Racal RA-117
Unit N0714 Log

Serial Number:N0714
Year of Manufacture: ?
Date of Receipt:~1996
State upon Receipt: Non-functional. Power supply circuitry a mess. Most paper caps snipped out.


2009 May 31: 3/4 mixer subchassis rebuilt. Stripped down completely, all new RC, except C336A (10pF). R302 replaced with 75 ohms instead of 47. C343 replaced with 800 pF instead of 820.

Tested in N0115. Functional. 1.7MHz crystal oscillator tweaked.

2009 Jul 06: VFO-1 finished.

All new RC, except 2 mica and 2 tubular ceramic caps. RF input coax replaced with piece of subminax (75 ohm). Band-switching rewired. Three output wires replaced.

2011 Jan 31: Work on VFO-2.
  • Oil drop placed in most bearings. Improved.
  • Front bearing guide plate for tuning cap shaft aligned to slightly pull gear away from vertical worm gear. Smoother.
  • Anti-backlash coupler removed and unseized. Re-installed with one tooth offset.
  • Film scale refitted.

2011 Feb 21: VFO-2 rebuild completed. 10pF mica cap original, other 2 micas replaced.

2011 Feb 21: Main chassis work begun. Power supply compartment cleaned out.

2011 Mar 10: IF strip rebuild completed.

2011 Apr 03: Main chassis rebuild completed.

Previously replaced oversized System switch replaced with another switch. Both replacements are typical break-before-make types rather than the proper make-before-break type used in these receivers.

2011 Apr 07: Chassis reassembled. Powered up. Functional. 2nd VFO alignment very good. 1st VFO good alignment at low end, off at high end.

2011 Apr 09: 1st VFO aligned with frequency counter.

Problem has developed giving high noise level and low sensitivity. Fixed after pulling and reinserting V9.

2011 Apr 13: 1st VFO aligned with frequency counter.

Restoration completed, except for optional alignment of bandpass filters.

2012 Feb 16: Second purchased crystal calibrator rebuilt and installed. Needed instrument alignment but still needed tweaking and tube replacement after instruments to get it to work.

2012 Feb 17: Significant arcing on break-before-make System switch observed.

Switch replaced with a proper make-before-break type from unit N0115. This switch was noted to have arc-damaged contacts on the S5.1L pole. Wafers rotated so the damaged pole is at S5.3R and used in the AVC circuit where the make-before-break facility is not needed. To accommodate the wires and simplify the wiring somewhat, the pole use has also been reorganised:

  • S5.1L: B+ main (as original)
  • S5.1R: B+ BFO (was S5.2L)
  • S5.2L: B+ 2nd Mixer (was S5.3L)
  • S5.2R: B+ Calibrator (was S5.1R)
  • S5.3L: AVC Manual (was S5.3R)
  • S5.3R: AVC Auto (was S5.2R)

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Racal RA-17 & RA-117