Re: Cleaning relay contacts


Mark GM4ISM
 

Mike

Hot switching a small  DC current  really does work in many cases.

 You generate micro-arcs at the contact surface  which disrupt the  oxide layer and promote  a lower contact resistance

 Some system designs  allow a few 10ms of mA DC to switch alongside the RF  in service to whet  the contact at each switching event

I used to use special very slightly abrasive paper pulled between contacts on old (large) PO relays It was routine maintenance but even that  did damage the contact surface and it  was a constant battle

Mechanical  'cleaning' of delicate contact surfaces as in most RF relays is a recipe for disaster.

Mark GM4ISM

 

On 28/03/2021 16:56, Mike GD6ICR wrote:
Been going through my sma relays and testing them on my primitive spectrum analyser has shown that I have quite a few lossy relay on TX as high as 4dB and quite a few showing around 1dB on RX side. I wonder if anyone can suggest a suitable contact cleaning method - one suggestion Ive had is connect 12v thru 500ohm resistors to NO and NC and leave them switching for about 5 minutes

Some of the relays of coarse can be dismantled and cleaned but most cannot - any comments please
--
Mike GD6ICR IO74PF73TW

Virus-free. www.avg.com

Join UKMicrowaves@groups.io to automatically receive all group messages.