On Friday, 10 November 2017 18:19:40 UTC, bitrex wrote:
On 11/10/2017 10:44 AM, tabbypurr wrote:

I thought almost all valve tvs used series heaters. Mine doesn't but it's an unusual design, Ekco tmb272.

For a brief period transformers were cheaper than a set of tubes with
weird custom filament voltages, but that didn't last long.

The 1954 TMB272 used parallel valve heaters for an entirely different reason. It was a dual voltage set, 12v & 240v. From either power it had to derive both filament volts and anode volts. It uses the same transformer on both voltages.


NT