09-12-2011, 01:56 AM
The ETR82
Now for the most unusual and possibly also the rarest set of the family. Released in 1959 the ETR82 was the second of the export sets and is interesting and unique for a couple of reasons. Firstly it is an hybrid (i.e. valve and transistor) and secondly I believe it is the only hybrid set that Bush ever made.
The circuitry is basically the front end of the EBM60 spliced to a TR82. This was done because the short wave coverage of the ETR82 extended to 18MC/s (16m-band) and the Mullard OC4x series transistors available at the time could not be guaranteed to operate reliably at that high a frequency. Bush got around the problem by using a solitary DK96 valve to perform the task of frequency changer with transistors used throughout the rest of the circuit.
The high voltage supply for the valve was produced from a miniature transistorised inverter (giving around 65 volts in my example) fed from the main 9 volt supply (6 x U2 cells) used for the transistors. The LT for the valve was from another single U2 cell.
Unlike the EBM60, the rear trim was not used as a sort of internal short wave aerial and the ETR82 has a proper built-in telescopic aerial instead of a detachable one which is easily lost. The colour scheme of the set was light blue/green case, dark blue rexine band and chrome metal trim as per the TR82C model.
Now for the most unusual and possibly also the rarest set of the family. Released in 1959 the ETR82 was the second of the export sets and is interesting and unique for a couple of reasons. Firstly it is an hybrid (i.e. valve and transistor) and secondly I believe it is the only hybrid set that Bush ever made.
The circuitry is basically the front end of the EBM60 spliced to a TR82. This was done because the short wave coverage of the ETR82 extended to 18MC/s (16m-band) and the Mullard OC4x series transistors available at the time could not be guaranteed to operate reliably at that high a frequency. Bush got around the problem by using a solitary DK96 valve to perform the task of frequency changer with transistors used throughout the rest of the circuit.
The high voltage supply for the valve was produced from a miniature transistorised inverter (giving around 65 volts in my example) fed from the main 9 volt supply (6 x U2 cells) used for the transistors. The LT for the valve was from another single U2 cell.
Unlike the EBM60, the rear trim was not used as a sort of internal short wave aerial and the ETR82 has a proper built-in telescopic aerial instead of a detachable one which is easily lost. The colour scheme of the set was light blue/green case, dark blue rexine band and chrome metal trim as per the TR82C model.
