Dear group, to whom it may concern:
several stations are using GPS modules to stabilize their main
oscillators - so did I since about 3 years by injecting the
10-kHz-signal from a Rockwell Jupiter TU30-D145 GPS module as an
external standard into my HF transceiver TS950SD. Some weeks ago I was
astonished to see my transmit frequency on a remote SDR being about 150
Hz too high at 28 MHz. Checking the 10-kHz-signal by a rubidium
controlled counter showed a deviation of +40 ... 60 mHz. At the same
time I realized that the 1-Hz-LED on the Jupiter was no longer
acustically coincident to the 1-s-click of the DCF77 radiocontrolled
analog clock in the shack which has always been the case in the past.
After a lot of tests I found a solution for this problem by adding
snap-on-ferrites at both ends of the GPS antenna line (abt 3m), the
+5-V-power supply line (abt 1m) and at both ends of the 10-kHz-output
line to the transceiver (abt 6m). Now the 10-kHz-signal is well between
+/- 0.5 x 10 exp -9 again as it shoud be.
Perhaps the increasing use of PLC and WLAN in the neighborhood (which
makes increasing problems at receiving) was the reason for the trouble
which could be eliminated by this simple procedure. If you use such GPS
modules its a good idea to check the output frequency on occasion.
73,
Tom, DK1IS
http://www.qrz.com/db/dk1is
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