Racal RA.63B

Single Sideband Adaptor

RA.63B Single Sideband Adaptor

RA.63 is the simplest of the sideband adaptors for RA.17, it is a Single Sideband Adaptor. While RA.63 is the UK version with Burndept type connector, RA.63B is the version for North-America with PL-connector. 

Due the Parmeko main transformer line voltage is not an issue: the transformer can accept everything from 100VAC to 125VAC and from 210VAC to 250VAC.

Racal promotion flyer for RA.63: TechPub 125C3

I got my RA.63B from Canada. It has a dust cover. The colour of the front panel has some spots, which I tried to repaint, but due to the "exotic" light battleship grey it is difficult to get a matching colour mixed.

Serial number is N 420. On the front panel an additional number was engraved: 2055.

The RA.63B has a fixed installed power cable, no Plessey connector like the english version. Audio output is close to the RA.17 receiver: 1 output with 50 mW at 3 ohms, and 3 outputs with 3 mW at 600 ohms. A 5 k attenuator helps to adjust the input signal.

Tube complement of RA.63 is:

* 6F33Spec is not a full substitution for 6AS6 (swapped connections for G2 and G3). Interesting enough Racal RA.17L is using 6F33, while RA.63 uses 6AS6

Interesting is the fact all RA.63 are using 6AS6, not only the northamerican versions, which is different to RA.17. And the difference between both tube typs is still noticable:

on left side a STC 6F33 (CV2209), right side a Tungsol 6AS6W (5725)

Also my RA.63B looks like a heavily used unit - the installed tubes were a really mix, and 2 of them were gone - I had only to check and replace the tubes, and 2 of the capacitors, then the device was ready to work.

One of the knobs was broken, so I used Stabilit Express to restore it. With a small saw and a little bit care this worked pretty well. After painting it is hardly noticable the knob is repaired:

This is the circuit diagram of RA.63 (.gif 267 k): RA.63 diagram