HQ-129 mechanical noise

[K9DXL]

I just finished re-capping my HQ-129X receiver, and gave it its first real test on the nets this morning.  The radio was on for about three hours and worked quite well!  But... about two or three minutes after I turned it off, I heard a metallic "shudder" sound that rattled the cabinet a little bit.  Here's my guess:  in addition to the power transformer, there are two fairly substantial chokes in the power supply.  I'm thinking that during operation, these components gradually warmed up (of course), but when power was turned off, the metal frame or windings on one or more of these guys contracted, causing the noise.  Has anyone else experienced this, and is it something I should worry about?

[KA0HCP]

Did you switch to unleaded solder?  I had a 1975 Ford Mustang II that used to do this.   

[W2JBL]

That's a mouse jumping around in the cabinet. They bounce all over the place inside a hot boatanchor when they get burned off tubes or shocked etc. I'm not joking, it has happened to me more than once. The mice in question are dead now.

[KA2DZT]

My guess it's some distortion in the cabinet that changes shape with the cooling off.  May also make some noise with the heating up but may go unheard with the receiver being on.

Fred

[KA2DZT]

That's a mouse jumping around in the cabinet. They bounce all over the place inside a hot boatanchor when they get burned off tubes or shocked etc. I'm not joking, it has happened to me more than once. The mice in question are dead now.

Yes,  but Chris you didn't mention just how the mice meet their demise.

Fred

[K9DXL]

No critters were injured or even involved.   This morning I turned the receiver on for the first time since the "incident".
Fuse blew after about three seconds.  I don't have time to look further today, but will report back when I find something.  At this point, fearing the worst!

[KA0HCP]

Awww.  Sound like that 'shudder' was really the 'Death Rattle" of a transformer.

[Opcom]

That's a mouse jumping around in the cabinet. They bounce all over the place inside a hot boatanchor when they get burned off tubes or shocked etc. I'm not joking, it has happened to me more than once. The mice in question are dead now.

Rodent version of Dante's Inferno..

[kb2vxa]

I'll go with the cabinet contracting on cool down. My microwave does the same thing after about a 30 minute cooking period and things get pretty heated up. It makes more of a bonk than a shudder, different cabinet but the same thing. I like the mouse theory, those little buggers get into everything!

[K9DXL]

I do believe now that it's a transformer problem.  Turned it on today for the first time and fuse blew after about 3 sec.