[Techman]

I've got a 1955 Model 7 that I bought for £1 at a local junk auction maybe a couple of years ago and it's got a home made 'P' knob. I've never actually opened it up, so no idea what it's like on the other side of that knob. It worked ok and is only slightly inaccurate. It was disgustingly filthy when I got it and just needed a really good clean. It's showing a reading in the first picture below as it's in use at the moment monitoring the receive and transmit current on a radio transceiver under test. The last picture shows a much earlier Model 7 like yours with the little disc on the pointer/needle. This meter dates from 1941 and I've had it for decades and made it up with shunt and multiplier parts from several scrap ones of the same age that were throw outs from work back in the day. The remains of the scrap ones that I cannibalised for parts seem to have got lost over the years, so no spares anymore unfortunately.