Question about old quartz crystal unit: Monitor CAL USA

Discussion in '"Boat Anchor" & Classic Equipment' started by G8VOQ, May 14, 2018.

ad: L-HROutlet
ad: l-rl
ad: Subscribe
ad: Left-3
ad: L-MFJ
ad: Left-2
ad: MessiPaoloni-1
ad: l-assoc
  1. G8VOQ

    G8VOQ Ham Member QRZ Page

    Hi. I'm in UK. I have some vintage quartz crystals, made for the Air Ministry in 1944. I think FT243 type. Anyway, they are marked thus: "QUARTZ CRYSTAL UNIT MONITOR CAL USA". I'm curious as to the word "MONITOR". Is MONITOR a place of manufacture in California, or is it a technical meaning? Thanks. Rich
     
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Well, strangely enough there's a California ghost town up in gold country named 'Monitor' but I'm pretty sure it was abandoned well before WWII. Gotta believe the markings on that crystal are technical and I'd guess 'Cal' is short for calibration not California.
     
  3. KP4SX

    KP4SX Subscriber QRZ Page

    Monitor Calibration?
     
  4. KF5FEI

    KF5FEI Ham Member QRZ Page

    Build a simple generic oscillator circuit and see what frequency they are -- may point you in the right direction.
     
  5. KV6O

    KV6O Ham Member QRZ Page

    How would that help answer his question?
     
  6. G8VOQ

    G8VOQ Ham Member QRZ Page

    Last edited: May 14, 2018
    N2EY, AI3V, WA7PRC and 2 others like this.
  7. KF5FEI

    KF5FEI Ham Member QRZ Page

    If they are an even frequency, CAL could mean calibration, like a marker oscillator. Otherwise, you could see if the frequency falls within the known military frequencies used at the time.
     
  8. KV6O

    KV6O Ham Member QRZ Page

    But the question is:
     
  9. KF5FEI

    KF5FEI Ham Member QRZ Page

    Monitor could mean it is made from lizard scales, and not quartz? :eek: Or maybe made from parts of a union iron-clad ship?
     
    KD2ACO, WA7PRC, KV6O and 1 other person like this.
  10. G8VOQ

    G8VOQ Ham Member QRZ Page

    I think they will be made by the Monitor Piizo Products Company. But I notice that the batch of crystals I have managed to obtain have frequencies of: 5020, 5030, 5040, 5050, 5080, 5100, 5120, 5170, 5240, 5270, 5300, 5500. Perhaps the truth then is that Monitor is the name of the manufacturer, and CAL means calibration? Not California as I thought.
     
    Last edited: May 15, 2018
    N2EY and WA7PRC like this.

Share This Page