can any one help me with a question on the pt-404 field telephone

Has any one got any info with regard to powering the 404 via say a central 12 volt battery?

I am a part time kiddy fiddler in the acf and we use them as part of the signals training

I was hoping that I could use a small 12 or 6 v volt sealed lead acid batteries as used on motor bikes with a subtle sized fuse and stick it between Each pair of telephones saving on batteries as it has the cbx function

I am a electrician so don’t be afraid to baffle me with Tec terminally or diagrams I have seen this done in my local army surplus store but with this being my own personal kit I would appreciate some help as I don’t want to blow it up
See the link below which has a basic wiring diagram. If you follow the path with SL2 operated (in CBX mode), you will see what components are included.

For what you are trying to do you oly have 2 options 1. battery in -line with A-Leg or 2. Battery in line with B-leg. It looks like the internal battery is in series with line 1 and is 6v. There are 2 issues:

1. If the A end rings the B end the internal battery and ring generator will send an AC ringing current over your battery.
2. If your trainees inadvertently turn the switch to Mag you could have up to 3 x 6V batteries in series. You could simply remove them from the phones.

If you could blag a field switchboard i.e. 16 Line ULS. Might be worth a try through RSS Blandford or the museum, you would have the ideal solution.

Anyway Link is: Telephone set UK PTC - 404 (1979)

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