Another tube amp becomes history... almost

[sluckey]

Today I'm changing the transmitter tube in my old Raytheon built ARSR-2 long range radar. Next month our old radar system will be replaced with a very modern all solid state system. No more tubes! This will likely be the last time I change this tube. So, I took a couple pics just for my own personal files. Thought y'all might like to see this tube.

This water cooled QK653 AMPLITRON tube, is a L band pulsed amplifier, capable of 5MW peak pulse power (about 3.6KW average power). The filament (white ceramic part at bottom) is rated 5VAC @ 50A and sits in a 'bathtub' filled with silicone oil to prevent arcing of the 100KV pulse applied to the cathode. The RF waveguide ports are air pressurized to 25 PSI. It weighs about 150 lbs. For scale, the stainless steel threaded rods are 3/8" diameter and 16" long. This amplitron is typically driven by a 500KW magnetron power oscillator.

[Willabe]

Sluckey if you could get the speaker they used in Back to the Future in the opening you could make the biggest, baddest champ in the World! What the heck their throwing that tube out right? Got to be some life left in it?


                        Brad     

[sluckey]

  Now that would be a nice little SE amp! Wonder if Doug could supply the filament tranny?

Actually, I'd love to see it thrown away. I want those magnets! Man, you could pull nails, maybe even deck screws with that! Unfortunately, there are still about 50 radar sites that use that same tube, so even though they will be upgraded in the next two years, those tubes will have to go back to the depot as spare inventory.

I've got a set of magnets from an old 1MW magnetron, but they're only about half the size of these. When you put the magnets together end to end, you have to use a couple 2x4s to twist them apart. Two people can't simply straight pull them apart.

[PRR]

My neighbor has one of the war-surplus magnetron magnets he uses to fish iron out of lakes. I hadn't seen one in decades.

[kagliostro]

Hi Sluckey

WOW what a tube

Got to be some life left in it?

may be a Headphone Amp ?  


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It will be interesting to see the rectifier used to give B+

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the bigger and stronger magnets I've seen where in a swapable Hard Disk in a 1980 Computer

(Olivetti S6000 - HD is blue in the bottom photo)



there was a linear motor to move the heads to read the data, this motor had a pair of very big magnets
something like a brick each one, with this magnet you must not go near monitors less than one meter one meter and half, if you go more near the monitor will be permanently damaged (I know as a fact and don't ask how)

Kagliostro

[sluckey]

It will be interesting to see the rectifier used to give B+

Here you go. There are ten 'doorknob' diodes stacked together next to the measuring tape. Each diode is rated for 10KV @ 1A. The HV power supply is three phase so there are three stacks of these doorknobs. B+ is only about 8-10KV but is not applied directly to the tube. Instead, 10KV is applied to a pulse modulator that develops a high voltage pulse. This pulse is connect through a huge pulse transformer that steps the pulse up to 100KV amplitude. This 100KV negative pulse is applied to the cathode of the amplitron and causes it to operate (The anode is grounded). The pulse is only 2 µS wide.

[Willabe]

Your worth evey penny you get paid for and then some if this is the kind of stuff you take care of at work! 100KV?

I wouldn't want to be in the same room with that kind of power.



                                    Brad        

[sluckey]

That's not 100KVDC. It's a 2µS wide pulse whose amplitude is 100KV. The duty cycle is on for 2µS, off for 2776µS. Still commands a lot of respect! We have a defibrillator (AED) in the transmitter room and are trained to use it. Never had to though.   

[Willabe]

Each diode is rated for 10KV @ 1A. The HV power supply is three phase so there are three stacks of these doorknobs. B+ is only about 8-10KV but is not applied directly to the tube.

8-10K at 30A, 3 phase? I still wouldn't want to be in the same room with that.    

If someone got shocked with that would you even be able to use the AED? I mean wouldn't a shock that big do more than just stop someones heart?


                          Brad      

[sluckey]

8-10K at 30A, 3 phase?

Where did you get 30A??? The 8-10KV power supply is only putting out about 600mA. Now the 5VAC filament supply operates at 50A. The filament supply is a bit unusual. It starts as 120VAC applied to a 20 amp variac. The variac output is applied to a 1:2 stepup transformer. The stepup transformer is applied through the huge pulse transformer separate windings and is stepped down to about 5VAC. This 5VAC is connected to the tube filaments whose resistance is 0.1Ω.

I still wouldn't want to be in the same room with that.

There are all kinds of safety interlocks that will prevent you from coming into contact with any of that dangerous stuff. However, all us smartasses have the door interlocks bypassed so we can look at the power supply, modulator, and transmitter while troubleshooting. You must be able to see this stuff to find many problems. You can't just hang a meter here or there and close it up.   

If someone got shocked with that would you even be able to use the AED? I mean wouldn't a shock that big do more than just stop someones heart?

I can only speculate what would happen if someone got hit with that. I would at least expect a pin hole burn at the entry and exit points.   

An AED is not used on a stopped heart and in fact, will not even deliver a shock if no heartbeat is detected. It's used on a fibrillating (quivering) heart only.  It's function is to deliver a shock that is sufficient to actually stop a quivering heart. Then you hope the brain will command the stopped heart to beat at a normal rate (or continue CPR). Kinda hard to do on yourself though! 

[Willabe]

There are ten 'doorknob' diodes stacked together next to the measuring tape. Each diode is rated for 10KV @ 1A. The HV power supply is three phase so there are three stacks of these doorknobs. B+ is only about 8-10KV but is not applied directly to the tube.

This is all way over my head. Still 8-10KV at 600mA is a lot of power.

When I was in grammar school we went on a field trip to the Museum of Science and Industry. They had a guy there that was showing us a box that had a PSU in it with a meter that would put out 1MV. He asked if any one wanted to have 1MV put through their body?

All the other kids were scared, so I did it. Didn't feel a thing. He said there was almost no current so it was safe. Being little kids all we understood at all was voltage, we had no clue about current.

What does that tube go for new?
    


                    Brad     

[FYL]

Serious stuff indeed.

[sluckey]

What does that tube go for new?

$60,000.00. But we don't buy them new anymore. A contractor (used to be Litton) rebuilds them for only $20,000.00. It's a bargain.

This one failed within 10 days of installation. Thankfully, the contractor has to eat this one. There was a defective weld on the internal coolant plumbing that surround the electron tube. Coolant leaked into the RF node transitions and KABOOM! The green stuff in the attached pic is water/antifreeze! NOT GOOD!!!

[kagliostro]

Here you go. There are ten 'doorknob' diodes stacked together next to the measuring tape. Each diode is rated for 10KV @ 1A. The HV power supply is three phase so there are three stacks of these doorknobs. B+ is only about 8-10KV but is not applied directly to the tube. Instead, 10KV is applied to a pulse modulator that develops a high voltage pulse. This pulse is connect through a huge pulse transformer that steps the pulse up to 100KV amplitude. This 100KV negative pulse is applied to the cathode of the amplitron and causes it to operate (The anode is grounded). The pulse is only 2 µS wide.

That is very interesting and absolutely new to me

thanks for explanations

Kagliostro

[Ritchie200]

Is there some sort of internal reflector in the tube that you must orient, or does it just all sit in the waveguide?  BTW, what does the waveguide look like?

Cool stuff!
Jim

[thermion]

why is the waveguide pressurized? just wondering...
cool post!

[sluckey]

Is there some sort of internal reflector in the tube that you must orient, or does it just all sit in the waveguide?  BTW, what does the waveguide look like?

The tube sits on to of a huge 400 lb. pulse transformer. The waveguide is a long hollow rectangular aluminum tube with a flange on the end. The flange bolts to the waveguide port on the amplitron (see the pic with the green bulb inside the waveguide port). The L-band waveguide is about the same dimensions as a 4x6 treated post. There are two waveguide ports on the tube, one for RF input coming from the manetron, and one for the RF output going toward the antenna.

[sluckey]

why is the waveguide pressurized?

The positive pressure prevents outside air which contains moisture from seeping into the tube and/or waveguide. Moisture is very bad inside high power waveguide systems. Even very low power microwave links or cell towers use a small amount of positive pressure inside the tiny waveguide to prevent moisture getting in. Small systems typically just use a small bottle of Nitrogen running at 2-5PSI.

[sluckey]

Well the ARSR-2 radar is gone now. No more tubes.      But I got some souvenirs.   

[tubenit]

Kind of sad to see things fade away like this.  Glad you have a piece of history to remember.

Totally by coincidence,  I was in the last office of active telephone operators in  the entire US on their last day of operation.  At least, that was what we were informed at the time.   I was a kid at the time. I still remember the operators connecting plugs to connect people knowing that midnite (or whatever time?) was going to be the end of an entire profession and era of communication.  It felt quite surreal.

Thanks for sharing, Sluckey!

With respect, Jeff

[PRR]

>> why is the waveguide pressurized?
> ...prevents outside air which contains moisture from seeping into..... Small systems typically just use a small bottle of Nitrogen running at 2-5PSI.

There are some (older?) telephone cables which run small pressure to keep dry. I used to see nitrogen tanks strapped to phone poles. Rarely. This may have been a fast-fix for a leaker, pending a real repair or replacement. It may have been more the old paper cables; which are now mostly replaced with plastic.

> I was in the last office of active telephone operators...

Come on up. You saw the last for-pay operators. The last of each generation of switching (manual boards, Strogers, ESSes, etc) tends to go to telephone museums run by retired telco geeks. There's one near me. They have multi-operator plugboards, also a room of clacking relays, and a large (office-size) trailer with relays and a microwave link used in some remote town quite recently. The guides know what everything does, and the differences between telco compressors and the broadcast compressors I know. If you won't come this far, there's probably a telephone museum in your state.

[thermion]

There are some (older?) telephone cables which run small pressure to keep dry. I used to see nitrogen tanks strapped to phone poles. Rarely.

I've seen this a few times in austin, mostly near downtown. Wondered why there was a random gas cylinder just hangin' out?.?

[sluckey]

I had the privilege to turn this old radar on in 1982. And I also had the privilege to shut it down in 2012. 30 years with this old gal. What a gig! I still don't believe they paid me to do this stuff! I'm really a lucky man.

[Willabe]

Hey Steve, is that you in the picture?   


                     Brad     

[sluckey]

Yep.

[John]

You look like a happy man. Had to be a fascinating job a lot of days!

[Willabe]

You look like a happy man.

Yes, he does.       

[sluckey]

Even happier today. Got my magnets! I had a tough time getting them outta the truck bed. Hope they never get stuck together. 

[Willabe]

I had a tough time getting them outta the truck bed. Hope they never get stuck together. 

   

[HotBluePlates]

Even happier today. Got my magnets! I had a tough time getting them outta the truck bed. Hope they never get stuck together. 

From the Amplitron? They didn't send it back to the depot?

[sluckey]

Yes, from the amplitrons. Our good spare went back to the depot. The two in the transmitter cabs went to salvage. Guess they didn't want to pay for the rebuild. The magnets weigh about 30lbs apiece! I don't have any need for them but they are just so neat. I've loved magnets since I was a toddler. 

[tubenit]

I had the privilege of meeting Sluckey in person and getting to jam with him a couple of yrs ago!

SUPER nice guy & a great guitar player!  Very amicable individual.  Nice sense of humor. 

Wished I had his knowledge about this stuff.


Steve, nice to see you finish well in your job!  Bravo!  

With respect,  Jeff  

[sluckey]

Jeff, always a kind word! I wish I had just a part of your people skills. And your ears. And especially your tenacity for experimenting and finding good tones. Maybe we should get together again and swap some skills... And pick a bit too! How 'bout my place this time?

It's good to have a job that you really love. I'm very fortunate. I'm at 237 days and counting down.