bogen rp-235
  This receiver was purchased as a parts donor. It lacked the 7408 power tubes and the more valuable 12AX7, 6EU7 and BAB4. In total, the receiver had 19 electron tubes on board. After removing the bottom cover, it turned out that apart from the tragic appearance of the chassis, it is practically new device. Electronics in very good condition, with no signs of overheating or even use. Potentiometers without any scratches or noises.
After supplementing the tubes, the receiver came to life and sounded like 50 years ago.
The RP 235 is a typical design from Bogen laboratories and has a lot in common with Harman-Kardon designs. Anyway, these two gentlemen worked for Bogen until they starts theirs own company. Such characteristic features shared by Bogen and HG are the 7408 output tubes (and in other 7355 constructions) which are the so-called the "industrial" version of the 6V6GT / 6P6S. Thanks to these tubes working in the Push & Pull system, the receiver got the power of 2 x 10 W. They were controlled by one 12AU7 / ECC82 tube, and the preamplifier operated by a 6EU7 tube (electronically interchangeable with the 12AX7 / ECC83, differing in the connection of the electrodes). The phono preamplifier is one 12AX7 / ECC83 per channel.
The radio part of the receiver is a decent construction, the FM head on two 6AB4 / EC92 and 12AT7 / ECC81 tubes (Bogen was probably the only non-European manufacturer using single 6AB4 / EC92 triodes in the FM heads). This was followed by an intermediate frequency amplifier with three tubes - one 6BA6 / EF93 and two 6AU6 / EF94. The radio track was supplemented by an extensive decoder based on three 12AT7 / ECC81, 12AU7 / ECC82 and 6BL8 / ECF80 / ECF82 tubes. Beside the FM range, the receiver allowed the reception of medium waves AM.

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