The horrible groan

[potter]

Do many run their ST heads at 220 ? . When I first received my head I tried it on 220 but with the slightest unbalance it would object loudly, so I went 110 with no problems but now have just gone 220 on my cloths dryer and would like to use the gen on wash days.
I have no objection to the loud groan if it is doing no harm, but it sounds as if it is loading the bearings or in some way doing damage .
Has anyone used their head like this and had no problems or is this a bad idea.

   thanks Staggley
 

[Crofter]

I cant tell you how harmful it might be or not, but I dont like to listen to it. Unless the load on both legs is balanced my ST 5 protests as you describe. For emergency supply to the house I could get by with twinning for all 110 but I need 220 back at the shop where the generator lives. It would be nice to have switch gear that would make the change over handy. Maybe the electrical gurus can give advice on what can be done in that respect.

[lowspeedlife]

Some have found that the set screw under the lifting eye in the top of the generator is loose & this has caused a groaning or vibrating noise in thier gen sets, it's something to check.

   Scott R.

[potter]

 Thanks Scott I will check but it is fine even at full load on 110 so I think it is the unbalance.

[bschwartz]

Try using a balancing transformer to even the loads between the two 120v legs.
Prior to switching to a permanent magnet head, I tried one briefly on my ST-5 that not only groaned, but also had HUGE voltage differences between the highly and lightly loaded legs.  I was never really happy with the ST-5, but the transformer helped a lot.

[BruceM]

A step down transformer for your 120V loads would solve the problem.  Check on ebay, they're not too bad.

[Ronmar]

Have you ever tried a mechanics stethescope to try and determine exactly where the noise is comming from.  If it is not a bearing or internal contact issue, which it probably is not, and the output voltages and waveforms are acceptable, I wouldn't think there should be any problem running it.

[mobile_bob]

my st7.5 at times after startup will put out a medium frequency whine that is much like a siren,, ear piercing
that can be heard from down the block it is so loud... its about a middle C on the piano or organ.

actually my wife has an electronic pitch thingamabob that she tunes her guitars with, maybe i can get a beat
with it and determine what the frequency is.  i may be wrong but it seems higher than 120 hz and is definetly
higher than a 60hz buzzing/humming sound.

usually does this on cold days, when the load is just put on the head, it doesn't seem to matter if i am drawing off
one leg or the other, or both evenly, although it will shift the frequency just a tad.

i attribute it to a loose lamination or something like that, figure to look very hard at the stator core
when i tear the unit down for new brgs before i place it into service.

bob g

[XYZER]

I have 2 st5 and they both will growl a bit if I'm using 1 side. Both have new bearings and good gyptol job? It's not bad but you can hear it.

[potter]

I guess I am just trying to get my head around what may be causing this, it seams that most think its either uneven bearing load or loose windings either will in time damage the head  so I think it will be best to use  a step up or down transformer. Thanks for all the replies.
  Potter 

[bschwartz]

For load balancing, I used a transformer, but it didn't step up or down.  I hooked up the 240 side (two hots and neutral) of a 480/240 buck boost transformer.  It was hooked up in parallel with the rest of my loads.  That's it!  The other side of the transformer was left disconnected.  I still had two 120 legs or 240 for my other loads.  It made a huge difference. 
Someone from the LEF had these diagrams.  I'd like to give credit, but don't remember who it was, I just saved the link.  http://www.weirdstuffwemake.com/sweetwatergems/geek/images/balance_xformer2.jpg
I picked up a similar 3K transformer on ebay for under $100 that did the job.

[Shipo]

....that was MacGyver.....

[BruceM]

Good going Bschwartz.  There is no need to hook up the neutral on the ST side, though obviously it's working OK with it.  Pity the ST's do so poorly with a load imbalance otherwise.

[TimSR2]

Your engine is too quiet. You need a louder engine. Then you will rest easy as you will not hear the laminated core growl any more. May I suggest a Dursley Lister air cooled?

TimSR2

[Jedon]

You got that right Tim, my SR2 is LOUD!