Ecf80 heater supplies kel 84

[grid leak]

A few years ago I tried the DC heater supply mod listed in the upgrades and tweaks section of the forum. It was not completely successful, the voltages were not very stable, so I reluctantly retuned to the original arangement.
Forward on a few years, I decided to take another look at this subject. Having noticed a power supply unit that would work with 6.3 ac to 6.3 dc that wasn't too expensive, I decided to have another go! The Tentlabs Tube Heater Supply was duly fitted in the chasis of my Kel 84. There is enough space between the mains and output transformer, it sits on 4 stand offs with self adhesive strips supplied. The bridge rectifier needs to be removed and 0.6mm single stand wire for connection to input and output. The DC is applied to the terminal pins directly supplying the ECF80 valves. Ensure that polarity is maintained.
When fired up the voltage can be adjusted with a trimmer in the unit. The improvements you may notice are outlined in the Upgrades and tweaks section. I have found it has improved my more humble versions of the ECF80 valves the most. The Telefunken E80 CF that takes top spot was, however , still most favoured.
ECF80 valves are prone to microphony we are told, so any improvement in DC supply noise and hum seems to make quite a difference!