I have a Racal SA33 frequency converter, which uses RA 17 technology to
subtract 1 to 29 MHz from the input frequency for feeding to a frequency
counter. It seems to have been designed in the era when most frequency
counters did not go above 1 MHz. It has been fitted with an internal 1 MHz
It has not been used for more than 30 years, so it may be of more interest to a
collector. Nevertheless, if anyone is interested will they please let me know.
The equipment is at present at my house in Suffolk.
I have a couple of pages of circuitry.