[Drake] Drake r 4b calibrator

[Garey Barrell]

Don -

NO calibrator signal, or can you hear the 100 kHz markers only?   They 
may be considerably weaker than normal.   If you have another receiver, 
see if you can pick up the 100 kHz signal by coupling the external 
receiver antenna to the area of the calibrator.

IF you CAN hear the 100 kHz marks, either on the R-4B OR the external 
receiver, most likely culprit is the electrolytic cap(s) for the logic 
supply, (C190, C192) or diode D16.  C190 is on the calibrator board, 
C192 is the big silver cap in the left rear corner under the chassis.  
These provide a 5-6 VDC supply off the filament winding of the power 
transformer that drives the logic driver and two logic divider chips.

IF you cannot hear the 100 kHz marks, the oscillator FET power comes 
from the dropping resistor/zener that drives the PTO, should be about 
10V at the low end of the 6k ohm 5W dropping resistor.

73, Garey - K4OAH
Atlanta

Drake 2-B, 4-B & C-Line Service CDs
<www.k4oah.com>



Don McConnell wrote:
> Need help. The calibrator on my R 4B quit working. No calibrator signal.
> Any ideas.
>
> Tnx Don, VE7EHP 
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