[Hallicrafters] HT-37 VOX Relay

[kc9cdt at aol.com]

Mark,
This is rare...but I had a strange issue back when I worked on IBM equip.
There was a very small sliver of metal (who knows where from) laying in he vicinity of the coil on the relay.
When the pick current came on the sliver would stick up a little & block the armature from pulling in all the way.
Cleaned the area between the coli & armature while holding the armature in manually...problem solved.
 
Clean that area ..its worth a remote chance it will help.
And yes when I manually pushed on the armature it felt fine...BUT when the magnet came on...the sliver would stand up.

One of many difficult problems I had to fix in the many years working on complex IBM equipment

Good luck.
73,
Lee

 
 

 

 
 
-----Original Message-----
From: Mark K3MSB <mark.k3msb at gmail.com>
To: Boatanchors List <boatanchors at mailman.qth.net>; List Hallicrafters <hallicrafters at mailman.qth.net>
Sent: Mon, Mar 14, 2016 8:50 pm
Subject: [Hallicrafters] HT-37 VOX Relay

I’m working on an HT-37 transmitter donated to our radio club.The VOX Relay RY1 wants to close when I change the function switch fromSTBY to MOX and I can see it move, but it will not travel far enough toclose the contacts.R69 Is OK, and I measured the RY1 coil resistance to be 9.5K.   The variousvoltage drops across R69 and the coil when the radio is in the MOX positionshow a current of 5 Ma.Specifically, the voltage drop across the 9.5K coil is 52V yielding 5 mA.   Ihave no idea if these numbers are correct, but the current seem prettysmall.The “Relay  Tube” V15B tested good, and I used a replacement with nodifference in relay action.Measured voltages on VR15-1:  278/196,  and VR15-3  5.6/1.7(STBY/MOX).   Thereare in the ballpark.I tested all the tubes etc, played musical tubes a while,  cleaned therelay coil (bottom) with DeOxit,  adjust the screw adjustment on the coilbottom etc.  Nothing helped the relay to perform as expected.Also, the 0A2 VR tube will not light.   I tried 2 tubes (tested OK in atester) and both show about 150V on pins 1 and 5 as expected.   With theOA2 removed, pin 5 is 187V.   It looks to be regulating, but I’d expect tosee some glow.The bias measured at TP-2 is -49V.Comments welcomed; I’m concerned RY1 is bad.73 Mark K3MSB______________________________________________________________Hallicrafters mailing listHome: http://mailman.qth.net/mailman/listinfo/hallicraftersHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:Hallicrafters at mailman.qth.netList Administrator: Duane Fischer, W8DBF** For Assistance: dfischer at usol.com **This list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.html