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starting work on the amp




 
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Author Topic: starting work on the amp  (Read 36284 times)
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Patrick J. / KD5OEI
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« on: April 25, 2016, 01:02:53 AM »

Its a modest start. We cut and installed 2x10 planking for rack floor. It can be held in place with screws. The parts can be fastened to  it with lag bolts. It was amazing that the planks fit side by side. Only the length had to be cut and a couple of notches. A block and tackle was used to move the plate transformer and variac into position. In the end I think the capacitor and choke will go under the Powerstat. It has not been possible to touch up the paint the rack, and its not a big deal as it only has surface corrosion a few spots at the bottom where it can be seen and this can be fixed later.


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« Reply #1 on: April 25, 2016, 01:05:26 AM »

2x10s on top of the rack with a chain  held up the block. The big transformer was on a dolly and it was not very hard to roll it up to the rack and as it was pulled up it slid into place Only one choke and capacitor has to be used in this. The choke is 30H@1.3A and the capacitor is 31.25uF@9600V. About the choke, the tube's data sheet says 2A max but as an amplifier the would only happen on in CW condition, so 1.3A should be enough. Not sure how to calculate that right now but it is a great choke and should be fine in here.


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« Reply #2 on: April 25, 2016, 01:16:12 AM »

Just some rigging. Might not be so great so don't do this at home.


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« Reply #3 on: April 25, 2016, 01:19:46 AM »

.


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« Reply #4 on: April 25, 2016, 01:32:12 AM »

The Powerstat was originally set up with the sections in series for 460V 28A. It is made of two 230V 28A sections and can be rewired for 230V 56A by putting them in parallel which is the more common arrangement. I have to find a balancing coil for it. I like the unique handwheel on this one. It has some burs on the inside making it hard to slide on the shaft so some filing might help. The Powerstat has a Ward Leonard 600 Ohm potentiometer on the main shaft. It's rated 600V and 2.62A t0 0.4A. I think this means 2.64A max and 0.4A when the whole element is used but it's not clear. There is a concentric 1/4" shaft running through the main shaft and an Ohmite 50 Ohm 2.12A potentiometer at the very back. The shaft can't protrude because the handwheel is not on all the way due to the shaft burs. There is supposed to be a big knob on the front for the Ohmite, but it has not been found yet. The Powerstat has to be moved forward. its not mounted yet. Need to find a special nut for it and also a die to run over one damaged bolt head on the front.


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« Reply #5 on: April 25, 2016, 08:04:35 AM »

Wow! That's BIG STCHUFF !

You'll easily be a contender in the Heavy Metal Rallies.

What'cha planning on running, tube wise, etc. from it?
Still thinking of using the 3cx3000a7 previously mentioned?  
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« Reply #6 on: April 25, 2016, 08:28:57 AM »

OMG - what's this a new VOA site? This going to be single band or multi band?
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« Reply #7 on: April 25, 2016, 10:28:06 AM »

If you care about aesthetics this might be a good time to mask off and do touch up paint to the bottom front faces of the racks??

but this looks like a fairly "manly" amp for manly men...  Grin

Hope you have it where you want it?
Also depending on your thinking, you may wish to bond a ground wire to the stuff on the wood.
Otoh, shorts to the core of the iron will not effect the operation, but could effect you if that happened.

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« Reply #8 on: April 25, 2016, 10:34:23 AM »

OMG - what's this a new VOA site? This going to be single band or multi band?

That was my thought too.....A tube(s) with handles being used??? Serious stuff going here.
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« Reply #9 on: April 25, 2016, 01:18:35 PM »

Stout stuff there Patrick!

Think that the tube will need Lifting Eyes.
Looking forward to progress reports and pics.

Have Fun,   GL,   Vic
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« Reply #10 on: April 25, 2016, 01:22:56 PM »

Here's a couple of the new VOB station.

(VOB  Voice Of Bakersfield)   I'm close enough to VOA Delano that I'm gonna consider myself facility B.

50 ohms at 200 Watt CCS glitch R assy.

12 kva ccs Dahl supply

3cx3000.

This one works OK,  the next will be the same size xformer (I have 2 here)  with a 4 by 5.

Looking good Pat,  can't wait to hear it!

--Shane
KD6VXI


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« Reply #11 on: April 25, 2016, 02:58:54 PM »

Beauty IRON, gentlemen!
Looking forward to seeing more great photos as progress occurs!
73
Frank
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« Reply #12 on: April 25, 2016, 08:56:50 PM »

It'll be the 3CX3000A7. There is only 100A service to the lab and the HVAC has to run, so it leaves about 60-70A for everything else. Up against a limit, I guess. Beside, +6dB capability is plenty to assure long component life and hopefully low distortion.

The transformer is a conversion to single phase from a 3 phase unit of an RCA Ampliphase if I recall right. BTA-10G? H? I wish I had the manual for the unit it's from to study. The secondaries in series should be about 6KVAC, rating at least 2 Amps CCS maybe a little more. 120V input made something like 3600V at no load.

I'm going with the classic choke input in compliance with the 'Electronic Renaissance'. As for the tube there are none in glass that seem practical for do this.

I'm somewhat of a Rat Builder. The term "Rat" is usually applied to vehicles but anything can be ratted.
It's somewhat of an art and does not mean poor work, bad parts, or low performance. There is usually at least a little rust somewhere. 8-)
No disrespect to those who put in more hours to make shiny things and replicas of classic apparatus.

I don't know how to get a pretty finish on something like this or match the color. The sides are black and doors blue, all are in similar condition.

But not to get ahead of myself. Many people start something like this and not all of them finish it, and even more talk about it and never start for lack of motivation, time, cash, etc. Jacob's help one day each weekend should keep me motivated. His energy and motivation must spill over to me when we are working. Never seen a kid with such a positive attitude and so ready to get to work. Kid.. 25 years old and with a wife that loves electronics. His favorite pursuit is modulated tube type Tesla coils so we will work on that at times. Two way street.

It's good to see the VOB station, its Dahl iron is perhaps more compact, but about the same 12-13KVA.  Interesting, 4KV @3A from that one, perhaps a capacitor input filter? It's very interesting and should have a topic with pictures as well.


p.s. not noticed til today, the way one set of notches came out on the flooring 2x12s. Look like anything?


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« Reply #13 on: April 25, 2016, 09:02:37 PM »

Yup.   I'm going cap input,  should be good for 6.4 kv,  unloaded.   I'm expecting 6+ kv loaded.

I actually have a pair of the xformers.   One an ordinary Pete Dahl and another mag cap Pete Dahl.

Took one xformer in on a trade for labor.   Can't beat that price.

I'll post some more pics later.   Sitting on the side of the road waiting on a wrecker.   In a big truck.

Gonna be expensive,  thank goodness it's not my dime.
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« Reply #14 on: April 25, 2016, 09:14:04 PM »

p.s. not noticed til today, the way one set of notches came out on the flooring 2x12s. Look like anything?

It appears that the saw blade had knowledge that this rig will be Amplitude Modulated......
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« Reply #15 on: April 25, 2016, 09:25:23 PM »

p.s. not noticed til today, the way one set of notches came out on the flooring 2x12s. Look like anything?

It appears that the saw blade had knowledge that this rig will be Amplitude Modulated......

A Milwaukee 'Sawzall' with a wrecking blade.
tool tip: sawdust on the concrete floor helps when sweeping up everything else, lowers dust, and leaves it looking clean.
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« Reply #16 on: April 26, 2016, 12:50:42 AM »

Hey Pat,

Before you fire that bad boy up, you better call Comanche Peak and tell them to bring up the reactors into the red! I'll know you're on the air when my lights flicker.

Mike/KE5YTV
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« Reply #17 on: April 26, 2016, 02:11:47 AM »

It will no doubt be months.. plenty of advance notice. Each time it gets worked on, I will try and post some pics.

Right now the status is:
Need to get a die to run over the threads on a Powewrstat bolt which I think is 3/8-20 as the 7/16-20  die goes on it loosely but the 3/8 dies in other TPI 24 and 16? do not fit. I have a nut the right size and have to go to the hardware store to find out exactly what it is.

Need make sure I have a drill for that size, have to drill the brackets a bit as they seem to be from a different Powerstat.

Buy some of that angle iron with the holes in it, retrieve some unistrut as well, there is 900# of it stashed in Gainesville TX. The Powerstat is just sitting there and needs to be mounted properly.

If there is some cheap tool for clearing burs out of a hole, that would be nice, otherwise a round file and elbow grease. The burs are at the inside rims of the setscrew holes. Dont know how they came to be there but seem original.

Once the variac is mounted I can temporarily mount a breaker and use them together to test out the 3 PH blower on single phase 240V -see how well the capacitor start setup works. Need a potential relay for that too. It'll do until a VFD shows up to make three phase from single.

So many little details.

Ahh yes I think the model transmitter the transformer is from should be a BTA-10L, or possibly the BTA-10J which is older.
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« Reply #18 on: May 01, 2016, 08:06:12 PM »

Today the front of the Powerstat was fixed in place. Much thought and checking was needed to see how this should fit. It took a few hours to get it done with hardware on hand.

One of the long threaded rods that goes from front to rear in the Powerstat had a messed up thread end. This was chased with a 3/8-24 die to restore it.

The right side of the rack had a gap in the rails from the factory. This is inconvenient. The lower section of those rails were moved up to face at the powerstat so a panel can be put there.

Inside the rack halfway to the back was another (third) set of rails that had supported some unknown item. These were removed and sawed to half height. Two parts are used to back-set the panel that holds the front of the Powerstat. The remaining halves can be used elsewhere.

Because the Powerstat is mounted recessed, the only front panel hole needed will be for the shaft. This makes it much easier.

The possible weakness is that only four rack bolts are used to support the front of the 100 LB Powerstat. More fasteners can be added if needed and they can be 1/4" grade 5 hardware.



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« Reply #19 on: May 01, 2016, 08:15:53 PM »

This Powerstat was originally set up for 460V @ 28A. It was done by connecting two 230V 28A units in series. These will be reconnected in parallel for 230V @ 56A. I need an "equalizing coil" yet. It is required to force equal currents in parallelled Powerstat sections.


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« Reply #20 on: May 01, 2016, 10:55:34 PM »

RAT it is!

Looks like you may have named the amp?

Clandestine Rat?

Btw, where can I find more pix of trucks like that??
And, WHY DIDN'T I THINK to build a car/truck like that??
I had a nice 55 Ford pick up at one time, but the idea of making it
all pretty was too much... too much money, too much time. If I had only realized
I could have gone RAT!!

Paint?

Paint whatcha got! That's what masking tape is for.
Or the paint store will match paint, then you can spray it with a spray gun and air compressor...

Why match the paint, if ur going RAD RAT!!

                       _-_-bear
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« Reply #21 on: May 10, 2016, 08:11:43 PM »

RAT it is!

Looks like you may have named the amp?

Clandestine Rat?

Btw, where can I find more pix of trucks like that??
And, WHY DIDN'T I THINK to build a car/truck like that??
I had a nice 55 Ford pick up at one time, but the idea of making it
all pretty was too much... too much money, too much time. If I had only realized
I could have gone RAT!!

Paint?

Paint whatcha got! That's what masking tape is for.
Or the paint store will match paint, then you can spray it with a spray gun and air compressor...

Why match the paint, if ur going RAD RAT!!

                       _-_-bear

That may be Candelstein Rat.. Radio Candelstein, Flagship Station of the NRK Radio Network.

RAT should maybe be an acronym in this case?  Hmmm...

Goog images "rat truck".   "rat bike" also gives results.

Anyway, Last Sunday update: was off for Mothers Day.
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« Reply #22 on: May 10, 2016, 09:31:18 PM »

Radical Atomic Totalizer?

Radio Attack Transmitter?

Ridiculous Amplifier Tenderizer?
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« Reply #23 on: May 11, 2016, 09:15:59 AM »

Very nice build!

Since the powerstat and the 3cx3000A7 seem to be major components, one by weight and the other by function, looks like the amps' name might honor them.

"PowerStash 3000"

The 3k not only honors the tube but a decent, loafing output.
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« Reply #24 on: May 11, 2016, 10:24:38 AM »


RAT 3000
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