‰  NOW 35 WPM  ‰  TEXT IS FROM JULY 2014 QST  PAGE 63‰

BAND, THEN THE RESULTING AUDIO SIGNAL WILL BE HEARD ON BOTH SIDES OF ZERO
BEAT, BUT IF IT IS OUTSIDE OF THE PASSBAND THAT WILL NOT OCCUR.  AND
FINALLY, HEARING THE SIGNAL ON BOTH SIDES OF ZERO BEAT HAS NOTHING TO DO
WITH THE IF FREQUENCY BEING 455 KHZ.  IT WILL OCCUR AT ANY IF FREQUENCY.
THE ARTICLE DESCRIBES THE XTAL PHASING AS CONTROLLING THE VARIABLE
BANDWIDTH OF THE FILTER.  ACTUALLY, AS DESCRIBED ABOVE, THIS CONTROL
POSITIONS THE REJECTION NOTCH WITHIN THE FILTER PASSBAND, BUT IT DOES NOT
OTHERWISE ADJUST THE OVERALL SELECTIVITY.  THE ARTICLE SAYS THAT MANY
CRYSTALS IN OLDER RECEIVERS HAVE FAILED.  I HAVE RESTORED MORE THAN 25
RECEIVERS WITH CRYSTAL FILTERS DATING BACK TO 1936, AND I HAVE YET TO FIND
A FAILED CRYSTAL.  ONE NEEDED TO BE CLEANED BECAUSE CIRCA WORLD WAR II ERA
WATERPROOFING WAX HAD CREPT INSIDE THE HOLDER ONTO THE CRYSTAL BUT NONE HAD
FAILED.  SO I DOUBT THATS A WIDESPREAD PROBLEM.  IF YOU DO NEED A
REPLACEMENT, WHICH THE ARTICLE SAYS IS HARD TO FIND IN A HERMETICALLY
SEALED PACKAGE, GO TO WWW. INRAD. NET/ OR TO WWW. AF4K. COM/ CRYSTALS.
HTM, WHERE 455R0 KHZ CRYSTALS ARE OFFERED FOR 30.  FINALLY, I OFFER ANOTHER
USEFUL HINT.  IF YOU FIND TUNING WITH YOUR CRYSTAL FILTER TOO SHARP, ADD AN
EXTERNAL VERNIER DRIVE TO YOUR TUNING DIAL.  OLD TIMERS POSITIONED A
VERNIER ON AN L BRACKET SUPPORTED FROM THE BOTTOM OF THE RECEIVER TO AVOID
‰  END OF 35 WPM TEXT  ‰  QST DE W1AW  ƒ