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Homebrew transmitter progress updates




 
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W8ACR
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« Reply #25 on: March 25, 2013, 02:36:15 AM »

Update#6 - 3/24/13 - The modulator power supply is now finished. It will supply 1000 or 1250 VDC depending on which tap I use. Either can be used with zero bias 811A's, so I'll probably use the 1250V tap. I also installed the door interlock and a terminal strip to distribute 120VAC to the various decks. The voltmeter on the bottom deck will be switchable to measure voltage to the RF final or modulator plates. The meter on the modulator power supply deck is a milliammeter to measure plate current to the modulator plates. I put it in the plate circuit so it has full B+ voltage on it. I'm not sure you can tell in the photos, but it is recessed and insulated from the front panel. The plate current meter for the RF final will be in the cathode circuit, so it will be at low DC potential, but of course will be measuring grid+plate current.

Photos show the rear view of all three decks. Bottom to top - RF power supply, rectifier deck, modulator power supply. The modulator deck will be immediately above its power supply, and the speech amp will be above that. The next thing to work on is a modification of the interlock circuit, then the voltmeter switching, both of which should be relatively uncomplicated. Next after that is to finish the RF deck and see if I can get this thing to produce some RF. Once I have that done, I'll do the audio decks, then AIR TIME!

Ron


* transmitter progress 3-24-13 001.jpg (1328.87 KB, 2048x1536 - viewed 739 times.)

* transmitter progress 3-24-13 002.jpg (1322.12 KB, 2048x1536 - viewed 719 times.)

* transmitter progress 3-24-13 003.jpg (1169.49 KB, 2048x1536 - viewed 719 times.)
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« Reply #26 on: March 25, 2013, 02:41:11 AM »

Current front view, yeah, the top meter is off center Angry


* transmitter progress 3-24-13 004.jpg (1375 KB, 1536x2048 - viewed 697 times.)

* transmitter progress 3-24-13 005.jpg (1388.13 KB, 2048x1536 - viewed 716 times.)
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« Reply #27 on: March 25, 2013, 12:50:47 PM »

Beautiful work Ron.   Nice to see some more Buzzardly construction still going on.  73   Have Fun,    Vic
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« Reply #28 on: March 25, 2013, 04:02:21 PM »

Looks great Ron. Can't be long now.  Cheesy
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« Reply #29 on: March 28, 2013, 01:59:31 AM »

Update#7 - 3/27/13 - I finished the modification to the interlock circuit (hence the additional relay on the control deck), the voltmeter circuit, and the final wiring of the control deck. Next will be a cable of interconnecting wires from one cabinet to the other, then wiring for primary power to each deck as well as grounding strap to connect all decks and cabinets. After that, I can start to work on the RF deck. Pictures show the control deck in its finished state with the two large variacs below as well as the terminal strip on the floor of the cabinet. The cable of wires to the other cabinet will emanate from this terminal strip.


* transmitter progress 3-27-13 001.jpg (1353.46 KB, 2048x1536 - viewed 695 times.)

* transmitter progress 3-27-13 002.jpg (1449.92 KB, 2048x1536 - viewed 711 times.)

* transmitter progress 3-27-13 003.jpg (1293.83 KB, 2048x1536 - viewed 714 times.)
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« Reply #30 on: March 28, 2013, 07:34:39 AM »

Another fan of lacing cord!  It would be such a shame to use zip ties with the vintage wire!  Nice to see the continuity, pardon the pun, on period matching techniques! 

Joe, GMS
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« Reply #31 on: March 28, 2013, 12:09:50 PM »

      ***  Ode to Buzzard Baby ***


Buzzard Baby, Sing me a tune.
  Shine on me from that ol' AM moon.

Let me admire your porcelan sockets.
  Beautifully built for little out of pocket.

Fabulous iron preciously polished.
  Spark gaps aligned and oh so shockish.

Softly lit tubes with that ol' orange glow,
  Wafting a strapping carrier with modulating flow.

Four 866's, count 'em, a flourescent four.
  Glowing complementary color of the other tubes of yore.

For what more could a Ronley ham ask,
  Than brightly lit pilots up to the task.

          (anon, 3/28/13)
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RICK  *W3RSW*
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« Reply #32 on: March 28, 2013, 02:22:17 PM »

      ***  Ode to Buzzard Baby ***


Buzzard Baby, Sing me a tune.
  Shine on me from that ol' AM moon.

Let me admire your porcelan sockets.
  Beautifully built for little out of pocket.

Fabulous iron preciously polished.
  Spark gaps aligned and oh so shockish.

Softly lit tubes with that ol' orange glow,
  Wafting a strapping carrier with modulating flow.

Four 866's, count 'em, a flourescent four.
  Glowing complementary color of the other tubes of yore.

For what more could a Ronley ham ask,
  Than brightly lit pilots up to the task.

          (anon, 3/28/13)


What a great OT Radio Poem!!  Put it on the wall in a frame.  I like it!

Joe, GMS
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Carl WA1KPD
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« Reply #33 on: March 28, 2013, 10:43:58 PM »

I like the old fuses....Part of my plan. Nice wrk es tnx for sharing
Carl
/KPD
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Carl

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« Reply #34 on: March 29, 2013, 02:28:26 AM »

Update#8 - 3/28/13 - The wiring harness coming down from the control deck looked awkward when it went straight down to the floor of the cabinet, so I moved it to the sidewall, and I think it looks better. I completed the wiring harness that runs from cabinet A to cabinet B and attached it to the terminal strips on either end. Lastly, I completed the primary power wiring to the individual decks.

OK, hold your breath, time to apply primary AC power to the power supplies. Turn on filament power. Wait 30 min for the 866's to cook a little bit. No sparks or flashes yet. Modulator power supply first - flip switch - nothing. OK let's check obvious things first. This one's easy, interlock wasn't closed. OK, well that's good, now I know it works. Adjust it a bit, now it closes. Flip switch again - nothing. Check fuses, found a bad one. replace it. Flip switch again - nothing. Checked fuses again. The one that I replaced wasn't screwed in all the way. Flip switch again - hey something's happening. All relays close. 866's glow blue, Voltmeter says 1100VDC. Cheesy SUCCESS!!

RF final power supply next. This one's on a variac so I can bring it up slow. Flip appropriate switches - nothing. Oh wait, variac is on ZERO. rotate variac. Voltmeter moves. 1000VDC..............1500...................2000..............2500..........FZZZZZTTT!! Oh no! 866 with internal arc!! Things go dark. Crap! did I zorch the plate transformer? Checked fuses, blew two of them. Hopefully they protected the plate tranny. Not gonna take that chance again, replace 866's with 3B28's, replace fuses. things light up again. Variac to zero. Flip switches. Rotate variac. 1000..............1500............2000........2500........2500.............2500.........2500.....
holding steady.  Cheesy Success!!

Off to Montana tomorrow for Easter with the family. Will finish RF deck when I get back. Some pics of today's work.

PS: Rick, please thank "anon" for his time and effort on Ode to BB. It's great!


* transmitter progress 3-28-13 005.jpg (1332.32 KB, 2048x1536 - viewed 676 times.)

* transmitter progress 3-28-13 004.jpg (1390.8 KB, 2048x1536 - viewed 688 times.)

* transmitter progress 3-28-13 003.jpg (1398.22 KB, 2048x1536 - viewed 689 times.)
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« Reply #35 on: March 29, 2013, 11:11:40 AM »

Quote
Off to Montana tomorrow for Easter with the family. Will finish RF deck when I get back. Some pics of today's work.

PS: Rick, please thank "anon" for his time and effort on Ode to BB. It's great!

Have a great time in Montana Ron. Nothing like family.

Modesty prevails. Consider "anon" thanked. 
It just looks "so Shakespeare" to sign stuff that way.
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RICK  *W3RSW*
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« Reply #36 on: April 08, 2013, 08:38:51 AM »

Update#8 - 3/28/13 - The wiring harness coming down from the control deck looked awkward when it went straight down to the floor of the cabinet, so I moved it to the sidewall, and I think it looks better. I completed the wiring harness that runs from cabinet A to cabinet B and attached it to the terminal strips on either end. Lastly, I completed the primary power wiring to the individual decks.

OK, hold your breath, time to apply primary AC power to the power supplies. Turn on filament power. Wait 30 min for the 866's to cook a little bit. No sparks or flashes yet. Modulator power supply first - flip switch - nothing. OK let's check obvious things first. This one's easy, interlock wasn't closed. OK, well that's good, now I know it works. Adjust it a bit, now it closes. Flip switch again - nothing. Check fuses, found a bad one. replace it. Flip switch again - nothing. Checked fuses again. The one that I replaced wasn't screwed in all the way. Flip switch again - hey something's happening. All relays close. 866's glow blue, Voltmeter says 1100VDC. Cheesy SUCCESS!!

RF final power supply next. This one's on a variac so I can bring it up slow. Flip appropriate switches - nothing. Oh wait, variac is on ZERO. rotate variac. Voltmeter moves. 1000VDC..............1500...................2000..............2500..........FZZZZZTTT!! Oh no! 866 with internal arc!! Things go dark. Crap! did I zorch the plate transformer? Checked fuses, blew two of them. Hopefully they protected the plate tranny. Not gonna take that chance again, replace 866's with 3B28's, replace fuses. things light up again. Variac to zero. Flip switches. Rotate variac. 1000..............1500............2000........2500........2500.............2500.........2500.....
holding steady.  Cheesy Success!!

Off to Montana tomorrow for Easter with the family. Will finish RF deck when I get back. Some pics of today's work.

PS: Rick, please thank "anon" for his time and effort on Ode to BB. It's great!

Any updates Ron?
Joe, GMS
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« Reply #37 on: April 08, 2013, 10:47:57 AM »

I'm gonna do a homebrew transmitter when the kids move out and I can use one of the downstairs spare bedrooms for a radio room. Right now, the Mad Scientist Lab is upstairs. This situation naturally poses some challenges.

PHILIP
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« Reply #38 on: April 09, 2013, 12:53:44 AM »

Hi Joe,

I was in Montana at the alternate QTH for the past week. I got back to ND yesterday, and will try to get started on the RF deck in the next day or two. As usual, after being gone for a week, the work piled up, so this will be a busy week, but I'll try to find time to start work on the RF deck. Will continue to post updates as they occur.

Thanks, Ron
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« Reply #39 on: April 09, 2013, 08:28:00 AM »

Hi Joe,

I was in Montana at the alternate QTH for the past week. I got back to ND yesterday, and will try to get started on the RF deck in the next day or two. As usual, after being gone for a week, the work piled up, so this will be a busy week, but I'll try to find time to start work on the RF deck. Will continue to post updates as they occur.

Thanks, Ron

Yep, I understand that "life" does get in the way of Ham Radio progress!   Just before I retired, I figured I should have another 50 or so "free" hours a week after retirement since that was my average work week.  Well, it sure has not happened!!   

The main thing is to enjoy the build and I know your making it a fun project.

Joe, GMS
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« Reply #40 on: April 10, 2013, 07:54:31 AM »

Gorgeous work here.

Philip
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« Reply #41 on: April 10, 2013, 07:56:56 AM »

Looking at your control deck schematic, do you really want to fuse the neutral?

Philip
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« Reply #42 on: April 12, 2013, 12:48:09 AM »

Update#9 - 4/11/13 - First of all, is it considered bad practice to fuse a neutral line? I guess I hadn't heard that before. The RF deck is finished. After much deliberation and arguing with myself I decided to go with the Taylor 822, AKA Fischer 3581. This is a triode with 200 watt plate dissipation (135 watts in AM mode) and 10V/4A filament. Beautiful big graphite plate structure. For AM, maximum plate rating is 2000VDC@250mA. Its biggest fault is 13.5 pf grid to plate capacitance which limits its utility above 7 mHz. But since this is a 160/75/40 meter RF deck, it should be OK. I really wanted to use this tube because of its 1930's look. I have two of these tubes, and could use another spare or two if someone out there wants to part with one. The circuit is pretty straightforward. It has a balanced grid circuit with plug in coils. The plate circuit is a pi network tank and it utilizes grid neutralization. There are two band switches in the plate tank, one to switch taps on the coil, and one to switch in additional capacitance on the loading cap. I plan to run it at about 1800VDC and 225mA (at least at first). Grid parameters are 45mA and -200V. Pics shown below. Please try to ignore the extra holes from my previous aborted attempt. The front panel is short because there will be a window panel above it. The tuning cap max is 470pf. It is on a vernier and has a very nice smooth movement. The loading cap is underneath, the filament transformer and the bias circuitry will be on the bias deck which is my project for this weekend. Once the bias deck is finished, I should be able to crank some RF into the RF deck and see if I get anything out.

Ron

PS. W3RSW has christened her as "Buzzard Baby" which I am agreeable with. So Buzzard Baby she is.


* transmitter progress 4-11-13 001.jpg (125.6 KB, 640x480 - viewed 698 times.)

* transmitter progress 4-11-13 002.jpg (129.99 KB, 640x480 - viewed 690 times.)

* transmitter progress 4-11-13 003.jpg (127.38 KB, 640x480 - viewed 658 times.)
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« Reply #43 on: April 12, 2013, 12:49:47 AM »

Two more pics


* transmitter progress 4-11-13 004.jpg (120.16 KB, 640x480 - viewed 668 times.)

* transmitter progress 4-11-13 005.jpg (125.32 KB, 640x480 - viewed 639 times.)
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« Reply #44 on: April 12, 2013, 07:38:53 AM »

Ron,

That 822 tube does look great.  I don't believe I have any around here otherwise I would donate a spare to your cause. 

Concerning the fuse in the neutral, I would not use it.  The neutral is connected to the ground buss in the breaker panel and I would always want that as a non fused circuit that could not be broken under a fault condition.  If the rig was running on 240 that would be a different story in that you would want both L1 and L2 protected.

Progress looks great and it will be interesting to see how things fire up!

Joe, W3GMS
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« Reply #45 on: April 12, 2013, 07:51:53 AM »

If you have Phase A and B, you will still have a neutral, ground, unless you're running a motor, which typically doesn't have a N connection. If the neutral connection is lost in a 240V/1 phase feed, you will lose your zero point reference. If the load isn't perfectly balanced betwixt A and B phase, the voltage on one or the other can exceed 120V per leg. This is a very bad situation.

DO NOT BOND N-G together at the equipment. This will defeat the ability of your main panel circuit breaker/ fuse to clear a fault. N-G is bonded together at your house main panel per NFPA 70.

Had to let the PE out of the box. Sorry about that.

PHILIP
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« Reply #46 on: April 12, 2013, 12:05:53 PM »

"Had to let the PE out of the box.  Sorry about that."

Philip, we'll let you slide this time, but don't let that happen again Grin

I've seen open building neutrals a few times, your right, bad things can and often do happen.


Ron,

As stated in the two previous posts,  DO NOT fuse the neutral line.

BTW, the rig looks great.  What's up with that 822.  I've never even heard of a 822.

Fred

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« Reply #47 on: April 12, 2013, 10:06:07 PM »

Fred, here is some info on the Taylor 822. I've attached a copy of a page from the 1940 Taylor tube manual. The 822 was used in Fischer diathermy machines, and my spare 822 is actually marked "Fischer 3581". The internal structures have a handwritten 822 on them. Later versions of the Fischer branded tubes actually had 822 stamped on their metal base. There were two other variations of the 822. One was called the 822S and had the grid lead come out the side of the glass envelope. Otherwise the tube parameters were identical. However, they marketed the 822S as being usable up to 30mHz, whereas the 822 was not recommended for use above 20 mHz. Not sure why, I think the interelectrode capacitances were the same. The other variation was the Taylor 814, Obviously much different than the RCA 814 tetrode. The Taylor 814 was the low mu version of the 822. Amplification factor of 822=30. Amplification factor of 814=12. Again, the tubes were otherwise identical. The 814 was marketed as a tube designed for grid modulation service.

Brief update on Buzzard Baby. I have cycled the HV power supplies on and off many times over the past few days, and everything seems to be in order. Blue glow of 866's right beside the purple of the 3B28's. Looks very nice. Of course, the only loads on the power supplies has been the bleeder resistors. Hopefully things will go as well with circuit loads applied.


* Fischer 3581 001.jpg (123.97 KB, 640x480 - viewed 622 times.)

* Fischer 3581 007.jpg (125.3 KB, 640x480 - viewed 615 times.)

* Taylor 822.jpg (344.55 KB, 1700x2320 - viewed 648 times.)
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« Reply #48 on: April 12, 2013, 10:21:15 PM »

Here is everything you ever wanted to know about the Taylor 822, 822S and 814. The first scan is from the 1945 Taylor tube manual, and the last two scans are from the 1937 Taylor tube manual.


* Taylor 8221.jpg (370.68 KB, 1700x2320 - viewed 659 times.)

* Taylor 8222.jpg (375.63 KB, 1700x2320 - viewed 648 times.)

* Taylor 8223.jpg (410.89 KB, 1700x2320 - viewed 647 times.)
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« Reply #49 on: April 13, 2013, 12:17:10 AM »

Ron,

Thanks for the 822 info.  With that base style the 822 sorta looks something like a 845.  The 822 looks larger than the 845.

FB on testing the supplies, hope they hold up under pressure.  I always test my HV supplies at near full load with giant load resistors. Makes a lot of heat.

Fred
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