The Rack

I thought it was time to ‘identify’ each of the items in the rack. The anonymous box at the top is my ‘personal 2.3GHz beacon which is connected to an 8-ele shrouded antenna outside.

This is my MA259 (serial number N1) Frequency Reference. See here for a full write-up.

This is an Adret 740A, 100KHz - 1120MHz signal generator which came to me with a whole raft of faults. Miraculously, I was able to repair it without a full set of diagrams. Fortunately, I now have 99% of the circuit diagrams.

This is my RA3701 … Racal’s HF receiver of the 1990s. The previous owner was convinced that it was faulty since none of the IF filter bandwidths could be selected. This was because the ‘settings’ on the processor board had been ‘wiped’. I found the password for this on a Japanese website and Danny Higgins, G3XVR provided the filter settings.

The RA1792 … Racal’s first uProcessor-controlled HF receiver from the early 1980s. Both of the custom LCD panels were u/s. But apart from that the receiver was and still is in good order. I obtained a completely new front panel assembly, complete with Italian-made replacement LCDs.

The legendary RA1772 … from the early 1970s … often described as the finest HF receiver ever produced. This came with several faults. The two major ones being a broken AFC switch (now replaced) and what was described as an AGC fault. The latter turned out to be a faulty resistor in the PSU which was affecting the -7V line.

The quirky and much maligned RA1217 … the rack-mounted version of the RA217 and in the late 1960s, was Racal’s first transistorised HF receiver. See here for a full write-up.

The MA197 Preselector. The world’s largest 8dB pre-amp! This unit allowed any connected receiver to use the same antenna as a 1KW transmitter PROVIDED the preselector (and the RX) were tuned to a frequency HF or LF of the TX  by a factor of at least 10% of the transmitter frequency … well, that’s the theory!