I found a KA sign in the city a little to the north of me, and decided to test the J alert with a real KA band threat, along with a real junk detector.
I tuned the osculator of my RD tester where right when I would push the KA button the v1 would alert and immediatly J it out. This was going to simulate the junky detector the v1 would pick up.
I went by the sign,and at first the v1 J'ed it out. Real bummer, but when I came by again, it didnt J it out. I sat right in front of the sign for about 30 seconds while it was at max KA, and then I pulled out my RD tester.
I fired it, and it J'ed out my RD tester, but continued alerting to the KA sign.
I think this may put some fears of a real KA threat while a junk detector is around, thus J'ing out the threat.
Dont know how VR did it, but they did it well