The RA1792
Racal’s first microprocessor controlled Radio

I think perhaps two Racal HF receivers do qualify for being described as legendary. These being the RA17 and the RA1772 … the latter for its sheer outstanding performance and the former for its ground breaking technology and the fact that it put Racal on the map regards HF communications. If there is anything for which the 1792 might be described legendary it would be its propensity for popping its tantalum bead capacitors … blue ones especially!

The 1792 came after the 177x series and was a direct response to a US government requirement for a low cost HF communications receiver with the minimum of front panel controls. The 177x might have fulfilled this requirement had it not been so expensive to manufacture.

Although some aspects of the 177x, such as the first and second mixers were more or less carried forward in the design, the 1792 was a completely new receiver. Designed in the US at Racal’s site in Rockville, Maryland, the RA1792 became Racal’s first microprocessor controlled receiver. It was also their first receiver to employ large custom-made LCD displays. Both of these features have since been the source of several issues that have essentially plagued the type. And then there’s the well know issue surrounding Racal’s choice of blue tantalum bead capacitors.

Perhaps the most common issue to blight the 1792 is the bleeding that can occur within the LCD modules. The extent of this can range from small aberrations which are little more than a cosmetic annoyance, to a completely unreadable display. The cause of this is largely down to the manufacturing process (such large custom displays were very rare in the early 1980s) and the environment that the receiver is used or stored in. Racal also made the decision to ‘single-source’ the display modules … not necessarily a good idea, but remember these were state-of-the art custom units.

Most processor boards have issues with corrosion around the via holes resulting in continuity issues. Admittedly this is a manufacturing process issue. The first batteries used for on-board backup tended to leak, resulting in severe corrosion to the extent that the board would need to be scrapped. Then there is the choice of processor, the Fairchild F8 or 3850 which became obsolete while the RA1792 was still in production, thus the cost of spares became extortionate.

Performance of the RA1792 can be described as adequate in that it in no way comes close to that of its predecessor, the 1778. However it is a joy to use and everything you need to know at any time is provided on the two LCD displays.

September 2016 …

Although I cannot claim to be an expert on the 1792, having recently rebuilt five working specimens from several crates of boards, I felt I should write a ‘piece’ on the type.

I once saw an Ebay auction where the seller described the item as an example of the ‘Legendary’ RA1792.  To me, being the owner of an RA1792, that description sounded a bit over the top.