AVANTEK YIG bias

Hi all.

I have a couple of AVANTEK YIG oscillators, models SF6- 0991 and AV7204M,

Both are 2 ? 4 GHz units. None of the oscillators have their pins marked, but FM coil, Main coil and heater are easily identifiable.

Does anyone have information about bias connection for these units? Most AVANTEK?s have +15V and ?5V connected to pins 1 and 2 (Clockwise from SMA), but these units have an 18V 1W Zener diode connected from pin 2 to casing.

It looks like these Zeners are there to protect pin 2 from over voltages above 18V, which doesn?t make much sense, unless Bias pins are swapped on these units (+15V on Pin 2 and ?5V on pin 1)

Anyone can help?

Regards

Augusto Duro

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I looked up data for the AV-7204: 2-4 GHz YIG tuned Osc. As you described, the first pin gets +15V. The 2nd (bias) pin has this note:

"Terminal Vc requires a linear voltage Ramp proportional to frequency. The voltage at 2 GHz is factory selected within the range +7 to +13 volts and the voltage at 4 GHz is +15.0 volts."

So, I think, basically you want to fire it up with an adjustable voltage on the 2nd pin. Tune to the low end of Freq with the tune current, and adjust the voltage on the 2nd pin for max power output. The voltage on this pin should then vary linearly between this voltage and +15 V as the tune current is ramped across the range.

It might be there to keep inductive spikes from the tuning or FM coil=20 out of the driver circuitry, or to keep negative-going voltages out of=20 the expensive stuff.

Here's the AV7204 info from my Avantek book:

-- jm

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