Restoring my Eberline PNC-1

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Richard Hull
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Restoring my Eberline PNC-1

Post by Richard Hull »

Some years ago, circa 2004, when I went to 3He neutron detection, I had used my Eberline PNC-1 a lot prior to 2004. At some point I accidentally arc'd the BF3 tube input ~1700 volts and killed it dead. Never mind, bring in the 3He system. Jim Kovalchick has an old PNC-1 and is using it and I remembered with nostalgia my early adventures with it. Plus it is the sole instrument used by the Farnsworth team in the 1961 time frame on right up until the end. I attach a photo of Gene Meeks with his MKII super fusor. I wanted mine back in operation.

I started about midnight last night and found a dead input diode and first PNP germanium transistor bad. Probably the arc killed the front end of the charge sensitive amp. I had the parts and by 2AM I had the old boy fixed as good a new. Next came calibration. Following, carefully, the Eberline calibration instructions, I calibrated all the ranges using my pulse generator and to my delight found them requiring only very minor tweaking. still, this was a 2.5 hour process with cleanup. Eager to see how it did with the fusor, at 5:30AM I stumbled out to the lab, (awake for 22 hours now), and ran the fusor to new heights of operation. The result was 2200 EPM (they label the meter in events per minute). This works out to close to 13.2mr/hr rate. After down loading the Rhodium counts and doing my Xcel graph, I limped out into daylight at 9AM. Hungry, I went to Hardees and got 2 bacon egg and cheese biscuits came home and allowed 2 hours for digestion, took a shower an hopped into bed about 12:20 PM in the afternoon, after being awake for 29 hours.

I attach a number of images of the gear. Next up is to cal and test my PNR-4 and mated remball. My PNC-1 is one of the earliest models with a serial # of 283. I bought it off e-bay in 1999. Yes, it could have been the one in the Farnsworth team image! Ha Ha. It is certainly one of the first year's run on this new instrument. Getting the old classics running and in tune is great fun.

Richard Hull
Attachments
MKII' 2 PNC-1.jpg
PNC-1shot (1).JPG
PNC-1shot (4).JPG
PNC-1shot (6)anno.jpg
PNR-4 remball (2).JPG
PNR-4 remball (1)anno.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Jim Kovalchick
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Re: Restoring my Eberline PNC-1

Post by Jim Kovalchick »

Richard,
I wish I had your skills repairing vintage electronics. My PNC-1 is down, and I need to work through the problem because it is hands down my favorite instrument.

I noticed in the picture that you have your moderator section sitting with its side towards your fusor. Don't forget that the Los Alamos study found that the optimum orientation is the bottom of the moderator can facing the flux.

Congrats on your repair. You have inspired me.

Regards,

Jim K
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Richard Hull
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Re: Restoring my Eberline PNC-1

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I have now tested the PNR-4 with mated remball and it matched closely the rate given by the PNC-1, while the fusor was run at an amazing level and recorded a peak rate of 15 mr/hr. I feel this instrument needs no calibration. This is bit over the 14.2 mrem measured with the calibrated PNC-1 meter last night. The best run yet with Rhodium was recorded. Graph below....

I now have two good old neutron instruments that are working and true. Before we get objections, I realize the geometry is all wrong with the two instruments to figure TIER using the rates. With both it is recommended to separate the source and ball and the PNC-1 moderator by at least 50cm. I ran them closer 20cm to get a maximized response over a range to see how they tracked. The lin-log meter is very frustrating in that the needle moves up range to 5mr/hr like a rocket, but being log in operation the scale gets real tight after with each little tick mark being a full 5mr/hr thereafter at 25mr/hr they go in about 10mr/hr per tick mark! On the high range 50mr/hr to 2500 mr/hr, the distance between 2500mr/hr to 5000 mr/hr has each additional little tick mark = 500mr/hr. One must rescale one's mind as the needles move up range.

Thus, I will store the Remball/PNR-4 as a working unit and continue to use the PNC-1 for mr/hour readings. As Jim notes, it is a handy little rig. I liked it in 1999 when I bought it, and after repair, I like it all over again. I will not blow it up out of ignorance again. Note: Back then I paid a fortune for both items on e-bay as they were both guaranteed functional.

Richard Hull
Attachments
RhodiumActivation8-2-21.JPG
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Bob Callis
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Re: Restoring my Eberline PNC-1

Post by Bob Callis »

It’s always a great feeling when you successfully bring something back to life after it’s sat stored away.
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Jim Kovalchick
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Re: Restoring my Eberline PNC-1

Post by Jim Kovalchick »

I think my urge to repair my PNC-1 may be rooted in empathy for being older and struggling to convince people that there is still worth. Well, my PNC-1, which is only a little younger than me, showed that it still can count neutrons with the youngsters.

After some fiddling cleaning contacts, fixing some suspect solder joints, and replacing the input cap, my really old PNC-1 is counting again after at least a few years of being inoperative. I have been using the tube and moderator with other electronics, but now the cool round meter works.

After a calibration of all the ranges using an MP-2 pulser, I tested it out with the fusor tonight. I didn't try for a record run, but I gave it a chance to see a respectable 3000 events per minute which include a range change to x10. All went as planned, and a scaler count from the speaker jack output matched the meter very well.

Thanks to Richard Hull for the coaching and encouragement.

I enjoy victories like this wherever they may be found.

Jim K
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Richard Hull
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Re: Restoring my Eberline PNC-1

Post by Richard Hull »

Great effort Jim. Both our PNC-1s were dead on July 28 both are now repaired and clicking away as of this date. Like you, I think nothing beats getting an old nuclear instrument working again.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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