Restoration of a PDR-43 radiac meter?

  • Thread starter ssbothwell
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In summary: It sounds like your meter may be in the same boat as the one in the photo. Unfortunately, it may be difficult to repair without a new ion chamber.
  • #1
hello. i found a pdr-43 radiac meter at my local ham radio swapmeet today. the device looks like this: http://www.civildefensemuseum.com/southrad/im125dpdr43.html

as a just for fun project, i would like to attempt to make it functional. right now the unit powers on but adjusting the check meter between beta and gamma does not do anything and the roentgen meter reads a 500roentgen/hr immediately upon powering up.

i don't know much of anything about radiation or radiation detection but i am a ham radio operating and am fairly comfortable with electronics design. any help or resources would be great.
 
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  • #2
Hi ssbothwell.
Was there not a probe associated with the device?
Many of these hand held meters had a plug to fit the actual probe, with the mica window for the geiger-mueller tube that serves as the sensor.
I have to say that the captions on the link you provide are not encouraging, as the unit has been 'stripped of the check source and some tubes'.
You need the check source to calibrate the meter and tubes missing sounds ungood. However, there is no obvious empty socket.
Maybe google the device number and see what turns up.
Good luck!
 
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  • #3
there is no socket or anything that a probe might plug into.

i don't see any spots that obviously used to have components other than perhaps the highlighted points in this image: http://i.imgur.com/fxhbo.jpg

those things look like clips but they might not be. perhaps they held the 'check source'?

i'm not sure exactly how these meters work. is the 'check source' a radioactive sample that is compared against the environment for determining radiation levels?
 
  • #4
The check source is exactly that, a known source that allows the meter to be properly calibrated.
The items you identify do sort of look like they might serve as clips to hold a probe, but it seems unlikely the probe would be clipped to the motherboard when the device is built into a robust hand held casing.
It may be that the greenish plastic surrounds the mica window for the sensor tube, but if so there should be a window on the casing, else the device would be shielded from what it is trying to read.
Try this site: http://www.civildefensemuseum.com/southrad/im125bpdr43.html
You were entirely right that the clips hold something, the GM tubes most likely.
 
  • #5
the pdr-43b in that photo has a slightly different board layout but clearly those things i highlighted are the same clips.

what do you think the likelihood of finding those tubes and a check source would be?

maybe i should just be satisfied with the device in its current state.
 
  • #6
ssbothwell said:
the pdr-43b in that photo has a slightly different board layout but clearly those things i highlighted are the same clips.

what do you think the likelihood of finding those tubes and a check source would be?

maybe i should just be satisfied with the device in its current state.

Finding replacement tubes should be feasible, there is a fair amount of data on the device on the web, including part numbers.
A check source is more difficult, they are still sold with geiger counters, but those are currently available after a long lead time and at fancy prices. EBay may be a better bet.
As is, the device is entirely unfunctional. It is too light to work as a doorstop, but would work as a paperweight.

It is always a bit depressing to have a piece of gear that no longer works. Sort of a standing reproach.
If you have the needed tools, you could build in an iPhone and use it as a communicator.
 
  • #7
haha, i would rather keep it as is then install an iphone in it. its a nice relic as is but it would be really amazing to get it functional. maybe i'll get lucky and find a check source and tubes, but until then its just going to sit on a shelf.
 
  • #8
I have a similar gamma survey meter (CDV-715) that has the same problem, it pegs out when on. I'm pretty sure that is a sign that the ion chamber has lost its gas or has otherwise malfunctioned. I don't think there is any way to fix it without getting a new ion chamber.
 

1. How do I disassemble a PDR-43 radiac meter?

To disassemble a PDR-43 radiac meter, you will need a small screwdriver, pliers, and a soldering iron. Start by removing the back cover and battery compartment. Then, carefully remove the knobs and switches. Next, unscrew and remove the front panel. Finally, desolder any components that are attached to the front panel and remove it completely.

2. What are the common issues with a PDR-43 radiac meter?

The most common issues with a PDR-43 radiac meter are degraded or faulty components, dirty or corroded internal connections, and damaged wiring. These can cause inaccurate readings or even prevent the meter from functioning properly.

3. How can I clean and restore the internal components of a PDR-43 radiac meter?

To clean and restore the internal components of a PDR-43 radiac meter, you can use a mixture of isopropyl alcohol and distilled water to gently clean the circuit board and connections. You can also use a small brush or compressed air to remove any dust or debris. For corroded connections, you can use a specialized cleaner or gently scrape off the corrosion with a small tool.

4. Can I replace damaged components in a PDR-43 radiac meter?

Yes, damaged components can be replaced in a PDR-43 radiac meter. However, it is important to ensure that the replacement components are compatible with the meter and are properly installed. It is also recommended to consult a professional or refer to the meter's manual for guidance on component replacement.

5. How do I calibrate a restored PDR-43 radiac meter?

Calibrating a restored PDR-43 radiac meter requires specialized equipment and knowledge. It is recommended to consult a professional or refer to the meter's manual for calibration instructions. Alternatively, you can also send the meter to a calibration laboratory for accurate and precise calibration.

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