Electronics > RF, Microwave, Ham Radio

Anyone experience with 28V microwave relays ? Bought one, coil current ~ 150mA ?

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I have no expererience  with microwave relais. Bought 2 used 18GHz relays. One from Sivers/Philips, draws about 40mA  @ 28V
The other one from Microwave Associates (brand seems to be sold regularly on Ebay, but I cannot find any details)
Coil does 160mA @ 28V which is over 4 Watts.

Does anyone knows if this is usual for those kines of relays ?

It can be normal depending on the design and size of the relay. Some have quite large and multiple mechanical moving parts that require a stronger coil.

Maybe it was designed for fast switching with higher energizing voltage and then to lower holding voltage.

Some include a freewheel diode internally (HP/Keysight relays in particular), so polarity matters for those. If forward biased, current draw will be high.

Are the eBay ones cheap?  Crack one open and see what's inside.

I'd also try and verify that their coils have been wound correctly (thickness of wire + number of turns) for 28V.  Try hooking up the coil inputs to a power supply and slowly turn up the voltage until the relay clicks.  If it moves at only 3V then you know it's wound incorrectly, if it latches at a bigger fraction (eg 12V?) of the full 28V then it's probably wound correctly for 28V.


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