An Interesting Transmitter

Radio Record, Volume III, Issue 20, 29 November 1929, Page 11

An Interesting Transmitter

/Phone Equipment of 1BC URING the Anckland Radio Exhibition, a considerable amount of interest centred round the large ’phone transmitter of ZLIBC. With this transmitter, which was made by the SS SS Ss ns

owner, My. Meikelborough, stations as far distant as Pérth have -been worked. In connection with his outfit the owner writes :-Everything possible is made on the spot, being what the "Hams" call "home-brew." All power but the microphone battery is rectified alternating current (R.A.C.) and AC is used for the filaments, The cireuit is a Master Oscillator Power Amplifier hook-up. The valves used up to the present .are a modulated TBO4/10, and the power amplifier a pair of TBO4/10’s modulated by a UX250 with two audio stages for the input amplifier using a A409 first and a ©509. The rectifiers are a pair of UX281’s with about 900 on each. The "C" Bias used in both fhe mod. and the PA is RAC using a UX 201A. "An ordinary microphone is used for speech, and a pick-up for records. The usual receiver is det. and one audio, although there is a SG four to call on if wanted.

The station has been off the air since the show, but will be on again in just over a week (this week). Being an experimenter, I am trying an improved circuit, and about three or four times the output. I am going to use TB1/50 in the MOPA, which will give me up to 100 watts output against the 25w I have had to date, so I should be able to cover far greater distances; anyway I am hoping to do so.-Op., ZLABC. —