Lotus AC Bandpass Three or "3-valve all electric"

Click the set to see much better pictures

 Does anyone have any details of the Lotus Radio Company who used to be in Mill Lane, Wavertree in Liverpool in the 1930's?

This grand old lady, with a walnut cabinet, was built in Liverpool in 1931 and seems to have been the target for restoration by someone who presumably gave up, as I bought it in the state shown.

 

 

 

 This set is a TRF type, using three tuned stages and predates the superhet design. The three tuned stages are enclosed in the large aluminium cans on the right of the chassis.

The set uses three valves viz. MM4V, 904V and Pen4V. Unusually it employs a large metal rectifier to provide the HT. The power supply is conveniently located adjacent to the loudspeaker which is energised by a large coil which doubles as a smoothing choke.

All was present except the bronze escutcheon (the bit through which one views the dial). My thanks to John Gibson in California, who has one of these fine receivers and very kindly sent me, not only a drawing of the escutcheon, but a copy of the user's handbook and some interesting notes and circuits. Surprise! I received a casting of the escutcheon from John. He made it himself and it looks absolutely perfect, even the right colour.

I now have no excuse to get started on the refurbishment!

There is enough information for me to make a replacement back panel, which was also missing.

I hadn't appreciated that the power supply uses a voltage doubler. Why this is so is not that easy to figure out. There are a few explanations...

1. First the high internal resistance of the metal rectifier had been overlooked and the doubler was an after-thought.

2. Secondly, the transformer design originally catered for a valve rectifier but they forgot, or later removed from the specification, the filament winding.

3. There was a reasonable saving in the transformer cost with the smaller HT winding.

Any other explanations?

Return to "a bit out of the ordinary"