[ARC5] Third Receiver Drift Test from KE6F Collins 75S3B

[millerke6f at aol.com]

Hi and here are the results of the third test of vintage receiver drift performance.  Once again the test conditions are about the same as the previous two receivers.  The signal source is an Agilent E4400B signal generator with an ovenized clock and calibrated against my Rubidium standard.  The ambient temperature at the time of the test was monitored and stayed pretty much around 58 degrees F.  The test receiver has been in my collection for quite a while and has been in dry storage but not operated for at least 10 years.  it is in good condition and all functions work properly.  Of special note:  The receiver frequency did exhibit a pulling of around 70 Hz when the RF gain control as set to maximum.  I kept this in mind all through the testing to ensure that the input signal level had no effect on the frequency.  While i used an input level of 500 microvolts on the two units prior to this test, I ran this test at 100 microvolts to guard against oscillator pulling.  


80 Meters (Ambient Temperature 58 degrees F)


1:10 pm   3.750000 MHz (Start of run)
1:20 pm	3.750085 MHz  (85 Hz change)
1:30 pm	3.750119 MHz (34 Hz change)
1:45 pm	3.750132 MHz (13 Hz change)
2:00 pm	3,750155 MHz	(23 Hz change)


40 Meters (Ambient temperature 58 degrees F)


2:01 pm	7.150000 MHz  (Start of run)
2:15 pm	7.150058	MHz (58 Hz change)
2:30 pm	7.150053	MHz (-5 Hz change)
2:45 pm	7.150055 MHz (2 Hz change)
3:00 pm	7.150067 MHz (12 Hz change)


20 Meters (Ambient temperature 58 degrees F)


3:04 pm	14.200000 MHz (Start of run)
3:18 pm	14.200005 MHz (5 Hz change)
3:36 pm	14.200001 MHz (-4 Hz change)
3:45 pm	14.200001 MHz (no change)
4:00 pm	14.200001 MHz (no change)


15 Meters (Ambient temperature 59 degrees F)


4:03 pm	21.250000 MHz (Start of run)
4:15 pm	21.250041 MHz (41 Hz change)
4:30 pm	21.249980 MHz (-61 Hz change)
4:45 pm	21.249973 MHz (-7 Hz change)
5:00 pm	21.249066 MHz (-7 Hz change)


10 Meters (Ambient temperature 59 degrees F)


5:06 pm	28.500000 MHz (Start of run)
5:22 pm	28.500006 MHz (6 Hz change)
5:40 pm	28.500008 MHz (2 Hz change)
6:00 pm	28.500010 MHz (2 Hz change)


	The results above suggest that the 75S3B needs a bit more heat up time than the prior receivers.  The Frequency pulling with the RF gain control with a fairly high level signal injections (100 microvolts) may be a maintenance problem, but keeping that problem at bay during the tests should mitigate those effects.  Overall this S line receiver lives up to the Collins reputation of being a fairly solid performer stability wise and especially on the upper bands where the crystal controlled front end show's its superior performance.  However, the NC303 and the Swan 600R are certainly competitive units in  frequency stability on the lower bands.


Next unit will be my HQ 129 Hammarlund if I can find it out in the Conex Followed by my grandson's S38 hallicrafters.


73


Bob, KE6F