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| Signal box telephones Medstead signal box. As well as a Norstar extension three signal boxes are fitted with working old telephones, the dial phone cannot make outgoing calls as the Norstar exchange it is connected to does not accept a digit of 1. From the left - phone for box to box circuit - code phone, next is the phone for Medstead SPTs and then an auto phone. The first two phones have since changed positions, Although externally the phones are different the internal workings are the same and based on the circuit board from a late 700 series telephone. Some are fitted with bells, some buzzers and some with neither. In total there are now nine of these "heritage" phones in service.  Ropley signal box. Picture above taken early 2007 shows installation of telephones in the new signal box, against all advice old equipment was required. Since the picture was taken a Norstar phone has also been installed but has to be kept hidden from view. Signal box in service - spot the Norstar phone! It is there.  The latest old style phone to have new inners fitted. This was installed and working in Ropley signal box for a time but has since been recovered as some signalmen had problems reaching the microphone. Now located in the Ropley booking office as a display item but not working, one wonders how long it will be before someone wants it connected. Ancient and modern at Medstead. Code phones Going back a number of years there were a number of wooden box phones used to give direct signal box to box service, these didn't work and the Ttelecom department was asked to sort matters out. On the understanding the old system wouldn't be used each signal box had a small relay set using Post Office 3000 type relays, these relays formed a transmission bridge, controlled calling and sounding a call buzzer for incoming calls. There were a number of MF signalling Viscount telephones in store, being unsuitable for use on the Strowger system then in service. The key pads were removed, this was the early days of MF phones and was done purely to make sure no one took the phone. These phones were used as the direct box to box phone, the entire system was built and installed in little over a week. 
Later modification were made to add "tone wetting" on the circuits, this caused a lot of problems and was removed. Later several of the old wooden phones had the circuit boards of a Viscount phone installed with varying degrees of success, shown below is the one in Ropley signal box. 
During 2008 these phones were fitted with the circuit board from 700 series phones, this is now standard for all "heritage" phones on the railway. 
Shown above is the latest variant using the components from a late model 700 type phone. It is a simpler design and makes any maintenance easier.  3000 type relays located in Medstead signal box locking room, in the centre is a set of relays for a Code phone circuit and the right hand set is the remote end of the Butts Junction circuit, now recovered from service.MF = Mains fail [not used] FA = Fuse Alarm PB = platform bell DF = detects if the main incoming 50 volt supply from the exchange becomes disconnected.  Ropley signal box, Code phone relay set on the left, two platform bell relays on the top right. For reasons forgotten in the mists of time SPTs became a responsibility of the telecoms department, there being no railway SPT equipment available new equipment was made using Post Office 3000 type relays. The original relay sets for the phones were built in multiples of 4 circuits and these are fitted at Alresford and Medstead, each having 8 lines installed. In the later installations at Ropley and Alton the relay sets have 5 circuits, giving a total of 10 lines. Alton and Alresford have ex Strowger exchange racks fitted for the SPT relay sets, lack of space at Ropley and Medstead exchanges meant the equipment is fitted in the signal boxes, here we have used cut down UAX13 racks, thanks to the railway Building Department for doing the metal work. Originally the Medstead equipment was in an external cabinet but suffered from relay coils going faulty despite having a heater installed. Medstead - old equipment in external cabinet. Original Medstead SPT equipment under test in the S and T workshop. Relay sets 1 and 2 - telephone line circuits, 4 per can 3 - common circuits 4 and 5 - main and standby ringers On the right are the electronic ring tone generator and connection strips. SPT in Medstead yard. New type clip joint and armoured cable. Modified Bakelite phone fitted in Medstead signal box for local SPT circuits, again a 700 type circuit board. The changes will not impress the purist. Alresford SPT concentrator and associated phone, it now has an approriate period handset cord. Thanks to the Telecoms department of the Festiniog Railway for donating the above two phones. SPT and miscellaneous equipment rack at Alresford. On the top shelf are 3 alarm circuits from the other 3 stations, below is an electronic Clock and associated Clock control relays. Shelf B is the SPT equipment, 2 relays sets each with 4 Line Circuits and the Common Equipment relay set. On the shelf below is the Electronic Ring Tone generator and on the right just in shot is the equipment that generates the 30 second clock pulse, there are main and standby generators. Alresford's two furthest SPTs had an additional relay set fitted to detect if the line went faulty. At the far end a 33k ohm resistor was fitted across the line, this caused a small current flow that was detetected by a transistor circuit at the local end, if the line went faulty an alarm was raised. Not very successful as the detector circuits often went faulty, usually after a thunder storm. These extra relay sets were later removed as they were a fault liability. An plan was made to use opto isolators instead, this had the advantage of a reduction in space required and all circuits could be monitored, one of those jobs to be done on a rainy day. Alton has a requirement that when the box is closed the SPTs are diverted to Medstead signal box. The equipment that had been stored for this job was removed from secure storage and dumped 6 miles away in the open, nobody had told us this was happening so by the time the items were discovered they were ruined. Being old technology it was not easy to replace it so a mixture of old and modern equipment has now been used. For a the time a direct circuit via the two Norstar exchanges was installed and tested should it be required to give the diversion service. As the circuit was in situ it has been made a direct line between the two signal box Norstar phones. Alresford, Ropley and Medstead use vibrator ringers, Alton has an electronic one. On two occassions Norstar switches have been used to give temporary SPT service, first at Alresford when the Strowger exchange was recovered and a new SPT rack was being installed. Second at Ropley, the relay sets from the old installation were required to be used during testing of the new system.  Alton - showing the start of installation of the SPT rack also shown is the PP2040 The SPT rack at Alton with all the relays sets in position, a quick count shows there are around 130 relays, 3 uni-selectors plus some more relays at Medstead. The top set of relays are the exchange alarm system. Relay set at Alton to switch SPTs to Medstead, 10 circuits, relays have been used to switch lines to reduce the wiring to the selection keys in signal box. Under auto working, which is most of the time, the relays are released and calls go to Medstead. Only when the box is opened are the relays operated. During the 2009 Spring steam gala the system was placed in service for testing, a phone acting as a SPT was installed in Alton signal box for these tests. The idea was to see if there were any unforseen problems. Apart from a noisy cable pair, which there was not sufficient time to sort out, there were no problems experienced, thanks to the Traffic Department staff for giving the system intensive use, over 100 calls were made in 3 days. What lurks under the panel in Alton signal box, termination of the SPT Key and Lamp unit, shown are Krone connection strips, phone circuit board, buzzer and a converter to change 50v to 5v for the lamps. The relay sets that are required to extend the SPT circuits from Alton to Medstead when Alton signal box is closed, 2 relay sets either end.
First and fourth sets for Alton and second and third sets for Medstead signal box Medstead - new equipment. The top shelf has 2 relays sets each with 4 Line Circuits and the Common Equipment relay set, the bottom shelf has the Ringer, with 2 spaces reserved for Alton circuits.  Concentrator at Medstead signal box where the circuits terminate when Alton box is closed. At the bottom of the wooden box are the 10 keys for the Alton SPTs and the associated handset on the side, the Green key is the CALL key and the Grey key on the far right allowed remote swiching of the Alton equipment from local to remote mode and vice versa but is no longer used. Two lamps indicate if the Alton equipment is in the local or remote mode. Modern equipment is being used as someone totally unconnected with the Telecoms department decided to throw out the older style keys, very thoughtful of them. Before building the parts for the Alton circuits a poll was conducted amongst the signalmen and the few who bothered to reply were happy with modern items. The top row of keys are for the Medstead SPTs. The top right hand key being in a down position shows the concentrator is switched off, any one attempting to call from a SPT will get a continuous tone instead of ring tone.  Medstead - new relay sets for Alton connection fitted - March 2009. Initially it was planned to have a bothway SPT circuit between Medstead and Alton but it got complicated with the limited number of relays there was space for so the final scheme had an outgoing and an incoming circuit. The method of operation is straighforward, to call from Medstead to Alton the required SPT key is operated, this puts a marking condition on a uni-selector bank. The non locking CALL key is operated and the uni-selector steps at 10 pulses per second (10 pps ) until the marked outlet is reached, a corresponding number of pulses are sent to the incoming relay set at Alton which acts in the same manner as a Final Selector, it tests the line and if free connect ring tone to the caller and ring current to the SPT. If a call is made and the SPTs are in the local mode Number Unobtainable tone is returned. An Alton SPT calling Medstead when in remote mode causes a Line Finder to step at 10 pulses per second to find the calling line and Ring tone is connected, a corresponding number of pulses are sent to Medstead to indicate which SPT is making the call. If the Medstead concentrator is switched off the line to Alton is reversed , this is detected at the distant end and Number Unobtainable tone is returned if someone attempts to use a SPT. For a while a Panasonic 308 switch was used at Ropley for the SPTs but was not popular being replaced with a relay based system shown below. Ropley (old box)- the SPT relay sets were located under the desk. From the left - 4 Line Circuits, Ringer and Common Equipment. Each line circuit had a LS relay coil, this had a 50 + 50 ohm coil differentially connected in the line, on lifting the SPT handset the LR relay would operate but not the LS relay, the line lamp would come on, there would be no audible indication. A caller would press a CALL button on the phone, this connected an earth condition to one leg unbalancing the line allowing the LS relay to operate which operated LZ in the Common Equipment relay set, this caused the buzzer to sound and the lamp associated with the SPT to flash. This method overcame the problem of SPT handsets being left off but the LS coils often went faulty leaving the SPT out of service, the LS relay was removed from the circuit. Ropley (new box)- replacement SPT equipment, the top shelf has 2 relays sets each with 5 Line Circuits and the Common Equipment relay set, the bottom shelf has the Ringer on the left plus a spare Ringer. On the right are the electronic Ring Tone generator and Krone connection box. The equipment is now enclosed in the cupboard shown below.
It will be noted on top of the cupboard is a Norstar phone, this is for emergency use for incoming calls from off site callers. When fitted it caused certain people to go into a state of apoplexy, there would have been less reaction if the box had been painted pink and covered in neon lights. It seems modern phones are a no no but modern 13 amp electrical fittings are alright. After this item was added there was a view of Swanage signal box on the local TV news, in a very prominent position could be seen a Norstar phone, in no way hidden, they must be made of stronger stuff in Dorset. | |
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