>>>2024-05-07 Electrical Characteristics Of Telephone Lines (…

This seems to have been Motorola's only AM cellular transmitter, and is a two piece set in which the power supply and modulator are in one case and the RF section in a second. It's also believed that assorted special versions have been made to buyer order, corresponding to non-standard power provide inputs, mounting schemes and so forth. Both of those modifications distant-wired the volume management so that it would be controlled at a separate control head, electrically, and have been mainly supposed to allow mounting the Police Cruiser within the car trunk. The -SP2 modification contains the -SP1 modification, but also permits trunk mounting of P-69-18 by adding a cable connector box (see photo below) which allows the receiver to interchange with a Deluxe Line FMR-13V VHF FM receiver and be suitable with an FMTR-30D radio accessory set. I'm on the lookout for other examples of old police radio equipment from the 1930's and 1940's - - do not let this gear wind up on the landfill! The one piece TR 20-18 set proven right here was used by the Tracy, California Fire Department in a hearth engine and was licensed as a police transmitter, into the late 1940's. It contains a P-69-18 receiver and a T-69-20A transmitter.

Shown below are the standard speedometer cable model "distant" management head for the P-69- series Police Cruiser receivers which did not feature electrical quantity management, namely the P-69-12, 13 and 18, and the "small" cell speaker. The brand new quantity control was then a DC remotely managed design reasonably than the speedometer style cable of earlier models. This cover is friction-fit only, there are no screws securing it as on different fashions. There have been at least two variations of T-69-20A management head style. Produced at the least via 1949. The knobs are the identical as shown on the P-69-12 above. Somewhat widespread. The squelch control was moved to the entrance panel and supplied with a knob, not like previous versions, the place it was situated behind a plug button on the side of the housing, as shown on the P-69-13 above. Shown beneath is an unusual, low voltage armored power cable apparently early P-69-18 with a blue nameplate and a handle on the higher cover. There was additionally a "giant" cellular speaker, featured within the photograph of the transmitter set up shown later on this page.

The photograph below reveals an early P-69-17 with the same control head as the opposite Police Cruisers which have been crystal managed. The photo below exhibits a typical early P-69-18 with a black housing and a purple nameplate. These had been shipped in a black wrinkle colour scheme until someday after 1945, when the shade was switched to grey wrinkle. Single channel. Exterior black wrinkle enamel. Selectable dual vibrators. Exterior blue-gray wrinkle enamel on SP2. Crystal control, twin vibrators. Crystal control, single channel. Operated in the 30-40 Megacycle vary, crystal control. The head for the P-69-17A added a toggle swap for squelch between the pilot lamp and the amount control. Any submissions might be added to this and different web pages I'm creating. The difference doesn't really matter that much on the phone end, but could be complicated if you're looking at documents that use totally different conventions. Historically splice cabinets have been typically mounted up utility poles, but this made them harder to safely work on so this arrangement is pretty much gone to history. Second, splice closure and cabinets are intentionally made for straightforward modification. Instead, fashionable splice cabinets are bigger ground-level pedestals, often a good 4-8 ft vast with massive double doorways.

For overhead wiring, splice closure are normally black plastic cylinders hung alongside the cable. Once your telephone loop makes it out of your telephone, through your own home wiring, down a drop cable, via an F2 cable, and then by an F1 cable, it arrives at the telephone trade. When you crack open a wall and look at your family phone wiring, you will nearly certainly discover a stunning variety of wires. This is without doubt one of the differences you will see when you look in different international locations: as a result of of tangible details of the electrical design of the alternate and the telephones, and the place completely different elements are positioned, some countries such because the UK require slightly more complicated family wiring than just putting all jacks in parallel. If the issue goes away, it is someplace in your household wiring, and subsequently not the phone company's problem. You would possibly count on some hefty ISO specification for analog telephone strains, however there isn't actually one exterior of tools specifications printed by manufacturers.