At last summer’s Ham Radio in Friedrichshafen, I was offered a YIG-tuned oscillator at the suspiciously generous price of 5 Euros. Since I’m always on the lookout for cheap instrumentation-grade YTOs, I took it without a second thought. After a brief chat with the friendly operator who sold it, I learned that it came from a recently discarded HP spectrum analyzer, which appears to have been beyond hope. However, he claimed that the oscillator worked ’til the end. Should he read this: thanks for the chat, and for the part :-)

A few months later: Grabbing a spectrum analyzer and a bunch of power supplies shows an indeed very healthy part.

The YTO in question here is Avantek-branded (typical for HP), model AIL 230186. According to its label, it should range from 1.75 to 4.3 GHz. On the casing, it features an SMA port and seven EMI-shielded pins for GND, V+, V-, tuning (+/-) and FM (+/-). In operation, it draws +20 VDC @ 104 mA and -5 VDC @ 109 mA. I did not notice too much of a difference during warm-up, but I guess a rough +20% should be accounted for in the power supply. However, the actual oscillator will only start up once a tuning current is applied to the tuning coil pins, while the FM modulation input can be left unconnected. At an I_tune of 61 mA (~0.91 VDC), it shows stable output of 1.54 GHz at 14.5 dBm. The highest frequency of 4.56 GHz is reached at 190 mA (~2.78 VDC). Beyond, oscillation stops again.

In case anybody needs it, here is a rough outline of the tuning characteristic:

I_tune / mA	V_tune / V	f_out / GHz	P_out / dBm
61	0.91	1.54	14.5
72	1.07	1.8	15.5
89	1.32	2.2	16
106	1.57	2.6	15.5
123	1.81	3.0	16
139	2.05	3.4	16
156	2.3	3.8	16
173	2.55	4.2	15.5
190	2.78	4.56	13

I plan to run it past a precision source analyzer when there’s time, to follow up with some actual performance data.