Electronics > RF, Microwave, Ham Radio

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

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prutser:
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 ?

TheMG:
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.

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

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

Whales:
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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