VCXO measurements

Christian Vogel vogelchr at vogel.cx
Sun May 9 14:29:06 UTC 2010


Hi,

I've measured how the 26 MHz VCXO changes frequency depending on the
AFC DAC output. See the attached plots and the data file.

Tapping point is between C132 and C210 (RITA Xout).
On my 20 MHz scope it's 300 mVpp, but I'm hitting the bandwidth
limit of the scope, the frequency counter says -0.03 V ...+0.02 V
after a x10 probe (500mVpp).

I'll put it in the fridge later on to check the temperature coefficient.

Pictures:

http://lh6.ggpht.com/_zKkNaqX3vkM/S-avbZbCmJI/AAAAAAAAAwE/EfsMRB08iJ8/s1600-h/IMG_1522%5B3%5D.jpg
http://lh3.ggpht.com/_zKkNaqX3vkM/S-ave-aRv_I/AAAAAAAAAwM/3f1RfuZD05E/s1600-h/IMG_1523%5B4%5D.jpg
http://lh3.ggpht.com/_zKkNaqX3vkM/S-aviUpzWNI/AAAAAAAAAwU/AshSJr3qzwM/s1600-h/IMG_1524%5B3%5D.jpg
http://lh3.ggpht.com/_zKkNaqX3vkM/S-avmomSpgI/AAAAAAAAAwc/NJSJoW5fqd4/s1600-h/IMG_1525%5B3%5D.jpg
http://lh6.ggpht.com/_zKkNaqX3vkM/S-avqB3veGI/AAAAAAAAAwk/uPQPARv3osk/s1600-h/IMG_1526_w_label%5B3%5D.jpg

	Chris
-------------- next part --------------
# GPSDO locked, Ch2, Frequency, Peak/Peak: 30mV/-20mV
# DAC, 1st measurement, 2nd measurement
0	25.999876	25.9998634
256	25.9999336	25.9999225
512	25.9999915	25.9999818
768	26.0000501	26.0000412
1024	26.0001089	26.0001008
1280	26.0001680	26.0001605
1536	26.0002275	26.0002203
1792	26.0002871	26.0002800
2048	26.0003454	26.0003396
2304	-		26.0003988
2560	26.0004637	26.0004581
2816	26.0005218	26.0005169
3072	26.0005791	26.0005754
3328	26.0006366	-
3584	26.0006935	26.0006915
3840	26.0007496	26.0007486
4095	26.0008047	26.0008047
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