The dosimeter charger is necessary to move the hairline on the dosimeter back to the starting position at zero. This is also known as zeroing the dosimeter.

    And because you can't do this unless you have a dosimeter charger, we'll talk of the charger first.

Dosimeter & Charger

    If you don't have a Charger, the dosimeter hairline can't be brought back to zero, when it has reached the end of the scale; say , for instance, on the CD V–742. But, with the dosimeter charger, CD V–750, the hairline (fiber) of the dosimeter can be re–zeroed.

• The charger has one control knob, called the voltage control. When the charger is turned so the printing on the top can be read, this knob is located on the top, far–right corner of the charger. On the top left corner there is a cap with a chain coming out of the top of it; beneath this cap is the charging contact. The chain keep the cap froom getting lost when it is unscrewed and lifted off the chargin contact. The cap should be kept screwed down over the charging contact when the charger is not in use, to keep the contact clean, to prevent medical damage, and to prevent accidental discharge of the battery.

• Installing the Battery in the Charger. The charger is powered with a single D–cell flashlight battery. The battery powers two things in the charger: The electronic circuit that charges the dosimeter, and the light bulb that illuminates the dosimeter scale while charging it. Caution: The charger should not be used as a flashlight, doing so will quickly run down the battery and then, unless you have spare batteries, you will not be able to charge the dosimeter(s). The battery should not be left in if the charger is not used for several days or longer.
  The Charger CD V–750 light bulbs can be order from Well Gain Electronics. The bulb you want is GE 131 E10. Last year they cost 8 cents a bulb! Now, they cost $5 per bulb. Toll Free Phone Number: 1–866–935–5424. Or, Go Here

• The Battery Is Installed As Follows:
  • Use a coin or screwdriver to unscrew the large screw at the center the of the charger, shown above. After turning the screw counterclockwise, the charger top will come off the bottom part of the case.

  • Lift the top of the case from the bottom and install the D–cell battery in the rectangular battery holder mounted on the inside of the top cover. Keep the polarities of the battery "+" and "-" aligned to the polarities of the battery holder. Prior to doing this, use fine sandpaper and clean the metal pieces that hold the battery in place until shiney; then, use electrical contact cleaner on a q–tip and clean more the polarities of the battery and of the battery holder.

  • Install the D–cell battery in the rectangular battery holder mounted on the inside of the top cover.

  • You may have a rubber pad glued to the inside floor of the bottom. Some chargers don't have them. Place the bottom part of the case over the top so the rubber pad is over the battery, and tighten the screw by turning it clockwise.

  • Checking the Battery and the Dosimeter Charger (Operational Check). This procedure is also used for resetting or zeroing a dosimeter. A dosimeter is needed for a full operational check of the charger.
    CAUTION: If the dosimeter has been in use to measure radiation dose, you should write down its reading before using it to check the charger. Otherwise, if the charger bulb doesn't light up, you may accidentally push the dosimeter down too far when you should press down just enough to turn the light looking through the dosimeter to read it. However, this problem can be avoided by using a flashlight or any light source, except the Sun! Still, by using light pressure to push down on the dosimeter in the Charging Contact you will learn how to control light pressure from higher pressure.

• The Operational Check Is Made The Following Way:
  • Put the charger on a firm, flat surface such as a table, on the floor; or, a desktop.

  • Unscrew the cap from the Charging Contact and lay it to the side.

  • Place the charging end of the dosimeter—the Charging Contact which is also called the Charging Pole; the opposite end of the Charting Pole is the Magnifying Lens. The Charging End is always opposite the end of the pocket clip. It is easy to spot as it is hollowed out with the Charging Pole in the center. You will need to use one hand to hold the dosimeter down on the charging contact and the other hand to adjust the voltage control. You may need to experiment to find out which arrangement of your hands is easiest for you to do the job. If the right hand is used on the dosimeter, you will need to rotate the charger so the printing is away from you.

  • Look through the dosimeter eyepiece on the end by the pocket clip, and push the dosimeter down genty on the charging contact against the spring pressure until you can see the dosimeter scale light up. If the charger doesn't come on, check the battery, light bulb, and contacts, which will be given shortly.

  • Push down the dosimeter with greater pressure on the Charging Contact until it reaches bottom of the Charger and won't go any farther. Hold it there.

  • While the dosimeter is being held solidly down on the charging contact with one hand, use the other hand to rotate the voltage Control Knob. Look through the eyepiece to watch the hairline. The hairline (fiber element) should move as you rotate the Voltage Control, and you should be ab le to make it move to the"0" (Zero) at the left end of the dosimeter scale. If you can't make it move to the zero, then go into Troubleshooting The Dosimeter Charger, given next.

  • Remove the dosimeter and replace the cap over the charging contact.

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  Troubleshooting The Dosimeter Charger.

  • Always keep the protective cap on the Charging Contact when the charger is not in use. The smooth surface of the clear plastic insulator around the Center Contact should be kept dry, no fingerprints (have oil from the epidermis—skin), clean of dust, dirt grit, moisture, and lint. Use a soft clean cloth to clean it. Then, on a q–tip, spray a few drops of contack cleaner and clean the Charging Contact of the dosimeter with the q–tip thoroughly; but gently. Avoid using strong solvents, cleaning fluids, and the like that could dissolve the plastic at both end of the dosimeter.

  • Take out the battery and keep the case closed when the charger is not to be used for periods of several days or longer.

  • If the light does not come on when the dosimeter is pressed down on the charging contact, do the following:

    • Check the battery to be sure that it is installed with the correct polarity—that is, in the right direction. And, that it is making good electrical contact (not loose in the holder).

    • If the condition of the battery is questionable, replace it with a battery that is known to be sound and good! Because of a nuclear war, when everything stops moving; have many batteries of this D–cell type and others you use in various flashlights and items.

    • Check the light bulb to see if it is loose in the sock and tighten if necessary; or, remove and sand or file contacts gently. Then, use a Cotton Tip Swab, saturated with electrical contact cleaner!

    • Replace the bulb in case the bulb is burned out.

    • You should have other bulbs in storage. You can get them now, and should, from Go Here!

    • If the light still does not come on after taking the above actions when the Charging Contact of the Dosimeter Charger is depressed, the charger should be sent to KI4U.com for repair, if possible provided the mail and other services are still up and running.

  • If the light is dim or appears weak, do the following:
    • Check the battery to make sure that good electrical contact is being made.

    • Clean the battery and light switch contacts with a pencil eraser, steel wood, or fine sand paper, and finishing with electrical contact cleaner. We have restored a number of CD V–750 Chargers this way; especially finishing with contact cleaner to remove any remaining oxide that could not be reached with the others. The electrical contacts should be bright and shiny.

    • Tighten the nut, if loose, on the Charging Contact charger.

    • If the battery is questionable, replace it with one that is new or known to be in working order!

  • If the dosimeter scale is illuminated, but when the voltage control knob is rotated and the hairline does not appear on scale, or the hairline is unsteady (jittery movement of the image), do the following:
    • Check for dirt, moisture, oxide on the Charging Contact on the charger or on Charging Contact on the dosimeter and clean them off.

    • Check for good electrical contact between the dosimeter and the outer aluminum sleeve of the charging receptacle. Press the dosimeter down firmly against the charging receptacle and rotate the dosimeter back and forth a half–dozen times. Keeping the dosimeter vertical, move the dosimeter sideways to make the chyarging contack sleeve touch the inside wall of the dosimeter charging receptacle.

    • Check for proper electrical contact between the light switch spring contacts, and clean them as above.

    • Try another dosimeter.

    • If the hairline image still cannot be made to appear on the scale after taking the above actions, send the charger in for repairs to KI4U.com.

  • Preparation For Using The Dosimeter:
    • Preliminary. A dosimeter is about the size of a ballpoint pen. The dosimeter has a clip so it can be attached to clothing worn on the body, and what the dosimeter shows it has collected is considered analogous to what your body has collected. It can be clipped to a collar, neckline, or belt. It may be mounted on walls, furniture, or post or hung by string.
      The dosimeter shows the total or accumulated amount of gamma radiation to which it has been exposed starting from the time of recharging or zeroing the instrument. This gamma exposure is read by holdiing the instrument so that it is pointed toward a bright light and looking through the end with the clip on it; that is, the Contact Contact of the dosimeter. The gamma exposure is shown by the position of a hairline along a scale of numbers marked "ROENTGENS." The scale has numbers that begin with zero at the left side and usually end with 200 at the right sidee.
      The dosimeter is constructed to be reliable and rugged. The only moving part is the hairline or fiber seen through the eyepiece. Its design is based on the principle that a charge of electricity is reduced when there are charged particles around, and charged particles are produced by gamma radiation through ionization. A special instrument is used to place a charged of electricity inside the dosimeter. This charge is just like the static elecftricity that builds up on a person who is walking along a carpet on a dry winter day.
      The position of the fiber depends on how much static electric charge is on it. When gamma rays interact with the walls of the dosimeter and enter the chamber in which the fiber is sealedm, charged particles are produced. These particles reduce the charge on the fiber, and the fiber moves to a different position. The position of the fiberas it is seen on the scale then indicates the total amount gamma radiation to which it has been exposed since it was charged.
      Keep in mind why one needs a dosimeter charger: To Place an Electric Charge on The Fiber Inside The Dosimeter So It Can Be reset To Zero. The charger can also be used to read the dosimeter when no light is available or when it is undesirable for various reasons to Turn On A Light To View The Dosimeter Scale.
      The dosimeter has no battery to install and run down and no controls to operate. As long as the hairline is on the scale when viewed through the eyepiece, the dosimeter can be considered to be turn on. It actually operates continuously. The position of the hairline on the scale can be read anytime and as often as you wish. If the hairline can't be seen, then the dosimeter is useless and must be recharged.

    • Charging or Zeroing the Dosimeter: An electric charge must be placed inside the dosimer to make the hairline visible ande to reset it to the zero position on the scale. A dosimeter charger is necessary for this oeration. Exactly the same procedure is used to zero or reset the hairline of the dosimeter as it is used for the operation check of the dosimeter charger.
      In a fallout situation, be sure to write down the reading on the dosimeter scale, as well as the time, just before the dosimeter is charged or reset to zero. The reason for keeping such records and how so you can average them up and see what your exposure has been; also, some will panic during this time due to fear and lack of understanding; therefore, you can help bring them back down to normalacy, hopefully, by showing them their dosimeter reading then and their average absorption of radiation gamma rays!
      If you use the charger to get the light to read the dosimeter, do not press down so firmly that you now have to reset the dosimeter! Also, pressing to firmly wipes out the dosimeter reading. You had better do this for one in a state of panic, as they will be too excited to follow directions and wipe out the dosimeter reading. When you see what the reading is, you can tell them, because of their dosimeter, it is not more than 5 R or just a little more, which is nothing to worry about.
      You have saved one person from generating to others in your Home Fallout Shelter, a Panic Situation from which some will, as doing WW–II, during the bombings in Europe, go into running fits! All to the detriment of your secure shelter as they will be opening windows and doors to 'Escape'!

  • The Dosimeter Is Zeroed As Follows:

    • Put the charger on a firm, flat surface such as a table desk top, or floor.

    • Unscrew the cap from the charging contact and lay it to one side of the charger.

    • Place the charging end of the dosimeter over the Charging Contact. The charging end is opposite the end with the pocket clip; and is hollowed out with a center postdown inside. Use one hand to hold thye dosimeter down on the charging contact and the other hand to adjust the voltage control. You may need to experiment to find out which arrangement of your hands is easiest for you to do the job. If the right hand is used on the dosimeterm you will need to rotate the charger so the printing is away from you.

    • Look through the dosimeter eyepiece on the end by the pocket clip, and push the dosimeter down gently on the charging contact against the spring pressure until you can see the dosimer scale light up. If the charger light doesn't come, check the battery, light bulb, and contacts as discussed earlier, and follow through with cleaning the polarities of all items involved.

    • Push the dosimeter with greater pressure down on the charging contact until it reaches bottom and won't go any farther. Hold the dosimeter there.

    • While the dosimeter is being held solidly down on the charging contact with one hand, use the other hand to rotate the voltage control knob, and look through the eyepiece to watch the hairline movement. The hairline or fiber should move as you rotate the voltage control, and you should be able to make it move to the "0" (zero) at the left end of the dosimeter scale. If you can't make it move to the zero, re–read "Troubleshooting The Dosimiter Charger."

    • After you have zeroed the hairline, lift the dosimeter from the Charging Position—which is all the way down, to the VIEWING POSITION—which is almost all the way up;, and checki the position of the hairline. It may have drifted to one side or the other of the zero, and you will need to zero it again. After some practice, you will be able to zero the hairline quidckly in one try.

    • Remove the dosimeter and replace the cap over the charging contact of the charger.

  • Checking Dosimeters for Leaks. Dosimeters are very reliable and rugged, but there may be occasionally be one which may "leak"; that is the hairline will slowly drift up–scale to the right of zero, even though there may not be enough radiation around to make the needle move at all in a nonleaker. Most of the leakers should have been weeded out or repaired while they were in storage, but remains a small chance that you may have a leaking dosimeter in your shelter. If there is time during a crisis period before a nuclear attack, check your dosimeters for leakage as follows:
    1. Zero all dosimeters. Record their serial niumbers and the time they are zeroed.

    2. Place the dosimeters in a secure place.

    3. Check each dosimeter and record the readings every 12 hours. You may wish to check them in a shorter time if you think a nuclear attack has begun to check the dosimeters for leakage. Record the readings and the time even though you check the dosimeters in intervals of less than 12 hours. If a nuclear attack doesn't begin, continue to check the dosimeters for four days (96 hours).

    4. At the end of the leak–period, whether four days or less (depending on the situation), calculate the leakage per 24–hr day for each dosimeter. For this calculation, use the final reading on the dosimeter at the end of the leak–checking period is 2 R in the eight hour period. You started with zero R and at the end of 8–hours, you found the dosimeter reading was 2 R; and there is no radiation fallout coming down. Ignore dosimeter readings taken at other times during the leak–checking period of 8 hours. Only go with the reading at the eighth hour. Then, the leakage is calculated as such: L, is L = (24 x 2) divided by 8 = 6 R/day. A formula for this would be L = 24 R/T; where L is the Leakage; 24 = a 24 hour day; R = Roentgens; and T is the total number of hours in the leak checking period. Hence, L will the the leakage per day in roentgens per day. The slash, /, means that the product of 24 R (24 times R; which is 2 in this example) is divided by the time, T, yielding 24 divided by 8 = 3 and this is multiplied by 2 R which gives 6 R—The Leakage!

    5. If a dosimeter leaks as badly as the dosimeter in this example, it can still be used, but you must calculate the leakage and subtract it from the dosimeter reading to get a correct radiation exposure reading. If there is not time or opportunity during a crisis period to exchange dosimeters that lead more than 2–3 R per day, they should be marked with an "L" on the body of the dosimeter, either with pain or fingernail polish or a Sharpie Marker. This tells one not to become unduly alarmed at a high reading on that dosimeter. If its leakage is greather than 10 R/day, it should be considered unreliable.

    6. The hairline on the dosimeter you read, can be estimated to the neares whole number.

    7. When gamma radiation is present, the hairline of the dosimeter is moving all the time, usually so slowly that the motion can't be seen. If the radiation exposure rate is very high, the movement will become visible. Say, if the radiation exposure rate is 7200 R/hr, the hairline of the dosimeter would march across the scale at the rate of 2 R every second! It would be quite apparent and it would be very unhealthy to stay and observe that motion for more than a few seconds.

  • What If You Do Not Have A Survey Meter!
    • If you don't have a survey meter, your dosimeter can be used as such to find the radiation exposure for a specific period of time or on a specific mission you had to go out on to rescue a life, get food and water; or, medicines, etc. Start with a dosimeter freshly zeroed, and then head out on the mission. At the end of a particular time or mission you read your dosimeter before leaving shelter, and you dosimeter read at or near zero; maybe 5 R. Write down what was shown. When you return, it read 35 R, substract the first reading from the second and get 30 R. You were going for 30 minutes; write your time of departure and return time down and substract the first from the second. In this case you were out in the Radiation Fallout for 30 minutes.

    • Using Your Dosimeter To Calculate Dose Rate:
      A dosimeter, however, only reads dose, or how much radiation you have absorbed over a period of time. So if you know the amount of time it took you to receive the dose recorded on your dosimeter, you can arrive at a good estimate of what the dose rate was.
      Suppose, as in the example above, you were outside for 30 minutes (1/2 hour), and your dosimeter, which read 0 roengtens when you went outside, now reads 30 R. Then if you divide the reading by the time you were outside (in hours), you can arrive at the dose rate, or how much radiation was arriving per hour.
      30 R / ˝ hr = 30 X 2/1 = 60 Roentgens/hr.
      This calculation will not be as accurate as a reading taken with a radiological meter, but it will give you some idea of how strong the radiation field is that you're in.

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    Here Is Another Way To Look At This:
    
     

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Here Are Three More Things You Need To Know About

Your Dosimeter:

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    Not knowing this can cause Chaos in Your Home Fallout Shelter! If you teach those in your shelter how to read their dosimeters, make sure they read it horizontally with the "0" of the scale to the left and the "200" R mark to the right. Otherwise, if one holds the dosimeter not horizontal to the light source; but vertical with the "0" to "200" scale vertical, you will find within minutes each time this is done, your exposure rate is climbing.

    The reason for this is that when held in this latter manner, Gravity actually pulls down the Hairline or Fiber each time you hold it vertical and not horizontal, and your Dose Exposure is artificially climbing higher. And, if the person panics and you show him there's nothing to be excited over by showing him his own meter and the shelteree's says 65 R!

    Immediately check your own Dosimeter and several of the ones hanging by a string on the wall to confirm your suspicions his dosimeter has malfunctioned; or, he or she is holding it the wrong way. Therefore, be sure and show the correct way to hold and read the Dosimeter!

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Now, let's talk about The Kick!

We'll Call This One: Kick#1.

Use of Civil Defense
Radiological Instruments
for Peacetime Radiological Emergencies

    Fiber Deflection. Dosimeters and chargers are used in sets with one charger assigned to several dosimeters. It is well known that low range (and certain intermediate range) dosimeters evidence an up or down scale deflection, i.e., a Kick when removed from the charger again when the charging electrode is discharged. The amount of deflection can vary with the make and model as well as age of the dosimeter.

    This is especially true when the dosimeter and/or charger have not been used for long periods of time. The Kick is due to poor electrical contact either between the dosimeter charging recess and the charging pedestal or in the charging pedestal itself, or both.

    Electrical contact degrades when metal surfaces become oxidized during storage:

(1) This can be usually corrected by cleaning the charging recess and bottom of the dosimeter and

(2) By pulsing the charging switch at least 10 times prior to use (pressing down firmly with the dosimeter in the charging recess).

(3) Applying a radial force (with the dosimeter perpendicular in charging recess) during the charging operation may also help; that is, press dosimeter down into charging recess moving it N; then S; then E; then W. several times.

    Dr. "B" also applies an oxide remover, gotten from Amazon.com. He is very partial to D-Series Deoxit, D5. But, any electrical contact cleaner will do! All dissolve Corrosion; Improve Connection; and Protect Surfaces.

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We'll Call This One, Kick#2

Instruction and Maintenance Manual for
Dosimeter Ratemeter CD V-736
Dosimeter CD V-746
Dosimeter Ratemeter Charger CD V-756

    A Word About The Difficulty ("Kick") sometimes experienced in zeroing the dosimeter and the ratemeter:

    The charging contact of the CD V-756 charger automatically compensates for the "Kick" when the ratemeter is withdrawn slowly from the contact. You can see this effect by holding the ratemeter on the charging contact while looking into the instrument.

    Withdraw the instrument slowly. You will note that just before the light turns off the hairline will shift. With a little practice in setting the hairline slightly in the left of the zero line, the hairline can be made to shift so that its final position coincides with the zero line.

     Optinum performance is obtained when electrostatic "Kick" is compensated for in this manner. The hairline will remain on or near the zero position for long periods when not exposed to radiation.

Remember, in storing your Dosimeters, that they operate on an electrical principle, so dampness can affect them. They should be stored in a location that is DRY as possible.

Insert them into two (one inserted inside another; Zip Locked bags) and insert a Desiccant, 2 & 2-3/4 inches.

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    You should get a Big Berkey with extra filters; a Katadyne (pocket water filter), and/or make the following from the Schematic given. They all remove Radioactive Particulate Matter:

 

The Red Needle Points To 3 And The Range–Selector Switch Is Set At X100. Therefore, 3 times X100 = 300 R/hr.

The Second Red Needle Points At 4.5 With The Ranger–Selector Switch Set At X10; Thus, 4.5 Times X10 = 45 R/hr.

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These Are In Our Future:

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... To Be Continued ...

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