February 2017: This is an interesting RA98 because the green MOD label indicates that it was used by the Canadian Airforce (RCAF).

The RA98C was the North American variant, yet this one started out as an RA98A. The special modifications appear to be the addition of three BNC sockets on the front panel for signal monitoring purposes … probably related to alignment of the adapter.

The underside of the RA98 is quite busy. There was evidence of some repair work around the top right in the photograph on the left, with ‘nasty’ soldering. Also, the large orange capacitor just above the mains transformer in the photograph is NOT on the circuit diagram and is much newer than the adapter, suggesting that it was added several years later. It is also of US origin, suggesting that it was added by the user rather than the manufacturer.

Above: The serial number plate shows that the ‘A’ after the 8 has been inked over and looks like ‘/B’ has been added. Note also the faded ‘stamp’ to the right. Looks like ‘RACAD 01 TEST’. Anyone shed some light on this?

Above: This is the label below the meter. I cannot find any information on what Contract CD665678 relates to. I believe this RA98 was manufactured around 1972, so this is a late modification.

Again, anyone shed any light on this?

RA98s can be used with any receiver in the RA17 series … i.e. RA17, RA17L or RA117. Since, due to the additional IF in the RA117 resulting in sideband reversal (in relation to the RA17), RA98s have a switch in the centre of the chassis for selecting the receiver type (RA17 or RA117). This RA98 does NOT have said switch but is hard-wired for use with RA117s

A further difference is that an additional resistor on one of the tag-boards led me to discover that the circuitry which drives the meter and the AFC motor is NOT as per the circuit diagram.

This was going to be an interesting project.