(Sherwood) and Meter No. 50A (Sherwood-Plus) are call cost monitors that do not rely on meter
pulses (SPM) for their operation. The Meter calculates the costs of a call by monitoring
loop disconnect pulses and then timing the call and relating the dialled digits to the
charging rates. This instrument is designed to give customers an indication of call costs
it does not record metered units and is not intended to be used to challenge telephone
The unit incorporates a 16 digit touch-sensitive keypad for customers to enter charging
information, a removable key to prevent unauthorised reprogramming and a flat surface area
for the associated telephone to stand on.
When fully programmed in accordance with the user guide, the meters will:-
(a) Monitor digits dialled by telephone(s) connected to the same exchange line/PBX
extension as the meter to determine call charging rate.
(b) Time the duration of any outgoing call from 25 seconds after the end of dialling to
(c) Display the estimated cost of a call as it progresses, based on the information
obtained in (a) and (b) above.
(d) Display on request (by pressing the 'ACC' button) the cost of the last call followed
by the accumulated cost of calls to date.
(e) Give an indication (by displaying a letter 'X' and a telephone symbol) if the Meter
has been continuously disconnected from line for more than 25 seconds.
(f) Display the time of day and day of week when not monitoring a call.
(g) Give an indication when batteries require replacement (by showing `BATT LOW' on the
(h) +Permit users to apply cheap rates e.g. on public holidays.
(i) +Permit users to reprogram call charge rates, dialling codes, time and day of week
(j) +Permit users to reprogram times for peak and cheap rates.
(k) +Display on request all codes that have been programmed in (review facility.
(l) +Permit users to program in a PABX access digit so that extension to extension calls
are not monitored.
In addition to the above facilities, Sherwood Plus can:-
(m) Print automatically or on request details of the last recorded call charge.
(n) Print the accumulated cost of calls made, since the accumulator was last reset.
NB: The security key must be in the off position for normal operation of the meter.
The facilities marked + can only be carried out with the security key switched on and by
entering the customers own 4 digit security code.
Made by Rathdown Industries Ltd
Meters 49A and 50A were supplied on sale terms only.
Sherwood Call Cost Monitor S/1000/3/D/021900
Sherwood Plus Call Cost Monitor S/1000/3/E/022325
Approved as supplied for connection to the Public Switched Telephone Network (PSTN). DELs
and PBX extensions.
Suitable for use with the 10 pps loop-disconnect pulsing telephones on phone Socket
installations on DELs or PABXs. The meters are designed to operate on 50 Volt-working
lines only, correct operation cannot be guaranteed if used on other voltages.
The operation of the Meters relies on the unit being programmed correctly by the customer.
This programming involves entering the dialling codes for:-
(a) Local-Rate charged calls beginning with digit '0'.
(b) The codes marked 'charge letter a and b1' in the dialling code book.
(c) The dialling code for the Irish Republic.
(d) International dialling codes.
The number of codes to be programmed in (a) and (b) above varies throughout the
country. In certain areas (e.g. London) the number of codes is such that complete
reprogramming would be a lengthy process and so it is most important The security code and
all programmed information may be reset by removing the batteries for approx. 15 minutes.
It is the users responsibility to replace the four batteries when the display shows BATT
|BT Item Code
|METER No. 49a (GREY)
|METER No. 50A (GREY)
|(Common to both meters, no longer available)
|LINE JACK 10/3A (DOUBLER)
The dial pulse monitor draws approximately 10 micro amps continuously from line and may
give apparent low-loop line test conditions.
The Meter 49A and 50A is powered by 4 'C Type' Alkaline batteries fitted in the base of
the instrument. A 'battery low' symbol will show on the display when these start to run
down, and require changing.
When replacing batteries, the new set must be inserted and the battery cover replaced
promptly to prevent loss of stored information.