:>>> Was this ever actually the case? :>>
:>> ** Yep. :>>
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:>> ........ Phil :>>
:> :> :> The jumper king who lived in the MDF room would test lines, I think doing a :> polarity reversal and see how long the meter needle took to fall back, :> giving an indication of the capacitance on across the line. More phones = :> more capacitance. :> :> IIRC the phones could be strapped share a single cap and still retain the :> bell in each phone. :> :> : : I worked in an exchange once ... what's a 'jumper king'? The place :had air conditioning and we didn't wear jumpers. ;) : : Yep, during a line test we could see how much capacitance there was :by watching the meter. Lots of times it was obvious that there was more :than one phone on the line, but I don't remember anyone ever doing :anything about it. : : The later 800 series 'colour' phones could be set up with only a :single capacitor on the line for more than one phone. I can't quite :remember if that was possible on the older 300 & 400 series bakelite phones. : : :Bob
When I sarted in the PMG in 1956 the standard phone was the 300 series and I carried out many parallel and portable installations in subsequent years. In order to reduce "bell tinkling" while dialling from a parallel phone the bell circuit capacitor in the second (or third) phones had to be disconnected. A 3 wire parallel connection was employed so that the only capacitor in all of the parallel phones was that in bell circuit of the first, or primary phone. All of the bells in the paralleled phones were effectively in parallel and in series with the capacitor in the primary phone. As far as the test desk "capacitor kick" test is concerned, when all phones are on-hook, there is almost no difference (if any at all) in the meter indication compared to when only a single phone is connected to the line.
A typical 300 series portable connection illustrates the principle of parallel connection. While this circuit indicates the use of a fixed bellset and a single portable phone (with handle), the PMG in WA did not use this method AFAIK. The standard method was that a primary, or "fixed", telephone had to be the first connection point (in a similar manner to a standard parallel service) and this was the only phone where the bell capacitor was in circuit.
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Since all 300 series (and earlier) phones used a permanent hardwired connection via a fixed terminal block (except where a portable service was used) there was little chance (apart from someone ripping the incoming cable or line cord from the terminal block) that a phone could be disconnected at the premises, so the capacitor kick from the phone was a very reliable indication of the line condition.
Ever since the mid 1930's when 162AT and the superior 232AT were the standard phones in Australia there has been a provision for a 3rd wire to allow a parallel phone connection using only a single capacitor in the bell circuit. In fact there is probably no reason that earlier models than these could not be connected in parallel using only a single capacitor in the bell circuit.
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The early 800 series phones were essentially improved versions of the older 300 and 400 series phones and still used a magneto bell as the ring indicator. When these were paralleled a 3 wire circuit had to be used similar to the 300/400 series.
The latest of the 800 series phones (eg. 8081) were essentially "all electronic" and the ring indicator was either a 2" loudspeaker or a piezo sounder and these phones could be effectively connected in parallel using a 2 wire connection.