{Collins} 516F-2 mechanical hum



Hi Collins folks. I'm in the process of restoring an S/Line (75S-3B, 32S-3, 516F-2). The project has gone very well - I'm almost finished - but the 516F-2 power supply has a mechanical hum that I'd like to get rid of. Here are the details:

- To my ear, it seems to be coming from the choke stack L1/L2. When I pull the 5R4 (V1) it goes away, so it looks like L1 is the guy.

- It starts a second or two after powering up. If I power up after having it on for a little while, the hum starts immediately.

- It goes away under load - i.e. when I transmit.

- I have tightened all the mounting hardware, top and bottom - no effect.

- I have not yet replaced the original capacitors, although I have replacements ready to go in.

Any advice would be greatly appreciated before I start testing and replacing parts. I would have searched the archives first but the link to them on the CCA site seems to be broken (http://mailman.listserve.com/archives/collins/).

73,
Chris, W2PA
(www.w2pa.com)




.
SHARE THE FUN: JOIN THE COLLINS COLLECTORS ASSOCIATION TODAY !
     http://www.collinsradio.org/membership/    -paypal accepted-
.
NETS: Tues & Thur: 3.805 MHz-2000 Central + Fri: 3.895 MHz-2000 Pacific
 SUNDAYS: 14.263 MHz-2000 UTC  +  AM Net: 29.050 MHz-1200 Central
      1st Wednesday AM Net 3.880 MHz-2000 local (ET, CT, MT, PT)




This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.