Replacement for HT Battery

Valve circuits and radios in particular are graced by vast crowds of enthusiasts. If you want to keep your prize vintage radio as authentic as possible while actually using it from time to time you need a HV (high voltage) battery or its electronic equivalent.
One of the most popular types of vintage radio running off a high voltage (HV) battery is the valved, portable,medium-wave or long-wave receiver. If you decide to use a switching stepup converter for the 90-volts plate supply then a design using the usual 30-50 kHz switching frequency will soon be found problematic when it comes to preventing harmonics from leaking into the receiver’s RF circuitry. In many cases, the problems are insurmountable.