Message-ID: <51571BED.6000508@kabelmail.de>
Date: Sat, 30 Mar 2013 18:07:57 +0100
From: DK1IS <DK1IS@kabelmail.de>
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To: rsgb_lf_group@blacksheep.org, rsgb_lf_group@yahoogroups.co.uk
Subject: LF: EMC Problems with Jupiter GPS Module
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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