Phone poln TP-25 ACR kit

field telephone TP -25 use of the Czech army supplied without power, need to add / sufficient to 1.5 V battery is used to power the microphone poze hints and tips from customers power supply is correct Phone TP-25 to be only 1.5 V =. On the power thus completely is enough only one AA size dry battery (original \ Bakelite \ article AS4 even had only 1.4 V). Because it jedenapůlvoltový article in full compliance with the device, it will last in service for many years, certainly much longer than more expensive and unsuitable deväťvoltovú battery. Personally, I have AA cell (alkaline) without any loss of volume in the phone more than 6 years (and still use the phone several times a day on the route home-garden). Prerequisite for proper function of the phone is to use the original inserts microphone and earpiece. And speaking to each other at both stations. As the microphone must be used with insert name \ MB \ and receiver must have the impedance of about 250ohmů. 50ohmů earpiece and microphone \ AUT \ of normal civil phones are not suitable, then the voice is very weak. It should be noted that the TP-25 is very hilarious Czech product. At a low power consumption (of the order of only 0.04 W) this field can be used for clear phone connection on a surprisingly long distances. When using a pair up to a distance of 25km. If the line was kept on poles with porcelain insulators (by inductive loading), and the literature indicates that even up to a distance of 500 km. What is due to the simplicity and power consumption unattainable by any other means of communication.