through.  One of my weaknesses is after getting a rig built, I have a low tolerance for the aggravation of crap-outs.  If I cannot get the rig running perfectly in say, a few days, I tend to want to tear it down and try a different approach.  After the initial PDM tube modulator problems and then the five IGBTs blowing up, I almost threw in the towel.  But often we are right at the point of success when we give up.  It paid to stay the course.

Now the next shakedown that I never finished before - Last night I had the 4-1000A X 4-1000As plate modulated rig on the air. (Fabio II)  At 4KV it flashed over four times and blew out my HV fuses.  Today I opened it up and found that the input tuning bandswitch was arcing over to ground. Melted the wafer.  I replaced it.  The arcing started again but this time the screen pin flashed 1/2" to ground. I thought I blew a 4X1 cuz the screen current was dead. Turns out that I forgot to solder back on the RF choke lead, so one screen was floating..

Gots it going again and this time I was running tone stress tests. Suddenly there was arcing on the scope under modulation. I thought I had blown the mod transformer... yikes!    Investigation showed that one of the Teflon SO-239s at the Bird wattmeter was shorting and was hot as a pistol.  Repaired that.

It's now hanging in there with no shutdowns.

I'm still left with some odd high frequency distortion to figger out.  It's all a matter of pushing the rig and discovering the weak links until nothing fails anymore under normal operating condix.  This is often the most difficult part of building a rig and takes lots of patience. I mean, all it takes is one part out of 100 to be arcing internally, out of sight. (in a scary high voltage environment) And each time it arcs it does damage to other expensive parts.  Try to find THAT problem and keep a sane attitude... Grin

**  I think the bottom line is that when we are actively building something, we see the progress every day. Satisfying.  But when troubleshooting, we can blow hours and hours and sometimes see nothing for our efforts. Frustrating.  When we finally lick a difficult problem, there is finally a payoff.

T

Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #90 on: March 10, 2014, 06:33:36 PM »

Just an update on the Dual Quads tube PDM rig...

The rig has been running very FB except that it would not modulate less than about -85% negative. As normal, the tube switch could not hold the pulse when the filter field collapsed as the pulse narrowed. This required some analog compensation to make the pulse more linear.

The biggest improvement was to drop the PDM switch frequency from 170 KHz to about  75 KHz.  This immediately improved the negative modulation to about -92%!   I then added a 2 ohm resistor to the source of the 11N90 MOSFET.  The 11N90 drives the four 6LF6 sweep tube switches. In addition, I added a 170 ohm resistor in parallel with a 1N4007 diode  in series with the 11N90 gate. (diode anode towards gate)   This improved the negative modulation capability approaching -95% or slightly better under voice modulation.  This is all we can hope for using a PDM tube rig without elaborate circuitry.  

With the PMC-300A SOFT negative peak limiter working, the extra -5% negative is masked and the rig sounds FB. I don't need the hard NPL clipper anymore.  The positive peaks are stellar - I've had them up in excess of 200%, depending on where the PDM carrier is set.  I usually run the pos peaks at about 140% max.

The rig sweeps and modulates as well as Fabio II, the 4-1000A rig, but is slightly cleaner and has more high end, due to the transformerless PDM tubes.   At 1700V, it is putting out about 350w carrier and 1500 w pep. I usually run it at about 250w carrier and 1400w pep.

It is buttoned up and except for modifications and maintenance, I consider this a finished rig, caw mawn.  Oh yeah - and drop the big PDM coils and build up a compact set. I'll wind them so they slip one inside the other.  And 6" short cables from filter to the rig.

My thanks to Frank / WA1GFZ for his email help getting me thru the hard parts.   These analog compensation suggestions were from him today.

This was a very difficult project for me and I almost gave up a few times. I couldn't be happier with the final results.

I'll be on with The Dual Quads and Fabio II over the coming weeks...  Grin

T


* DSCF0002.JPG (325.43 KB, 960x1280 - viewed 687 times.)

* DSCF0011.JPG (315.72 KB, 1280x960 - viewed 699 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #91 on: April 15, 2014, 10:01:41 PM »

As a final post to show the results of this tube PDM project, here's a recording Jeff / W2NBC made today of this rig on 40M.  (150 mile path.)


I finally hooked up the CRL-PMC-300A modulation limiter and the Dominator II peak limiter.  I think the audio is getting dialed in for my voice.   My goal is large dynamic range with minimum processing. The limiters come in only on the peaks.  I have more density available if conditions get poor.   Since this recording I've added a slight touch  of compression (about 2-3 dB)  right after the mic preamp, for better voice control.


You are hearing a cool and quiet four 6146Bs in class C parallel,  pulse width modulated by four 6LF6s in switch class D parallel at 200 watts of carrier, about 1250 watts pep, 1600 V total across the finals and modulators, muffin fan air on all tubes.   (W1AEX followed by K1JJ):

T

* K1JJ-40 meters.mp3 (4137 KB - downloaded 357 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Steve - K4HX
Administrator
Member

Offline Offline

Posts: 2722



« Reply #92 on: April 15, 2014, 10:49:13 PM »

Fantastic! As close to "in-person" as I've ever heard from your station. Lock it down.
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #93 on: April 16, 2014, 11:49:15 PM »

Fantastic! As close to "in-person" as I've ever heard from your station. Lock it down.

TNX Steve.  Yep, it's getting better.  

To be critical, I hear a little undesirable mid bass in there.  (100 - 125 Hz)  I EQed it out today.  

This little 6146B PDM rig is working so well I am tempted to scale up a new one using 813s.    


I played around with the new Aphex noise gate. The PDM rig is silent, but when using the 4-1000A rig, if we reduce out about 3-5 dB of blower noise with a smooth release, it is reasonably transparent. Any more and the gating starts to become noticeable.  But 3-5 dB can sometimes make a difference when on the threshold of "OK"  or "Good"  background noise levels.


T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
WD5JKO
Member

Offline Offline

Posts: 1996


WD5JKO


« Reply #94 on: April 17, 2014, 05:03:18 PM »

Tom,

  Any chance that rig could be on 14,330 this coming Monday night?  Wink

Jim
Wd5JKO
Logged
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #95 on: April 18, 2014, 06:05:42 PM »

Tom,
Any chance that rig could be on 14,330 this coming Monday night?  Wink
Jim
Wd5JKO


Sorry, Jim, but the rig was built for 160, 75 and 40M only. 


Looks like the noise gate for AM was a bust. Even a small amount of noise reduction was noticed and got negative comments. Same as last time. Why would it be any different this time?  Guess I'll let it be on AM.  On SSB, the noise gate works FB and seems tolerable by the masses.

I'm thinking of taking out the four 6146B finals and replacing them with four 4D32s.   That would double the output power to an easy 500w using small octal-type tubes.  Small, silent and cool, caw mawn.
 

T
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8308



WWW
« Reply #96 on: April 21, 2014, 02:13:52 AM »

Tom, if that is you on the MP3, that station really sounds great!

RF equipment using sweep tubes as intended!  - a twist back to normalcy for certain! Bet they last a long time.
Logged

Radio Candelstein - Flagship Station of the NRK Radio Network.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #97 on: April 21, 2014, 11:50:21 AM »

Thanks, Pat.


I went ahead and ripped out the four 6146 finals.  The sockets for (4) 4D32s are being installed now. 

So the rig will soon be (4) 4D32s in RF class C .....pulse width modulated by (4) 6LF6 sweep tubes in class D.   1800V on the whole thing. Probably good for 500- 600 watts carrier. Amazing power for a compact, quiet, low heat summertime rig.

Should have it working once the tubes arrive by the end of the week.  Will take some pictures.

T


Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #98 on: April 23, 2014, 09:47:06 PM »

It's always easier when the final deck is built on a removable mounting plate.  I pulled out the 6146Bs  plate and almost have the 4D32s ready to go.  I figger four may make an efficient 500 watts of carrier. Maybe compare to a Johnson 500.

See the empty space in there in the second pic?  Tight fit - JUST fits.  (Those suppressors are non-inductive 50 ohm resistors - I measured them with an MFJ-259B at 1:1 at 30 Mhz.)


The 4D32 is an amazing looking tube, like a baby 813.  The  internal plate structure is about 70% of the 813's size. Wish I had done a little rig like this for the summertime long ago.

T


* DSCF0002.JPG (321.86 KB, 1280x960 - viewed 636 times.)

* DSCF0006.JPG (322.27 KB, 1280x960 - viewed 674 times.)

* DSCF0007.JPG (321.25 KB, 1280x960 - viewed 678 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8893


"Let's go kayaking, Tommy!" - Yaz


« Reply #99 on: April 23, 2014, 09:49:00 PM »

Easy to put in or take out for servicing.

These ceramic sockets are also used for the 8877 tube. Very strapping.  At 2KV total PDM voltage, they need to be well insulated..

T


* DSCF0010.JPG (317.46 KB, 1280x960 - viewed 698 times.)
Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Pages: 1 ... 3 [4] 5 6   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.085 seconds with 18 queries.