My newly acquired Ra1792. Although it's a Racal, I just can't seem to get very excited about it. It has nothing to do with its looks or any lack of performance or anything else like that. I think it's more likely because there isn't a valve in sight. In fact, once the top cover is removed, you can see very little for your money and this gives the impression that it was very cheap and easy to mass produce. The receiver is in quite good condition, only spoilt by a bleeding mode display, sorry, a mode display that's bleeding. Unfortunately non-backlit versions are fitted which are impossible to read in the dark but beggars can't be choosers.

The PCB shown above-left is the optional (A6A1) IEEE-488 bus system. This is a little rarer than the "SCORE" card that is normally installed in this position but, none the less, allows the receiver to be controlled remotely in much the same way. Next to this image is the troublesome CPU module. You can find a number of different versions fitted to the Ra1792, this being the later "3 x EPROM" type and has the battery mounted on a small sub-board for obvious reasons.

Installed filters are STC/ITT 8-pole at 300Hz, 1KHz, 3.2KHz, 6KHz, a 16KHz roofing filter and 2.7KHz USB/LSB. The grey box seen in the right hand image is the (A11) option, the type 9442 high stability frequency standard. This is an essential option as this receiver has the frequency measuring firmware installed which displays the received frequency to the nearest 1Hz. Like DVM's, this causes a form of digititus in the operator, who now spends ages trying to tune down to the very last digit.

As part of the frequency measuring conversion, the 100KHz IF option has been installed allowing the receiver to utilize signal analysis units such as the MA1105 Bar graph display.

An unusual picture of my Ra1792 prior to the new mode LCD being fitted.

Now for a quote from the Racal manual... "The Ra1792 is a fully synthesized solid state receiver, suitable for all forms of reception and monitoring over the frequency range 150khz to 30Mhz. Rapid and precise frequency selection in 10hz increments over the entire frequency range is achieved either through the use of a keypad or through the use of a single tuning control. The keypad permits instant selection of a new frequency regardless of the frequency the receiver is currently set to. The tuning control is an optically coupled device that provides a continuously variable tuning rate according to the speed at which it is turned.

The receiver is also equipped with a 100 channel memory. Each channel may be preset to a particular frequency and operating mode through the front panel controls. When a particular channel is selected, the receiver will instantly tune to that frequency and mode. The receiver may also be set to scan mode. In this mode the receiver will automatically scan 10 (or less) selected channels: stopping for a preset time interval (0.1 to 10 seconds) at each channel.

All receiver operating functions may be selected through the receiver front panel controls or through a remote device. Complete receiver status is shown through the LCD on the front panel."

• Circuit - Multi conversion, solid state with continuously tunable synth.
• Range - 150khz-30Mhz
• Sensitivity - 1uV for 10db CW/SSB, 3uV for 10db AM
• Phones - 600 ohms
• Weight - 31lbs
• Supply - 110-240Vac
• Dimensions - 5.25"(h)x18"(d)x19"(w)