Looking for LND 725 Geiger tube
? I need a LND 725 Geiger tube and thought that I would ask this list before buying one from LND just in case someone had one that they would part with. ?
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Re: Landers, Frary and Clark CD V-715 Retrofit
Dear Clint,
Try contacting Eric Green at the Civil Defense Museum directly at:
<webmaster@...>
Good luck,
~Cliff
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On 6/17/23, Clint <clintb@...> wrote: Stephen,
Thanks for the reply. That looks like it's only for the Victoreen and not
the Landers, Frary and Clark. ?Unless I missed it, I don't see where a
capacitor was added to the PCB. ?This is section 9.1 of a larger document.
It is possible that the procedure for the Landers, Frary snd Clark is, say,
section 9.2 or 9.3, perhaps.
Hopefully something will turn up, or someone may have an example of one of
the retrofit LFC 715's.
Clint
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Re: Landers, Frary and Clark CD V-715 Retrofit
Stephen,
Thanks for the reply. That looks like it's only for the Victoreen and not the Landers, Frary and Clark. ?Unless I missed it, I don't see where a capacitor was added to the PCB. ?This is section 9.1 of a larger document. It is possible that the procedure for the Landers, Frary snd Clark is, say, section 9.2 or 9.3, perhaps.
Hopefully something will turn up, or someone may have an example of one of the retrofit LFC 715's.
Clint
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Re: Landers, Frary and Clark CD V-715 Retrofit
This might be what you are looking for?
-Stephen N.
On Sat, Jun 17, 2023 at 8:56?AM Clint < clintb@...> wrote: It was discovered that the Victoreen CD V-715, in order to improve calibration stability, had to be modified slightly and a procedure was provided. We have the document for the procedure.??The Victoreen CD V-715's sold on eBay can be compared against that document to verify that they have been retrofit?
?
I've recently seen a number of photos of CD V-715's made by Landers, Frary and Clark on eBay, stamped with an "R" to indicate a retrofit that have a capacitor soldered to the foil side of the printed circuit board but nowhere in my research have I come across anything that says that the LFC 715's were retrofit. I own one that does not have the capacitor or the "R".
?
I am reaching out to the community for the lost Landers, Frary and Clark CD V-715 Retrofit Procedure document. Is anyone aware of a retrofit for the LFC survey meters?
?
Clint
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Landers, Frary and Clark CD V-715 Retrofit
It was discovered that the Victoreen CD V-715, in order to improve calibration stability, had to be modified slightly and a procedure was provided. We have the document for the procedure.??The Victoreen CD V-715's sold on eBay can be compared against that document to verify that they have been retrofit?
?
I've recently seen a number of photos of CD V-715's made by Landers, Frary and Clark on eBay, stamped with an "R" to indicate a retrofit that have a capacitor soldered to the foil side of the printed circuit board but nowhere in my research have I come across anything that says that the LFC 715's were retrofit. I own one that does not have the capacitor or the "R".
?
I am reaching out to the community for the lost Landers, Frary and Clark CD V-715 Retrofit Procedure document. Is anyone aware of a retrofit for the LFC survey meters?
?
Clint
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? Thanks Mike, ? I have a line on one but I will get back to you if it does not work out. ? I really appreciate your offer. ? Lenox ? ? ? ? Subject: Re: [CDV700CLUB] Need pulse generator ? Lenox,
If you still need a pulser, I have a homemade job with set ranges and I have been traveling through the DFW area quite often lately.? If the CPM values shown on these panel plates would work for you, reply privately.
Regards,
Mike Loughlin
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Lenox,
If you still need a pulser, I have a homemade job with set ranges and I have been traveling through the DFW area quite often lately.? If the CPM values shown on these panel plates would work for you, reply privately.
Regards,
Mike Loughlin
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Lenox, old friend, I didn't realize that was you asking.
Contact me off list and I'll fix you up with the perfect 0.3% CDV-700 instrument at no cost.
George?
----- Original Message ----- From: Lenox Carruth <radios@...> To: [email protected]Sent: Tue, 11 Apr 2023 18:54:26 -0400 (EDT) Subject: [CDV700CLUB] Need pulse generator
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Geo Dowell sell pulse calibrators that work on any model. The
price has gone up a bit since I bought mine. He asks $150 for them
now, but they are simple and work.
On 4/11/2023 6:54 PM, Lenox Carruth
wrote:
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_
I have a Bicron
Surveyor 2000 that I would like to pulse calibrate.
?
Does anyone in
the Dallas, Texas, area have a pulse generator that I
could use to calibrate this instrument??
?
I estimate that
it would take about twenty minutes to do it.
?
Thanks for your
consideration.
?
Lenox Carruth
?
_,_._,_
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_ I have a Bicron Surveyor 2000 that I would like to pulse calibrate. ? Does anyone in the Dallas, Texas, area have a pulse generator that I could use to calibrate this instrument?? ? I estimate that it would take about twenty minutes to do it. ? Thanks for your consideration. ? Lenox Carruth ? _,_._,_
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On my 720 and 717, drifting appears to be contamination on the high ohm resistors next to the triode under the cover. I looked at the procedure to clearn those and I feel I better leave that alone. When you add desiccant, and it behaves a little better, that tells me there is moisture reacting with stuff on those resistors causing leakage currents.
Team: Does KI4U also fix units that have issues or only provide calibration?
-Stephen N.
On Mon, Jan 30, 2023 at 9:02 PM Clint < clintb@...> wrote: Yes.? I ruled out the second and third things shown below leaving possible moisture contamination.? I tried desiccant but it didn't completely fix the problem.? I would like to have more confidence that it will pass calibration before sending it in.? I have a couple of meters that pass the circuit check and have a steady needle on all ranges, but that doesn't guarantee they can be calibrated.? Maybe I'm mistaken but I doubt a meter with a drifting or erratic needle will pass.?
Looking at the John E Fast cap it appears to have a porous ceramic casing, so I was curious if anyone was aware of a problem with those capacitors before swapping them out.
Clint
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Clint:
Is your issue just in the self check or zero settings or when the unit is switched to X0.1 range ?
I had a CDV-717 which had a oscillating needle on the X0.1 range. Did you look at sec 8.3 of the CDV-717manual ?
calibration adjustment by adding or removing a solder bridge on the pwb.
P
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Thank you, Michael. ?I bought an OCD-M-151 meter to replace a bad one my ion chamber survey meter and plan to practice on the bad one before tackling the ENI meter that's hard to find. I'd rather just replace it and offer it to anyone who has a better chance of fixing it. It's a shame it has an issue... it looks brand new.
Clint
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Yes. ?I ruled out the second and third things shown below leaving possible moisture contamination. ?I tried desiccant but it didn't completely fix the problem. ?I would like to have more confidence that it will pass calibration before sending it in. ?I have a couple of meters that pass the circuit check and have a steady needle on all ranges, but that doesn't guarantee they can be calibrated. ?Maybe I'm mistaken but I doubt a meter with a drifting or erratic needle will pass.?  Looking at the John E Fast cap it appears to have a porous ceramic casing, so I was curious if anyone was aware of a problem with those capacitors before swapping them out.  Clint
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Clint:?
In my experience with vintage( 1950's 1960's) equipment, I have not come across a non-electrolytic cap that has gone bad due to age. Of course there are exceptions.
Electrolytic caps dry out and loose value and their ESR increases. Old carbon composition resistors seem to drift off, think that was due to moisture +/-20%
Is there a particular reason why you suspect a bad cap ?
Peter
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Generally speaking, we feel there's only one way to trust the CDV- 7xx ion chambers detectors. That is to buy one fully calibrated from KI4U.??
The amateur is just not equipped, nor could he be legally to even test them for function much less calibration.
It's hard to trust an instrument that "passes ckt check" even with the sensor completely? removed!
Just my personal opinion of course.
Geo
On Jan 30, 2023 9:02 PM, Clint <clintb@...> wrote: Example
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If you are worried about it, pull one leg off the PCB and throw it on a cap tester and look for leakage at half voltage rating, then at full. I personally have not replaced this type before and always got a meter up by replacing the electrolytics.
-Stephen N.
On Mon, Jan 30, 2023 at 7:03 PM Clint < clintb@...> wrote: Example
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All,
Please excuse me if this is not the right place for this but there appear to be no discussion groups for the CD survey meters.
Does anyone know if the John E Fast capacitors are susceptible to moisture and should be replaced?
They appear in both the CD V-715 and CD V-717 survey meters.
Thanks,
Clint
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I see it's the 10x less sensitive 101 tubed model.? Maybe he thinks that makes it worth ten times as much.? Nope, greedy pricing on most of his other stuff too:?
-Chris
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don't everyone jump on it at once..? there is a $1,250 ENI on E-Pay.? Can't tell if it's plated in gold or what but must be something special at $1,250.? ?;)
https://www.ebay.com/itm/144812439391?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ZAxdCcCrQq-&sssrc=2047675&ssuid=punt3lqcrjm&widget_ver=artemis&media=COPY
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don't everyone jump on it at once..? there is a $1,250 ENI on E-Pay.? Can't tell if it's plated in gold or what but must be something special at $1,250.? ?;)
https://www.ebay.com/itm/144812439391?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ZAxdCcCrQq-&sssrc=2047675&ssuid=punt3lqcrjm&widget_ver=artemis&media=COPY
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Mike L.
David71
Michael C