|Year of Manufacture: ||1962 ("15 May 1962" stamped on inside of front panel).|
|Date of Receipt:||2007|
|State upon Receipt:||Non-functional. Some corrosion.|
|Dismantled, sub-chassis removed for assessment, cleaning and repairs.|
|Stiff KC tuning mechanism. KC tuning mechanism cleaned, bearings freed up with light oil, film reels area cleaned of sticky grease, thrust bearing adjusted.|
|VFO switch sloppy action. Shaft removed, collet on shaft cut off due to stuck screw, collet replaced. Hole reemed (manufacturing flaw).|
|Front panel dismantled, cleaned and polished. Two broken posts on bakelite tuning bezel reglued. New KC and MC windows cut and glued. White position markers on knobs repainted.|
|Power-Supply/Audio compartment dismantled due to corroded wires and components. Chassis back panel milled out for IEC power connector.|
|3 wide-throat toggle switches removed for use in other unit, replaced with common 1/2"-throat toggles with washers.|
Power-Supply/Audio compartment rewiring completed.
|Recapping of 1st VFO completed. Some resistors replaced also.|
|2nd VFO & BFO completed.|
|VFOs and front panel reinstalled.|
|IF section recapped.|
|Mixer sub-chassis completed and reinstalled.|
|Powered up. Audio OK, BFO OK. 1 MHz, 1.7 MHz present. 2nd VFO tunes 3.48 to 4.31 MHz. 1 MHz harmonics present from 2 to 30 MHz as indicated by another shortwave receiver. No reception.|
|2nd VFO adjusted to tune 4.6 MHz at 0 KHz on the scale and 3.6 MHz at 1000 (reverse of what might be expected), by loosening 2 clamp screws on drive shaft and rotating variable capacitor so vanes are meshed at high end of scale.|
|1st VFO aligned by pulling V4 and connecting frequency counter to pin 1. Reception is now possible but noise level is very high, sensitivity low.|
Working backwards from the audio, shorting stage inputs will quiet the receiver back to the 4th mixer.
Following this path, the noise level jumps up around the 1.6 MHz bandpass filter.
Mixer sub-chassis removed, some rewiring and more components replaced around the 1.6 MHz filter.
Installed C329 is 0.01, not 0.005 as indicated in schematic and parts list.
Not much change. Should investigate further.
Unit does seem to work above 1 MHz. Below 1 MHz the noise level is high because the Wideband preselector setting must be used. Tuning the preselector significantly reduces the noise level when it can be used (above 1 MHz).
|Most R & C in crystal calibrator replaced. Installed, functions.|
|3-4 mixer subchassis from other unit substituted. Similar performance.|
|More R & C in original 3-4 mixer replaced. Substitute 3-4 mixer removed and original re-installed.|
|2nd VFO linearity is out by 6 KHz over the span, particularly at ends of scale (0 & 1000). Improved with some re-positioning of variable cap and vane-tweaking, down to < +/- 1 KHz.|
|RE-wiring error discovered: B+ on plate instead of screen of audio output (V22). Corrected, audio much better.|
|L302 adjusted for null (1.6 MHz trap into 3rd mixer).|
|Used for testing other rebuilt 3/4 mixer subchassis. Upon reassembly, signals are barely audible; traced to open connection of green-mark coax from 2-3 MHz bandpass filter, inside the filter, from repeated torquing. Resoldered.|
| Unit N16 Log
| Unit N0115 Log
| Unit N0144 Log
| Unit N0714 Log
Racal RA-17 & RA-117