Agree 100%!!!
Bert VE3NR
On 2020-10-20 8:11, jimn4kh wrote:
I wasn't my intention to resurrect an old thread. I checked the
archives before posting my message yesterday. I found a little info
but not much. Perhaps I missed it. I delayed going to the list but
Elecraft tech support is apparently really backed up because I've
gotten zero response to my emails and voicemails beyond one email with
the hum mitigation tech note I mentioned before. I thought perhaps the
larger community had a specific solution. Judging from the widely
varied responses I've gotten ovciously not. I've tightened, loosened,
and moved the transformer around multiple times with no change. I'll
go get a torque wrench and try that but I cant imagine it resolving
the problem given how loud it is. Ill take it all apart first and try
the procedure once and see if it helps. I just dont like having to
solve problems through expermention on a $2k+ amplifier.
Jim N4KH
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
From: Eric Norris <[email protected]>
Date: 10/19/20 11:37 PM (GMT-06:00)
To: Bert <[email protected]>
Cc: "elecraft@mailman qth. net" <[email protected]>
Subject: Re: [Elecraft] KPA500 Transformer
The torque spec is called out in the manual. Why not use a torque wrench?
Can we please not resurrect the KPA500 hum thread already beat to death
multiple times years ago? Or does everyone need to chime in yet again?
55 inch-pounds.
73 Eric WD6DBM
On Mon, Oct 19, 2020, 9:15 PM Bert <[email protected]> wrote:
> Toroidal transformers cause very little acoustic hum, unless the core
> is not tightly wound or the copper wire windings are loose!
>
> If you have to tighten the mounting bolt with a torque wrench
> to get the transformer quiet, something is wrong!
>
> Bert VE3NR
>
>
>
>
> On 2020-10-19 19:59, Jim Spikes N4KH wrote:
> > Looking for details from anyone who resolved issues with excessive
> > transformer hum during transmit on a KPA-500.
> >
> >
> >
> > I have a hum mitigation application note sent from Elecraft tech
support.
> > But the procedure recommended is pretty involved - removing front/side
> > panels, un-plugging connections, removing the transformer, changing
> > positions of the rubber discs, and putting it back together. Possibly
> more
> > than once, depending on the results.
> >
> >
> >
> > There is a risk of breaking something, and I'm not sure its going to
> solve
> > the problem if I'm successful. This is a new out of the box KPA500
kit.
> >
> >
> >
> > If anybody has any lessons learned I would appreciate hearing them.
> >
> >
> >
> > Jim, N4KH
> >
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