In a previous blog, I described the introduction of a the Mullard World Series range of valves, now I should like to describe each one of them briefly. Let's start with the EF80 which is an RF pentode. This versatile valve can be used as an RF amplifier, a mixer, an IF amplifier and additionally a video output valve.
It was designed specifically for use in the 40 - 70 MHz frequency range to suit contemporary television receivers along with the ability to operate satisfactorily from a 170V HT supply which was the operating voltage of choice for contemporary transformerless TV receiver designs of the time.
It's peformance when presented with a 100uV signal was impressive - the minimum signal required for a watchable monochrome picture needed a gain of approx 100dB is required to achive satisfactory viewing - using a bandwidth of 3 - 6MHz centered at 65MHz in a transformer coupled circuit stage, a gain of approx 130dB was achievable, so a good picture with plenty of headroom was possible. Well done to the EF80 I say!