A simple bit of alignment will give this legendary radio full sensitivity on our newest band. The cam for the top wavelength octave of 500 to 1000 KC actually has about 45 KC of overrun. This cam, which sits on the extreme right front of the receiver, can be easily "slid" to "up" grade wavelength for full coverage of the new 630 meter band. Performance on other frequencies is unaffected. Re-alignment of the three slugs and perhaps a touch up of the three trimmer caps on the affected slug rack completes the upgrade.

 

Initially, set the frequency to 3999, which puts the rollers of the three rightmost slugracks very near the tips of their cams. Next, break loose (but don't loosen) the clamp on the front end of the 500-1000KC slugrack shaft that sits between the two  gears. It usually will be "heads up" in the top frequency position, and will fit the same .096" Bristol tool that takes care of knobs and slug rack alignment. If it's stubborn, give it a couple of drops of liquid wrench and let it soak awhile.  

 

Now the fun begins.  Inspection should show the last bit of the 500-1000 KC  cam profile is consistent with the rest of the cam, so we can shove it under the roller with no detrimental effects on the tracking once the slugs are re-adjusted.  This shove needs to be applied to the cam without moving either gear, which means a two handed surgical procedure.  While one finger pushes with moderate force on the cam tip to the left, the other hand gradually loosens the clamp between the gears.  When the cam starts to move, be ready to re tighten the clamp.  Moving the cam tip to within about 1/8" of the roller contact point should take about a quarter inch of travel.  Don't overtighten the clamp once the cam is firmly in place. Re -check on the two slug racks to the left.  If thre two gears didn't move, they will still be in the same positions as before, very close to the tips of their cams.  If not, re-loosen and reposition them to within 1/4 inch of their respective cam tips. 

 

Once the clamp is tight, spin the KC Change down frequency until the descent of the roller along the cam reaches its lowest point.  The KC readout will now indicate the new bottom frequency for full performance. If it is not below 472, repeat the above steps until it is.  With 45 KC of overrun, one could theoretically get down to 455 before performance above 1000 is affected, which might come in handy for troubleshooting other radios. 

 

To finish the upgrade, turn each slug in the 500-1000 KC rack downward 1 turn (clockwise) to compensate for the cam's increased height.  Tune to 500KC with the calibrator or other signal near 500 KC and adjust these slugs for peak.  The trimmer capacitors should then be checked as well, at or near 1000 KC, though the adjustment should be minimal if the radio was aligned before.