Bring out ya' dead! Restoring a scavenged Ludlum 3

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Richard Hull
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Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Richard Hull »

The title here is reminiscent of Monty Python.... and the "I'm not dead yet" plea of a Ludlum model 3.

I have just restored a seriously worn out, beat up, scavenged and left for parts Ludlum 3 GM counter.
I remember I got this for free in a buy some many years ago as part of "here take this" along with other things I bought.
It had a note on it ….. “ Richard, You might want this for parts”.
It lay about for years and in cleaning out some junk, I took pity on it.....

It had alkaline battery destruction all over the battery compartment. I had to re-machine a couple of the terminals in brass. ( I hate alkalines! They are the worst battery made by man related to corrosion)
The corrosive vapors had spread over much of the circuit board damaging IC pins and traces, etc. (this is common when alkaline batteries are left in a device over time.)
Both battery compartment springs were completely eaten into three pieces. Luckily, I have a huge selection of smaller compression springs and easily found two suitable replacements.
Once I got the batteries in, following the compartment repairs, the circuit board would not generate High Voltage.
Found two bad IC’s and got the HV working.
The two toggle switches were corroded, cleaned those. The main knob was missing. (scavenged) I put on an old bar-pointer knob, circa WWII.
I plugged in a pancake probe after adjusting the HV to 875 volts. No clicks on the audio. (little annunciator was OK)
Found and replaced defective audio amp IC that had alkaline corrosion all over the pins. Also two of the 1/8 watt resistors had their leads corroded completely through. (replaced)
The speaker now worked great….IT WAS COUNTING!!!

The counter's meter had been scavenged (missing).
The meter presented a problem as it was small and the original was square faced with special scale and of unknown movement sensitivity.
I knew that the battery position, with good batts, moved ~7/8 of the way to full sale on all my other Ludlum counters.
I hooked up a multi-switched 1ma to 50 ua meter I had for years. Turned on the model 3 to BATT, and as I worked down range on the meter, it turned out to be a 50ua meter movement in the original Ludlum 3 GM counter.
Now, what did I have in the way of 50ua meters that might be made to work? I had (23) 50ua meters in my inventory and it turned out a Radio Crack “Archer-Micronta" 50ua meter would cover the hole and only needed me to drill two new holes in the Ludlum's front panel.
I put it all together and re-calibrated for 5000 cpm full scale on X1 and so on for all the other ranges using my NIM pulser.

The handle was also missing (scavenged) but it will be a snap to make…No problem…

Now full of new life, via the resurrection that I afforded this badly wounded warrior, it will join my menagerie of Ludlum meters and detectors. It was a 4 day part time project while working on fusor V activation efforts.

I attach two images.

Richard Hull
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Ludlum model 3 (1)ANNO.jpg
Ludlum model 3 ANNO1.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
Retired now...Doing only what I want and not what I should...every day is a saturday.
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Dennis P Brown
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Re: Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Dennis P Brown »

Richard, you are a true crasftman! Great restore!
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Richard Hull
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Re: Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Richard Hull »

Thanks, it was a fun restoration that needed stuff I had in my lab stores here, (read vast collection of junk boxes). I finished making up a nice handle for the counter today...'er last night just before dawn.

Workin' in the lab every day and night, doing lots of reading from my large scientific library. The old gal and I are watching our myriad of DVD and VHS PBS masterpiece theater series and PBS who dunit series. Not much on TV worth watching these days. Still have 12 working VCRs and 4 DVD players, Gotta' have backups. Well, it's 7:30 am and I've been up all night in the lab. I'll take a shower and hit th' hay. Just another normal day... 'er night.

I have three more old relic GM counters from the 50's to restore (vacuum tube portables). I have little boards already done to create the 120 volts needed for the tube plates in these babies. They and the 6 volt batt needed to power the boards fit easily into the old dual 67.5 volts battery bays. More as I finish them.

Kickin' back and havin' a blast

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
Retired now...Doing only what I want and not what I should...every day is a saturday.
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Richard Hull
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Re: Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Richard Hull »

It is said, "All things come to he who waits." Well it is true in the case of this resurrection related to my Ludlum model 3, above, two years ago. At this year's big HEAS event, (October 2022), in the flea market in my yard, I found a box of meters being sold for $3.00 each. I picked out three meters all scaled for use in nuclear GM and neutron counters.

Low and behold, there was a genuine NOS meter for a Ludlum model 3! I attach the image of my trove of goodies purchased at the event below. The meter can be seen in it.

I dawdled in my usual manner and only this week, removed the Radio Shack Micronta brand 50ua meter that had served well in my original restoration, seen in the above images, and replaced it with the proper model 3 meter obtained at my October event flea market. Latest image is attached.

A keen eye for real need at a hamfest or any tech fair flea market or even e-bay, can usually bring a brutalized, parted-out shell of a nuclear instrument closer to, not only its original functionality, as above, but closer to its original appearance as well, seen below.

Richard Hull
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Lucky find of proper meter for Ludlum 3 in and amongst my purchases at HEAS flea market event October 2022.
Lucky find of proper meter for Ludlum 3 in and amongst my purchases at HEAS flea market event October 2022.
New proper Ludlum meter in place.  Handle, improvised and knob remain to be replaced, maybe.
New proper Ludlum meter in place. Handle, improvised and knob remain to be replaced, maybe.
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
Retired now...Doing only what I want and not what I should...every day is a saturday.
Rex Allers
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Re: Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Rex Allers »

Congrats on restoring that Ludlum 3 to good function. Leaky batteries did an extensive amount of damage. Kudos for finding and repairing all of that.

I got a Ludlum 3 on ebay recently with an end-window probe. This one has extra scales for mR that match my probe. Not necessary and cool that your new-found meter doesn't have extra scales that are only right for a certain probe.

Mine is early 90's vintage but different from yours. Guessing, without trying to look it up, yours is earlier. Mine has all the adjustment screws under a little cover to the right of the main knob. Yours has them arranged (logically) around the switch positions.

Don't change the knob you have. It's great. Points just fine and has a classic style.

Looks like the handle screws on yours are different. Seems to have a screw parallel to the surface at the meter end and one more at the bottom of the case near the battery compartment. Not easy to deal with access at that meter end. Mine has one screw at the top (meter) end that goes down vertically into the case and two screws that go into the outside end of the case. Easier, I think, but just different.

Mine arrived working fine but has a bit of crazing in the paint near the on/off, F/S switches. Like a solvent was on there too long. The outside case surface of yours looks pristine.

------
Diverging now but in line with celebrating your serendipity of finding the proper meter.

Years back I bought an AO binocular scope. It was, I think 12 X. Looking up documentation, there seemed to be a version that had a selector knob that could make it 6 or 12 or 24 power. Mine had plastic covers on the sides where that knob would go.

Back in the 90's / early 2000's there were several surplus stores around here (south silicon valley). Browsing one day, on a random shelf, I found a thing. Sort of cylindrical, radial knob on one end. Two holes through radially on the cylinder and two lens assemblies perpendicular to the holes.

Umm, gamble but I think I know what this is. Can't remember what I paid but cheap for a random unknown thing.

Yep, it worked. Had to pop the two covers from my scope and do a bit of shimming to make it fit smoothly in the opened hole. I use the scope often. Mostly in the 6X which is provided by the backwards 2X lenses, but sometimes on higher powers too.

Low power scopes get more valuable as our eyes age. Two such scopes I have are used often. I find it unfortunate that as we age and lose the ability to see small things the technology gets smaller and smaller.

Serendipity on finding an unobtanium part for a thing is a great satisfaction.

Congrats to us both.
Rex Allers
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Richard Hull
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Re: Bring out ya' dead! Restoring a scavenged Ludlum 3

Post by Richard Hull »

Rex, thanks for the kudos and info on your model 3. Likewise, thanks for your note on serendipity finds related to your AO microscope. Foreknowledge of what something is supposed to look like helps in any search for upgrading to original conditions through junk box finds at hamfests and tech sales points, surplus dealers, etc.

I have a monster collection of GM counters, Scintillation counters, ion chambers and neutron counters. most all are fully functional, but many of the oldest from the 40s,50s, and 60s demand the no longer extant 22.5 volt, 45volt, 67volt pile batteries which were still available into the early 2000's.
I have already upgraded two or three of my oldest GM counters to my custom designed modern transistorized high frequency HV supplies using the normal filament D cells for power to generate the 100-140 volts for the plate circuits. This allows them to continue to use their original vacuum tube circuitry and remain original save for the OEM high voltage battery needed back then. I will feature one of my old chromed plastic "Precision Corp" meters of the early 1950's "U boom" public sales series reworked GM counters soon.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.
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