Batteries for the PRC-77  

                  
                     
         Problem: The CY-2562 battery case is available but fitting D cells batteries into the case using OTS battery holders is extremely difficult because you can not close the case.
                                    
 

  

                                     
                                        K4CHE PRC-77 keeper that has been extended in length.

         All of the D cell battery holders that I tried did not fit inside the CY-2562 case. I had to extend the length of the "keepers" on the battery case to allow more expansion of the case.
                           There is no free lunch. Keeper info below.
                                                       Improvise - Adapt - Overcome

        

 

                                 

        BTW  Brooke Clarke N6GCE makes a really neat D cell battery holder for the PRC-77/PRC-25. His craftsmanship is superb and his compacted D cell battery holder fits inside the CY-2562 case. Note the built in connector on the right.

                      http://prc68.com/I/257477BA.shtml

 

               

 

 

  
                               

          All of the D cell battery holders when stacked in a "normal" manner would not fit due to the overall heigth of the assembly.

  
                                   

         During bench trials is was discovered that if you "inverted"one of the battery holders when stacking you could have more room and the batteries will get to know each other better.		  
                                  

            By inverting the top D cell battery holder the portions of the batteries that are exposed form a cradle for the upper battery case which is inverted.


     		 

                               

          An extra bonus, when the batteries are enclosed in the case the pressure of the bottom of the case keeps them in the holders. Mark your connector with the plus and minus symbol. There is no reverse voltage protection for the input of the PRC-77.

              

 


  
                               

         Several types of D cell battery holders will fit. Either Horizontal or vertical but the top of the battery holder has to be exposed. 		 

                                 

         The vertical cases shown above will work if you invert the top case in the stack.

 

  

                             
                Rusty scrap metal with a 90 degree bend requisitioned from the K4CHE storage bin
                   located under the tree in the back yard.

               Take a piece of steel scrap metal that has a 90 degree bend and use that as material for the new extended keepers. As a general rule if I can't fabricate the project with simple hand tools than I shy away from the project. Visit your local home supply store or make friends with your local welding shop. Take a keeper removed from your case to judge the thickness of the metal stock which is approx .070.

  
                                  

         You can always purchase some strip stock and bend your own using a vice and a hammer.		  

                                              

                          One of my keepers measured out at .070. Which is a #14 or #15 standard thickness.

 

       

 

 

  
                          

                         A quick use of the hacksaw and you have the basis of a new "extended" keeper. By using 90 degree stock the difficult bend is all ready made.
 
                                  
                                                          Original keeper on the left.

              One of my favorite tools shown above to increase the bend of the keeper past 90 degrees. 		 
                                 

                  Drill some holes and the new extended keepers will be ready for testing.		  
                                  

                           Its not complicated and a 30 minute project.		  
                                

                                       Test fitting of the new keeper.
  

                              
                                                 Original keeper on the bottom

     Size comparison. The distance between the mounting holes and the bend has been extended .25 inches.

 

 

  
                                     

              When removing the original keepers do not lose the nut plate - you will be sorry.

  

                                  

               Use a file to round off the corners etc. Original keeper in the center.

 

 

 

 

  
                                 

             You do not have to remove the rubber cushion strips from the bottom of the CY-2562 case as the D cell holders will fit in between. 		 

                            

                    Finished keeper on my beat up twenty dollar Hamfest Frankenstein PRC-77. The additional .25 inch keeper length expansion allows the battery cases to fit inside and to be able to close the case.

 

 
                                   

        A connector can be cannibalize from a old battery but you can also fabricate a connector.


              		 
                                  

              Visit the local hobby store and purchase some 6/32 OD brass tubing.
  
                                  

             Crimp the tubing slightly to ensure good connection.		  
                           
                
                     Its easy to locate the positive and ground pins on the connector.
 
                                 

                  Solder and cover with heat shrink. Don't screw up the polarity of the connector. There is no reverse voltage protection on the input of the PRC-77.		  
                                    

                                           "Improvise - Adapt - Overcome		  
                                    

                     Keeping things simple I use my favorite connector.     A wire nut.		  
                                 

                   I prefer to fuse all my battery projects. A 2 amp fuse was installed.		  

                                  

         TIP: When selecting a fuse holder or system look for the style above that clamps around the ends of the fuse. A lot of fuse holders just have a spring loaded contact that makes a pressure contact on the end and they are very unreliable.

 

                                        

            TIP:Use Clear Gorilla tape to hold the connector in place. Handy stuff.

  
                K4CHE PRC-77 Noise Squelch conversion page:
                           http://k4che.com/PRC77-Squelch/PRC77-Squelch.htm		  
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